INTRODUCTION

The energy requirements of the 21st century are growing by the second.
Our society's power and energy demand is met largely through the combustion of fossil fuels. The world economy relies upon on a limited resource; and trends suggest that global energy use is expected to double in the coming decades. At the same time, concerns about the effects of anthropogenic carbon dioxide and criteria pollutants and about energy security continue to mount. Meeting our energy needs in a sustainable manner is a historic challenge that will cause us to diverge from the pattern of the last couple of centuries.

Storage and conversion of energy becomes increasingly relevant as we move towards greater reliance on renewable or non-traditional energy sources. Fuel cells are an efficient means to convert chemical energy into electrical energy with little or no emissions. Fuel cells and batteries are therefore expected to be an important energy technology for the future.



Effects Of Excessive Fossil Fuel Consumption

Faced with a future replete with erratic weather, shifting rainfall patterns and loss of genetic diversity from the effects of global warming, there are choices that we as citizens can make which can help to reverse the suffocating effects of globalization and the associated consumption of fossil fuels. In addition to driving less carpooling and using mass transit, growing food at home and increasing regional food production can reduce corporate control of our food supply and alleviate global ecological crises. (Karl, 3-12)

Overall it is estimated that the US food system consumes 17% of our country's huge total of fossil fuels. Only 3% of that total is directly attributed to on-farm food production. The remaining fuels are consumed in packaging, processing and transportation of agriculture's produce. The vast distance between consumption and production of food is one aspect of our out of whack industrial food system. The average morsel of food consumed in the US travels an average of 1300 miles before it is eaten.

In 1880 fully one half of the US population was employed in agriculture. In today's industrialized US food system less than 2% of our population are farmers, while in contrast in India. 75% of their population is engaged in agriculture. The US leads the world in CO2 emissions with 19.5 tons a year contributing to the problem of global warming. Each of India's billion people only contribute .81 tons of CO2, making our individual contribution 24 times greater. (Santer, 39-46)


In the past 25 years US agriculture has become 22% less efficient as more and more tasks are becoming mechanized. Increases in the price of fossil fuels will ultimately result in increasing food costs, reflected in the level of petroleum-based transport energy imbedded in the food. Community food security is hinged upon this important fact. Increasingly our planet's population is becoming urbanized, with an increasing proportion of those people living in poverty. Current estimates show that as many of 800 million people in the world are malnourished, with fifty-seven percent of them urbanized. Is there a way to feed the hungry urbanites?
As little as 100 years ago Paris was an agriculturally productive city, where approximately one sixth of the land was dedicated to food production. On that space Parisians annually produced l00,000 tons of high-value vegetable crops. This production was matte possible through the availability of manure from the city's vast population of horses, which provided the power for the public works, fire department, and transportation of the city's populace. The key to any sustainable agriculture is the increased use of non-fossil fuel energy sources like draft animals. While 19th century Paris stables contributed a million tons of manure annually to grow food and sustain the population, modern city's automobiles clog urban areas and give us atmospheric and water pollution, as they secularize our world.
In some cities agriculture continues to play a significant role in providing residents with their sustenance. In Hong Kong today 45% of the vegetables consumed in the city of 6.7 million people are grown on 5-6% of the total land area . Singapore, a Republic of 3.5 million and a population density of 14 000 per square mile produces 80% of its poultry needs and 25% of it vegetables. Growing food 1ocally insures higher quality, fresher and more nutritious foods, reduces energy consumption and assures greater access to food for more people especially the poor. (McMichael & Haines, 805-9)

America's animal powered agriculture wasn't really so long ago. As late as 1955 the number of horses and mules on US farms equaled the number of tractors. Prior to the industrial revolution it required 716,000 kcal of energy to produce one hectare of corn, whereas today's consumption is 11 million kcal or an increase of 1500 percent. Meanwhile harvests have only increased 350 percent. Adding to the unsustainable practices of agriculture is the massive increase of fertilizers which, in the years 1945 to 1983 increased by a whopping 2000%. In the same period the number of insect pests that became resistant to insecticides leaped from 7 to 447. Today in California alone the annual application of pesticides is an astounding 100,000,000 pounds.

While there are plenty of examples to show agriculture's ravenous depletion of natural resources, there are likewise ample ways to demonstrate possible alternatives. Agriculture has been successfully practiced around the world by primitive cultures for thousands of years before the "green revolution" which, contrary to glowing reports made by the corporate interests who have profited, has had severely damaging environmental and economic consequences Worldwide. Native people on this continent were engaged in agriculture 7000 years before the first European settlers arrived in Jamestown Virginia. Indigenous agriculture was polycultural, in contrast with today's monocultures, and provided protection from pests and diseases in addition to contributing to diversified economies. (Working Group…, 1341-9)

Obviously our world is vastly different than that of pre-Columbian America, but it is more vital today than ever that our actions remain in harmony with nature to protect the ecology of the Earth. It may seem preposterous to suggest that farmers in Iowa and California put their tractors in mothballs and instead use hoes and dibble sticks, put its not so far fetched to consider the potential for wide-spread climate change combined with species extinctions, loss of ecological process and depleted aquifers to evoke widespread famine and crop failures across the globe if industrial agriculture continues in its present form. For example, the projected rise of sea levels due to climate changes will eliminate 30% of the world's cropland.
Extreme events such as 100-year floods are happening every decade; the drought continues in some regions like the Great Lakes where the snow pack is at an all time record low and the American south is likewise in the midst of a drought not seen since the famous dustbowl years of the 1930's. When will our country wake up and smell the CO2 fuming from the tailpipes of our cars and trucks and realize that our lifestyles are choking the life out of the earth? (Working Group…, 1341-9)
Over the past few decades many countries have experienced an increase in both morbidity and mortality from asthma. Air pollution is a possible culprit, and researchers have paid special attention to NO2 concentrations, which have risen steadily as the result of burning of fossil fuels, mainly from motor vehicle engines. Epidemiological and clinical studies have addressed the effects of exposure to low concentrations of NO2 on respiratory health indoors and outdoors. Most of the studies assessing the relation between indoor NO2 and respiratory health have been conducted in children and the results are inconsistent. (Samet et al, 1258-65) In adults, many experimental studies have been conducted, showing on average a small increase in airways reactivity to NO2 by comparison with clean air. (Folinsbee, 273-83) However, the approach of exposing subjects to individual pollutants bears little resemblance to the complexities of atmospheric pollution. Molfino et al (199-203) used a different approach--low concentrations of ozone--to test and corroborate the hypothesis that air pollution enhances airways responsiveness to ragweed and grass allergens. Two recent reports in The Lancet show that NO[ sub 2] alone (Tunnicliffe et al, 1733-36) and in combination with SO2, (Dayalia et al, 1668-71) at concentrations that may be encountered in daily life, enhance the bronchoconstrictive response to inhaled house dust mite in patients with mild asthma. Neither of these latest experimental studies allows estimation of the clinical magnitude of the reported functional change, although Tunnicliffe et al (1733-36) suggest that these effects are likely to be small.


Increased airways reactivity is not the only effect induced by low levels of NO2. Devalia et al, (1308-16) in an in-vitro study, found that exposure to 400-800 ppb of NO2 caused bronchial epithelial cell dysfunction. Whether the enhanced airway reactivity to inhaled allergens is the consequence of cellular damage remains unclear. Aris et al (1363-72) showed that exposure of healthy subjects to 200 ppb of ozone was followed by an influx of inflammatory cells into the airway, although there was no correlation with spirometric changes. Concurrent exposure to different air pollutants could induce significant inflammation and enhance the reactivity of asthmatics to a wide range of asthma triggers. Derails et al (1668-71) showed that joint exposure to NO2 and SO2 led to increased bronchial reactivity to allergens whereas NO2 alone did not. The more complex mixtures of pollutants likely to be present in urban air could induce even larger inflammatory and functional changes than the ones reported so far. Thus, the effect of air pollution on allergic asthma could be larger than that seen in the experimental studies.

From a public health perspective, we need to know the size of the population at risk; and to determine that we need to integrate the individual opportunities for exposure at specific time-space ordinates. Here both indoor and outdoor sources of NO2 are relevant. In a US study, cooking with a gas stove generated concentrations of 200 to 400 ppb of NO2, with transient peaks as high as 1000 ppb. (Harlos, 1211-23) In a study of children in New Mexico, Samet et al. (Samet et al, 1258-65) found that, in 30% of their bimonthly calls, children reported having been in the kitchen while meals were being cooked during the previous 24 hours, for an average of 20 minutes. However, frequency and characteristics of these indoor exposures to NO2 probably differ from one country to another. Outdoor levels of NO2 around 400 ppb are reached only during the severe air pollution episodes that occur sporadically. Peak hourly levels of 382-423 ppb were recorded during a pollution episode in London in December, 1991. (Brought GFJ, 598-623) Thus, while it is clear that allergic asthmatics can experience cellular and functional damage if exposed to levels of NO2 of 400 ppb or higher, we do not know either the magnitude of the subsequent clinical effects or the prevalence of exposure of asthmatics to such levels of pollution. This lack of knowledge hinders a more precise evaluation of the problem from a public health perspective.

Increasing levels of NO2 over recent decades could have influenced asthma in two ways: (a) by decreasing the threshold of allergen exposure needed to develop sensitization and allergic asthma; and (b) by increasing morbidity of existing asthma. There is growing evidence for the latter possibility. (Tunnicliffe et al, 1733-36; Devalia et al, 1308-16) By contrast, evidence for an increased incidence of asthma due to air pollution has not yet been provided. However, if NO2 and other air pollutants increase the permeability of bronchial mucosa to allergens, (Devalia et al, 1308-16) the threshold for allergen exposure to produce sensitization may decrease and the incidence of allergic asthma may increase.

Until lately the association between NO2 and asthma was inconsistent. The studies reported by Tunnicliffe et al (1733-36) and by Devalia et al (1668-71) confirm the findings reported by Molfino et al (199-203) for ozone and should stimulate further research to characterize the synergism between NO2 and aeroallergens as causal or contributory factors in asthma.






Alternaive Energy Sources



Fusion


Fusion power

Fusion power refers to power generated by nuclear fusion reactions. In this kind of reaction, two light atomic nuclei fuse together to form a heavier nucleus and release energy. The largest current experiment, JET, has resulted in fusion power production slightly less than the power put into the plasma, maintaining an output of 16 MW for a few seconds. In June 2005, the construction of the experimental reactor ITER, designed to produce several times more fusion power than the power into the plasma over many minutes, was announced. The production of net electrical power from fusion is planned for the next generation experiment after ITER.


Fuel cycle

For two nuclei to fuse, they must collide with enough energy to overcome the repulsive electrostatic force between them. Most fusion generation experiments therefore raise their fuel to very high temperatures. If two light nuclei come close enough to each other, they may fuse to form a single nucleus with a slightly smaller mass than the sum of their original masses. The difference in mass is released as energy according to Einstein's equation E = mc². (If the input nuclei are sufficiently massive, the resulting fusion product will be heavier than the reactants, and the reaction requires the addition of energy to convert into the additional mass; in this case the reverse process of nuclear fission will release energy, which can be used, for example, in nuclear reactors or bombs.)

Hydrogen, the most abundant element in the universe, also has the smallest nuclear charge and therefore reacts at the lowest temperature. Helium has an extremely low mass per nucleon and therefore is energetically favored as a fusion product. As a consequence, most fusion reactions combine isotopes of hydrogen ("protium", deuterium, or tritium) to form isotopes of helium (3He or 4He).
Image:Question_dropshade.png
Unsolved problems in physics: Is it possible to construct a practical nuclear reactor that is powered by nuclear fusion rather than nuclear fission?

Perhaps the three most widely considered fuel cycles are based on the D-T, D-D, and p-11B reactions. Other fuel cycles (D-3He and 3He-3He) would require a supply of 3He, either from other nuclear reactions or from extra-terrestrial sources, such as the surface of the moon or the atmospheres of the gas giant planets. The details of the calculations comparing these reactions can be found here.
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The D-T fuel cycle
Diagram of the D-T reaction
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Diagram of the D-T reaction

The easiest and most immediately promising nuclear reaction to be used for fusion power is:

D + T → 4He + n

Deuterium is a naturally occurring isotope of hydrogen and as such is universally available. The large mass ratio of the hydrogen isotopes makes the separation rather easy compared to the difficult uranium enrichment process. Tritium is also an isotope of hydrogen, but it occurs naturally in only negligible amounts due to its radioactive half-life of 12 years. Consequently, the deuterium-tritium fuel cycle requires the breeding of tritium from lithium using one of the following reactions:

n + 6Li → T + 4He
n + 7Li → T + 4He + n

The reactant neutron is supplied by the D-T fusion reaction shown above, the one which also produces the useful energy. The reaction with 6Li is exothermic, providing a small energy gain for the reactor. The reaction with 7Li is endothermic but does not consume the neutron. At least some 7Li reactions are required to replace the neutrons lost by reactions with other elements. Most reactor designs use the naturally occurring mix of lithium isotopes. The supply of lithium is more limited than that of deuterium, but still large enough to supply the world's energy demand for hundreds of years.

Several drawbacks are commonly attributed to D-T fusion power.

1. It produces substantial amounts of neutrons that result in induced radioactivity within the reactor structure, and it requires the handling of the radioisotope tritium.
2. Only about 20% of the fusion energy yield appears in the form of charged particles (the rest neutrons), which limits the extent to which direct energy conversion techniques might be applied.
3. The use of D-T fusion power depends on lithium resources, which are less abundant than deuterium resources.

The neutron flux expected in a commercial D-T fusion reactor is about 100 times that of current fission power reactors, posing problems for material design. Design of suitable materials is underway but their actual use in a reactor is not proposed until the generation after ITER. After a single series of D-T tests at JET, the largest fusion reactor yet to use this fuel, the vacuum vessel was sufficiently radioactive that remote handling needed to be used for the year following the tests.

On the other hand, the volumetric deposition of neutron power can also be seen as an advantage. If all the power of a fusion reactor had to be transported by conduction through the surface enclosing the plasma, it would be very difficult to find materials and a construction that would survive, and it would probably entail a relatively poor efficiency.
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The D-D fuel cycle

After the reaction of tritium with deuterium, it is easiest to achieve fusion through the reaction of deuterium with itself. This reaction has two branches that occur with nearly equal probability:

D + D → T + p
→ 3He + n

The optimum temperature for this reaction is 15 keV, only slightly higher than the optimum for the D-T reaction. The first branch does not produce neutrons, but it does produce tritium, so that a D-D reactor will not be completely tritium-free, even though it does not require an input of tritium or lithium. Most of the tritium produced will be burned before leaving the reactor, which reduces the tritium handling required, but also means that more neutrons are produced and that some of these are very energetic. The neutron from the second branch has an energy of only 2.45 MeV, whereas the neutron from the D-T reaction has an energy of 14.1 MeV, resulting in a wider range of isotope production and material damage. Assuming complete tritium burn-up, the reduction in the fraction of fusion energy carried by neutrons is only about 18%, so that the primary advantage of the D-D fuel cycle is that tritium breeding is not required. Other advantages are independence from limitations of lithium resources and a somewhat softer neutron spectrum. The price to pay compared to D-T is that the energy confinement (at a given pressure) must be 30 times better and the power produced (at a given pressure and volume) is 68 times less.
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The p-11B fuel cycle

If aneutronic fusion is the goal, then the ideal reaction may be the proton-boron reaction:

p + 11B → 3 4He

Under reasonable assumptions, side reactions will result in about 0.1% of the fusion power being carried by neutrons. At 123 keV, the optimum temperature for this reaction is nearly ten times higher than that for the pure hydrogen reactions, the energy confinement must be 500 times better than that required for the D-T reaction, and the power density will be 2500 times lower than for D-T.
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History of fusion energy research

Fission, as well as fusion, were first used in the military field, in order to build very powerful bombs: Nuclear weapons - "atomic bombs" - using only fission reactions, and Thermonuclear weapons - "hydrogen bombs" - which use a conventional fission bomb to provide sufficient heat and pressure to trigger the fusion reaction.

Civilian applications, in which explosive energy production must be replaced by a controlled production, were developed later. Although it took less than ten years to go from military applications to civilian fission energy production[1], it was very different in the fusion energy field, more than fifty years having already passed[2] without any energy production plant being started up.

Registration of the first patent related to a fusion reactor[3] by the United Kingdom Atomic Energy Authority, the inventors being Sir George Paget Thomson and Moses Blackman, dates back to 1946. Some basic principles used in ITER experiment are described in this patent: toroidal vacuum chamber, magnetic confinement, and radio frequency plasma heating.

In the magnetic confinement field, the theoretical works fulfilled in 1950-1951 by I.E. Tamm and A.D. Sakharov in Soviet Union, laid the foundations of the tokamak, subsequent research and developments inside the Kurchatov Institute of Moscow having materialized these ideas. Research equipments of this type were subsequently developed in numerous countries and, although stellarator competed with it for a while, the tokamak principle was selected for the ITER project.
A "wires array" used in Z-pinch confinement, during the building process.
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A "wires array" used in Z-pinch confinement, during the building process.

The Z-pinch phenomenon has been known since the end of the 18th century[4]. Its use in the fusion field comes from research made on toroidal devices, initially in the Los Alamos National Laboratory right from 1952 (Perhapsatron), and in the United Kingdom from 1954 (ZETA), but its physical principles remained for a long time poorly understood and controlled. The appearance of the "wires array" concept in the 1980's allowed a more efficient use of this technique.

Although laser use in order to initiate fusions had been considered as early as immediately after the invention of the laser itself in 1960, serious ICF experiments began in the early 1970's, when lasers of the required power were first designed. The technique of implosion of a microcapsule irradiated by laser beams, the basis of laser inertial confinement, was first suggested in 1962 by scientists at Lawrence Livermore National Laboratory.

In April, 2005, a team from UCLA announced it had produced fusion using a machine that "fits on a lab bench" ([[1]]), using lithium tantalate to generate enough voltage to smash deuterium atoms together. However, the process does not generate net power. See Pyroelectric fusion.


Safety and environmental issues


Accident potential

The likelihood of a catastrophic accident in a fusion reactor in which injury or loss of life occurs is much smaller than that of a fission reactor. The primary reason is that the fuel contained in the reaction chamber is only enough to sustain the reaction for about a minute, whereas a fission reactor contains about a year's supply of fuel. Furthermore, fusion requires very extreme and precisely controlled conditions of temperature, pressure and magnetic field parameters. If the reactor were damaged, these would be disrupted and the reaction would be rapidly quenched (extinguished).

Although the plasma in a fusion power plant will have a volume of 1000 cubic meters or more, the total amount of fusion fuel in the vessel is very small: only two grams, enough for just a short time of operation.[citation needed] If the fuel supply is closed, the reaction stops without problems within seconds. Fusion is not a chain reaction and can therefore not run out of hand: in the normal situation, the fusion process runs at the fastest possible rate, and any deviation from this optimum leads to a decrease in energy production.


Effluents during normal operation

The natural product of the fusion reaction is a small amount of helium, which is completely harmless to life and does not contribute to global warming. Of more concern is tritium, which, like other isotopes of hydrogen, is difficult to retain completely. During normal operation, some amount of tritium will be continually released. There would be no acute danger, but the cumulative effect on the world's population from a fusion economy could be a matter of concern. The 12 year half-life of tritium would at least prevent unlimited build-up and long-term contamination.
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Waste management

The large flux of high-energy neutrons in a reactor will make the structural materials radioactive. The radioactive inventory at shut-down may be comparable to that of a fission reactor, but there are important differences. The half-life of the radioisotopes produced by fusion tend to be less than those from fission, so that the inventory decreases more rapidly. Furthermore, there are fewer unique species, and they tend to be non-volatile and biologically less active. As opposed to nuclear fission, where there is hardly any possibility to influence the spectrum of fission products, the problems can be further reduced by careful choice of the materials used. "Low activation" materials like vanadium, for example, would become much less radioactive than stainless steel. This involves the design of new alloys with unusual chemical compositions, which is a complex, expensive process as the chemical composition also affects the materials' mechanical properties. However rather than the thousands of years for radioactive waste produced from fission, the bulk of the material will be low activation materials would have half-lives of tens of years and rapidly approach the radioactivity of coal ash. [2]. Some material will remain in current designs with longer half-lives. [3]
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Nuclear proliferation

Although fusion power uses nuclear technology, the overlap with nuclear weapons technology is small. Tritium is a component of the trigger of hydrogen bombs, but not a major problem in production. The copious neutrons from a fusion reactor could be used to breed plutonium for an atomic bomb, but not without extensive redesign of the reactor, so that clandestine production would be easy to detect. The theoretical and computational tools needed for hydrogen bomb design are closely related to those needed for inertial confinement fusion, but have very little in common with (the more scientifically developed) magnetic confinement fusion.
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Fusion power as a sustainable energy source

Fusion power is often described as a "clean", "renewable", or "sustainable" energy source. While it has the potential to be used practically indefinitely, like most forms of renewable energy, large scale reactors using neutronic fuels (e.g. ITER) and thermal power production (turbine based) are in fact most comparable from an engineering and economics viewpoint to fission power. Both fission and fusion power plants involve a relatively compact heat source powering a conventional steam turbine based power plant, while producing enough neutron radiation to make activation of the plant materials problematic. The main distinction is that fusion power produces no high-level radioactive waste (though activated plant materials still need to be disposed of). There are some power plant ideas which may significantly lower the cost or size of such plants, however research in these areas is nowhere near as advanced as in tokamaks.
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Theoretical Power plant designs
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Confinement concepts
Parameter space occupied by inertial fusion energy and magnetic fusion energy devices as of the mid 1990's. The regime allowing thermonuclear ignition with high gain lies near the upper right corner of the plot.
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Parameter space occupied by inertial fusion energy and magnetic fusion energy devices as of the mid 1990's. The regime allowing thermonuclear ignition with high gain lies near the upper right corner of the plot.

Confinement refers to all the conditions necessary to keep a plasma dense and hot long enough to undergo fusion:

* Equilibrium: There must be no net forces on any part of the plasma, otherwise it will rapidly disassemble. The exception, of course, is inertial confinement, where the relevant physics must occur faster than the disassembly time.
* Stability: The plasma must be so constructed that small deviations are restored to the initial state, otherwise some unavoidable disturbance will occur and grow exponentially until the plasma is destroyed.
* Transport: The loss of particles and heat in all channels must be sufficiently slow. The word "confinement" is often used in the restricted sense of "energy confinement".

The first human-made, large-scale production of fusion reactions was the test of the hydrogen bomb, Ivy Mike, in 1952. It was once proposed to use hydrogen bombs as a source of power by detonating them in underground caverns and then generating electricity from the heat produced, but such a power plant is unlikely ever to be constructed, for a variety of reasons. (See the PACER project for more details.) Controlled thermonuclear fusion (CTF) refers to the alternative of continuous power production, or at least the use of explosions that are so small that they do not destroy a significant portion of the machine that produces them.

To produce self-sustaining fusion, the energy released by the reaction (or at least a fraction of it) must be used to heat new reactant nuclei and keep them hot long enough that they also undergo fusion reactions. Retaining the heat is called energy confinement and may be accomplished in a number of ways.

The hydrogen bomb really has no confinement at all. The fuel is simply allowed to fly apart, but it takes a certain length of time to do this, and during this time fusion can occur. This approach is called inertial confinement. If more than milligram quantities of fuel are used (and efficiently fused), the explosion would destroy the machine, so theoretically, controlled thermonuclear fusion using inertial confinement would be done using tiny pellets of fuel which explode several times a second. To induce the explosion, the pellet must be compressed to about 30 times solid density with energetic beams. If the beams are focused directly on the pellet, it is called direct drive, which can in principle be very efficient, but in practice it is difficult to obtain the needed uniformity. An alternative approach is indirect drive, in which the beams heat a shell, and the shell radiates x-rays, which then implode the pellet. The beams are commonly laser beams, but heavy and light ion beams and electron beams have all been investigated.

Inertial confinement produces plasmas with impressively high densities and temperatures, and appears to be best suited to weapons research, X-ray generation, very small reactors, and perhaps in the distant future, spaceflight. They rely on fuel pellets with close to a "perfect" shape in order to generate a symmetrical inward shock wave to produce the high-density plasma, and in practice these have proven difficult to produce. A recent development in the field of laser induced ICF is the use of ultrashort pulse multi-petawatt lasers to heat the plasma of an imploding pellet at exactly the moment of greatest density after it is imploded conventionally using terawatt scale lasers. This research will be carried out on the (currently being built) OMEGA EP petawatt and OMEGA lasers at the University of Rochester and at the GEKKO XII laser at the institute for laser engineering in Osaka Japan, which if fruitful, may have the effect of greatly reducing the cost of a laser fusion based power source.

At the temperatures required for fusion, the fuel is in the form of a plasma with very good electrical conductivity. This opens the possibility to confine the fuel and the energy with magnetic fields, an idea known as magnetic confinement. The Lorenz force works only perpendicular to the magnetic field, so that the first problem is how to prevent the plasma from leaking out the ends of the field lines. There are basically two solutions.

The first is to use the magnetic mirror effect. If particles following a field line encounter a region of higher field strength, then some of the particles will be stopped and reflected. Advantages of a magnetic mirror power plant would be simplified construction and maintenance due to a linear topology and the potential to apply direct conversion in a natural way, but the confinement achieved in the experiments was so poor that this approach has been essentially abandoned.

The second possibility to prevent end losses is to bend the field lines back on themselves, either in circles or more commonly in nested toroidal surfaces. The most highly developed system of this type is the tokamak, with the stellarator being a distant second, but still a serious contender. A third toroidal machine type is the Reversed-Field Pinch, which was never sufficiently able to realize its potential advantages. Compact toroids, especially the Field-Reversed Configuration and the spheromak, attempt to combine the advantages of toroidal magnetic surfaces with those of a simply connected (non-toroidal) machine. Compact toroids still have some enthusiastic supporters but are not backed as readily by the majority of the fusion community.


A more subtle technique is to use more unusual particles to catalyse fusion. The best known of these is Muon-catalyzed fusion which uses muons, which behave somewhat like electrons and replace the electrons around the atoms. These muons allow atoms to get much closer and thus reduce the kinetic energy required to initiate fusion. Muons require more energy to produce than we can get back from muon-catalysed fusion, making this approach impractical for the generation of power.

Finally, there are also electrostatic confinement fusion systems, in which ions in the reaction chamber are confined and held at the center of the device by electrostatic forces, as in the Farnsworth-Hirsch Fusor, but these are not believed capable of being developed into a practical power plant.

Most controversially, some researchers have claimed to have observed excess heat, neutrons, tritium, helium and other nuclear effects in so-called cold fusion systems. Most scientists consider cold fusion to be a pseudoscience. A peer review panel was commissioned by the US Department of Energy to study these claims [4] [5] and the majority of the panel did not consider the evidence for low energy nuclear reactions convincing, nor did any of the panel members advocate funding for cold fusion. However, some researchers, including some from Los Alamos, and the Naval Research Laboratory[6] continue to conduct research relating to cold fusion. Research into sonoluminescence induced fusion, sometimes known as "bubble fusion", also continues, although it is met with almost as much skepticism as cold fusion is by most of the scientific community.
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Subsystems

In fusion research, achieving a fusion energy gain factor Q = 1 is called breakeven and is considered a significant although somewhat artificial milestone. Ignition refers to an infinite Q, that is, a self-sustaining plasma where the losses are made up for by fusion power without any external input. In a practical fusion reactor, some external power will always be required for things like current drive, refueling, profile control, and burn control. A value on the order of Q = 20 will be required if the plant is to deliver much more energy than it uses internally.

There have been many design studies for fusion power plants. Despite many differences, there are several systems that are common to most. To begin with, a fusion power plant, like a fission power plant, is customarily divided into the nuclear island and the balance of plant. The balance of plant is the conventional part that converts high-temperature heat into electricity via steam turbines. It is much the same in a fusion power plant as in a fission or coal power plant. In a fusion power plant, the nuclear island has a plasma chamber with an associated vacuum system, surrounded by a plasma-facing components (first wall and divertor) maintaining the vacuum boundary and absorbing the thermal radiation coming from the plasma, surrounded in turn by a blanket where the neutrons are absorbed to breed tritium and heat a working fluid that transfers the power to the balance of plant. If magnetic confinement is used, a magnet system, using primarily cryogenic superconducting magnets, is needed, and usually systems for heating and refueling the plasma and for driving current. In inertial confinement, a driver (laser or accelerator) and a focusing system are needed, as well as a means for forming and positioning the pellets.
Inertial confinement fusion implosion on the NOVA laser creates "microsun" conditions of tremendously high density and temperature.
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Inertial confinement fusion implosion on the NOVA laser creates "microsun" conditions of tremendously high density and temperature.

Although the standard solution for electricity production in fusion power plant designs is conventional steam turbines using the heat deposited by neutrons, there are also designs for direct conversion of the energy of the charged particles into electricity. These are of little value with a D-T fuel cycle, where 80% of the power is in the neutrons, but are indispensable with aneutronic fusion, where less than 1% is. Direct conversion has been most commonly proposed for open-ended magnetic configurations like magnetic mirrors or Field-Reversed Configurations, where charged particles are lost along the magnetic field lines, which are then expanded to convert a large fraction of the random energy of the fusion products into directed motion. The particles are then collected on electrodes at various large electrical potentials. Typically the claimed conversion efficiency is in the range of 80%, but the converter may approach the reactor itself in size and expense.
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Materials

Developing materials for fusion reactors has long been recognized as a problem nearly as difficult and important as that of plasma confinement, but it has received only a fraction of the attention. The neutron flux in a fusion reactor is expected to be about 100 times that in existing pressurized water reactors (PWR). Each atom in the blanket of a fusion reactor is expected to be hit by a neutron and displaced about a hundred times before the material is replaced. Furthermore the high-energy neutrons will produce hydrogen and helium in various nuclear reactions that tends to form bubbles at grain boundaries and result in swelling, blistering or embrittlement. One also wishes to choose materials whose primary components and impurities do not result in long-lived radioactive wastes. Finally, the mechanical forces and temperatures are large, and there may be frequent cycling of both.

The problem is exacerbated because realistic material tests must expose samples to neutron fluxes of a similar level for a similar length of time as those expected in a fusion power plant. Such a neutron source is nearly as complicated and expensive as a fusion reactor itself would be. Proper materials testing will not be possible in ITER, and a proposed materials testing facility, IFMIF, is still at the design stage in 2005.

The material of the plasma facing components (PFC) is a special problem. The PFC do not have to withstand large mechanical loads, so neutron damage is much less of an issue. They do have to withstand extremely large thermal loads, up to 10 MW/m², which is a difficult but solvable problem. Regardless of the material chosen, the heat flux can only be accommodated without melting if the distance from the front surface to the coolant is not more than a centimeter or two. The primary issue is the interaction with the plasma. One can choose either a low-Z material, typified by graphite although for some purposes beryllium might be chosen, or a high-Z material, usually tungsten with molybdenum as a second choice. Use of liquid metals (lithium, gallium, tin) has also been proposed, e.g., by injection of 1-5 mm thick streams flowing at 10 m/s on solid substrates.

If graphite is used, the gross erosion rates due to physical and chemical sputtering would be many meters per year, so one must rely on redeposition of the sputtered material. The location of the redeposition will not exactly coincide with the location of the sputtering, so one is still left with erosion rates that may be prohibitive. An even larger problem is the tritium co-deposited with the redeposited graphite. The tritium inventory in graphite layers and dust in a reactor could quickly build up to many kilograms, representing a waste of resources and a serious radiological hazard in case of an accident. The consensus of the fusion community seems to be that graphite, although a very attractive material for fusion experiments, cannot be the primary PFC material in a commercial reactor.

The sputtering rate of tungsten can be orders of magnitude smaller than that of carbon, and tritium is not so easily incorporated into redeposited tungsten, making this a more attractive choice. On the other hand, tungsten impurities in a plasma are much more damaging than carbon impurities, and self-sputtering of tungsten can be high, so it will be necessary to ensure that the plasma in contact with the tungsten is not too hot (a few tens of eV rather than hundreds of eV). Tungsten also has disadvantages in terms of eddy currents and melting in off-normal events, as well as some radiological issues.
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Economics

It is far from clear whether or not nuclear fusion will be economically competitive with other forms of power. The many estimates that have been made of the cost of fusion power cover a wide range, and indirect costs of and subsidies for fusion power and its alternatives make any cost comparison difficult. The low estimates for fusion appear to be competitive with but not drastically lower than other alternatives. The high estimates are several times higher than alternatives.

While fusion power is still in early stages of development, vast sums have been and continue to be invested in research. In the EU almost € 10 billion was spent on fusion research up to the end of the 90s, and the new ITER reactor alone is budgeted at €10 billion. It is estimated that up to the point of possible implementation of electricity generation by nuclear fusion, R&D will need further promotion totalling around € 60-80 billion over a period of 50 years or so (of which € 20-30 billion within the EU)[7]. In the current EU research programme (FP6), nuclear fusion research receives € 750 million (excluding ITER funding), compared with € 810 million for all non-nuclear energy research combined [8], putting research into fusion power well ahead of that of any single rivaling technology.

Unfortunately, despite optimism dating back to the 1950's about the wide-scale harnessing of fusion power, there are still significant barriers standing between current scientific understanding and technological capabilities and the practical realization of fusion as an energy source. Research, while making steady progress, has also continually thrown up new difficulties. Therefore it remains unclear that an economically viable fusion plant is even possible.

An important aspect of fusion energy in contrast to many other energy sources is that the cost of production is nearly perfectly elastic. With wind energy, for example, power from the best locations is cheap, but as more generators are installed, poorer sites must be used so the price goes up. With fusion energy, the production cost will not increase much, even if an extremely large number of plants are built. It has been suggested that perhaps even 100 times the current energy consumption of the world is within the realm of possibility. Some problems which are expected to be an issue in the next century such as fresh water shortages can actually be thought of merely as problems of energy supply. For example, in desalination plants, seawater can be converted into pure freshwater through a process of either distillation or reverse osmosis. However, these processes are energy intensive. Even if the first fusion plants are not competitive with alternative sources, fusion could still become competitive if large scale desalination requires more power than the alternatives are able to provide. However, the technical potential for other renewable energy sources is many times greater than the current world energy demand (see Renewable energy). Nevertheless, the capacity limit to biomass, hydropower, solar power, and wind power, is used as an argument by some for research into fusion power in spite of the large costs of such research and the relatively simple and inexpensive nature of other long-term energy solutions. Fusion power has many of the benefits of these long-term energy sources (such as a long-term continuous energy supply and no greenhouse gas emissions) but also some of the benefits of (relatively) short-term energy sources like hydrocarbons and nuclear fission (without reprocessing) , such as very high power-generation density and uninterrupted power delivery (i.e. coal plants work almost entirely independent of the day's weather, unlike wind and solar power).

Geothermal

Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.

Geothermal power is the use of geothermal heat for electricity generation. It is often referred to as a form of renewable energy, but because the heat at any location can eventually be depleted it technically may not be strictly renewable. Geothermal comes from the Greek words geo, meaning earth, and therme, meaning heat. Geothermal literally means "earth heat".
Types of geothermal sources

Geothermal power is generated by mining the earth's heat. In areas with high temperature ground water at shallow depths, wells are drilled into natural fractures in basement rock or into permeable sedimentary rocks. Hot water or steam flows up through the wells either by pumping or through boiling (flashing) flow. Experiments are in progress to determine if a fourth method, deep wells into "hot dry rocks", can be economically used to heat water pumped down from the surface. A hot dry rock project in the United Kingdom was abandoned after it was pronounced economically unviable in 1989. HDR programs are currently being developed in Australia, France, Switzerland and Germany. Magma (molten rock) resources offer extremely high-temperature geothermal opportunities, but existing technology does not allow recovery of heat from these resources.
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Electrical generation

Geothermal-generated electricity was first produced at Larderello, Italy, in 1904. Since then, the use of geothermal energy for electricity has grown worldwide to about 8,000 megawatts of which the United States produces 2,700 megawatts


Four types of power plants are used to generate power from geothermal energy: Dry steam, salt, flash, and binary. Dry steam plants take steam out of fractures in the ground and use it to directly drive a turbine that spins a generator. Flash plants take hot water, usually at temperatures over 200°C, out of the ground, and allows it to boil as to rises to the surface then separates the steam phase in steam/water separators and then runs the steam through a turbine. In binary plants, the hot water flows through heat exchangers, boiling an organic fluid that spins the turbine. The condensed steam and remaining geothermal fluid from all three types of plants are injected back into the hot rock to pick up more heat. This is why geothermal energy is viewed as sustainable. The heat of the earth is so vast that there is no way to remove more than a small fraction even if most of the world's energy needs came from geothermal sources.

The largest dry steam field in the world is The Geysers, about 90 miles (145 km) north of San Francisco. The Geysers began in 1960 which has 1360 MW of installed capacity and produces about 1000 MW net. Calpine Corporation now owns 19 of the 21 plants in The Geysers and is currently the United States' largest producer of renewable geothermal energy. The other two plants are owned jointly by the Northern California Power Agency and Santa Clara Electric. Since the activities of one geothermal plant affects those nearby, the consolidation plant ownership at The Geysers has been beneficial because the plants operate cooperatively instead of in their own short-term interest. The Geysers is now recharged by injecting treated sewage effluent from the City of Santa Rosa and the Lake County sewage treatment plant. This sewage effluent used to be dumped into rivers and streams and is now piped to the geothermal field where it replenishes the steam produced for power generation.

Another major geothermal area is located in south central California, on the southeast side of the Salton Sea, near the cities of Niland and Calipatria, California. As of 2001, there were 15 geothermal plants producing electricity in the area. CalEnergy owns about half of them and the rest are owned by various companies. Combined the plants produce about 570 megawatts.

The Basin and Range geologic province in Nevada, southeastern Oregon, southwestern Idaho, Arizona and western Utah is now an area of rapid geothermal development. Several small power plants were built during the late 1980s during times of high power prices. Rising energy costs have spurred new development. Plants in Nevada at Steamboat near Reno, Brady/Desert Peak, Dixie Valley, Soda Lake, Stillwater and Beowawe now produce about 235 MW. New projects are under development across the state.

Geothermal power is very cost-effective in the Rift area of Africa. Kenya's KenGen has built two plants, Olkaria I (45 MW) and Olkaria II (65 MW), with a third private plant Olkaria III (48 MW) run by Israeli geothermal specialist Ormat. Plans are to increase production capacity by another 576 MW by 2017, covering 25% of Kenya's electricity needs, and correspondingly reducing dependency on imported oil.

Geothermal power is generated in over 20 countries around the world including Iceland (producing 17% of its electricity from geothermal sources), the United States, Italy, France, New Zealand, Mexico, Nicaragua, Costa Rica, Russia, the Philippines (production output of 1931MW (2nd to US, 27% of electricity), Indonesia, the People's Republic of China and Japan. Canada's government (which officially notes some 30,000 earth-heat installations for providing space heating to Canadian residential and commercial buildings) reports a test geothermal-electrical site in the Meager Mountain–Pebble Creek area of British Columbia, where a 100 MW facility might be developed at that site.
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Desalination

Douglas Firestone began working with evaporation/condensation air loop desalination about 1998 and proved that geothermal waters could be used as process water to produce potable water in 2001. In 2003 Professor Ronald A. Newcomb, now at San Diego State University Center for Advanced Water Technologies began to work with Firestone to enhance the process of using geothermal energy for the purpose of desalination. Geothermal Energy is a primary energy source.

In 2005 testing was done in the fifth prototype of a device called the “Delta T” a closed air loop, atmospheric pressure, evaporation condensation loop geothermally powered desalination device. The device used filtered sea water from Scripps Institute of Oceanography and reduced the salt concentration from 35,000 ppm to 51 ppm w/w. [1]
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Water injection

In some locations, the natural supply of water producing steam from the hot underground magma deposits has been exhausted and processed waste water is injected to replenish the supply. Most geothermal fields have more fluid recharge than heat, so re-injection can cool the resource, unless it is carefully managed. In at least one location, this has resulted in small but frequent earthquakes (see external link below). This has led to disputes about whether the plant owners are liable for the damage the earthquakes cause.
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Heat depletion

Although geothermal sites are capable of providing heat for many decades, eventually they are depleted as the ground cools. [2] The government of Iceland states It should be stressed that the geothermal resource is not strictly renewable in the same sense as the hydro resource. It estimates that Iceland's geothermal energy could provide 1700 MW for over 100 years, compared to the current production of 140 MW. However, the natural heat flow of the earth largely from radioactive decay does replenish the heat lost in geothermal heat mining.
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Cost

Geothermal power is more competitive in countries that have limited hydrocarbon resources, such as Iceland, New Zealand, and Italy. During the period of low power prices in the 1980s up to the recent rise in oil and gas prices, few geothermal resource areas in the United States were capable of generating electricity at a cost competitive with other energy sources. However, recent rises in power prices make geothermal more cost competitive.

Not all areas of the world have a usable geothermal resource, though many do. Also, some geothermal areas do not have a high enough temperature to produce steam. In those areas, geothermal power can be generated using a process called binary cycle technology, though the efficiency is lower. Other areas do not have the water to produce steam, which is necessary for current plant designs. Geothermal areas without steam are called hot dry rock areas and methods for exploiting them are being researched. Also, instead of producing electricity, lower temperature areas can provide space and process heating. As of 1998, the United States has 18 district heating systems, 28 fish farms, 12 industrial plants, 218 spas and 38 greenhouses that use geothermal heat.

Hydrogen

Hydrogen is a clean energy carrier (like electricity) made from diverse domestic resources such as renewable energy (e.g. solar, wind, geothermal), nuclear energy, and fossil energy (combined with carbon capture/sequestration). Hydrogen in the long-term will simultaneously reduce dependence on foreign oil and emissions of greenhouse gases and criteria pollutants.

In his 2003 State of the Union Address, President Bush announced the Hydrogen Fuel Initiative, a $1.2 billion commitment over 5 years to accelerate hydrogen related research to overcome obstacles in taking hydrogen fuel cell vehicles from the laboratory to the showroom. Fuel cell vehicles operating on hydrogen are zero-emission vehicles.








Natural Gas

Other names Marsh gas, Swamp gas
Molecular formula CH4
Appearance Clear Gas, Blue Flame
Properties
Density and phase 0.717 kg/m3, gas
Melting point −182.5°C (90.6 K) at 1 atm

25 °C (298 K) at 1.5 GPa
Boiling point −161.6°C (111.55 K)
Triple point 90.7 K, 0.117 bar
Hazards
MSDS External MSDS
EU classification Highly flammable (F+)
NFPA 704

4
1
0

R-phrases R12
S-phrases S2, S9, S16, S33
Flash point −188°C
Autoignition temperature 537°C
Maximum burning
temperature: 2148°C
Explosive limits 5–15%
Related compounds
Related alkanes Ethane
Propane
Related compounds Methanol
Chloromethane
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references
See methane for a more complete list.
Portal:Energy
Energy Portal

Natural gas, commonly referred to as gas, is a gaseous fossil fuel consisting primarily of methane. It is found in oil fields and natural gas fields, and in coal beds. When methane-rich gases are produced by the anaerobic decay of non-fossil organic material, these are referred to as biogas. Sources of biogas include swamps, marshes, and landfills (see landfill gas), as well as sewage sludge and manure by way of anaerobic digesters, in addition to enteric fermentation particularly in cattle.



Chemical composition

The primary component of natural gas is methane (CH4), the shortest and lightest hydrocarbon molecule. It also contains heavier gaseous hydrocarbons such as ethane (C2H6), propane (C3H8) and butane (C4H10), as well as other sulphur containing gases, in varying amounts, see also natural gas condensate. Natural gas also contains and is the primary market source of helium.
Component %
Methane (CH4) 80-95
Ethane (C2H6) 5-15
Propane (C3H8) and Butane (C4H10) < 5

Nitrogen, helium, carbon dioxide and trace amounts of hydrogen sulfide, water and odorants can also be present [1]. Mercury is also present in small amounts in natural gas extracted from some fields[2]. The exact composition of natural gas varies between gas fields.

Organosulfur compounds and hydrogen sulfide are common contaminants which must be removed prior to most uses. Gas with a significant amount of sulfur impurities, such as hydrogen sulfide, is termed sour gas and often referred to as "acid gas". Processed Natural gas that is available to end-users is tasteless and odorless, however, before gas is distributed to end-users, it is odorized by adding small amounts of thiols, to assist in leak detection. Processed Natural gas is, in itself, harmless to the human body, however, natural gas is a simple asphyxiant and can kill if it displaces air to the point where the oxygen content will not support life.

Natural gas can also be hazardous to life and property through an explosion. Natural gas is lighter than air, and so tends to dissipate into the atmosphere. But when natural gas is confined, such as within a house, gas concentrations can reach explosive mixtures and, if ignited, result in blasts that could destroy buildings. Methane has a lower explosive limit of 5% in air, and an upper explosive limit of 15%.

Explosive concerns with compressed natural gas used in vehicles are almost non-existent, due to the escaping nature of the gas, and the need to maintain concentrations between 5% and 15% to trigger explosions.
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Energy content and statistics

Combustion of one cubic metre of commercial quality natural gas yields 39 megajoules (10.6 kWh). Equivalently, one cubic foot of natural gas produces 1031 British Thermal Units (BTUs).

In the USA, at retail, natural gas is often sold in units of therms (th); 1 therm = 100,000 BTU. Wholesale transactions are generally done in decatherms (Dth), or in thousand decatherms (MDth), or in million decatherms (MMDth). A million decatherms is roughly a billion cubic feet of natural gas.
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Storage and transport
Polyethylene gas main being laid in a trench.
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Polyethylene gas main being laid in a trench.

The major difficulty in the use of natural gas is transportation and storage. Natural gas pipelines are economical, but are impractical across oceans. Many existing pipelines in North America are close to reaching their capacity, prompting some politicians in colder climates to speak publicly of potential shortages.

LNG carriers can be used to transport liquefied natural gas (LNG) across oceans, while tank trucks can carry liquefied or compressed natural gas (CNG) over shorter distances. They may transport natural gas directly to end-users, or to distribution points such as pipelines for further transport. These may have a higher cost, requiring additional facilities for liquefaction or compression at the production point, and then gasification or decompression at end-use facilities or into a pipeline.

In the past, the natural gas which was recovered in the course of recovering petroleum could not be profitably sold, and was simply burned at the oil field (known as flaring). This wasteful practice is now illegal in many countries, especially since it adds greenhouse gas pollution to the earth's atmosphere. Additionally, companies now recognize that value for the gas may be achieved with LNG, CNG, or other transportation methods to end-users in the future. The gas is now re-injected back into the formation for later recovery. This also assists oil pumping by keeping underground pressures higher. In Saudi Arabia, in the late 1970s, a "Master Gas System" was created, ending the need for flaring. The natural gas is used to generate electricity and heat for desalinization. Similarly, some land-fills that also discharge methane gases have been set-up to capture the methane and generate electricity.

Natural gas is often stored in underground caverns formed inside depleted gas reservoirs from previous gas wells, salt domes, or in tanks as liquefied natural gas. The gas is injected during periods of low demand and extracted during periods of higher demand. Storage near the ultimate end-users helps to best meet volatile demands, but this may not always be practicable.
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Natural gas crisis
Blue flames of a burner on a natural gas stove.
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Blue flames of a burner on a natural gas stove.

Many politicians and prominent figures in North America have spoken publicly about a possible natural gas crisis. This includes former Secretary of Energy Spencer Abraham, former Chairman of the Federal Reserve Alan Greenspan, and Ontario Minister of Energy Dwight Duncan.

The natural gas crisis is typically described by the increasing price of natural gas in the U.S. over the last few years, due to the decline in indigenous supply and the increase in demand for electricity generation. Indigenous supply has fallen from 20,570,295 MMcf in 2001 to 19,144,768 MMcf in 2005.[3] Because of the drop in production (exacerbated by the dramatic hit to production that came from Hurricanes Katrina and Rita) and the continuing growth in demand, the price has become so high that many industrial users, mainly in the petrochemical industry, have closed their plants causing loss of jobs. Greenspan has suggested that a solution to the natural gas crisis is the import of LNG.

This solution is both capital intensive and politically charged due to the public perception that LNG terminals are explosive risks, especially in the wake of the 9/11 terrorist attacks in the United States. The U.S. Department of Homeland Security is responsible for maintaining their security.

New or expanded LNG terminals create tough infrastructure problems and require high capital spending. LNG terminals require a very spacious—at least 40 feet (12.2 m) deep[4]—harbor, as well as being sheltered from wind and waves. These "suitable" sites are thus deep in well-populated seaports, which are also burdened with right-of-way concerns for LNG pipelines, or conversely, required to also host the LNG expansion plant facilities and end use (petrochemical) plants amidst the high population densities of major cities, with the associated fumes, multiple serious risks to safety.

Typically, to attain "well-sheltered" waters, suitable harbor sites are well up rivers or estuaries, which are unlikely to be dredged deep enough. Since these very large vessels must move slowly and ponderously in restricted waters, the transit times to and from the terminal become costly, as multiple tugboats and security boats shelter and safeguard the large vessels. Operationally, LNG tankers are (for example, in Boston) effectively given sole use of the harbor, forced to arrive and depart during non-peak hours, and precluded from occupying the same harbor until the first is well-departed. These factors increase operating costs and make capital investment less attractive.

To substantially increase the amount of LNG used to supply natural gas to North America, not only must "re-gasification" plants be built on North American shores -- difficult for the reasons stated above -- someone also must put substantial, new liquefaction stations in Indonesia, the Middle East, and Africa, in order to concentrate the gas generally associated with oil production in those areas. A substantial expansion of the fleet of LNG carriers also must occur, to move the huge amount of fuel needed to make up for the coming shortfall in Northeast America.
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Uses
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Power generation

Natural gas is a major source for electricity generation through the use of gas turbines and steam turbines. Particularly high efficiencies can be achieved through combining gas turbines with a steam turbine in combined cycle mode. Natural gas burns cleaner than other fossil fuels, such as oil and coal, and produces less greenhouse gas per unit energy released. For an equivalent amount of heat, burning natural gas produces about 30% less carbon dioxide than burning petroleum and about 45% less than burning coal [1]. Combined cycle power generation using natural gas is thus the cleanest source of power available using fossil fuels, and this technology is widely used wherever gas can be obtained at a reasonable cost. Fuel cell technology may eventually provide cleaner options for converting natural gas into electricity, but as yet it is not price-competitive. Also, the natural gas supply is said to peak around the year 2030, 20 years after the peak of oil. It is also projected that the world's supply of natural gas should be exhausted around the year 2085.
A bus using natural gas in 1980 Romania
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A bus using natural gas in 1980 Romania
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Hydrogen

Natural gas can be used to produce hydrogen that can be used in hydrogen vehicles.
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Natural gas vehicles

Compressed natural gas (methane) is used as a clean alternative to other automobile fuels such as gasoline (petrol) and diesel. As of 2005, the countries with the largest number of natural gas vehicles were Argentina, Brazil, Pakistan, Italy, and India. [2] The energy efficiency is generally equal to that of gasoline engines, but lower compared with modern diesel engines, partially due to the fact that natural gas engines function using the Otto cycle, but research is on its way to improve the process (Westport Cycle).

Liquified petroleum gas (a propane and butane blend) is also used to fuel vehicles, but it is only suitable for gasoline engines. LPG and CNG vehicle fuel systems are not compatible. CNG also requires higher pressure tanks which are typically much heavier than those used for LPG.
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Residential domestic use

Natural gas is supplied to homes, where it is used for such purposes as cooking in natural gas-powered ranges and/or ovens, natural gas-heated clothes dryers, and heating/cooling. Home or other building heating may include boilers, furnaces, and water heaters. CNG is used in rural homes without connections to piped-in public utility services, or with portable grills.
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Fertilizer

Natural gas is a major feedstock for the production of ammonia, via the Haber process, for use in fertilizer production.1,2,and..3
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Other

Natural gas is also used in the manufacture of fabrics, glass, steel, plastics, paint, and other products.
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Sources
Natural gas production by country (countries in brown and then red have the largest production)
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Natural gas production by country (countries in brown and then red have the largest production)

Natural gas is commercially produced from oil fields and natural gas fields. Gas produced from oil wells is called casinghead gas or associated gas. The largest two natural gas fields are probably South Pars Gas Field in Iran and Urengoy gas field in Russia, with reserves on the order of 1013 m³. See also List of natural gas fields. Qatar also has 25 trillion cubic meters of natural gas (5% of the world's proven supply), enough to last 250 years at current production levels.

Town gas is a mixture of methane and other gases which can be used in a similar way to natural gas and can be produced by treating coal chemically. This is a historic technology, still used as 'best solution' in some local circumstances, although coal gasification is not usually economic at current gas prices, depending upon infrastructure considerations.

Methanogenic archaea are responsible for all biological sources of methane, some in symbiotic relationships with other life forms, including termites, ruminants, and cultivated crops. Methane released directly into the atmosphere would be considered a pollutant, however, methane in the atmosphere is oxidised, producing carbon dioxide and water.
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Possible future sources
Image:USNatGasProdution1900-2005.gif‎
U.S. Natural Gas Production 1900 - 2005 Source: EIA

Future sources of methane, the principal component of natural gas, include landfill gas, biogas and methane hydrate. Biogas, and especially landfill gas, are already used in some areas, but their use could be greatly expanded. Landfill gas is a type of biogas, but biogas usually refers to gas produced from organic material that has not been mixed with other waste.

Landfill gas is created from the decomposition of waste in landfills. If the gas is not removed, the pressure may get so high that it works its way to the surface, causing damage to the landfill structure, unpleasant odor, vegetation die-off and an explosion hazard. The gas can be vented to the atmosphere, flared or burned to produce electricity or heat.

Once water vapor is removed, about half of landfill gas is methane. Almost all of the rest is carbon dioxide, but there are also small amounts of nitrogen, oxygen and hydrogen. There are usually trace amounts of hydrogen sulfide and siloxanes, but their concentration varies widely. Landfill gas cannot be distributed through natural gas pipelines unless it is cleaned up to the same quality. It is usually more economical to combust the gas on site or within a short distance of the landfill using a dedicated pipeline. Water vapor is often removed, even if combusting the gas on site. Other non-methane components may also be removed in order to meet emissions standards, to prevent fouling of the equipment or for environmental considerations. Co-firing landfill gas with natural gas improves combustion, which lowers emissions.

Biogas is usually produced using agricultural waste materials, such as unmerchantable parts of plants and manure. Biogas can also be produced by separating organic materials from waste that otherwise goes to landfills, which is more efficient than just capturing the landfill gas it produces. Using materials that would otherwise generate no income, or even cost money to get rid of, improves the profitability and energy balance of biogas production.

Anaerobic lagoons are used to produce biogas from manure, while biogas reactors can be used for manure or plant parts. Like landfill gas, biogas is mostly methane and carbon dioxide, with small amounts of nitrogen, oxygen and hydrogen. However, with the exception of pesticides, there are usually lower levels of contaminants.

A speculative source of enormous quantities of methane is from methane hydrate, found under sediments in the oceans. However, as of 2006 no technology has been developed to recover it economically.
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Safety

In any form, a minute amount of odorant such as t-butyl mercaptan, with a rotting-cabbage-like smell, is added to the otherwise colorless and odorless gas, so that leaks can be detected before a fire or explosion occurs. Sometimes a related compound, thiophane is used, with a rotten-egg smell. Adding odorant to natural gas began in the United States after the 1937 New London School explosion. The buildup of gas in the school went unnoticed, killing three hundred students and faculty when it ignited. Odorants are considered non-toxic in the extremely low concentrations occurring in natural gas delivered to the end user.

In mines, where methane seeping from rock formations has no odor, sensors are used, and mining apparatus has been specifically developed to avoid ignition sources, e.g., the Davy lamp.

Explosions caused by natural gas leaks occur a few times each year. Individual homes, small businesses and boats are most frequently affected when an internal leak builds up gas inside the structure. Frequently, the blast will be enough to significantly damage a building but leave it standing. In these cases, the people inside tend to have minor to moderate injuries. Occasionally, the gas can collect in high enough quantities to cause a deadly explosion, disintegrating one or more buildings in the process. The gas usually dissipates readily outdoors, but can sometimes collect in dangerous quantities if weather conditions are right. Also, considering the tens of millions of structures that use the fuel, the individual risk of using natural gas is very low.

Some gas fields yield sour gas containing hydrogen sulfide (H2S). This untreated gas is toxic. Scrubbers which remove acidic gaseous components can be used to remove hydrogen sulfide from natural gas.

Extraction of natural gas (or oil) leads to decrease in pressure in the reservoir. This in turn may lead to subsidence at ground level. Subsidence may affect ecosystems, waterways, sewer and water supply systems, foundations, etc.
Nuclear

Solar

Nuclear power

Nuclear power is the controlled use of nuclear reactions to release energy for work including propulsion, heat, and the generation of electricity. Human use of nuclear power to do significant useful work is currently limited to nuclear fission and radioactive decay. Nuclear energy is produced when a fissile material, such as uranium-235 (235U), is concentrated such that nuclear fission takes place in a controlled chain reaction and creates heat — which is used to boil water, produce steam, and drive a steam turbine. The turbine can be used for mechanical work and also to generate electricity. Nuclear power is used to power most military submarines and aircraft carriers and provides 7% of the world's energy and 17% of the world's electricity. The United States produces the most nuclear energy, with nuclear power providing 20% of the electricity it consumes, while France produces the highest percent of its energy from nuclear reactors—80% as of 2006. [1] [2]

International research is ongoing into various safety improvements, the use of nuclear fusion and additional uses such as the generation of hydrogen (in support of hydrogen economy schemes), for desalinating sea water, and for use in district heating systems.

Construction of nuclear power plants declined following the 1979 Three Mile Island accident and the 1986 disaster at Chernobyl. Lately, there has been renewed interest in nuclear energy from national governments, the public, and some notable environmentalists due to increased oil prices, new passively safe designs of plants, and the low emission rate of greenhouse gas which some governments need to meet the standards of the Kyoto Protocol. A few reactors are under construction, and several new types of reactors are planned.

The use of nuclear power is controversial because of the problem of storing radioactive waste for indefinite periods, the potential for possibly severe radioactive contamination by accident or sabotage, and the possibility that its use in some countries could lead to the proliferation of nuclear weapons. Proponents believe that these risks are small and can be further reduced by the technology in the new reactors. They further claim that the safety record is already good when compared to other fossil-fuel plants, that it releases much less radioactive waste than coal power, and that nuclear power is a sustainable energy source. Critics, including most major environmental groups believe nuclear power is an uneconomic, unsound and potentially dangerous energy source, especially compared to renewable energy, and dispute whether the costs and risks can be reduced through new technology. There is concern in some countries over North Korea and Iran operating research reactors and fuel enrichment plants, since those countries refuse adequate IAEA oversight and are believed to be trying to develop nuclear weapons. North Korea claims it is developing Nuclear Weapons and the Iranian government vehemently denies these claims.
Contents
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Origins

The first successful experiment with nuclear fission was conducted in 1938 in Berlin by the German physicists Otto Hahn, Lise Meitner and Fritz Strassmann.

During the Second World War, a number of nations embarked on crash programs to develop nuclear energy, focusing first on the development of nuclear reactors. The first self-sustaining nuclear chain reaction was obtained at the University of Chicago by Enrico Fermi on December 2, 1942, and reactors based on his research were used to produce the plutonium necessary for the "Fat Man" weapon dropped on Nagasaki, Japan. Several nations began their own construction of nuclear reactors at this point, primarily for weapons use, though research was also being conducted into their use for civilian electricity generation.

Electricity was generated for the first time by a nuclear reactor on December 20, 1951 at the EBR-I experimental fast breeder station near Arco, Idaho, which initially produced about 100 kW.

In 1952 a report by the Paley Commission (The President's Materials Policy Commission) for President Harry Truman made a "relatively pessimistic" assessment of nuclear power, and called for "aggressive research in the whole field of solar energy". [3]

A December 1953 speech by President Dwight Eisenhower, "Atoms for Peace", set the U.S. on a course of strong government support for the international use of nuclear power.
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Early years
The Beaver Valley Nuclear Generating Station in Shippingport, Pennsylvania was the first commercial reactor in the USA and was opened in 1957.
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The Beaver Valley Nuclear Generating Station in Shippingport, Pennsylvania was the first commercial reactor in the USA and was opened in 1957.

On June 27, 1954, the world's first nuclear power plant to generate electricity for a power grid started operations at Obninsk, USSR [4]. The reactor was graphite moderated, water cooled and had a capacity of 5 megawatts (MW). The world's first commercial nuclear power station, Calder Hall in Sellafield, England was opened in 1956, a gas-cooled Magnox reactor with an initial capacity of 50 MW (later 200 MW) [5]. The Shippingport Reactor (Pennsylvania, 1957), a pressurized water reactor, was the first commercial nuclear generator to become operational in the United States.

In 1954, the chairman of the United States Atomic Energy Commission (forerunner of the U.S. Nuclear Regulatory Commission) famously declared that nuclear power would be "too cheap to meter" [6] and foresaw 1000 nuclear plants on line in the USA by the year 2000.

In 1955 the United Nations' "First Geneva Conference", then the world's largest gathering of scientists and engineers, met to explore the technology. In 1957 EURATOM was launched alongside the European Economic Community (the latter is now the European Union). The same year also saw the launch of the International Atomic Energy Agency (IAEA).

Thanks to the presence of the nearby Bettis Laboratory and the Shippingport power plant, Pittsburgh, Pennsylvania became the world's first nuclear powered city in 1960.
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Development

Installed nuclear capacity initially rose relatively quickly, rising from less than 1 gigawatt (GW) in 1960 to 100GW in the late 1970s, and 300GW in the late 1980s. Since the late 1980s capacity has risen much more slowly, reaching 366GW in 2005, primarily due to Chinese expansion of nuclear power. Between around 1970 and 1990, more than 50GW of capacity was under construction (peaking at over 150GW in the late 70s and early 80s) — in 2005, around 25GW of new capacity was planned. More than two-thirds of all nuclear plants ordered after January 1970 were eventually cancelled.[7]

During the 1970s and 1980s rising economic costs (related to vastly extended construction times largely due to regulatory delays) and falling fossil fuel prices made nuclear power plants then under construction less attractive. In the 1980s (U.S.) and 1990s (Europe), flat load growth and electricity liberalization also made the addition of large new baseload capacity unnecessary.
Washington Public Power Supply System Nuclear Power Plants 3 and 5 were never completed
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Washington Public Power Supply System Nuclear Power Plants 3 and 5 were never completed

A general movement against nuclear power arose during the last third of the 20th century, based on the fear of a possible nuclear accident and on fears of latent radiation, and on the opposition to nuclear waste production, transport and final storage. Perceived risks on the citizens health and safety, the 1979 accident at Three Mile Island and the 1986 Chernobyl accident played a key part in stopping new plant construction in many countries. Austria (1978), Sweden (1980) and Italy (1987) voted in referendums to oppose or phase out nuclear power, while opposition in Ireland prevented a nuclear programme there. However, the Brookings Institution suggests in [8] that new nuclear units have not been ordered primarily for economic reasons rather than fears of accidents.

Financing for new reactors dried up when Wall Street's enthusiasm ended. Disillusionment was complete when new research discredited the claim (previously accepted as fact even by opponents) that nuclear power was still, despite all its problems, the most cost-effective source of electrity. Industry figures had omitted the factor of downtime. The newest and biggest U.S. plants were actually producing only half the energy they were supposed to, due to shutdowns for refueling, routine maintenance, retrofitting, and frequent minor mishaps. (See Charles Komanoff, "U.S. Nuclear Plant Performance," Bulletin of the Atomic Scientists, November 1980. See also Komanoff's overview of the reasons for the nuclear industry's decline in the critical period from 1973 to 1981, which includes some economic analysis [9])

As of 2006, the stated desire to use nuclear power for electricity generation has been suspected of being a cover for nuclear proliferation in Iran and North Korea.
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Reactor types
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Current technology

There are two types of nuclear power sources in current use:

1. The nuclear fission reactor produces heat through a controlled nuclear chain reaction in a critical mass of fissile material.
All current nuclear power plants are critical fission reactors, which are the focus of this article. The output of fission reactors is controllable. There are several subtypes of critical fission reactors, which can be classified as Generation I, Generation II and Generation III. All reactors will be compared to the Pressurized Water Reactor (PWR), as that is the standard modern reactor design.
The difference between fast-spectrum and thermal-spectrum reactors will be covered later. In general, fast-spectrum reactors will produce less waste, and the waste they do produce will have a vastly shorter halflife, but they are more difficult to build, and more expensive to operate. Fast reactors can also be breeders, whereas thermal reactors generally cannot.

A. Pressurized water reactors (PWR)
These are reactors cooled and moderated by high pressure, liquid (even at extreme temperatures) water. They are the majority of current reactors, and are generally considered the safest and most reliable technology, although Three Mile Island is a reactor of this type. This is a thermal neutron reactor design.
B. Boiling water reactors (BWR)
These are reactors cooled and moderated by water, under slightly lower pressure. The water is allowed to boil in the reactor. The thermal efficiency of these reactors can be higher, and they can be simpler, and even potentially more stable and safe. Unfortunately, the boiling water puts more stress on many of the components, and increases the risk that radioactive water may escape in an accident. These reactors make up a substantial percentage of modern reactors. This is a thermal neutron reactor design.
C. Pressurised Heavy Water Reactor (PHWR)
A Canadian design, (known as CANDU) these reactors are heavy-water-cooled and -moderated Pressurized-Water reactors. Instead of using a single large containment vessel as in a PWR, the fuel is contained in hundreds of pressure tubes. These reactors are fuelled with natural uranium and are thermal neutron reactor designs. PHWRs can be refueled while at full power, which makes them very efficient in their use of uranium (it allows for precise flux control in the core). Most PHWR's exist within Canada, but units have been sold to Argentina, China, India (pre-NPT), Pakistan (pre-NPT), Romania, and South Korea. India also operates a number of PHWR's, often termed 'CANDU-derivatives', built after the 1974 Smiling Buddha nuclear weapon test.
D. RBMKs
A Soviet Union design, built to produce plutonium as well as power, the dangerous and unstable RBMKs are water cooled with a graphite moderator. RBMKs are in some respects similar to CANDU in that they are refuelable On-Load and employ a pressure tube design instead of a PWR-style pressure vessel. However, unlike CANDU they are very unstable and too large to have containment buildings. Because of this RBMK reactors are generally considered one of the most dangerous reactor designs in use. Chernobyl was an RBMK.
E. Gas Cooled Reactor (GCR) and Advanced Gas Cooled Reactor (AGCR)
These are generally graphite moderated and CO2 cooled. They have a high thermal efficiency compared with PWRs and an excellent safety record. There are a number of operating reactors of this design, mostly in the United Kingdom. Older designs (i.e. Magnox stations) are either shut down or will be in the near future. However the AGCRs have an anticipated life of a further 10 to 20 years. This is a thermal neutron reactor design.
F. Super Critical Water-cooled Reactor (SCWR)
This is a theoretical reactor design that is part of the Gen-IV reactor project. It combines higher efficiency than a GCR with the safety of a PWR, though it is perhaps more technically challenging than either. The water is pressurized and heated past its critical point, until there is no difference between the liquid and gas states. A CWR is similar to a BWR, except there is no boiling (as the water is critical), and the thermal efficiency is higher as the water behaves more like a classical gas. This is an epithermal neutron reactor design.
G. Liquid Metal Fast Breeder Reactor (LMFBR)
This is a reactor design that is cooled by liquid metal, and totally unmoderated. These reactors can function much like a PWR in terms of efficiency, and don't require much high pressure containment, as the liquid metal doesn't need to be kept at high pressure, even at very high temperatures. Superphénix in France was a reactor of this type, as was Fermi-I in the United States. The Monju reactor in Japan suffered a sodium leak in 1995 and is approved for restart in 2008. All three use/used liquid sodium. These reactors are fast neutron, not thermal neutron designs. These reactors come in two types:

Lead Cooled
Using lead as the liquid metal provides excellent radiation shielding, and allows for operation at very high temperatures. Also, lead is (mostly) transparent to neutrons, so fewer neutrons are lost in the coolant, and the coolant does not become radioactive. Unlike sodium, lead is mostly inert, so there is less risk of explosion or accident, but such large quantities of lead may be problematic from toxicology and disposal points of view. Often a reactor of this type would use a lead-bismuth eutectic mixture. In this case, the bismuth would present some minor radiation problems, as it is not quite as transparent to neutrons, and can be transmuted to a radioactive isotope more readily than lead.
Sodium cooled
Most LMFBRs are of this type. The sodium is relatively easy to obtain and work with, and it also manages to actually remove corrosion on the various reactor parts immersed in it. However, sodium explodes violently when exposed to water, so care must be taken, but such explosions wouldn't be vastly more violent than (for example) a leak of superheated fluid from a CWR or PWR.

2. The radioisotope thermoelectric generator produces heat through passive radioactive decay.

Some radioisotope thermoelectric generators have been created to power space probes (for example, the Cassini probe), some lighthouses in the former Soviet Union, and some pacemakers. The heat output of these generators diminishes with time; the heat is converted to electricity utilising the thermoelectric effect.

For more details on this topic, see Nuclear power plant.

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How it works

Nuclear energy is produced by atomic fission. A large atom (usually uranium or plutonium) breaks into two smaller ones, releasing energy and neutrons. The neutrons then trigger further break-ups. And so on. If this “chain reaction” can be controlled, the energy released can be used to boil water, produce steam and drive a turbine that generates electricity. If it runs away, the result is a meltdown and an accident (or, in extreme circumstances, a nuclear explosion—though circumstances are never that extreme in a reactor because the fuel is less fissile than the material in a bomb).

In many new designs the neutrons, and thus the chain reaction, are kept under control by passing them through water to slow them down. (Slow neutrons trigger more break ups than fast ones.) This water is exposed to a pressure of about 150 atmospheres—a pressure that means it remains liquid even at high temperatures. When nuclear reactions warm the water, its density drops, and the neutrons passing through it are no longer slowed enough to trigger further reactions. That negative feedback stabilises the reaction rate.
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Experimental technologies

A number of other designs for nuclear power generation, the Generation IV reactors, are the subject of active research and may be used for practical power generation in the future. A number of the advanced nuclear reactor designs could also make critical fission reactors much cleaner, much safer and/or much less of a risk to the proliferation of nuclear weapons.

* Integral Fast Reactor - The link at the end of this paragraph references an interview with Dr. Charles Till, former director of Argonne National Laboratory West in Idaho and outlines the Integral Fast Reactor and its advantages over current reactor design, especially in the areas of safety, efficient nuclear fuel usage and reduced waste. The IFR was built, tested and evaluated during the 1980s and then retired under the Clinton administration in the 1990s due to nuclear non-proliferation policies of the administration. Recycling spent fuel is the core of its design and it therefore produces a fraction of the waste of current reactors. [10]
* Pebble Bed Reactor - This reactor type is designed so high temperatures reduce power output by doppler broadening of the fuel's neutron cross-section. It uses ceramic fuels so its safe operating temperatures exceed the power-reduction temperature range. Most designs are cooled by inert helium, which cannot have steam explosions, and which does not easily absorb neutrons and become radioactive, or dissolve contaminants that can become radioactive. Typical designs have more layers (up to 7) of passive containment than light water reactors (usually 3). A unique feature that might aid safety is that the fuel-balls actually form the core's mechanism, and are replaced one-by-one as they age. The design of the fuel makes fuel reprocessing expensive.
* SSTAR, Small, Sealed, Transportable, Autonomous Reactor is being primarily researched and developed in the US, intended as a fast breeder reactor that is tamper resistant, passively safe.
* Subcritical reactors are designed to be safer and more stable, but pose a number of engineering and economic difficulties.
* Controlled nuclear fusion could in principle be used in fusion power plants to produce safer, cleaner power, but significant scientific and technical obstacles remain. Several fusion reactors have been built, but as yet none has 'produced' more thermal energy than electrical energy consumed. Despite research having started in the 1950s, no commercial fusion reactor is expected before 2050 [11]. The ITER project is currently leading the effort to commercialize fusion power.
* Thorium based reactors

It is possible to convert Thorium-232 into U-233 in reactors specially designed for the purpose. In this way, Thorium , which is more plentiful than uranium, can be used to breed U-233 nuclear fuel. U-233 is also believed to have favourable nuclear properties as compared to traditionally used U-235, including better neutron economy and lower production of long lived transuranic waste.

* Advanced Heavy Water Reactor - A proposed heavy water moderated nuclear power reactor that will be the next generation design of the PHWR type. Under development in the Bhabha Atomic Research Centre (BARC).
* KAMINI - A unique reactor using Uranium-233 isotope for fuel. Built by BARC and IGCAR Uses thorium.
* India is also building a bigger scale FBTR or fast breeder thorium reactor to harness the power with the use of thorium.

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Life cycle
The Nuclear Fuel Cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel, (1) which is delivered to a nuclear power plant. After usage in the power plant, the spent fuel is delivered to a reprocessing plant (2) or to a final repository (3) for geological disposition. In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant (4).
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The Nuclear Fuel Cycle begins when uranium is mined, enriched, and manufactured into nuclear fuel, (1) which is delivered to a nuclear power plant. After usage in the power plant, the spent fuel is delivered to a reprocessing plant (2) or to a final repository (3) for geological disposition. In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant (4).
Nuclear fuel - a compact, inert, insoluble solid.
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Nuclear fuel - a compact, inert, insoluble solid.

Main article: Nuclear fuel cycle

A nuclear reactor is only a small part of the life-cycle for nuclear power. The process starts with mining. Generally, uranium mines are either open-pit strip mines, or in-situ leach mines. In either case, the uranium ore is extracted, usually converted into a stable and compact form such as yellowcake, and then transported to a processing facility. At the reprocessing facility, the yellowcake is converted to uranium hexafluoride, which is then enriched using various techniques. At this point, the enriched uranium, containing more than the natural 0.7% U-235, is used to make rods of the proper composition and geometry for the particular reactor that the fuel is destined for. The fuel rods will spend about 3 years inside the reactor, generally until about 3% of their uranium has been fissioned, then they will be moved to a spent fuel pool where the short lived isotopes generated by fission can decay away. After about 5 years in a cooling pond, the spent fuel is radioactively cool enough to handle, and it can be moved to dry storage casks or reprocessed.
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Fuel resources

Main article: Uranium market

Uranium is a common element, occurring almost everywhere on land and in the oceans. It is about as common as tin, and 500 times more common than gold. Most types of rocks and soils contain uranium, although often in low concentrations. At present, economically viable deposits are regarded as being those with concentrations of at least 0.1 per cent uranium. At this cost level, available reserves would last for 50 years at the present rate of use. Doubling the price of uranium, which would have only little effect on the overall cost of nuclear power, would increase reserves to hundreds of years. To put this in perspective; a doubling in the cost of natural uranium would increase the total cost of nuclear power 5 per cent. On the other hand, if the price of natural gas was doubled, the cost of gas-fired power would increase by about 60 per cent. Doubling the price of coal would increase the cost of power production in a large coal-fired power station by about 30 per cent.[12]

Current light water reactors make relatively inefficient use of nuclear fuel, leading to energy waste. More efficient reactor designs or nuclear reprocessing [13] would reduce the amount of waste material generated and allow better use of the available resources.

As opposed to current light water reactors which use uranium-235 (0.7% of all natural uranium), fast breeder reactors use uranium-238 (99.3% of all natural uranium). It has been estimated that there is anywhere from 10,000 to five billion years worth of uranium-238 for use in these power plants [14]. Breeder technology has been used in several reactors [15]. Currently (December 2005), the only breeder reactor producing power is BN-600 [16] in Beloyarsk, Russia. (The electricity output of BN-600 is 600 MW - Russia has planned to build another unit, BN-800, at Beloyarsk nuclear power plant.) Also, Japan's Monju reactor is planned for restart (having been shut down since 1995), and both China and India intend to build breeder reactors.

Another alternative would be to use uranium-233 bred from thorium as fission fuel - the thorium fuel cycle. Thorium is three times more abundant in the Earth's crust than uranium [17], and (theoretically) all of it can be used for breeding, making the potential thorium resource orders of magnitude larger than the uranium fuel cycle operated without breeding. Unlike the breeding of U-238 into plutonium, fast breeder reactors are not necessary - it can be performed satisfactorily in more conventional plants.

Proposed fusion reactors assume the use of deuterium, an isotope of hydrogen, as fuel and in most current designs also lithium. Assuming a fusion energy output equal to the current global output and that this does not increase in the future, then the known current lithium reserves would last 3,000 years, lithium from sea water would last 60 million years, and a more complicated fusion process using only deuterium from sea water would have fuel for 150 billion years. [18] For comparison, the Sun has an estimated remaining life of 5 billion years.
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Reprocessing

For more details on this topic, see Nuclear reprocessing

Reprocessing can recover up to 95% of the remaining uranium and plutonium in spent nuclear fuel, putting it into new mixed oxide fuel. Reprocessing of civilian fuel from power reactors is currently done on large scale in England, France and (formerly) Russia, will be in China and perhaps India, and is being done on an expanding scale in Japan. Iran has announced its intention to complete the nuclear fuel cycle via reprocessing, a move which has led to criticism from the United States and the International Atomic Energy Agency. [19] Reprocessing of civilian nuclear fuel is not done in the United States due to proliferation concerns.
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Solid waste

For more details on this topic, see Nuclear waste.

Nuclear power produces spent fuel, a unique solid waste problem. Highly radioactive spent fuel needs to be handled with great care and forethought due to the long half-lives of the radioactive isotopes in the waste. In fact, fresh spent fuel is so radioactive that less than a minute's exposure to it will cause death. However, spent nuclear fuel becomes less radioactive over time. After 40 years, the radiation flux is 99.9% lower than it was the moment the reactor was last shut off[20], although still dangerously radioactive.

Spent fuel is primarily composed of unconverted uranium, as well as significant quantities of transuranic actinides (plutonium and curium, mostly). In addition, about 3% of it is made of fission products. The actinides (uranium, plutonium, and curium) are responsible for the bulk of the long term radioactivity, whereas the fission products are responsible for the bulk of the short term radioactivity. It is possible through reprocessing to separate out the actinides and use them again for fuel, but this often requires special fast spectrum reactors, which produce a reduction in long term radioactivity within the remaining waste. In any case, the remaining waste will be substantially radioactive for at least 300 years even if the actinides are removed, and for up to thousands of years if the actinides are left in. Even in the most optimistic scenarios, complete consumption of all actinides, and using fast spectrum reactors to destroy some of the long-lived non-actinides as well, the waste must be segregated from the environment for at least several hundred years, and therefore this is properly categorized as a long-term problem. There are, however, chemical plants which also produce hazardous waste staying in the environment for hundreds of years.

A large nuclear reactor produces 3 cubic metres (25-30 tonnes) of spent fuel each year.[21] As of 2003, the United States had accumulated about 49,000 metric tons of spent nuclear fuel from nuclear reactors. Unlike other countries, U.S. policy forbids recycling of used fuel and it is all treated as waste. After 10,000 years of radioactive decay, according to United States Environmental Protection Agency standards, the spent nuclear fuel will no longer pose a threat to public health and safety.

The safe storage and disposal of nuclear waste is a difficult challenge. Because of potential harm from radiation, spent nuclear fuel must be stored in shielded basins of water, or in dry storage vaults or dry cask storage until its radioactivity decreases naturally ("decays") to safe levels. This can take days or thousands of years, depending on the type of fuel. Most waste is currently stored in temporary storage sites, requiring constant maintenance, while suitable permanent disposal methods are discussed. Underground storage at Yucca Mountain in U.S. has been proposed as permanent storage. See the article on the nuclear fuel cycle for more information.

The nuclear industry produces a volume of low-level radioactive waste in the form of contaminated items like clothing, hand tools, water purifier resins, and (upon decommissioning) the materials of which the reactor itself is built. In the United States, the Nuclear Regulatory Commission has repeatedly attempted to allow low-level materials to be handled as normal waste: landfilled, recycled into consumer items, etc. Much low-level waste releases very low levels of radioactivity and is essentially considered radioactive waste because of its history. For example, according to the standards of the NRC, the radiation released by coffee is enough to treat it as low level waste. Overall, nuclear power produces far less waste material than fossil-fuel based power plants. Coal-burning plants are particularly noted for producing large amounts of radioactive ash due to concentrating naturally occurring radioactive material in the coal.

In addition, the nuclear industry fuel cycle produces many tons of depleted uranium (DU) which consists of U-238 with the easily fissile U-235 isotope removed. U-238 is a tough metal with several commercial uses, for example aircraft production, radiation shielding, and for making bullets and armor as it has a higher density than lead. There are concerns that U-238 may lead to health problems in groups exposed to this material excessively, like tank crews and civilians living in areas where large quantities of DU ammunition have been used.

The amounts of waste can be reduced in several ways. Both nuclear reprocessing and fast breeder reactors can reduce the amounts of waste and increase the amount of energy gained per fuel unit. Subcritical reactors or fusion reactors could greatly reduce the time the waste has to be stored [22]. Subcritical reactors may also be able to do the same to already existing waste. It has been argued that the best solution for the nuclear waste is above ground temporary storage since technology is rapidly changing. The current waste may well become valuable fuel in the future, particularly if it is not reprocessed, as in the U.S.

In countries with nuclear power, radioactive wastes comprise less than 1% of total industrial toxic wastes, which remain hazardous indefinitely unless it decomposes or is treated so that it is less toxic or non-toxic. [23].
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Economy

Opponents of nuclear power argue that any of the environmental benefits are outweighed by safety compromises and by the costs related to construction and operation of nuclear power plants, including costs for spent-fuel disposal and plant retirement. Proponents of nuclear power respond that nuclear energy is the only power source which explicitly factors the estimated costs for waste containment and plant decommissioning into its overall cost, and that the quoted cost of fossil fuel plants is deceptively low for this reason. The cost of some renewables would be increased too if they included necessary back-up due to their intermittent nature.

A UK Royal Academy of Engineering report in 2004 looked at electricity generation costs from new plants in the UK. In particular it aimed to develop "a robust approach to compare directly the costs of intermittent generation with more dependable sources of generation". This meant adding the cost of standby capacity for wind, as well as carbon values up to £30 (€45.44) per tonne CO2 for coal and gas. Wind power was calculated to be more than twice as expensive as nuclear power. Without a carbon tax, the cost of production through coal, nuclear and gas ranged £0.022-0.026/kWh and coal gasification was £0.032/kWh. When carbon tax was added (up to £0.025) coal came close to onshore wind (including back-up power) at £0.054/kWh - offshore wind is £0.072/kWh.

Nuclear power remained at £0.023/kWh either way, as it produces negligible amounts of CO2. Nuclear figures included decommissioning costs.[24][25][26]

In one study, certain gas cogeneration plants were calculated to be three to four times more cost-effective than nuclear power, if all the heat produced was used onsite or in a local heating system. However, the study estimated only 25 year plant lifetimes (60 is now common), 68% capacity factors were assumed (above 90% is now common), other conservatisms were applied, and nuclear power also produces heat which could be used in similar ways (although most nuclear power plants are located in remote areas). The study then found similar costs for nuclear power and most other forms of generation if not including external costs (such as back-up power). [27]
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Capital costs

Generally, a nuclear power plant is significantly more expensive to build than an equivalent coal-fuelled or gas-fuelled plant. However, coal is significantly more expensive than nuclear fuel, and natural gas significantly more expensive than coal - thus, capital costs aside, natural gas-generated power is the most expensive.

In many countries, licensing, inspection and certification of nuclear power plants has added delays and construction costs to their construction. In the U.S. many new regulations were put in place after the Three Mile Island partial meltdown. Building gas-fired or coal-fired plants has not had these problems. Because a power plant does not yield profits during construction, longer construction times translated directly into higher interest charges on borrowed construction funds. However, the regulatory processes for siting, licensing, and constructing have been standardized since their introduction, to make construction of newer and safer designs more attractive to companies.

In Japan and France, construction costs and delays are significantly diminished because of streamlined government licensing and certification procedures. In France, one model of reactor was type-certified, using a safety engineering process similar to the process used to certify aircraft models for safety. That is, rather than licensing individual reactors, the regulatory agency certified a particular design and its construction process to produce safe reactors. U.S. law permits type-licensing of reactors, a process which is about to be used. [28].

To encourage development of nuclear power, under the Nuclear Power 2010 Program the U.S. Department of Energy (DOE) has offered interested parties the opportunity to introduce France's model for licensing and to subsidize 25% to 50% of the construction cost overruns due to delays for the first six new plants. Several applications were made, two sites have been chosen to receive new plants, and other projects are pending.
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Operating costs

In general, coal and nuclear plants have the same types of operating costs (operations and maintenance plus fuel costs). However, nuclear and coal differ in the relative size of those costs. Nuclear has lower fuel costs but higher operating and maintenance costs. In recent times in the United States savings due to lower fuel cost have not been low enough for nuclear to repay its higher investment cost. Thus new nuclear reactors have not been built in the United States. Coal's operating cost advantages have only rarely been sufficient to encourage the construction of new coal based power generation. Around 90 to 95 percent of new power plant construction in the United States has been natural gas-fired.

To be competitive in the current market, both the nuclear and coal industries must reduce new plant investment costs and construction time. The burden is clearly greater for nuclear producers than for coal producers, because investment costs are higher for nuclear plants. Operation and maintenance costs are particularly important because they represent a large portion of costs for nuclear power.

One of the primary reasons for the uncompetitiveness of the U.S. nuclear industry has been the lack of any measure that provides an economic incentive to reduce carbon emissions (carbon tax). Many economists and environmentalists have called for a mechanism to take into account the negative externalities of coal and gas consumption. In such an environment, it is argued that nuclear will become cost-competitive in the United States.
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Subsidies

Critics of nuclear power claim that it is the beneficiary of inappropriately large economic subsidies — mainly taking the forms of taxpayer-funded research and development and limitations on disaster liability — and that these subsidies, being subtle and indirect, are often overlooked when comparing the economics of nuclear against other forms of power generation. However, competing energy sources also receive subsidies. Fossil fuels receive large direct and indirect subsidies, like tax benefits and not having to pay for their pollution [29]. Renewables receive large direct production subsidies and tax breaks in many nations [30].

Energy research and development (R&D) for nuclear power has and continues to receive much larger state subsidies than R&D for renewable energy or fossil fuels. However, today most of this takes places in Japan and France: in most other nations renewable R&D get more money. In the U.S., public research money for nuclear fission declined from 2,179 to 35 million dollars between 1980 to 2000 [31] - however, in order to restart the industry, the next six U.S. reactors will receive subsidies equal to those of renewables and, in the event of cost overruns due to delays, at least partial compensation for the overruns (see Nuclear Power 2010 Program).

According to the DOE, insurance for nuclear or radiological incidents in the U.S., is subsidized [32] by the Price-Anderson Nuclear Industries Indemnity Act - in July 2005, Congress extended this Act to newer facilities. In the UK, the Nuclear Installations Act of 1965 governs liability for nuclear damage for which a UK nuclear licensee is responsible. The Vienna Convention on Civil Liability for Nuclear Damage puts in place an international framework for nuclear liability.
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Other economic issues

Nuclear Power plants tend to be most competitive in areas where other fuel resources are not readily available - France, most notably, has almost no native supplies of fossil fuels.[33] The province of Ontario, Canada is already using all of its best sites for hydroelectric power, and has minimal supplies of fossil fuels, so a number of nuclear plants have been built there. India too has few resources and is building new nuclear plants. Conversely, in the United Kingdom, according to the government's Department Of Trade And Industry, no further nuclear power stations are to be built, due to the high cost per unit of nuclear power, compared to fossil fuels.[34] However, the British government's chief scientific advisor David King reports that building one more generation of nuclear power plants may be necessary.[35] China tops the list of planned new plants, due to its rapidly expanding economy and fervent construction in many types of energy projects.[36]

Most new gas-fired plants are intended for peak supply. The larger nuclear and coal plants cannot quickly adjust their instantaneous power production, and are generally intended for baseline supply. The market price for baseline power has not increased as rapidly as that for peak demand. Some new experimental reactors, notably pebble bed modular reactors, are specifically designed for peaking power.

Any effort to construct a new nuclear facility around the world, whether an older design or a newer experimental design, must deal with NIMBY objections. Given the high profile of both the Three Mile Island and Chernobyl accidents, few municipalities welcome a new nuclear reactor, processing plant, transportation route, or experimental nuclear burial ground within their borders, and many have issued local ordinances prohibiting the development of nuclear power. However, a few U.S. areas with nuclear units are campaigning for more (see Nuclear Power 2010 Program).

Current nuclear reactors return around 40-60 times the invested energy when using life cycle analysis. This is better than coal, natural gas, and current renewables except hydropower.[37]

The Rocky Mountain Institute gives other reasons why nuclear power plants may not be economical.[38] In the U.S. this includes long lead times on risky investments, and the more cost-effective approach of investing in efficiency instead of new power plants.

Nuclear power, coal, and wind power are currently the only realistic large scale energy sources that would be able to replace oil and natural gas after a peak in global oil and gas production has been reached (see peak oil). However, The Rocky Mountain Institute claims that in the U.S. increases in transportation efficiency and stronger, lighter cars would replace most oil usage with what it calls negawatts.[39] Biofuels can then substitute for a significant portion of the remaining oil use. Efficiency, insulation, solar thermal, and solar photovoltaic technologies can substitute for most natural gas usage after a peak in production.

Nuclear proponents often assert that renewable sources of power have not solved problems like intermittent output, high costs, and diffuse output which requires the use of large surface areas and much construction material and which increases distribution losses. For example, studies in Britain have shown that increasing wind power production contribution to 20% of all energy production, without costly pumped hydro or electrolysis/fuel cell storage, would only reduce coal or nuclear power plant capacity by 6.7% (from 59 to 55 GWe) since they must remain as backup in the absence of power storage. Nuclear proponents often claim that increasing the contribution of intermittent energy sources above that is not possible with current technology.[40] Some renewable energy sources, such as solar, overlap well with peak electricial production and reduce the need of spare generating capacity. Future applications that use electricity when it is available (e.g. for pressurizing water systems, desalination, or hydrogen generation) would help to reduce the spare generation capacity required by both nuclear and renewable energy sources.[41]
[edit]

Risks

Some opponents of nuclear power, such as Greenpeace, and numerous anti-nuclear groups argue against its use due the long term problems of storing radioactive waste, the possibility that its use will lead to the proliferation of nuclear weapons, and the potential for severe radioactive contamination by an accident, often pointing to prior nuclear accidents. Recently, some opponents have softened their stance on nuclear power since it is currently the only mature technology used in the production of electricity that does not create greenhouse gases and therefore does not contribute to global warming.


Other critics of nuclear power, who may not necessarily oppose it as a viable source of energy, point out that industry oversight and compliance with safety regulations is often not up to par. Such critics include the Union of Concerned Scientists, the Nuclear Information and Research Service, The Bulletin of the Atomic Scientists, Physicians for Social Responsibility, The Nuclear Control Institute, and many others, as well as renowned physicists such as Dr. Michio Kaku.

According to a 1978 finding by the Supreme Court of the United States, comprehensive testing and study had not yet removed the risk of a major nuclear accident [42]. In the 1980s and 1990s each U.S. nuclear plant underwent an Individual Plant Examination process using probabilistic risk assessment to quantify the risks and identify and address high-risk areas.

To highlight what they believe are the risks, opponents quote the situation in the United States, where under the Price-Anderson Nuclear Industries Indemnity Act corporations requested and were granted immunity beyond (in 2005) $10 billion (all the available insurance plus pool monies combined) from civil liability (including from possible criminal behavior, although that would be subject to criminal prosecution) from a nuclear incident which causes harm to the public. (Beyond the $10 billion, Congress is required by law to act.)

Proponents argue that the risks are small and that fear has been the single largest obstacle to the widespread use of nuclear power. Assessment of nuclear risk was last done in the 1991 NUREG-1150 report. Additionally, competing technologies may have equivalent risks. Coal currently contributes significantly to problems like global warming, acid rain, various diseases due to airborne pollution, and the storage of large amounts of ash. Contrary to popular belief, coal power actually results in more radioactive waste being released into the environment than nuclear power [43], though the health risks of the coal-based radioactive release is small [44], particularly when compared with the hazards of other pollutants from coal burning.
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Accident or attack
The Ignalina nuclear power plant in Lithuania contains two RBMK reactors. Because of the safety flaws of the design, the closure of the plant was a condition of Lithuania's entry into the EU. The first of the two reactors was closed down in 2004 and the second is scheduled for shutdown by 2009. (Photograph courtesy of the Nordic Council).
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The Ignalina nuclear power plant in Lithuania contains two RBMK reactors. Because of the safety flaws of the design, the closure of the plant was a condition of Lithuania's entry into the EU. The first of the two reactors was closed down in 2004 and the second is scheduled for shutdown by 2009. (Photograph courtesy of the Nordic Council).

Opponents argue that a major disadvantage of the use of nuclear reactors is the threat of a nuclear accident or terrorist attack and the possible resulting exposure to radiation.

Proponents argue that the potential for a meltdown in non-Russian-designed reactors is very small due to the care taken in designing adequate safety systems, and that the nuclear industry has much better statistics regarding humans deaths from occupational accidents than coal or hydropower [45]. While the Chernobyl accident caused great negative health, economic, environmental and psychological effects in a widespread area, the accident at Chernobyl was caused by a combination of the faulty RBMK reactor design, the lack of a properly designed containment building, poorly trained operators, and a non-existent safety culture. The RBMK design, unlike nearly all designs used in the Western world, featured a positive void coefficient, meaning that a malfunction could result in ever-increasing generation of heat and radiation until the reactor was breached. Even at Three Mile Island, the most severe civilian nuclear accident in the non-Soviet world, the reactor vessel and containment building were never breached so that very little radiation (well below natural background radiation levels) was released into the environment.

Design changes are being pursued in the hope of lessening some of the risks of fission reactors; in particular, automated and passively safe designs are being pursued. Fusion reactors which may come to exist in the future theoretically have little risk since the fuel contained in the reaction chamber is only enough to sustain the reaction for about a minute, whereas a fission reactor contains about a year's supply of fuel. Subcritical reactors never have a self sustained nuclear chain reaction.

Opponents of nuclear power express concerns that nuclear waste is not well protected, and that it can be released in the event of terrorist attack, quoting a 1999 Russian incident where workers were caught trying to sell 5 grams of radioactive material on the open market [46], or the incident in 1993 where Russian workers were caught selling 4.5 kilograms of enriched uranium.[47] [48][49] The UN has since called upon world leaders to improve security in order to prevent radioactive material falling into the hands of terrorists [50], sometimes leading to the guarding of nuclear shipments by thousands of police [51] (see spent nuclear fuel shipping cask). Other energy sources, such as hydropower plants and LNG carriers, are more vulnerable to accidents and attacks. Proponents of nuclear power contend, however, that nuclear waste is already well protected, and state their argument that there has been no accident involving any form of nuclear waste from a civilian program worldwide. In addition, they point to large studies carried out by NRC and other agencies that tested the robustness of both reactor and waste fuel storage, and found that they should be able to sustain a terrorist attack comparable to the September 11 terrorist attacks.[52] Spent fuel is usually housed inside the plant's "protected zone" [53]; stealing it for use in a "dirty bomb" is extremely difficult - somewhat ironically, because the exposure to the intense radiation would almost certainly quickly incapacitate and kill any terrorists who attempt to do so.[54]

According to the Nuclear Regulatory Commission, 20 American States have requested stocks of potassium iodide which the NRC suggests should be available for those living within 10 miles of a nuclear power plant in the unlikely event of a severe accident.[55]
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Health effects on populations near nuclear plants

Most of the human exposure to radiation comes from natural background radiation. Most of the remaining exposure comes from medical procedures. Several large studies in the U.S., Canada, and Europe have found no evidence of any increase in cancer mortality among people living near nuclear facilities. For example, in 1990, the National Cancer Institute (NCI) of the National Institutes of Health announced that, after doing a large-scale study which evaluated the mortality rates from 16 types of cancer, no increased incidence of cancer mortality was found for people living near 62 nuclear installations in the United States. The study also showed no increase in the incidence of childhood leukemia mortality in the study of surrounding counties after the start-up of the nuclear facilities. The NCI study, the broadest of its kind ever conducted, surveyed 900,000 cancer deaths in counties near nuclear facilities.

Aside from the immediate effects of the Chernobyl accident (see above), there is continuing impact from soils containing radioactivity in Ukraine and Belarus. For this reason a Zone of alienation was established around the Chernobyl plant.

In March, 2006, safety reviews found that several nuclear plants in the United States have been leaking water contaminated with tritium into the ground, which will likely eventually drain into rivers.[56] The attorney general of Illinois announced she was filing a lawsuit against Exelon because of six such leaks, demanding that the utility provide substitute water supplies to residents although no well outside company property shows levels that exceed drinking water standards. According to the NRC, "The inspection determined that public health and safety has not been adversely affected and the dose consequence to the public that can be attributed to current onsite conditions is negligible with respect to NRC regulatory limits." [57]. However, the chairman of the Nuclear Regulatory Commission, said, "They're going to have to fix it."
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Nuclear proliferation

For more details on this topic, see Nuclear proliferation.

Opponents of nuclear power point out that nuclear technology is often dual-use, and much of the same materials and knowledge used in a civilian nuclear program can be used to develop nuclear weapons. This concern is known as nuclear proliferation and is a major reactor design criterion.

The military and civil purposes for nuclear energy are intertwined in most countries with nuclear capabilities. In the U.S., for example, the first goal of the Department of Energy is "to advance the national, economic, and energy security of the United States; to promote scientific and technological innovation in support of that mission; and to ensure the environmental cleanup of the national nuclear weapons complex." [58]

The enriched uranium used in most nuclear reactors is not concentrated enough to build a bomb. Most nuclear reactors run on 4% enriched uranium; Little Boy used 90% enriched uranium; while lower enrichment levels could be used, the minimum bomb size would rapidly become infeasibly large as the level was decreased. However, the technology used to enrich uranium for power generation could be used to make the highly enriched uranium needed to build a bomb.

In addition, the plutonium produced in power reactors, if concentrated through reprocessing, can be used for a bomb. While the plutonium resulting from normal reactor fuelling cycles is less than ideal for weapons use because of the concentration of Pu-240, a usable weapon can be produced from it. [59] If the reactor is operated on very short fuelling cycles, bomb-grade plutonium can be produced.

It is widely believed that the nuclear programs of India and Pakistan used CANDU reactors to produce fissionable materials for their weapons; however, this is not true. India used a research reactor named CIRUS, based on the Canadian NRX design[60]. Pakistan is believed to have produced the material for its weapons from an indigenous enrichment program [61].

To prevent weapons proliferation, safeguards on nuclear technology were published in the Nuclear Non-Proliferation Treaty (NPT) and monitored since 1968 by the International Atomic Energy Agency (IAEA). Nations signing the treaty are required to report to the IAEA what nuclear materials they hold and their location. They agree to accept visits by IAEA auditors and inspectors to verify independently their material reports and physically inspect the nuclear materials concerned to confirm physical inventories of them in exchange for access to nuclear materials and equipment on the global market.

Several states did not sign the treaty and were able to use international nuclear technology (often procured for civilian purposes) to develop nuclear weapons (India, Pakistan, Israel, and South Africa). South Africa has since signed the NPT, and now holds the distinction of being the only known state to have indigenously produced nuclear weapons, and then verifiably dismantled them[62]. Of those who have signed the treaty and received shipments of nuclear paraphernalia, many states have either claimed to or been accused of attempting to use supposedly civilian nuclear power plants for developing weapons, including Iran and North Korea. Certain types of reactors are more conducive to producing nuclear weapons materials than others, and a number of international disputes over proliferation have centered on the specific model of reactor being contracted for in a country suspected of nuclear weapon ambitions.

New technology, like SSTAR, may lessen the risk of nuclear proliferation by providing sealed reactors with a limited self-contained fuel supply and with restrictions against tampering.

One possible obstacle for expanding the use of nuclear power might be a limited supply of uranium ore, without which it would become necessary to build and operate breeder reactors. However, at current usage there is sufficient uranium for an extended period - "In summary, the actual recoverable uranium supply is likely to be enough to last several hundred (up to 1000) years, even using standard reactors." [63] (see Fuel resources above). Breeder reactors have been banned in the U.S. since President Jimmy Carter's administration prohibited reprocessing because of what it regarded as the unacceptable risk of proliferation of weapons-grade materials.

Some proponents of nuclear power agree that the risk of nuclear proliferation may be a reason to prevent nondemocratic developing nations from gaining any nuclear technology but argue that this is no reason for democratic developed nations to abandon their nuclear power plants. Especially since it seems that democracies never make war against each other (See the democratic peace theory).

Proponents also note that nuclear power, like some other power sources, provides steady energy at a consistent price without competing for energy resources from other countries, something that may contribute to wars.

In February, 2006, a new U.S. initiative, the Global Nuclear Energy Partnership was announced - it would be an international effort to reprocess fuel in a manner making proliferation infeasible, while making nuclear power available to developing countries.
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Environmental effects
[edit]

Air pollution

Non-radioactive water vapour is the significant operating emission from nuclear power plants [64]. Fission produces gases such as iodine-131 or Xenon-133 which have to be stored on-site for several half-lives until they have decayed to safe levels.

Nuclear generation does not directly produce sulphur dioxide, nitrogen oxides, mercury or other pollutants associated with the combustion of fossil fuels. (Pollution from fossil fuels is blamed for many deaths each year in the U.S. alone [65].) It also does not directly produce carbon dioxide, which has led some environmentalists to advocate increased reliance on nuclear energy as a means to reduce greenhouse gas emissions (which contribute to global warming)[66].

Like any power source (including renewables like wind and solar energy), the facilities to produce and distribute the electricity require energy to build and subsequently decommission. Mineral ores must be collected and processed to produce nuclear fuel. These processes are either directly powered by diesel and gasoline engines, or draw electricity from the power grid, which may be generated from fossil fuels. Life cycle analysis assesses the amount of energy consumed by these processes (given today's mix of energy resources) and calculates, over the lifetime of a nuclear power plant, the amount of carbon dioxide saved (related to the amount of electricity produced by the plant) vs. the amount of carbon dioxide used (related to construction and fuel acquisition).

Several life cycle analyses show similar emissions per kilowatt-hour from nuclear power and from renewables such as wind power [67]. According to one life cycle study (van Leeuwen and Smith 2001-2005 [68]), carbon dioxide emissions from nuclear power per kilowatt hour could range from 20% to 120% of those for natural gas-fired power stations depending on the availability of high grade ores. The study was rebutted in detail by the World Nuclear Association [69].

In 2006 a UK government advisory panel (the Sustainable Development Commission) concluded that if the UK's existing nuclear capacity were doubled, it would provide an 8% decrease in total UK CO2 emissions by 2035. This can be compared to the country's goal to reduce greenhouse gas emissions by 60 % by 2050. As of 2006, the UK government was to publish its official findings later in the year. [70]
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Waste heat in water systems

Nuclear reactors require cooling, typically with water (sometimes indirectly). The process of extracting energy from a heat source, called the Rankine cycle, requires the steam to be cooled down. Rivers are the most common source of cooling water, as well as the destination for waste heat. The temperature of exhaust water must be regulated to avoid killing fish; long-term impact of hotter-than-natural water on ecosystems is an environmental concern. In most new facilites, this problem is solved by implementing cooling towers.

The need to regulate exhaust temperature also limits generation capacity. On extremely hot days, which is when demand can be at its highest, the capacity of a nuclear plant may go down because the incoming water is warmer to begin with and is thus less effective as a coolant, per unit volume. This was a significant factor during the European heat wave of 2003. Engineers consider this in making improved power plant designs because increased cooling capacity will increase costs.

Developing technologies that take advantage of the clean abundant energy of the sun is important to reducing greenhouse gasses and helps stimulate the economy. Examples of solar technologies being developed by the Industry are Photovoltaic cells, concentrating solar power technologies and low temperature solar collectors.

Photovoltaic cells convert sunlight directly into electricity and are made of semiconductors such as crystalline silicon or various thin-film materials. Photovoltaics can provide tiny amounts of power for watches, large amounts for the electric grid, and everything in between.

Concentrating solar power technologies use reflective materials to concentrate the sun's heat energy, which ultimately drives a generator to produce electricity. These technologies include dish/engine systems, parabolic troughs, and central power towers.

Low-temperature solar collectors also absorb the sun's heat energy, but the heat is used directly for hot water or space heating for residential, commercial, and industrial facilities.


Wind

Wind energy uses the energy in the wind for practical purposes like generating electricity, charging batteries, pumping water, or grinding grain. Wind turbines convert the kinetic energy of the wind into other forms of energy. Large, modern wind turbines operate together in wind farms to produce electricity for utilities. Small turbines are used by homeowners and remote villages to help meet energy needs.



Wind power is the conversion of wind energy into more useful forms, usually electricity using wind turbines. In 2005, worldwide capacity of wind-powered generators was 58,982 megawatts, their production making up less than 1% of world-wide electricity use. Although still a relatively minor source of electricity for most countries, it accounts for 23% of electricity use in Denmark, 4.3% in Germany and around 8% in Spain. Globally, wind power generation more than quadrupled between 1999 and 2005.

Most modern wind power is generated in the form of electricity by converting the rotation of turbine blades into electrical current by means of an electrical generator. In windmills (a much older technology) wind energy is used to turn mechanical machinery to do physical work, like crushing grain or pumping water.

Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity in isolated locations.

Wind energy is abundant, renewable, widely distributed, clean, and mitigates the greenhouse effect if it is used to replace fossil-fuel-derived electricity.

Cost and growth

- The cost of wind-generated electric power has dropped substantially. Since 2004, according to some sources, the price in the United States is now lower than the cost of fuel-generated electric power, even without taking externalities into account.[1][2][3] In 2005, wind energy cost one-fifth as much as it did in the late 1990s, and that downward trend is expected to continue as larger multi-megawatt turbines are mass-produced.[4] A British Wind Energy Association report gives an average generation cost of onshore wind power of around 3.2 pence per kilowatt hour. [5]

- Wind power is growing quickly, at about 38% in 2003,[6] up from 25% growth in 2002. In the United States, as of 2003, wind power was the fastest growing form of electricity generation on a percentage basis.[7]
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Wind energy

Main article: Wind

An estimated 1 to 3% of energy from the Sun that hits the earth is converted into wind energy. This is about 50 to 100 times more energy than is converted into biomass by all the plants on earth through photosynthesis. Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur. Eventually, the wind energy is converted through friction into diffuse heat all through the earth's surface and atmosphere.

The origin of wind is simple. The earth is unevenly heated by the sun resulting in the poles receiving less energy from the sun than the equator does. Also the dry land heats up (and cools down) more quickly than the seas do. The differential heating powers a global atmospheric convection system reaching from the earth's surface to the stratosphere which acts as a virtual ceiling.
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Wind variability and turbine power
A Darrieus wind turbine.
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A Darrieus wind turbine.

The power in the wind can be extracted by allowing it to blow past moving wings that exert torque on a rotor. The amount of power transferred is directly proportional to the density of the air, the area swept out by the rotor, and the cube of the wind speed.

The power P available in the wind is given by:

P = \frac{1}{2}\rho\pi D^2 v^3.

where P is in watts, ρ (density of air) is measured in kg/m³, D (turbine blade length) is in m, and v (velocity of wind) is in m/s.

The mass flow of air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a cool 15°C (59°F) day at sea level, air density is about 1.22 kilograms per cubic metre (it gets less dense with higher humidity). An 8 m/s breeze blowing through a 100 meter diameter rotor would move about 76,000 kilograms of air per second through the swept area.

The kinetic energy of a given mass varies with the square of its velocity. Because the mass flow increases linearly with the wind speed, the wind energy available to a wind turbine increases as the cube of the wind speed. The power of the example breeze above through the example rotor would be about 2.5 megawatts.

As the wind turbine extracts energy from the air flow, the air is slowed down, which causes it to spread out and diverts it around the wind turbine to some extent. Albert Betz, a German physicist, determined in 1919 that a wind turbine can extract at most 59% of the energy that would otherwise flow through the turbine's cross section. The Betz limit applies regardless of the design of the turbine. More recent work by Gorlov shows a theoretical limit of about 30% for propeller-type turbines.[8] Actual efficiencies range from 10% to 20% for propeller-type turbines, and are as high as 35% for three-dimensional vertical-axis turbines like Darrieus or Gorlov turbines.
Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed. Energy is the Betz limit through a 100 meter diameter circle facing directly into the wind. Total energy for the year through that circle was 15.4 gigawatt-hours.
Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed. Energy is the Betz limit through a 100 meter diameter circle facing directly into the wind. Total energy for the year through that circle was 15.4 gigawatt-hours.

Windiness varies, and an average value for a given location does not alone indicate the amount of energy a wind turbine could produce there. To assess the climatology of wind speeds at a particular location, a probability distribution function is often fit to the observed data. Different locations will have different wind speed distributions. The distribution model most frequently used to model wind speed climatology is a two-parameter Weibull distribution because it is able to conform to a wide variety of distribution shapes, from gaussian to exponential. The Rayleigh model, an example of which is shown plotted against an actual measured dataset, is a specific form of the Weibull function in which the shape parameter equals 2, and very closely mirrors the actual distribution of hourly wind speeds at many locations.

Because so much power is generated by higher windspeed, much of the average power available to a windmill comes in short bursts. The 2002 Lee Ranch sample is telling: half of the energy available arrived in just 15% of the operating time. The consequence of this is that wind energy is not dispatchable as for fuel-fired power plants; additional output cannot be supplied in response to load demand. - - Since wind speed is not constant, a wind generator's annual energy production is never as much as its nameplate rating multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. A well-sited wind generator will have a capacity factor of as much as 35%. This compares to typical capacity factors of 90% for nuclear plants, 70% for coal plants, and 30% for oil plants.[9] When comparing the size of wind turbine plants to fueled power plants, it is important to note that 1000 kW of wind-turbine potential power would be expected to produce as much energy in a year as approximately 500 kW of coal-fired generation. Though the short-term (hours or days) output of a wind-plant is not completely predictable, the annual output of energy tends to vary only a few percent points between years. - - When storage, such as with pumped hydroelectric storage, or other forms of generation are used to "shape" wind power (by assuring constant delivery reliability), commercial delivery represents a cost increase of about 25%, yielding viable commercial performance.[1] Electricity consumption can be adapted to production variability to some extent with Energy Demand Management and smart meters that offer variable market pricing over the course of the day. For example, municipal water pumps that feed a water tower do not need to operate continuously and can be restricted to times when electricity is plentiful and cheap. Consumers could choose when to run the dishwasher or charge an electric vehicle.
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List of wind power availability

Many electric utility companies across the United States allow customers to sign up to have some or all of their electricity supplemented by alternative energy - wind in most cases.

Here is a list of some places where customers can sign up for this.

* Colorado
o Fort Collins - Fort Collins Utilities, Wind Power Program
o Denver - Xcel Energy - Windsource Online Sign up
* Florida - Florida Power & Light - Sunshine Energy
* Midwest - Aliant Energy, Second Nature Program
* Minnesota
o North Saint Paul - Sign up for the "Green Power" program
* Oklahoma - OG&E - Wind Power Sign Up
* Wisconsin
o Madison - Madison Gas & Electric, Sign Up for Wind Power
* Washington
o Seattle - Seattle City Light, Green Up Program
* Oregon
o Portland - Portland General Electric, Clean Wind

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Turbine siting
Map of available wind power over the United States. Color codes indicate wind power density class.
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Map of available wind power over the United States. Color codes indicate wind power density class.

As a general rule, wind generators are practical where the average wind speed is 10 mph or greater. Obviously, meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations. Meteorological wind data is not usually sufficient for accurate siting of a large wind power project. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year and would not suffer too many sudden powerful bursts of wind.

The wind blows faster at higher altitudes because of the reduced influence of drag of the surface (sea or land) and the reduced viscosity of the air. The increase in velocity with altitude is most dramatic near the surface and is affected by topography, surface roughness, and upwind obstacles such as trees or buildings. Typically, the increase of wind speeds with increasing height follows a logarithmic profile that can be reasonably approximated by the wind profile power law, using an exponent of 1/7th, which predicts that wind speed rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases the expected wind speeds by 10% and the expected power by 34%.[citation needed]

Wind farms or wind parks often have many turbines installed. Since each turbine extracts some of the energy of the wind, it is important to provide adequate spacing between turbines to avoid excess energy loss. Where land area is sufficient, turbines are spaced three to five rotor diameters apart perpendicular to the prevailing wind, and five to ten rotor diameters apart in the direction of the prevailing wind, to minimize efficiency loss. The "wind park effect" loss can be as low as 2% of the combined nameplate rating of the turbines.

Utility-scale wind turbine generators have minimum temperature operating limits which restrict the application in areas that routinely experience temperatures less than −20°C. Wind turbines must be protected from ice accumulation, which can make anemometer readings inaccurate and which can cause high structure loads and damage. Some turbine manufacturers offer low-temperature packages at a few percent extra cost, which include internal heaters, different lubricants, and different alloys for structural elements, to make it possible to operate the turbines at lower temperatures. If the low-temperature interval is combined with a low-wind condition, the wind turbine will require station service power, equivalent to a few percent of its output rating, to maintain internal temperatures during the cold snap. For example, the St. Leon, Manitoba project has a total rating of 99 MW and is estimated to need up to 3 MW (around 3% of capacity) of station service power a few days a year for temperatures down to −30°C. This factor affects the economics of wind turbine operation in cold climates.[citation needed]
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Onshore
Wind turbines near Walla Walla in Washington
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Wind turbines near Walla Walla in Washington

Onshore turbine installations tend to be on ridgelines. This is done to exploit the so-called topographic acceleration. The hill or ridge causes the wind to accerate as it is forced over it. The additial wind speeds gained in this way make large differences to the amount of energy that produced. Great attention must be paid to the exact positions of the turbines (a process known as micro-siting) because a difference of 30 m can sometimes mean a doubling in output. Local winds are often monitored for a year or more with anemometers and detailed wind maps constructed before wind generators are installed.

For smaller installations where such data collection is too expensive or time consuming, the normal way of prospecting for wind-power sites is to directly look for trees or vegetation that are permanently "cast" or deformed by the prevailing winds. Another way is to use a wind-speed survey map, or historical data from a nearby meteorological station, although these methods are less reliable.

Sea shores also tend to be windy areas and good sites for turbine installation, because a primary source of wind is convection from the differential heating and cooling of land and sea over the course of day and night. Winds at sea level carry somewhat more energy than winds of the same speed in mountainous areas because the air at sea level is more dense.

Wind farm siting can sometimes be highly controversial, particularly as the hilltop, often coastal sites preferred are often picturesque and environmentally sensitive (for instance, having substantial bird life). Local residents in a number of potential sites have strongly opposed the installation of wind farms, and political support has resulted in the blocking of construction of some installations [10].
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Offshore
Wind blows briskly and smoothly over water since there are no obstructions. The large and slow turning turbines of this offshore wind farm near Copenhagen take advantage of the moderate yet constant breezes here.
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Wind blows briskly and smoothly over water since there are no obstructions. The large and slow turning turbines of this offshore wind farm near Copenhagen take advantage of the moderate yet constant breezes here.

Offshore wind turbines cause less aesthetic controversy since they often cannot be seen from the shore. Because there are fewer obstacles and stronger winds, such turbines also don´t need to be built as high into the air. However, offshore turbines are more inaccessible and offshore conditions are harsh, abrasive, and corrosive, thereby increasing the costs of operation and maintenance compared to onshore turbines.

In areas with extended shallow continental shelves and sand banks (such as Denmark), turbines are reasonably easy to install, and give good service. At the site shown, the wind is not especially strong but is very consistent. The largest offshore wind turbines in the world are seven 3.6 MW rated machines off the east coast of Ireland about sixty kilometres south of Dublin. The turbines are located on a sandbank approximately ten kilometres from the coast that has the potential for the installation of 500 MW of generation capacity. As of 2006, the largest offshore wind farm is the Nysted Offshore Wind Farm at Rødsand, located about ten kilometres south of Nysted and thirteen kilometres west of Gedser Denmark. The wind farm consists of seventy two turbines of 2.3 MW, which produces 165.6 MW of power at rated wind speed.[11]. Three offshore wind farms in the United Kingdom are currently operating, North Hoyle (30 x 2 MW), Scroby Sand (30 x 2 MW) and Kentish flat (30 x 3 MW). Another offshore wind farm, Barrow (30 x 3 MW), is under construction. Under the energy policy of the United Kingdom further offshore facilities are feasible and expected by the year 2010.

Not all offshore wind farms have been without siting controversies, such as the proposed Cape Wind offshore development in the United States and the Havsul development in Norway.
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Airborne

Main article: Airborne wind turbine

Wind turbines might also be flown in high speed winds at altitude[12], although no such systems currently exist in the marketplace. An Ontario company, Magenn Power, Inc., is attempting to commercialize tethered aerial turbines suspended with helium[13]
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Vertical axis turbines

A prototype of vertical axis wind turbine is the Italian project called "Kitegen". It is an innovative plan (still in phase of construction) that consists in one wind farm with a vertical spin axis, and employs kites to exploit high-altitude winds.

The Kite Wind Generator (KWG) or KiteGen is claimed to eliminate all the static and dynamic problems that prevent the increase of the power (in terms of dimensions) obtainable from the traditional horizontal axis wind turbine generators. According to its developers, a one GigaWatt installation will be 1/40 the cost of the corresponding nuclear powerplant.

The project kitegen has received 15 million euro financing from the Italian state. It will begun with a 1 MW prototype and then with the planning of a power kitegen of 20 MW. [citation needed]
[edit]

Utilization
[edit]

Large scale
Total installed windpower capacity
(end of year & latest estimates)[14]
Capacity (MW)
Rank Nation Latest 2005 2004
1 Germany 19,267 18,428 16,629
2 Spain 10,941 10,027 8,263
3 USA 9,972 9,149 6,725
4 India 5,340 4,430 3,000
5 Denmark 3,128 3,124
6 Italy 1,717 1,265
7 United Kingdom 1,937 1,353 888
8 China 1,260 764
9 Netherlands 1,219 1,078
10 Japan 1,040 896
11 Portugal 1,022 522
12 Austria 819 606
13 France 918 757 386
14 Canada 1,049 683 444
15 Greece 573 473
16 Australia 817 572 379
17 Sweden 510 452
18 Ireland 496 339
19 Norway 270 270
20 New Zealand 168 168
21 Belgium 167 95
22 Egypt 145 145
23 South Korea 119 23
24 Taiwan 103 13
25 Finland 82 82
26 Poland 107 73 63
27 Ukraine 73 69
28 Costa Rica 70 70
29 Morocco 64 54
30 Luxembourg 35 35
31 Iran 32 25
32 Estonia 30 3
33 Philippines 29 29
34 Brazil 79 29 24
35 Czech Republic 28 17
36 Turkey 50 20 ?
World total ~63,000 58,982 47,671

There are many thousands of wind turbines operating, with a total capacity of 58,982 MW of which Europe accounts for 69% (2005). The average output of one megawatt of wind power is equivalent to the average consumption of about 160 American households. Wind power was the most rapidly-growing means of alternative electricity generation at the turn of the century and world wind generation capacity more than quadrupled between 1999 and 2005. 90% of wind power installations are in the US and Europe, but the share of the top five countries in terms of new installations fell from 71% in 2004 to 55% in 2005. By 2010, World Wind Energy Association expects 120,000 MW to be installed worldwide.[14]

Germany, Spain, the United States, India and Denmark have made the largest investments in wind generated electricity. Denmark is prominent in the manufacturing and use of wind turbines, with a commitment made in the 1970s to eventually produce half of the country's power by wind. Denmark generates over 20% of its electricity with wind turbines, the highest percentage of any country and is fifth in the world in total power generation (which can be compared with the fact that Denmark is 56th on the general electricity comsumption list). Denmark and Germany are leading exporters of large (0.66 to 5 MW) turbines.

Wind accounts for 1% of the total electricity production on a global scale (2005). Germany is the leading producer of wind power with 32% of the total world capacity in 2005 (6% of German electricity); the official target is that by 2010, renewable energy will meet 12.5% of German electricity needs - it can be expected that this target will be reached even earlier. Germany has 16,000 wind turbines, mostly in the north of the country - including three of the biggest in the world, constructed by the companies Enercon (4.5 MW), Multibrid (5 MW) and Repower (5 MW). Germany's Schleswig-Holstein province generates 25% of its power with wind turbines.

Spain and the United States are next in terms of installed capacity. In 2005, the government of Spain approved a new national goal for installed wind power capacity of 20,000 MW by 2012. According to trade journal Windpower Monthly, however, in 2006 they abruptly halted subsidies and price supports for wind power. According to the American Wind Energy Association, wind generated enough electricity to power 0.4% (1.6 million households) of total electricity in US, up from less than 0.1% in 1999. In 2005, both Germany and Spain have produced more electricity from wind power than from hydropower plants. US Department of Energy studies have concluded wind harvested in just three of the fifty U.S. states could provide enough electricity to power the entire nation, and that offshore wind farms could do the same job.[1] Wind power could grow by 50% in the U.S. in 2006.[15]

India ranks 4th in the world with a total wind power capacity of 5,340 MW. Wind power generates 3% of all electricity produced in India. The World Wind Energy Conference in New Delhi in November 2006 will give additional impetus to the Indian wind industry.[14] In December 2003, General Electric installed the world's largest offshore wind turbines in Ireland, and plans are being made for more such installations on the west coast, including the possible use of floating turbines.

On August 15, 2005, China announced it would build a 1000-megawatt wind farm in Hebei for completion in 2020. China reportedly has set a generating target of 20,000 MW by 2020 from renewable energy sources - it says indigenous wind power could generate up to 253,000 MW. Following the World Wind Energy Conference in November 2004, organised by the Chinese and the World Wind Energy Association, a Chinese renewable energy law was adopted. In late 2005, the Chinese government increased the official wind energy target for the year 2020 from 20 GW to 30 GW.[citation needed]

Another growing market is Brazil, with a wind potential of 143 GW.[16] The federal government has created an incentive program, called Proinfa,[17] to build production capacity of 3300 MW of renewable energy for 2008, of which 1422 MW through wind energy. The program seeks to produce 10% of Brazilian electricity through renewable sources. Brazil produced 320 TWh in 2004. France recently annonced a very ambitious target of 12 500 MW installed by 2010.

Over the 6 years from 2000-2005, Canada experienced rapid growth of wind capacity - moving from a total installed capacity of 137 MW to 943 MW, and showing a growth rate of 38% and rising.[18] This growth was fed by provincial measures, including installation targets, economic incentives and political support. For example, the government of the Canadian province of Ontario announced on 21 March 2006 that it will introduce a feed-in tariff for wind power, referred to as 'Standard Offer Contracts', which may boost the wind industry across the entire country.[19] In the Canadian province of Quebec, the state-owned hydroelectric utility plans to generate 2000 MW from wind farms by 2013.[20]
[edit]

Small scale

Main article: Small wind turbine

This rooftop-mounted urban wind turbine charges a 12 volt battery and runs various 12 volt appliances within the building on which it is installed.
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This rooftop-mounted urban wind turbine charges a 12 volt battery and runs various 12 volt appliances within the building on which it is installed.

Wind turbines have been used for household electricity generation in conjunction with battery storage over many decades in remote areas. Household generator units of more than 1 kW are now functioning in several countries.

To compensate for the varying power output, grid-connected wind turbines may utilise some sort of grid energy storage. Off-grid systems either adapt to intermittent power or use photovoltaic or diesel systems to supplement the wind turbine.

Wind turbines range from small four hundred watt generators for residential use to several megawatt machines for wind farms and offshore. The small ones have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind; while the larger ones generally have geared power trains, alternating current output, laps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched and direct current generators are sometimes used.

In urban locations, where it is difficult to obtain large amounts of wind energy, smaller systems may still be used to run low power equipment. Distributed power from rooftop mounted wind turbines can also alleviate power distribution problems, as well as provide resilience to power failures. Equipment such as parking meters or wireless internet gateways may be powered by a wind turbine that charges a small battery, replacing the need for a connection to the power grid and/or maintaining service despite possible power grid failures.
Small-scale wind power in rural Indiana.
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Small-scale wind power in rural Indiana.

Small scale turbines are available that are approximately 7 feet (2 m) in diameter and produce 900 watts. Units are lightweight, e.g. 16 kilograms (35 lbs), allowing rapid response to wind gusts typical of urban settings and easy mounting much like a television antenna. It is claimed that they are inaudible even a few feet under the turbine.[citation needed] Dynamic braking regulates the speed by dumping excess energy, so that the turbine continues to produce electricity even in high winds. The dynamic braking resistor may be installed inside the building to provide heat (during high winds when more heat is lost by the building, while more heat is also produced by the braking resistor). The proximal location makes low voltage (12 volt, or the like) energy distribution practical. An additional benefit is that owners become more aware of electricity consumption, possibly reducing their consumption down to the average level that the turbine can produce.

According to the World Wind Energy Association, it is difficult to assess the total number or capacity of small-scaled wind turbines, but in China alone, there are roughly 300,000 small-scale wind turbines generating electricity.[14]
[edit]

Debate for and against wind power

Arguments for and against wind power are listed below.
[edit]

Arguments of supporters
Erection of an Enercon E70-4
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Erection of an Enercon E70-4

Supporters of wind energy state that:
[edit]

Pollution

Wind power is a renewable resource, which means using it will not deplete the earth's supply of fossil fuels. It also is a clean energy source, and operation does not produce carbon dioxide, sulfur dioxide, mercury, particulates, or any other type of air pollution, as do conventional fossil fuel power sources.

During manufacture of the wind turbine, however, steel, concrete, aluminum and other materials will have to be made and transported using energy-intensive processes, generally using fossil energy sources. Nevertheless, the energy used for manufacture of a wind turbine is earned back in four to six months of operation.
[edit]

Long-term potential

Wind's long-term theoretical potential is much greater than current world energy consumption. The most comprehensive study to date[21] found the potential of wind power on land and near-shore to be 72 TW (~54,000 Mtoe), or over five times the world's current energy use and 40 times the current electricity use. The potential takes into account only locations with Class 3 (mean annual wind speeds ≥ 6.9 m/s at 80 m) or better wind regimes, which includes the locations suitable for low-cost (0.03–0.04 $/kWh) wind power generation and is in that sense conservative. It assumes 6 turbines per square km for 77-m diameter, 1,5 MW turbines on roughly 13% of the total land area. This potential assumes a capacity factor of 48% and does not take into account the practicality of reaching the windy sites or of transmission (including 'choke' points) or of competing land uses or of wheeling power over large distances or of switching to wind power.

To determine the more realistic technical potential it is essential how large a fraction of this land could be made available to wind power. In the 2001 IPCC report, it is assumed that a use of 4% - 10% of that land area would be practial. Even so, the potential comfortably exceeds current world electricity demand.

Offshore resources experience mean wind speeds ~90% greater than that of land, so offshore resources could contribute about seven times more energy than land.[22][23] This number could also increase with higher altitude or airborne wind turbines.[24]
[edit]

Coping with intermittency

* As the fraction of energy produced by wind ("penetration") increases, different technical and economic factors affect the need for grid energy storage facilities, demand side management, and/or other management of system load. Large networks, connected to multiple wind plants at widely separated geographic locations, may accept a higher penetration of wind than small networks or those without storage systems or economical methods of compensating for the variability of wind. In systems with significant amounts of existing pumped storage, hydropower or other peaking power plants, such as natural gas-fired power plants, this proportion may be higher. Isolated, relatively small systems with only a few wind plants may only be stable and economic with a lower fraction of wind energy (e.g. Ireland).

* On most large power systems a moderate proportion of wind generation can be connected without the need for storage. For larger proportions, storage may be economically attractive or even technically necessary. The profile of other generation facilities in the system (nuclear, coal, natural gas, hydro, etc.) will also influence the potential need for storage. At present, there are few large systems (for example, at the national or regional level) with sufficiently high wind generation to drive demand for storage, and discussion of the issue and potential upper limits for wind penetration remain largely hypothetical.

* Long-term storage of electrical energy involves substantial capital costs, space for storage facilities, and some portion of the stored power will be lost during conversion and transmission. The percentage retrievable from stored power is called the "efficiency of storage." The cost incurred to "shape" intermittent wind power for reliable delivery is about a 20% premium for most wind applications on large grids, but approaches 50% of the cost of generation when wind comprises more than 70% of the local grid's input power. See: Grid energy storage

Cement works in New South Wales, Australia. Energy-intensive process like this could utilize burst electricity from wind.
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Cement works in New South Wales, Australia. Energy-intensive process like this could utilize burst electricity from wind.

* Electricity demand is variable but generally very predictable on larger grids; errors in demand forecasting are typically no more than 2%. Because conventional powerplants can drop off the grid within a few seconds, for example due to equipment failures, in most systems the output of some coal or gas powerplants is intentionally part-loaded to follow demand and to replace rapidly lost generation. The ability to follow demand (by maintaining constant frequency) is termed "response." The ability to quickly replace lost generation, typically within timescales of 30 seconds to 30 minutes, is termed "spinning reserve." Nuclear power plants in contrast are not very flexible and are not intentionally part-loaded. A power plant that operates in a steady fashion, usually for many days continuously, is termed a "base load" plant. Generally thermal plants running as "peaking" plants will be less efficient than if they were running as base load. Hydroelectric facilities with storage capacity (such as the traditional dam configuration) may be operated as base load or peaking plants, and complement high levels of wind penetration.

* What happens in practice therefore is that as the power output from wind varies, part-loaded conventional plants, which must be there anyway to provide response (due to continuously changing demand) and reserve , adjust their output to compensate; they do this in response to small changes in the frequency (nominally 50 or 60 Hz) of the grid. In this sense wind acts like "negative" load or demand.

* The maximum proportion of wind power allowable in a power system will thus depend on many factors, including the size of the system, the attainable geographical diversity of wind, the conventional plant mix (coal, gas, nuclear, hydroelectric) and seasonal load factors (heating in winter, air-conditioning in summer) and their statistical correlation with wind output. For most large systems the allowable penetration fraction (wind nameplate rating divided by system peak demand) is thus at least 15% without the need for any energy storage whatsoever. Note that the interconnected electrical system may be much larger than the particular country or state (e.g. Denmark, California) being considered.

* It should also be borne in mind that wind output, especially from large numbers of turbines/farms can be predicted with a fair degree of confidence many hours ahead using weather forecasts.

* The allowable penetration may of course be further increased by increasing the amount of part-loaded generation available, or by using energy storage facilities, although if purpose-built for wind energy these may significantly increase the overall cost of wind power.

* Existing European hydroelectric power plants can store enough energy to supply one month's worth of European electricity consumption. Improvement of the international grid would allow using this in the relatively short term at low cost, as a matching variable complementary source to wind power. Excess wind power could even be used to pump water up into collection basins for later use. In practice, Denmark's system is well-integrated with the hydro-electric dominated Norwegian system, and Norwegian hydropower is used to balance fluctuations and shortfalls in Denmark; on occasion, Denmark exports electricity to Norway when generation is higher than demand (thereby increasing stored hydropower). Increased wind penetration may raise the value of existing peaking or storage facilities and particularly hydroelectric plants, as their ability to compensate for wind's variability will be under greater demand.

* Energy Demand Management or Demand-Side Management refers to the use of communication and switching devices which can release deferrable loads quickly to correct supply/demand imbalances. Incentives can be created for the use of these systems, such as favorable rates or capital cost assistance, encouraging consumers with large loads to take advantage of renewable energy by adjusting their loads to coincide with resource availability. For example, pumping water to pressurize municipal water systems is an electricity intensive application that can be performed when electricity is available.[25] Real-time variable electricity pricing can encourage all users to reduce usage when the renewable sources happen to be at low production.

* In energy schemes with a high penetration of wind energy, secondary loads, such as desalination plants and electric boilers may be encouraged because their output (water and heat) can be stored. The utilization of "burst electricity", where excess electricity is used on windy days for opportunistic purposes greatly improves the economic efficiency of wind turbine schemes. An ice storage device has been invented which allows cooling energy to be consumed during resource availability, and dispatched as air conditioning during peak hours.

* Multiple wind farms spread over a wide geographic area and gridded together produce power much more constantly.

* Electricity produced from solar energy could be a counter balance to the fluctuating supplies generated from wind. It tends to be windier at night and during cloudy or stormy weather, so there is likely to be more sunshine when there is less wind.

* Wind speeds tend to be higher in the winter and at night, so the appropriateness of wind power in high concentrations may crucially depend on the prevalence of air conditioning in a given jurisdiction. Wind power may be weakest in the hot summer months, and particularly during the day when air conditioning demand is highest. Conversely, systems where heat is electrical may be well-suited to higher penetration of wind power.

[edit]

Ecology

* Because it uses energy already present in the atmosphere, and can displace fossil-fuel generated electricity (with its accompanying carbon dioxide emissions), wind power mitigates global warming. While wind turbines might impact the numbers of some bird species, conventionally fueled power plants could wipe out hundreds or even thousands of the world's species through climate change, acid rain, and pollution.

* Energy payback ratio (ratio of energy produced compared to energy expended in construction and operation) for wind turbines has been estimated in one report to be between 17 and 39 (i.e. over its life-time a wind turbine produces 17-39 times as much energy as is needed for its manufacture, construction, operation and decommissioning). A similar Danish study determined the payback ratio to be 80, which means that a wind turbine system pays back the energy invested within approximately 3 months. [26] This is to be compared with payback ratios of 11 for coal power plants and 16 for nuclear power plants, though such figures do not take into account the energy content of the fuel itself, which would lead to a negative energy 'payback'.[27]

* Unlike fossil fuel or nuclear power stations, which circulate or evaporate large amounts of water for cooling, wind turbines do not need water to generate electricity.

* Studies show that the number of birds killed by wind turbines is negligible compared to the amount that die as a result of other human activities such as traffic, hunting, power lines and high-rise buildings and especially the environmental impacts of using non-clean power sources. For example, in the UK, where there are several hundred turbines, about one bird is killed per turbine per year; 10 million per year are killed by cars alone.[28] In the United States, turbines kill 70,000 birds per year, compared to 57 million killed by cars and 97.5 million killed by collisions with plate glass.[29] Another study suggests that migrating birds adapt to obstacles; those birds which don't modify their route and continue to fly through a wind farm are capable of avoiding the large offshore windmills,[30] at least in the low-wind non-twilight conditions studied. In the UK, the Royal Society for the Protection of Birds (RSPB) concluded that "The available evidence suggests that appropriately positioned wind farms do not pose a significant hazard for birds."[31] It notes that climate change poses a much more significant threat to wildlife, and therefore supports wind farms and other forms of renewable energy.

* Clearing of wooded areas is often unnecessary, as the practice of farmers leasing their land out to companies building wind farms is common. Farmers receive annual lease payments of two thousand to five thousand dollars per turbine.[32] The land can still be used for farming and cattle grazing.

* The ecological and environmental costs of wind plants are paid by those using the power produced, with no long-term effects on climate or local environment left for future generations.

* Less than 1% of the land would be used for foundations and access roads, the other 99% could still be used for farming.[33] Turbines can be sited on land unused in techniques such as center-pivot irrigation.

[edit]

Economic feasibility

* Conventional and nuclear power plants receive massive amounts of direct and indirect governmental subsidies. If a comparison is made on real production costs, wind energy is competitive in many cases. If the full costs (environmental, health, etc.) are taken into account, wind energy is competitive in most cases. Furthermore, wind energy costs are continuously decreasing due to technology development and scale enlargement.
* Nuclear power plants receive special immunity from the disasters they may cause, which prevents victims from recovering the cost of their continued health care from those responsible, even in the case of criminal malfeasance.
* Conventional and nuclear plants also have sudden unpredictable outages (see above). Statistical analysis shows that 1000 MW of wind power can replace 300 MW of conventional power.[citation needed]

[edit]

Aesthetics
Wind power is nothing new. Windmills at La Mancha, Spain.
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Wind power is nothing new. Windmills at La Mancha, Spain.

* Improvements in blade design and gearing have quietened modern turbines to the point where a normal conversation can be held underneath one

* Newer wind farms have more widely spaced turbines due to the greater power of the individual wind turbines, and so look less cluttered

* Wind turbines can be positioned alongside motorways, significantly reducing aesthetic concerns

* The aesthetics of wind turbines have been compared favourably to those of pylons from conventional power stations

* Areas under windfarms can be used for farming, and are protected from development

* Offshore sites have on average a higher energy yield than onshore sites, and often cannot be seen from the shore.

[edit]

Arguments of opponents
Some of the over 4000 wind turbines at Altamont Pass, in California. Developed during a period of tax incentives in the 1980s, this wind farm has more turbines than any other in the United States. These turbines are only a few tens of kilowatts each.
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Some of the over 4000 wind turbines at Altamont Pass, in California. Developed during a period of tax incentives in the 1980s, this wind farm has more turbines than any other in the United States. These turbines are only a few tens of kilowatts each.
[edit]

Economics

* To compete with traditional sources of energy, wind power often receives financial incentives. In the United States, wind power receives a tax credit currently of 1.9 cents per kilowatt-hour produced, with a yearly inflationary adjustment. Another tax benefit is accelerated depreciation. Many American states also provide incentives, such as exemption from property tax, mandated purchases, and additional markets for "green credits." Countries such as Canada and Germany also provide tax credits and other incentives for wind turbine construction.

* Many potential sites for wind farms are far from demand centers, requiring substantially more money to construct new transmission lines and substations.

[edit]

Yield

* The goals of renewable energy development are reduction of reliance on fossil and nuclear fuels, reduction of greenhouse gas and other emissions, and establishment of more sustainable sources of energy. Critics question wind energy's ability to significantly move society towards these goals. They point out that 20-30% annual load factor is typical for wind facilities. The intermittent and non-dispatchable nature of wind turbine power requires that "spinning reserves" are kept burning for supply security. The fluctuation in wind power requires more frequent load ramping of such plants to maintain grid system frequency. This can force operators to run conventional plants below optimal thermal efficiency, resulting in greater emissions. A recent European Nuclear Society study estimates that the equivalent of one third of energy saved from wind generation is lost to these inefficiencies.[citation needed]

[edit]

CO2 Emissions

* Electric power production is only part (about 39% in the USA[34]) of a country's energy use, so wind power alone does little to mitigate the larger part of the effects of energy use (except with a potential transition to electric or hydrogen vehicles). For example, despite more than doubling the installed wind power capacity in the U.K. from 2002 to 2004, wind power contributed less than 1% of the national electricity supply,[5] and that country's CO2 emissions continued to rise in 2002 and 2003 (Department of Trade and Industry). Six of the U.K.'s nuclear reactors were closed in this period.[35]

* Groups such as the UN's Intergovernmental Panel on Climate Change state that the desired mitigation goals can be achieved at lower cost and to a greater degree by continued improvements in general efficiency — in building, manufacturing, and transport — than by wind power.[36]

[edit]

Ecological Footprint

* The clearing of trees around tower bases may be necessary to enable installation. This is an issue for potential sites on mountain ridges, such as in the northeastern U.S.[37].

* Wind turbines should ideally be placed about ten times their diameter apart in the direction of prevailing winds and five times their diameter apart in the perpendicular direction for minimal losses due to wind park effects. As a result, wind turbines require roughly 0.1 square kilometres of unobstructed land per megawatt of nameplate capacity. A wind farm that produces the energy equivalent of a conventional power plant might have turbines spread out over an area of approximately 200 square kilometres.

A wind turbine at Greenpark, Reading, England
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A wind turbine at Greenpark, Reading, England

* Some windmills kill birds, especially birds of prey.[38] More recent siting generally takes into account known bird flight patterns, but some paths of bird migration, particularly for birds that fly by night, are unknown. A Danish survey in 2005 (Biology Letters 2005:336) showed that less than 1% of migrating birds passing a wind farm in Rønde, Denmark, got close to collision, though the site was studied only during low-wind non-twilight conditions. A survey at Altamont Pass, California, conducted by a California Energy Commission in 2004 showed that turbines killed between 1,766 and 4,721[39] birds annually (881 to 1,300 of which were birds of prey). Radar studies of proposed sites in the eastern U.S. have shown that migrating songbirds fly well within the reach of large modern turbine blades.

* A wind farm in Norway's Smøla islands is reported to have destroyed a colony of sea eagles, according to the British Royal Society for the Protection of Birds.[40] The society said turbine blades killed nine of the birds in a 10 month period, including all three of the chicks that fledged that year. Norway is regarded as the most important place for white-tailed eagles.

* The numbers of bats killed by existing facilities has troubled even industry personnel.[41] A six-week study in 2004 estimated that over 2200 bats were killed by 63 turbines at two sites in the eastern U.S.[42] This study suggests some site locations may be particularly hazardous to local bat populations, and that more research is urgently needed. Migratory bat species appear to be particularly at risk, especially during key movement periods (spring and more importantly in fall). Lasiurines such as the hoary bat (Lasiurus cinereus), and red bat (Lasiurus borealis) along with semi-migratory silver-haired bats (Lasionycteris noctivagans) appear to be most vulnerable at North American sites. Almost nothing is known about current populations of these species and the impact on bat numbers as a result of mortality at windpower locations.

[edit]

Scalability

* To meet the energy demands worldwide in the future in a sustainable way, a much larger number of turbines than we have today will be required. Naturally this will affect more people and wildlife habitat. In Denmark, wind power now accounts for close to 20% of electricity consumption [43] and a recent poll of Danes show that 90% want more wind power installed [44]. Danish wind power is dependent on the import and export of electricity to Germany, Sweden, and Norway at short notice when wind generated power is less than or greater than current demand, respectively. As its neighbors increase their own wind energy, this will not be as simple a solution.

[edit]

Aesthetics

* Recorded experience that wind turbines are noisy and visually intrusive creates resistance to the establishment of land-based wind farms in most places. Moving the turbines far offshore mitigates the problem, but offshore wind farms are more expensive to maintain and there is an increase in transmission loss due to longer distances of power lines.

* Some residents near windmills complain of "shadow flicker," which is the alternating pattern of sun and shade caused by a rotating windmill casting a shadow over residences. Efforts are made when siting turbines to avoid this problem.

* Large wind towers require strobe lights, which "pollute" the rural night sky.

Biomass
From Wikipedia, the free encyclopedia
Jump to: navigation, search

See biomass (ecology) for the use of the term in ecology, where it refers to the cumulation of living matter

Switchgrass, a hardy plant used in the biofuel industry in the United States
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Switchgrass, a hardy plant used in the biofuel industry in the United States

Biomass, in the energy production industry, refers to living and recently living biological material which can be used as fuel or for industrial production. Most commonly biomass refers to plant matter grown for use as biofuel, but also includes plant or animal matter used for production of fibres, chemicals or heat. Biomass may also include biodegradable wastes that can be burnt as fuel. It excludes organic material which has been transformed by geological processes into substances such as coal or petroleum. It is usually measured by dry weight.

The term "biomass" is especially useful for plants, where some internal structures may not always be considered living tissue, such as the wood (secondary xylem) of a tree.

Biofuels include bioethanol, biobutanol, biodiesel & biogas. Biodiesel and biobutanol are direct biofuels and can be used directly in petroleum engines.

Biomass is grown from several plants, including switchgrass, hemp, corn, willow and sugarcane[1]. The particular plant used is usually not very important to the end products, but it does affect the processing of the raw material. Production of biomass is a growing industry as interest in sustainable fuel sources is growing.

Though biomass is a renewable fuel, it can still contribute to global warming. This happens when the natural carbon equilibrium is disturbed; for example by deforestation or urbanisation of green sites.

Biomass is part of the carbon cycle. Carbon from the atmosphere is converted into biological matter by photosynthesis. On decay or combustion the carbon goes back into the atmosphere. This happens over a relatively short timescale and plant matter used as a fuel can be constantly replaced by planting for new growth. Therefore a reasonably stable level of atmospheric carbon results from its use as a fuel.

Although fossil fuels have their origin in ancient biomass, they are not considered biomass by the generally accepted definition because they contain carbon that has been 'out' of the carbon cycle for a very long time. Their combustion therefore disturbs the carbon dioxide content in the atmosphere.

Other uses of biomass, besides fuel:

* Building materials
* Biodegradable plastics and paper (using cellulose fibers)
Biomass Conversion
We are in the early phases of a truly historic transition--from an economy based largely on petroleum to a more diversified economy in which renewable plant biomass will become a significant feedstock for both fuel and chemical production. The development of the petroleum refining industry over the past century provides many instructive lessons for the future biobased economy and also many reasons for supposing that the new biobased economy will be different from the hydrocarbon economy in crucial ways.

While remaining supplies of petroleum, coal and natural gas are very large, it is nonetheless obvious that the world is using these nonrenewable resources at a huge and growing rate. Some experts believe that the peak rate of production of conventional oil will occur within this decade, (http://www.peakoil.net/) while others predict this turning point will occur before mid century. After that point, conventional, inexpensive oil production will irreversibly decline. Natural gas production will peak later than conventional oil, but will still begin permanent decline within the next few decades. Although other sources of petroleum exist (eg, tar sands, deepwater oil), they will be more difficult and much more expensive to produce. Whatever the exact date of peak oil production, we are approaching a major change in the way we must provide energy and other services to the world’s population as the era of “cheap oil” draws to a close.

Renewable agricultural and forestry resources have been used since ancient times as fuels and the raw materials for numerous products. Our laboratory research work and sustainability analyses are directed toward development of a mature, efficient economy based on renewable plant materials. We assume a mature biobased economy--as the petroleum economy is mature today--and from that assumption we extrapolate likely features of the mature biobased economy. Among the technical, social and economic forces that will drive the mature biobased economy are:

1. Yield (using the whole "barrel of biomass")
2. Gradual diversification of biobased products, probably starting with higher value chemical products and trending toward fuels over time
3. The great diversity of biomass resources combined with their considerable compositional similarity,
4. Possible/likely limits on agricultural productivity
5. Integration of biorefining and agricultural ecosystems in a local social and political context (the "all biomass is local" paradigm)
6. The sustainability of the mature biobased economy and its most important underlying resource--productive soils

Biofuel
From Wikipedia, the free encyclopedia
Jump to: navigation, search

For articles on specific fuels used in vehicles, see Biogas, Bioethanol, Biobutanol and Biodiesel

Environmental science
Environmental technology

* Air pollution control
* Energy conservation
* Hydrogen technologies
* Renewable energy
* Remediation
* Solid waste treatment
* Waste water treatment
* Water purification
* Waste management

Biofuel is any fuel that is derived from biomass — recently living organisms or their metabolic byproducts, such as manure from cows. It is a renewable energy source, unlike other natural resources such as petroleum, coal and nuclear fuels.

One definition of biofuel is any fuel with an 80% minimum content by volume of materials derived from living organisms harvested within the ten years preceding its manufacture[citation needed].

Like coal and petroleum, biomass is a form of stored solar energy. The energy of the sun is "captured" through the process of photosynthesis in growing plants. (See also: Systems ecology) One advantage of biofuel in comparison to most other fuel types is it is biodegradable, and thus relatively harmless to the environment if spilled.
Sugar cane a biofuel
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Sugar cane a biofuel

Agricultural products specifically grown for use as biofuels include corn and soybeans, primarily in the United States; as well as flaxseed and rapeseed, primarily in Europe; sugar cane in Brazil and palm oil in South-East Asia. Biodegradable outputs from industry, agriculture, forestry, and households can also be used to produce bioenergy; examples include straw, timber, manure, rice husks, sewage, biodegradable waste and food leftovers. These feedstocks are converted into biogas through anaerobic digestion. Biomass used as fuel often consists of underutilized types, like chaff and animal waste.

Much research is currently in progress into the utilization of microalgae as an energy source, with applications being developed for biodiesel, ethanol, methanol, methane, and even hydrogen. On the rise is use of hemp, although politics currently restrains this technology.
Portal:Energy
Energy Portal

Paradoxically, in some industrialized countries like Germany, food is cheaper than fuel compared by price per joule [citation needed]. Central heating units supplied by food grade wheat or maize are available.

Biofuel can be used both for central- and decentralized production of electricity and heat. As of 2005, bioenergy covers approximately 15% of the world's energy consumption. Most bioenergy is consumed in developing countries and is used for direct heating, as opposed to electricity production. However, Sweden and Finland supply 17% and 19% [1] respectively, of their energy needs with bioenergy, a high figure for industrialized countries.

The production of biofuels to replace oil and natural gas is in active development, focusing on the use of cheap organic matter (usually cellulose, agricultural and sewage waste) in the efficient production of liquid and gas biofuels which yield high net energy gain. The carbon in biofuels was recently extracted from atmospheric carbon dioxide by growing plants, so burning it does not result in a net increase of carbon dioxide in the Earth's atmosphere. As a result, biofuels are seen by many as a way to reduce the amount of carbon dioxide released into the atmosphere by using them to replace non-renewable sources of energy. Noticeable is the fact that the quality of timber or grassy biomass does not have a direct impact on its value as an energy-source.

Genencor and Novozymes are two other companies that have received United States government Department of Energy funding for research into reducing the cost of cellulase, a key enzyme in the production cellulosic ethanol by enzymatic hydrolysis.

Other enzyme companies, such as Dyadic International, Inc. (AMEX: DIL), have been using fungi to develop and manufacture cellulases in 150,000 liter industrial fermenters.

Dried compressed peat is also sometimes considered a biofuel. However, it does not meet the criteria of being a renewable form of energy, or of the carbon being recently absorbed from atmospheric carbon dioxide by growing plants. Though more recent than petroleum or coal, on the time scale of human industrialisation, peat is a fossil fuel and burning it does contribute to atmospheric CO2.
Contents
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History

Biofuel was used since the early days of the car industry. Nikolaus August Otto, the German inventor of the combustion engine, conceived his invention to run on ethanol. While Rudolf Diesel, the German inventor of the Diesel engine, conceived it to run on peanut oil. The Ford Model T, a car produced between 1903 and 1926 used ethanol. However, when crude oil began being cheaply extracted from deeper in the soil (thanks to drilling starting in the middle of the 19th century), cars began using fuels from oil. Nevertheless, before World War II, biofuels were seen as providing an alternative to imported oil in countries such as Germany, which sold a blend of gasoline with alcohol fermented from potatoes under the name Reichskraftsprit. In Britain, grain alcohol was blended with petrol by the Distillers Company Ltd under the name Discol and marketed through Esso's affiliate Cleveland.

After the War cheap Middle Eastern Oil lessened interest in biofuels. Then with the oil shocks of 1973 and 1979, there was an increase in interests from governments and academics in biofuels. However, interest decreased with the counter-shock of 1986 that made oil prices cheaper again. But since about 2000 with rising oil prices, concerns over the potential oil peak, greenhouse gas emissions (Global Warming), and instability in the Middle East are pushing renewed interest in biofuels. Government officials have made statements and given aid in favour of biofuels. For example, U.S. president George Bush said in his 2006 State of Union speech, that he wants for the United States, by 2025, to replace 75% of the oil coming from the Middle East.
[edit]

Types of high volume industrial biomass on Earth

Certain types of biomass have attracted research and industrial attention. Many of these are considered to be potentially useful for energy or for the production of bio-based products. Most of these are available in very large quantities and have low market value.

* Algae
* Bagasse from Sugarcane
* Dried distiller's grain
* Firewood
* Hemp
* Jatropha
* Landscaping waste
* Maiden Grass
* Maize (corn)
* Manure



* Meat and bone meal
* Miscanthus
* Peat
* Pet waste
* Plate waste
* Rice hulls
* Silage
* Stover
* Switchgrass
* Whey

[edit]

Examples of biofuels
[edit]

Biologically produced alcohols

Biologically produced alcohols, most commonly ethanol and methanol, and less commonly propanol and butanol produced by the action of bacteria — see alcohol fuel.

* Methanol, which is currently produced from natural gas, can also be produced from biomass — although this is not economically viable at present. The methanol economy is an interesting alternative to the hydrogen economy.
* Biomass to liquid, synthetic fuels produced from syngas. Syngas in turn, is produced from biomass by gasification.
* Ethanol fuel produced from sugar cane is being used as automotive fuel in Brazil. Ethanol produced from corn is being used mostly as a gasoline additive (oxygenator) in the United States, but direct use as fuel is growing. Cellulosic ethanol is being manufactured from straw (an agricultural waste product) by Iogen Corporation of Ontario, Canada; and other companies are attempting to do the same. ETBE containing 47% Ethanol is currently the biggest biofuel contributor in Europe.
* Butanol is formed by A.B.E. fermentation (Acetone, Butanol, Ethanol) and experimental modifications of the ABE process show potentially high net energy gains with butanol being the only liquid product. Butanol can be burned "straight" in existing gasoline engines (without modification to the engine or car), produces more energy and is less corrosive and less water soluble than ethanol, and can be distributed via existing infrastructures.
* Mixed Alcohols (e.g., mixture of ethanol, propanol, butanol, pentanol, hexanol and heptanol, such as EcaleneTM), obtained either by biomass-to-liquid technology (namely gasification to produce syngas followed by catalytic synthesis) or by bioconversion of biomass to mixed alcohol fuels.
* GTL or BTL both produce synthetic fuels out of biomass in the so called Fischer Tropsch process. The synthetic biofuel containing oxygen is used as additive in high quality diesel and petrol.

[edit]

Biologically produced gases

Biogas is produced by the process of anaerobic digestion of organic material by anaerobes. Biogas can be produced either from biodegradable waste materials or by the use of energy crops fed into anaerobic digesters to supplement gas yields. The solid ouput, digestate, can also be used as a biofuel.

Biogas contains methane and can be recovered in industrial anaerobic digesters and mechanical biological treatment systems. Landfill gas is a less clean form of biogas which is produced in landfills through naturally occurring anaerobic digestion. Paradoxically if this gas is allowed to escape into the atmosphere it is a potent greenhouse gas.
[edit]

Biologically produced gases from wastes

Biologically produced oils and gases can be produced from various wastes:

* Thermal depolymerization of waste can extract methane and other oils similar to petroleum.
* Pyrolysis oil may be produced out of biomass, wood waste etc. using heat only in the flash pyrolysis process. The oil has to be treated before using in conventional fuel systems or internal combustion engines (water + pH).
* One company, GreenFuel Technologies Corporation, has developed a patented bioreactor system that utilizes nontoxic photosynthetic algae to take in smokestacks flue gases and produce biofuels such as biodiesel, biogas and a dry fuel comparable to coal [2].

[edit]

Biologically produced oils

Biologically produced oils can be used in diesel engines:

* Straight vegetable oil (SVO).
* Waste vegetable oil (WVO) - waste cooking oils and greases produced in quantity mostly by commercial kitchens
* Biodiesel obtained from transesterification of animal fats and vegetable oil, directly usable in petroleum diesel engines.

[edit]

Applications of biofuels

One widespread use of biofuels is in home cooking and heating. Typical fuels for this are wood, charcoal or dried dung. The biofuel may be burned on an open fireplace or in a special stove. The efficiency of this process may vary widely, from 10% for a well made fire (even less if the fire is not made carefully) up to 40% for a custom designed charcoal stove1. Inefficient use of fuel may be a minor cause of deforestation (though this is negligible compared to deliberate destruction to clear land for agricultural use) but more importantly it means that more work has to be put into gathering fuel, thus the quality of cooking stoves has a direct influence on the viability of biofuels.

"American homeowners are turning to burning corn in special stoves to reduce their energy bills. Sales of corn-burning stoves have tripled this year [...] Corn-generated heat costs less than a fifth of the current rate for propane and about a third of electrical heat" [3].
[edit]

Direct electricity generation

The methane in biogas is often pure enough to pass directly through gas engines to generate green energy. Anaerobic digesters or biogas powerplants convert this renewable energy source into electricity. This can either be used commercially or on a local scale.
[edit]

Use on farms

In Germany small scale use of biofuel is still a domain of agricultural farms. It is an official aim of the German government to use the entire potential of 200,000 farms for the production of biofuel and bioenergy. (Source: VDI-Bericht "Bioenergie - Energieträger der Zukunft".
[edit]

Home use

Different combustion-engines are being produced for very low prices lately [4]. They allow the private house-owner to utilize low amounts of "weak" compression of methane to generate electrical and thermal power (almost) sufficient for a well insulated residential home.
[edit]

Rolling Network

Although decentralised biofuel production is possible the so called island operation bears problems with capacity and load balancing. In case vehicles for commuting and social or procurement trips may be used to transport energy we have a so called rolling network. We expect a higher efficiency with wood based biogas which may be purified in a home filling station and released into the natural gas network at work or special receiving gas stations. This kind of business is not bound to constant delivery amounts but very flexible in both directions. Ie. also gas refilling is possible if the wood gas production is low at the moment or the distance travelled was high. With so called plug in hybrid electric vehicles in theory it would be also possible to carry energy produced underway to work or to home and feed it into the grid. But this is less efficient and also less probable.
[edit]

Problems and solutions

Unfortunately, much cooking with biofuels is done indoors, without efficient ventilation, and using fuels such as dung causes airborne pollution. This can be a serious health hazard; 1.5 million deaths were attributed to this cause by the World Health Organisation as of 2000 2. There are various responses to this, such as improved stoves, including those with inbuilt flues and switching to alternative fuel sources. Most of these responses have difficulties. One is that fuels are expensive and easily damaged. Another is that alternative fuels tend to be more expensive, but the people who rely on biofuels often do so precisely because they cannot afford alternatives. 3 Organisations such as Intermediate Technology Development Group work to make improved facilities for biofuel use and better alternatives accessible to those who cannot currently get them. This work is done through improving ventilation, switching to different uses of biomass such as the creation of biogas from solid biomatter, or switching to other alternatives such as micro-hydro power. Many environmentalists are concerned that first growth forest may be felled in countries such as Indonesia to make way for palm oil plantations, driven by rising demand for diesel in SE Asia and Europe.
[edit]

Direct biofuel

Direct biofuels are biofuels that can be used in existing unmodified petroleum engines. Because engine technology changes all the time, exactly what a direct biofuel is can be hard to define; a fuel that works without problem in one unmodified engine may not work in another engine. In general, newer engines are more sensitive to fuel than older engines, but new engines are also likely to be designed with some amount of biofuel in mind.

Straight vegetable oil can be used in some (older) diesel engines. Only in the warmest climates can it be used without engine modifications, so it is of limited use in colder climates. Most commonly it is turned into biodiesel. No engine manufacturer explicitly allows any use of vegetable oil in their engines.

Biodiesel can be a direct biofuel. However, no current manufacturer covers their engine under warranty for 100% biodiesel[verification needed] (some have allowed 100% in the past, and it appears that changes in emission standards are the only reason they don't today, but no official statement exists). Many people have run thousands of miles on biodiesel without problem, and many studies have been made on 100% biodiesel.

Butanol is often claimed as a direct replacement for gasoline. It is not in wide spread production at this time, and engine manufacturers have not made statements about its use[verification needed]. While on paper (and a few lab tests) it appears that butanol has sufficiently similar characteristics with gasoline such that it should work without problem in any gasoline engine, no widespread experience exists.

Ethanol is the most common biofuel, and over the years many engines have been designed to run on it. Many of these could not run on regular gasoline. It is open to debate if ethanol is a direct replacement in these engines though - they cannot run on anything else. In the late 1990's engines started appearing that by design can use either fuel. Ethanol is a direct replacement in these engines, but it is debatable if these engines are unmodified, or factory modified for ethanol[verification needed].

Small amounts of biofuel are often blended with traditional fuels. The biofuel portion of these fuels is a direct replacement for the fuel they offset, but the total offset is small. For biodiesel, 5% or 20% are commonly approved by various engine manufacturers[citation needed]. See Common ethanol fuel mixtures for information on ethanol.
[edit]

International efforts

On the other hand, recognizing the importance of bioenergy and its implementation, there are international organizations such as IEA Bioenergy, established in 1978 by the International Energy Agency (IEA), with the aim of improving cooperation and information exchange between countries that have national programs in bioenergy research, development and deployment.
[edit]

Energy content of biofuel

For a comprehensive chart of energy contents from different biofuels please see Energy content of Biofuel

* Alcohol fuel
* Algaculture
* Anaerobic digestion
* Biobutanol, a direct biofuel that replaces gasoline.
* Biodiesel
* Biofuel in the United States
* Biogas powerplant
* Biogas
* Bioheat, a biofuel blended with heating oil.
* Biomass to liquid
* Biosphere
* By-product



* Energy content of biofuel
* Energy crop
* Ethanol fuel
* Ethanol fuel in Brazil
* Greenhouse gas
* Hybrid vehicle
* Hydrogen vehicle
* List of vegetable oils section on oils used as biofuel
* Mechanical biological treatment



* Thermal depolymerization
* Waste vegetable oil


Alcohol fuel
From Wikipedia, the free encyclopedia
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Gasoline on the left, alcohol on the right at a filling station in Brazil
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Gasoline on the left, alcohol on the right at a filling station in Brazil

Rising energy prices and environmental problems have led to increased interest in alcohol as a fuel. Alcohol has been used as a fuel in other points in history but fossil fuels have become the dominant energy resource for the modern world. Much attention has been placed on the prospects of using ethanol as fuel for cars.

The first four aliphatic alcohols (methanol, ethanol, propanol, and butanol) are of interest as fuels because they can be synthesized biologically, and they have characteristics which allow them to be used in current engines. One advantage shared by all four alcohols is octane rating. Biobutanol has the additional attraction that its energy per kilogram is closer to gasoline than the other alcohols (while still retaining over 25% higher octane rating).

Alcohol fuels are usually of biological rather than petroleum sources. When obtained from biological sources, they are sometimes known as bioalcohols (e.g. bioethanol). It is important to note that there is no chemical difference between biologically produced alcohols and that obtained from other sources. However, ethanol that is derived from petroleum should not be considered safe for consumption as this alcohol contains about 5% methanol and may cause blindness or death. This mixture may also not be purified by simple distillation, as it forms an azeotropic mixture.

Bioalcohols are not used in most industrial processes, as alcohols derived from petroleum are usually cheaper in the current economic millieu. Many economists argue that this fact illustrates the economic infeasibility of using bioalcohol as a petroleum substitute and argue that government programs that mandate the use of bioalcohol are simply agricultural subsidies. [citation needed] Lines of counter-argument point out that estimations of feasibility assume the current, status quo infrastructure, which already exists, and therefore is not an initial cost.[citation needed]

Recent "full up" energy analyses have shown that there is a net energy loss for use of bioalcohols. Use of more optimized crops, elimination of pesticides and fertilizers based on petroleum, and a more rigorous accounting process will help improve the feasibility of bioalcohols as fuels. [citation needed] The "full up" energy analysis does not include the energetic cost of synthesizing crude oil, making the comparison a largely moot point. This merely illustrates that extracting pre-made fuel requires less input energy than producing the fuel from other (potentially renewable) sources of energy.

Brazil is by far the largest producer of Alcohol Fuel in the world. They typically ferment Ethanol from sugarcane and suger beets.
Contents
[hide]

* 1 Methanol and ethanol
* 2 Propanol and Butanol
* 3 See also
* 4 External links

[edit]

Methanol and ethanol

For more details on this topic, see Methanol fuel.

For more details on this topic, see Ethanol fuel.

Ethanol and methanol both have advantages and disadvantages over fossil fuels, such as petrol and diesel. For instance, ethanol can run at a much higher compression ratio without octane-boosting additives (its octane rating is 129 as opposed to approximately 91 for ordinary petrol). It burns more completely because ethanol molecules contain oxygen; carbon monoxide emissions can be 80-90% lower than for fossil-fuelled engines[citation needed].

However, ethanol is degrading to some plastic or rubber parts of fuel delivery systems designed to use petrol, and has 37% less energy per litre than petrol. Methanol is even more corrosive and its energy per liter is 55% lower than that of petrol. High compression ratios and corrosion-resistant materials can overcome these issues, but require extensive engine modification.

Methanol has also been proposed as a fuel of the future. There has been extensive use of methanol fuel in Funny Cars for years, and it has been the fuel of Indy car racing in North America since 1965.

Ethanol is already being used extensively as a fuel additive, but the use of ethanol fuel alone or as part of a mix with gasoline is increasing. In 2007, the Indy Racing League will use ethanol as its exclusive fuel, after 40 years of using methanol [1].
[edit]

Propanol and Butanol

Propanol and butanol are considerably less toxic and less volatile than methanol. In particular, butanol has a high flashpoint of 35 °C, which is a benefit for fire safety, but may be a difficulty for starting engines in cold weather. The concept of flash point is however not directly applicable to engines as the compression of the air in the cylinder means that the temperature is several hundred degrees Celsius before ignition takes place.

The fermentation processes to produce propanol and butanol from cellulose are fairly tricky to execute, and the Weizmann organism (Clostridium acetobutylicum) currently used to perform these conversions produces an extremely unpleasant smell, and this must be taken into consideration when designing and locating a fermentation plant. This organism also dies when the butanol content of whatever it is fermenting rises to 7%. For comparison, yeast dies when the ethanol content of its feedstock hits 14%. Specialized strains can tolerate even greater ethanol concentrations - so-called turbo yeast can withstand up to 16% ethanol [2].

Despite these drawbacks, DuPont, British Petroleum, and British Sugar Corporation have reportedly started to convert an ethanol plant in the United Kingdom to produce butanol fuel from sugar beets (and in the future perhaps other starting materials).[3]


Biogas powerplant
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Environmental science
Environmental technology

* Air pollution control
* Energy conservation
* Hydrogen technologies
* Renewable energy
* Remediation
* Solid waste treatment
* Waste water treatment
* Water purification
* Waste management

A biogas powerplant is a system where biogas is used to generate electricity. The gas which is produced via anaerobic digestion is used to drive an electricity generator. By-products of this process are steam and hot water. The hot water can be recycled in a combined heat and power cycle to increase the temperature of the digesters to optimal conditions.
Contents
[hide]

* 1 Overview
* 2 Principle procedure
o 2.1 Plant engines
o 2.2 Plant types
o 2.3 Plant sizes
* 3 See also
* 4 External links
* 5 References
* 6 Education

[edit]

Overview
ArrowBio anaerobic digesters powering electricity generators, Hiriya, Tel Aviv, Israel
Enlarge
ArrowBio anaerobic digesters powering electricity generators, Hiriya, Tel Aviv, Israel

Biogas power plants are a combination of anaerobic digestion systems with associated electricity generators such as gas turbines or gas engines. The electricity they produce is classified as renewable or green energy and if sold into the national grid may attract subsidies (such as Renewables Obligation Certificates in the UK).

Feedstock into the biogas power plants must be biodegradable in order to produce methane. Suitable feedstocks include (but are not limited to):

* Biodegradable waste
* Sewage treatment sludge (primary or raw sludge and/or secondary sludge)
* Slaughterhouse waste
* Food waste
* Farm waste
* Organic component of mixed municipal waste (in mechanical biological treatment)
* Biomass like maize

There are three stages of anaerobic digestion: hydrolysis, acidogenesis, and methanogenesis. These stages can occur in the same digestion tank or can be controlled independently and optimised according to the requirements of the different bacterial processes.

The more complex and efficient a biogas plant the more expensive it will be for the locality. Biogas plants can be simplified to produce gas for villages in countries where organic wastes are available and funds are limited. Alternatively, in more developed countries pressure in the form of legislation and high energy costs is increasing the amount of projects generating renewable energy from waste.

Biogas plants can be found in countries such as India, China, Philippines, Germany, Austria and Turkey.

Advanced processing systems can recover the organic fraction mixed waste streams. These systems are a subgroup of mechanical biological treatment plants. They sort the recyclable elements of the waste and process the organic fraction into a high surface area low solids soup which are then passed into a biogas power plant (anaerobic digester). Advanced systems like this can be found in Israel.[1]. (ArrowBio) and Australia and are being widely considered in Europe to meet the EU Landfill Directive.

Further energy can be produced by the combustion of the digestate which may be classified as a biofuel.
[edit]

Principle procedure

Biogas production

* 1 Preparing the biomass
* 2 Mixing
* 3 Digester/fermenter (Heating 40-90 °C)

Gas input

* 4 Raw biogas input 40 °C
* 5 Liquid gas Separator → condensates
* 6 Gas dryer (refridge) 4 °C → condensates
* 7 Gas compressor about 400kPa
* 8 Gas filter (cleaning of dust particles, less then 5 parts per billion by mass of siloxanes)
* 9 Gas heating (minimum about 10 °C)

Gas combustion → thermal energy

* 10 Gas turbine exhaust output 300 to 400 °C
* 11 Generator → electric energy

Exhaust output → heat exchange

* 12 HRSG heat recovery steam generation
* 13 Heat exchanger for hot water

Siloxane might be present in the biogas and must be removed prior to input in the gas engines as it erodes moving parts. Hydrogen sulphide may also be produced in the process if there are high levels of sulphur in the biogas. The exhaust gas must be cleaned up as sulphur dioxide is toxic.
[edit]

Plant engines

* Gas motor engines
* Micro–gas turbines
* Fuel cells
* Boiler

[edit]

Plant types

Plant type depends on the type of biogas and usage of energy.

* CHP combined heat & power or HRSG
* CCHP combined cooling heat & power

[edit]

Plant sizes
Size Power Plant Size
Small 500W to 5 kW 10 m²
Medium 5 kW to 75 kW 15 to 100 m²
Large 75 kW to 4MW 1 km²

The plant can also be segmented including gas motors and gas turbines.

Ethanol fuel in Brazil
From Wikipedia, the free encyclopedia
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Gasoline on the left, alcohol on the right at a filling station in Brazil
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Gasoline on the left, alcohol on the right at a filling station in Brazil

In Brazil, ethanol fuel is produced from sugar cane which is a more efficient source of fermentable carbohydrates than corn as well as much easier to grow and process. Brazil has the largest sugarcane crop in the world, and is the largest producer of ethanol in the world. Sugar cane growing requires little labor, while government tax and pricing policies have made ethanol production a very lucrative business for big farms. Nearly all fueling stations in Brazil offer a choice of either E25 or pure ethanol.
Contents
[hide]

* 1 The National Program for Alcohol
* 2 Ethanol production basics
* 3 Electricity from bagasse
* 4 Program statistics
* 5 Effect on oil consumption
* 6 Environmental effects
* 7 Social implications
* 8 Exports of Brazilian ethanol
* 9 References
* 10 External links


The National Program for Alcohol
An early poster, prior to flexi-fuel engines, promoting alcohol fuel warns Brazilians not to mix standard petrol with alcohol fuel, and not to use alcohol in unconverted engines
Enlarge
An early poster, prior to flexi-fuel engines, promoting alcohol fuel warns Brazilians not to mix standard petrol with alcohol fuel, and not to use alcohol in unconverted engines

With the 1973 oil crisis the Brazilian government, then ran by a military junta, initiated in 1975 the Pró-Álcool program.

The Pró-Álcool or Programa Nacional do Álcool (National Alcohol Program) was wide-scale nation program financed by the government to phase out all automobile fuels derivated from fossil fuels (such as gasoline) in favour of ethanol. The program successfully reduced by 10 million the amount of cars running on gasoline in Brazil, therefore reducing the country's dependency of oil imports.

The decision to produce ethanol from fermented sugarcane was based on the low costs of sugar at the time. Other sources of fermentable carbohydrates were tested such as the manioc.
[edit]

Ethanol production basics

Sugarcane is harvested manually or mechanically and shipped to a processing plant, which is typically owned and run by big farms or farm consortia and located near the producing fields. There the cane is roller-pressed to extract the juice (garapa), leaving behind a fibrous residue (bagasse). The juice is fermented by yeasts which break down the sucrose into CO2 and ethanol. The resulting "wine" is distilled, yielding hydrated ethanol (5% water by volume) and "fusel oil". The acidic residue of the distillation (vinhoto) is neutralized with lime and sold as fertilizer. The hydrated ethanol may be sold as is (for ethanol cars) or be dehydrated and used as a gasoline additive (for gasohol cars). In either case, the bulk product was sold until 1996 at regulated prices to the state oil company (Petrobras). Today it is no longer regulated.

One tonne (1,000 kg) of harvested sugarcane, as shipped to the processing plant, contains about 145 kg of dry fiber (bagasse) and 138 kg of sucrose. Of that, 112 kg can be extracted as sugar, leaving 23 kg in low-valued molasses. If the cane is processed for alcohol, all the sucrose is used, yielding 72 liters of ethanol. Burning the bagasse produces heat for distillation and drying, and, through low-pressure boilers and turbines, about 288 Megajoule (MJ) of electricity, of which 180 MJ is used by the plant itself and 108 MJ sold to utilities.

The average cost of production, including farming, transportation and distribution, was US$0.23-0.29/litre in Brazil in mid-2005 [1], or US$0.87-1.10 per US gallon. The lower energy content of ethanol means that you need roughly a third more ethanol to drive the same number of miles as 1 gallon of petrol/gasoline - US Dept of Energy tests in 1998 saw a Ford Taurus (Mondeo) and Dodge Caravan (people carrier) needing 35-37% more E85 to travel the same distance. So to replace a gallon of fossil fuel you need US$1.16-1.47 of ethanol at mid-2005 prices. Adjusting for recent exchange rates, that is now US$1.25-1.57. The alcohol industry, entirely private, has invested heavily in crop improvement and agricultural techniques. As a result, average yearly ethanol yield increased steadily from 300 to 550 m³/km² between 1978 and 2000, or about 3.5% per year. But Brazil remains much the lowest cost producer of sugar, at a third of world sugar prices, and produces at 75% of the cost of other major producers like Australia and Thailand. With feedstock accounting for 70% of the cost of Brazilian bioethanol, no other country could produce ethanol from cane at much below US$2 per gallon of hydrocarbon equivalent with current technology.
[edit]

Electricity from bagasse
Sugar cane plant (Saccharum officinarum).
Enlarge
Sugar cane plant (Saccharum officinarum).

Sucrose accounts for little more than 30% of the chemical energy stored in the mature plant; 35% is in the leaves and stem tips, which are left in the fields during harvest, and 35% are in the fibrous material (bagasse) left over from pressing.

Part of the bagasse is currently burned at the mill to provide heat for distillation and electricity to run the machinery. This allows ethanol plants to be energetically self-sufficient and even sell surplus electricity to utilities; current production is 600 MW for self-use and 100 MW for sale. This secondary activity is expected to boom now that utilities have been convinced to pay fair price (about US$10/GJ or US$0.036/kWh) for 10 year contracts. The energy is especially valuable to utilities because it is produced mainly in the dry season when hydroelectric dams are running low. Estimates of potential power generation from bagasse range from 1,000 to 9,000 MW, depending on technology. Higher estimates assume gasification of biomass, replacement of current low-pressure steam boilers and turbines by high-pressure ones, and use of harvest trash currently left behind in the fields. For comparison, Brazil's Angra I nuclear plant generates 657 MW.

Presently, it is economically viable to extract about 288 MJ of electricity from the residues of one tonne of sugarcane, of which about 180 MJ are used in the plant itself. Thus a medium-size distillery processing 1 million tonnes of sugarcane per year could sell about 5 MW of surplus electricity. At current prices, it would earn US$ 18 million from sugar and ethanol sales, and about US$ 1 million from surplus electricity sales. With advanced boiler and turbine technology, the electricity yield could be increased to 648 MJ per tonne of sugarcane, but current electricity prices do not justify the necessary investment. (According to one report, the World bank would only finance investments in bagasse power generation if the price were at least US$19/GJ or US$0.068/kWh.)

Bagasse burning is environmentally friendly compared to other fuels like oil and coal. Its ash content is only 2.5% (against 30-50% of coal), and it contains no sulfur. Since it burns at relatively low temperatures, it produces little nitrous oxides. Moreover, bagasse is being sold for use as a fuel (replacing heavy fuel oil) in various industries, including citrus juice concentrate, vegetable oil, ceramics, and tyre recycling. The state of São Paulo alone used 2 million tonnes, saving about US$ 35 million in fuel oil imports.
[edit]

Program statistics

Except where noted, the following data apply to the 2003/2004 season.
land use: 45,000 km² in 2000
labour: 1 million jobs (50% farming, 50% processing)
sugarcane: 344 million metric tonnes (50% sugar, 50% alcohol)
sugar: 23 million tonnes (30% is exported)
ethanol: 14 million m³ (7.5 anhydrous, 6.5 hydrated; 2.4% is exported)
dry bagasse: 50 million tonnes
electricity: 1350 MW (1200 for self use, 150 sold to utilities) in 2001

The labour figures are industry estimates, and do not take into account the loss of jobs due to replacement of other crops by sugarcane
[edit]

Effect on oil consumption

Most cars in Brazil run either on alcohol or on gasohol; only recently dual-fuel ("Flex Fuel") engines have become available. Gas stations sell both fuels. The market share of the two car types has varied a lot over the last decades, in response to fuel price changes. Ethanol-only cars were sold in Brazil in significant numbers between 1980 and 1995; between 1983 and 1988, they accounted for over 90% of the sales. 80% of the cars produced in Brazil in 2005 were dual-fuel, compared to only 17% in 2004.

Ethanol-fuelled small planes for farm use have been developed by giant Embraer and by a small Brazilian firm (Aeroálcool), and are currently undergoing certification.

Domestic demand for alcohol grew between 1982 and 1998 from 11,000 to 33,000 cubic metres per day, and has remained roughly constant since then. In 1989 more than 90% of the production was used by ethanol-only cars; today that has reduced to about 40%, the remaining 60% being used with gasoline in gasohol-only cars. Both the total consumption of ethanol and the ethanol/gasohol ratio are expected to increase again with deployment of dual-fuel cars.

Presently the use of ethanol as fuel by Brazilian cars - as pure ethanol and in gasohol - replaces gasoline at the rate of about 27,000 cubic metres per day, or about 40% of the fuel that would be needed to run the fleet on gasoline alone. However, the effect on the country's overall oil use was much smaller than that: domestic oil consumption still far outweighs ethanol consumption (in 2005, Brazil consumed 2,000,000 barrels of oil per day, versus 280,000 barrels of ethanol)[2]. Although Brazil is a major oil producer and now exports gasoline (19,000 m³/day), it still must import oil because of internal demand for other oil byproducts, chiefly diesel fuel (which cannot be easily replaced by ethanol).
[edit]

Environmental effects

The improvement in air quality in big cities in the 1980s, following the widespread use of ethanol as car fuel, was widely evident; as was the degradation that followed the partial return to gasoline in the 1990s.

However, the ethanol program also brought a host of environmental and social problems of its own. Sugarcane fields were traditionally burned just before harvest, in order to remove the leaves and kill snakes. Therefore, in sugarcane-growing parts of the country, the smoke from burning fields turns the sky gray throughout the harvesting season. As winds carry the smoke into nearby towns, air pollution goes critical and respiratory problems soar. Thus, the air pollution which was removed from big cities was merely transferred to the rural areas (and multiplied). This practice has been decreasing of late, due to pressure from the public and health authorities. In Brazil, a recent law has been created in order to ban the burning of sugarcane fields, and machines will be used to harvest the cane instead of people. This not only solves the problem of pollution from burning fields, but such machines have a higher productivity than people.

Many nations have produced alcohol fuel with no destruction to the environment. Advancements in fertilizers and natural pesticides have eliminated the need to burn fields. With condensed agriculture, like hydroponics and greenhouses, less land is used to grow more crops.
[edit]

Social implications

The ethanol program also led to widespread replacement of small farms and varied agriculture by vast seas of sugarcane monoculture. This led to a decrease in biodiversity and further shrinkage of the residual native forests (not only from deforestation but also through fires caused by the burning of adjoining fields). The replacement of food crops by the more lucrative sugarcane has also led to a sharp increase in food prices over the last decade.

Since sugarcane only requires hand labor at harvest time, this shift also created a large population of destitute migrant workers who can only find temporary employment as cane cutters (at about US$3 to 5 per day) for one or two months every year. This huge social problem has contributed to political unrest and violence in rural areas, which are now plagued by recurrent farm invasions, vandalism, armed confrontations, and assassinations.

Some question the viabiliy of biofuels like ethanol as total replacements for gasoline/crude oil. One concern is that sugarcane cultivation will displace other crops, thus causing food shortages. However, these concerns seem to be groundless. Despite having the world's largest sugarcane crop, the 45,000 km² Brazil currently devotes to sugarcane production amount to only about one-half of one percent of its total land area of some 8.5 million km². In addition, the country has more unused potential cropland than any other nation. Some commentators, like George Monbiot, fear that the marketplace will convert crops to fuel for the rich, while the poor starve and biofuels cause environmental problems. It is unclear how this would be different from the current situation, as most food crops are grown and exported to richer nations, and neglects the very real environmental problems that the burning of fossil fuels causes. The cultivation of sugarcane for energy production is only likely to increase as fossil fuels become increasingly scarce and more expensive.
[edit]

Exports of Brazilian ethanol

On 19 December 2005, the government-based Petrobras announced a contract with the Japanese Nippon Alcohol Hanbai for the creation of a joint-venture based in Japan to import ethanol from Brazil. The company, Brazil-Japan Ethanol, will have as its main object the creation of an ethanol market in Japan.

The U.S., potentially the largest market for the Brazilian ethanol, currently imposes trade restrictions on the product in order to encourage domestic production of corn ethanol, which is, however, much less efficient than its sugarcane counterpart.

Ethanol fuel in Brazil
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Jump to: navigation, search
Gasoline on the left, alcohol on the right at a filling station in Brazil
Enlarge
Gasoline on the left, alcohol on the right at a filling station in Brazil

In Brazil, ethanol fuel is produced from sugar cane which is a more efficient source of fermentable carbohydrates than corn as well as much easier to grow and process. Brazil has the largest sugarcane crop in the world, and is the largest producer of ethanol in the world. Sugar cane growing requires little labor, while government tax and pricing policies have made ethanol production a very lucrative business for big farms. Nearly all fueling stations in Brazil offer a choice of either E25 or pure ethanol.
Contents
[hide]

* 1 The National Program for Alcohol
* 2 Ethanol production basics
* 3 Electricity from bagasse
* 4 Program statistics
* 5 Effect on oil consumption
* 6 Environmental effects
* 7 Social implications
* 8 Exports of Brazilian ethanol
* 9 References
* 10 External links

[edit]

The National Program for Alcohol
An early poster, prior to flexi-fuel engines, promoting alcohol fuel warns Brazilians not to mix standard petrol with alcohol fuel, and not to use alcohol in unconverted engines
Enlarge
An early poster, prior to flexi-fuel engines, promoting alcohol fuel warns Brazilians not to mix standard petrol with alcohol fuel, and not to use alcohol in unconverted engines

With the 1973 oil crisis the Brazilian government, then ran by a military junta, initiated in 1975 the Pró-Álcool program.

The Pró-Álcool or Programa Nacional do Álcool (National Alcohol Program) was wide-scale nation program financed by the government to phase out all automobile fuels derivated from fossil fuels (such as gasoline) in favour of ethanol. The program successfully reduced by 10 million the amount of cars running on gasoline in Brazil, therefore reducing the country's dependency of oil imports.

The decision to produce ethanol from fermented sugarcane was based on the low costs of sugar at the time. Other sources of fermentable carbohydrates were tested such as the manioc.
[edit]

Ethanol production basics

Sugarcane is harvested manually or mechanically and shipped to a processing plant, which is typically owned and run by big farms or farm consortia and located near the producing fields. There the cane is roller-pressed to extract the juice (garapa), leaving behind a fibrous residue (bagasse). The juice is fermented by yeasts which break down the sucrose into CO2 and ethanol. The resulting "wine" is distilled, yielding hydrated ethanol (5% water by volume) and "fusel oil". The acidic residue of the distillation (vinhoto) is neutralized with lime and sold as fertilizer. The hydrated ethanol may be sold as is (for ethanol cars) or be dehydrated and used as a gasoline additive (for gasohol cars). In either case, the bulk product was sold until 1996 at regulated prices to the state oil company (Petrobras). Today it is no longer regulated.

One tonne (1,000 kg) of harvested sugarcane, as shipped to the processing plant, contains about 145 kg of dry fiber (bagasse) and 138 kg of sucrose. Of that, 112 kg can be extracted as sugar, leaving 23 kg in low-valued molasses. If the cane is processed for alcohol, all the sucrose is used, yielding 72 liters of ethanol. Burning the bagasse produces heat for distillation and drying, and, through low-pressure boilers and turbines, about 288 Megajoule (MJ) of electricity, of which 180 MJ is used by the plant itself and 108 MJ sold to utilities.

The average cost of production, including farming, transportation and distribution, was US$0.23-0.29/litre in Brazil in mid-2005 [1], or US$0.87-1.10 per US gallon. The lower energy content of ethanol means that you need roughly a third more ethanol to drive the same number of miles as 1 gallon of petrol/gasoline - US Dept of Energy tests in 1998 saw a Ford Taurus (Mondeo) and Dodge Caravan (people carrier) needing 35-37% more E85 to travel the same distance. So to replace a gallon of fossil fuel you need US$1.16-1.47 of ethanol at mid-2005 prices. Adjusting for recent exchange rates, that is now US$1.25-1.57. The alcohol industry, entirely private, has invested heavily in crop improvement and agricultural techniques. As a result, average yearly ethanol yield increased steadily from 300 to 550 m³/km² between 1978 and 2000, or about 3.5% per year. But Brazil remains much the lowest cost producer of sugar, at a third of world sugar prices, and produces at 75% of the cost of other major producers like Australia and Thailand. With feedstock accounting for 70% of the cost of Brazilian bioethanol, no other country could produce ethanol from cane at much below US$2 per gallon of hydrocarbon equivalent with current technology.
[edit]

Electricity from bagasse
Sugar cane plant (Saccharum officinarum).
Enlarge
Sugar cane plant (Saccharum officinarum).

Sucrose accounts for little more than 30% of the chemical energy stored in the mature plant; 35% is in the leaves and stem tips, which are left in the fields during harvest, and 35% are in the fibrous material (bagasse) left over from pressing.

Part of the bagasse is currently burned at the mill to provide heat for distillation and electricity to run the machinery. This allows ethanol plants to be energetically self-sufficient and even sell surplus electricity to utilities; current production is 600 MW for self-use and 100 MW for sale. This secondary activity is expected to boom now that utilities have been convinced to pay fair price (about US$10/GJ or US$0.036/kWh) for 10 year contracts. The energy is especially valuable to utilities because it is produced mainly in the dry season when hydroelectric dams are running low. Estimates of potential power generation from bagasse range from 1,000 to 9,000 MW, depending on technology. Higher estimates assume gasification of biomass, replacement of current low-pressure steam boilers and turbines by high-pressure ones, and use of harvest trash currently left behind in the fields. For comparison, Brazil's Angra I nuclear plant generates 657 MW.

Presently, it is economically viable to extract about 288 MJ of electricity from the residues of one tonne of sugarcane, of which about 180 MJ are used in the plant itself. Thus a medium-size distillery processing 1 million tonnes of sugarcane per year could sell about 5 MW of surplus electricity. At current prices, it would earn US$ 18 million from sugar and ethanol sales, and about US$ 1 million from surplus electricity sales. With advanced boiler and turbine technology, the electricity yield could be increased to 648 MJ per tonne of sugarcane, but current electricity prices do not justify the necessary investment. (According to one report, the World bank would only finance investments in bagasse power generation if the price were at least US$19/GJ or US$0.068/kWh.)

Bagasse burning is environmentally friendly compared to other fuels like oil and coal. Its ash content is only 2.5% (against 30-50% of coal), and it contains no sulfur. Since it burns at relatively low temperatures, it produces little nitrous oxides. Moreover, bagasse is being sold for use as a fuel (replacing heavy fuel oil) in various industries, including citrus juice concentrate, vegetable oil, ceramics, and tyre recycling. The state of São Paulo alone used 2 million tonnes, saving about US$ 35 million in fuel oil imports.
[edit]

Program statistics

Except where noted, the following data apply to the 2003/2004 season.
land use: 45,000 km² in 2000
labour: 1 million jobs (50% farming, 50% processing)
sugarcane: 344 million metric tonnes (50% sugar, 50% alcohol)
sugar: 23 million tonnes (30% is exported)
ethanol: 14 million m³ (7.5 anhydrous, 6.5 hydrated; 2.4% is exported)
dry bagasse: 50 million tonnes
electricity: 1350 MW (1200 for self use, 150 sold to utilities) in 2001

The labour figures are industry estimates, and do not take into account the loss of jobs due to replacement of other crops by sugarcane
[edit]

Effect on oil consumption

Most cars in Brazil run either on alcohol or on gasohol; only recently dual-fuel ("Flex Fuel") engines have become available. Gas stations sell both fuels. The market share of the two car types has varied a lot over the last decades, in response to fuel price changes. Ethanol-only cars were sold in Brazil in significant numbers between 1980 and 1995; between 1983 and 1988, they accounted for over 90% of the sales. 80% of the cars produced in Brazil in 2005 were dual-fuel, compared to only 17% in 2004.

Ethanol-fuelled small planes for farm use have been developed by giant Embraer and by a small Brazilian firm (Aeroálcool), and are currently undergoing certification.

Domestic demand for alcohol grew between 1982 and 1998 from 11,000 to 33,000 cubic metres per day, and has remained roughly constant since then. In 1989 more than 90% of the production was used by ethanol-only cars; today that has reduced to about 40%, the remaining 60% being used with gasoline in gasohol-only cars. Both the total consumption of ethanol and the ethanol/gasohol ratio are expected to increase again with deployment of dual-fuel cars.

Presently the use of ethanol as fuel by Brazilian cars - as pure ethanol and in gasohol - replaces gasoline at the rate of about 27,000 cubic metres per day, or about 40% of the fuel that would be needed to run the fleet on gasoline alone. However, the effect on the country's overall oil use was much smaller than that: domestic oil consumption still far outweighs ethanol consumption (in 2005, Brazil consumed 2,000,000 barrels of oil per day, versus 280,000 barrels of ethanol)[2]. Although Brazil is a major oil producer and now exports gasoline (19,000 m³/day), it still must import oil because of internal demand for other oil byproducts, chiefly diesel fuel (which cannot be easily replaced by ethanol).
[edit]

Environmental effects

The improvement in air quality in big cities in the 1980s, following the widespread use of ethanol as car fuel, was widely evident; as was the degradation that followed the partial return to gasoline in the 1990s.

However, the ethanol program also brought a host of environmental and social problems of its own. Sugarcane fields were traditionally burned just before harvest, in order to remove the leaves and kill snakes. Therefore, in sugarcane-growing parts of the country, the smoke from burning fields turns the sky gray throughout the harvesting season. As winds carry the smoke into nearby towns, air pollution goes critical and respiratory problems soar. Thus, the air pollution which was removed from big cities was merely transferred to the rural areas (and multiplied). This practice has been decreasing of late, due to pressure from the public and health authorities. In Brazil, a recent law has been created in order to ban the burning of sugarcane fields, and machines will be used to harvest the cane instead of people. This not only solves the problem of pollution from burning fields, but such machines have a higher productivity than people.

Many nations have produced alcohol fuel with no destruction to the environment. Advancements in fertilizers and natural pesticides have eliminated the need to burn fields. With condensed agriculture, like hydroponics and greenhouses, less land is used to grow more crops.
[edit]

Social implications

The ethanol program also led to widespread replacement of small farms and varied agriculture by vast seas of sugarcane monoculture. This led to a decrease in biodiversity and further shrinkage of the residual native forests (not only from deforestation but also through fires caused by the burning of adjoining fields). The replacement of food crops by the more lucrative sugarcane has also led to a sharp increase in food prices over the last decade.

Since sugarcane only requires hand labor at harvest time, this shift also created a large population of destitute migrant workers who can only find temporary employment as cane cutters (at about US$3 to 5 per day) for one or two months every year. This huge social problem has contributed to political unrest and violence in rural areas, which are now plagued by recurrent farm invasions, vandalism, armed confrontations, and assassinations.

Some question the viabiliy of biofuels like ethanol as total replacements for gasoline/crude oil. One concern is that sugarcane cultivation will displace other crops, thus causing food shortages. However, these concerns seem to be groundless. Despite having the world's largest sugarcane crop, the 45,000 km² Brazil currently devotes to sugarcane production amount to only about one-half of one percent of its total land area of some 8.5 million km². In addition, the country has more unused potential cropland than any other nation. Some commentators, like George Monbiot, fear that the marketplace will convert crops to fuel for the rich, while the poor starve and biofuels cause environmental problems. It is unclear how this would be different from the current situation, as most food crops are grown and exported to richer nations, and neglects the very real environmental problems that the burning of fossil fuels causes. The cultivation of sugarcane for energy production is only likely to increase as fossil fuels become increasingly scarce and more expensive.
[edit]

Exports of Brazilian ethanol

On 19 December 2005, the government-based Petrobras announced a contract with the Japanese Nippon Alcohol Hanbai for the creation of a joint-venture based in Japan to import ethanol from Brazil. The company, Brazil-Japan Ethanol, will have as its main object the creation of an ethanol market in Japan.

The U.S., potentially the largest market for the Brazilian ethanol, currently imposes trade restrictions on the product in order to encourage domestic production of corn ethanol, which is, however, much less efficient than its sugarcane counterpart.

Hydrogen vehicle
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Sequel, a fuel cell powered vehicle from General Motors
Enlarge
Sequel, a fuel cell powered vehicle from General Motors

A hydrogen vehicle is a vehicle, such as an automobile or aeroplane which uses hydrogen as its primary source of power for locomotion. These cars generally use the hydrogen in one of two methods: combustion or fuel-cell conversion. In combustion, the hydrogen is "burned" in engines in fundamentally the same method as traditional gasoline cars. In fuel-cell conversion, the hydrogen is turned into electricity through fuel cells which then power electric motors.

Hydrogen can be obtained through various thermochemical methods utilizing methane (natural gas), coal (by a process known as coal gasification), liquified petroleum gas, biomass (biomass gasification), or from water by electrolysis or by a process called thermolysis. A primary benefit of using pure hydrogen as a power source would be that it uses oxygen from the air to produce water vapor as exhaust. Another benefit is that, theoretically, the source of pollution created today by burning fossil fuels could be moved to centralized power plants, where the byproducts of burning fossil fuels can be better controlled. Hydrogen could also be produced from renewable energy sources with no net increase in carbon dioxide emissions. However, as explained below, the technical challenges required to realize this benefit may not be solved for many decades.


Contents
[hide]

* 1 Research and prototypes
* 2 Hydrogen fuel cell difficulties
o 2.1 Low volumetric energy
o 2.2 High cost of fuel cells
o 2.3 Hydrogen production costs
o 2.4 Hydrogen infrastructure
o 2.5 Political considerations
* 3 Hydrogen internal combustion
* 4 Related Patents
* 5 Automobile and bus makers
* 6 Fuel stations
* 7 Planes
* 8 References
* 9 See also
* 10 External links

[edit]

Research and prototypes

Hydrogen does not act as a pre-existing source of energy like fossil fuels, but a carrier, much like a battery. It can be made from both renewable and non-renewable energy sources. The largest potential advantage is that it could be produced and consumed continuously, using solar, water, wind and nuclear power for electrolysis. Current hydrogen production methods utilizing hydrocarbons produce less pollution than would direct consumption of the same hydrocarbon fuel, gasoline, diesel or methane, in a modern internal combustion engine. Hydrogen will generate less CO2 than conventional internal combustion engines if emissions throughout the entire fuel cycle are compared [1] [2] and thus would contribute less to atmospheric radiative forcing per mile driven. Methods of hydrogen production that do not use fossil fuel would be more sustainable and would exhibit price volatility to a lesser degree than would methods relying on fossil fuels.

A small number of experimental hydrogen cars currently exist, and a significant amount of research is underway to try to make the technology viable. The common internal combustion engine, usually fueled with gasoline (petrol) or diesel liquids, can be converted to run on gaseous hydrogen. However, the more energy efficient use of hydrogen involves the use of fuel cells and electric motors instead of a traditional engine. Hydrogen reacts with oxygen inside the fuel cells, which produces electricity to power the motors. One primary area of research is hydrogen storage, to try to increase the range of hydrogen vehicles, while reducing the weight, energy consumption, and complexity of the storage systems. Two primary methods of storage are metal hydrides and compression.

High speed cars, buses, submarines, and space rockets already can run on hydrogen, in various forms at great expense. There is even a working toy model car that runs on solar power, using a reversible fuel cell to store energy in the form of hydrogen and oxygen gas. It can then convert the fuel back into water to release the solar energy.[3]
[edit]

Hydrogen fuel cell difficulties

For more details on this topic, see Fuel cell.

While fuel cells themselves are potentially highly energy efficient, and working prototypes were made by Roger E. Billings in the 1960s, at least four technical obstacles and other political considerations exist regarding the development and use of a fuel cell-powered hydrogen car.
[edit]

Low volumetric energy

For more details on this topic, see Energy density.

Hydrogen has a very low volumetric energy density at ambient conditions, equal to about one-third that of methane. Even when the fuel is stored as a liquid in a cryogenic tank or in a pressurized tank as a gas, the volumetric energy density (megajoules per liter) is small relative to that of gasoline. Because of the energy required to compress or liquefy the hydrogen gas, the supply chain for hydrogen has lower well-to-tank efficiency compared to gasoline. Some research has been done into using special crystalline materials to store hydrogen at greater densities and at lower pressures.

Instead of storing molecular hydrogen on-board, some have advocated using hydrogen reformers to extract the hydrogen from more traditional fuels including methane, gasoline, and ethanol. Many environmentalists are irked by this idea, as it promotes continued dependence on fossil fuels, at least in the case of gasoline. However, vehicles using reformed gasoline or ethanol to power fuel cells could still be more efficient than vehicles running internal combustion engines, if the technology can be invented.
[edit]

High cost of fuel cells

Currently, fuel cells are costly to produce and fragile. However, technologies currently under development may eventually result in robust and cost efficient versions.

Hydrogen fuel cells were initially plagued by the high production costs associated with converting the gas to electricity ultimately required to power a hydrogen car. Scientists are also studying how to produce inexpensive fuel cells that are robust enough to survive the bumps and vibrations that all automobiles have to handle. Furthermore, freezing conditions are a major consideration because fuel cells produce water and utilize moist air with varying water content. Most fuel cell designs are fragile and can't survive in such environments. Also, many designs require rare substances such as platinum as a catalyst in order to work properly. Such a catalyst can be contaminated by impurities in the hydrogen supply. In the past few years, however, a nickel-tin catalyst has been under development which may lower the cost of cells.
[edit]

Hydrogen production costs

For more details on this topic, see Hydrogen production.

While hydrogen can be used as an energy carrier, it is not an energy source. It still must be produced from fossil fuels, or from some other energy source, with a net loss of energy. There are also relatively high costs associated with packaging, distribution, storage and transfer. Altoghether, between 1.65 and 2.12 times as much energy needs to be input to the process as the higher heating value of the hydrogen in the car.[4]

Using hydrogen in a fuel cell is nearly twice as efficient as traditional combustion engines, which only have an efficiency of 15-25%. Hydrogen fuel cells can achieve thermodynamic efficiencies of 50-60%. The percentage will never be 100% because of the second law of thermodynamics. While hydrogen fuel cells produce only water as its byproduct, the production of hydrogen using fossil fuels creates emissions of greenhouse gases, which adds an additional enviromental cost.
[edit]

Hydrogen infrastructure

Fourth, in order to distribute hydrogen to cars, the current gasoline fueling system would need to be replaced, or at least significantly supplemented with hydrogen fuel stations.
[edit]

Political considerations

Since all energy sources have drawbacks, a shift into hydrogen powered vehicles may require difficult political decisions on how to produce this energy. The United States Department of Energy has already announced a plan to produce hydrogen directly from generation IV reactors. These nuclear power plants would be capable of producing hydrogen and electricity at the same time. The main problem with the nuclear-to-hydrogen economy is that hydrogen is ultimately only a carrier of electricity. The costs associated with electrolysis and transportation and storage of hydrogen may make this method uneconomical in comparison to direct utilization of electricity. Electric power transmission is about 95% efficient and the infrastructure is already in place, so tackling the current drawbacks of electric cars or hybrid vehicles may be easier than developing a whole new hydrogen infrastructure that mimics the obsolete model of oil distribution. Continuing research on cheaper, higher capacity batteries is needed. Direct transmission though electric rails, for example in a guided vehicle configuration such as personal rapid transit, may turn out to make electric vehicles more economic than hydrogen fuel cell vehicles.

Recently, alternative methods of creating hydrogen directly from sunlight and water through a metallic catalyst have been announced. This may provide a cheap, direct conversion of solar energy into hydrogen, a very clean solution for hydrogen production.[1].

Sodium borohydride (NaBH4) a chemical compound may hold future promise due to the ease at which hydrogen can be stored under normal atmospheric pressures in automobiles that have fuel cells.

United States President George W. Bush was optimistic that these problems could be overcome with research. In his 2003 State of the Union address, he announced the U.S. government's hydrogen fuel initiative, which complements the President's existing FreedomCAR initiative for safe and cheap hydrogen fuel cell vehicles. Critics charge that focus on the use of the hydrogen car is a dangerous detour from more readily available solutions to reducing the use of fossil fuels in vehicles[citation needed].
[edit]

Hydrogen internal combustion

Hydrogen internal combustion engine cars are different from hydrogen fuel cell cars. The hydrogen internal combustion car is a slightly modified version of the traditional gasoline internal combustion engine car. Hydrogen internal combustion cars burn hydrogen directly, with no other fuels and produce pure water vapor exhaust. As in hydrogen fuel cell vehicles, the volume of the vehicle that the tank occupies is significant. Research is underway to increase the amount of hydrogen that can be stored onboard, be it through high pressure hydrogen, cryogenic liquid hydrogen, or metal hydrides.

In 1807, François Isaac de Rivaz built the first hydrogen-fueled internal combustion vehicle. However, the design was very unsuccessful.

It is estimated that more than a thousand hydrogen powered vehicles were produced in Germany before the end of the WWII prompted by the acute shortage of oil.

BMW's CleanEnergy internal combustion hydrogen car has more power and is faster than hydrogen fuel cell electric cars. A BMW hydrogen car ( H2R[5]) broke the speed record for hydrogen cars at 300 km/h (186 mi/h), making automotive history. Mazda has developed Wankel engines to burn hydrogen. The Wankel engine uses a rotary principle of operation, so the hydrogen burns in a different part of the engine from the intake. This reduces intake backfiring, a risk with hydrogen-fueled piston engines. Like the Wankel the rotary Atkinson cycle engine burns the fuel in a separate gas expansion part of the engine. In the R.A.C.E. this expansion volume is larger than the intake volume increasing the thermodynamic efficiency. However the major car companies like DaimlerChrysler and General Motors Corp, are investing in the slower, weaker, but more efficient hydrogen fuel cells instead. Ford Motor Company is investing in both fuel cell and hydrogen internal combustion engine research.

A small proportion of hydrogen in an otherwise conventional internal combustion engine can both increase overall efficiency and reduce pollution. Such a conventional car can employ an electrolizer to decompose water, or a mixture of hydrogen and other gasses as produced in a reforming process. Since hydrogen can burn in a very wide range of air/fuel mixtures, a small amount of hydrogen can also be used to ignite various liquid fuels in existing internal combustion engines under extremely lean burning conditions. This process requires a number of modifications to existing engine air/fuel and timing controls. Roy McAlister of the American Hydrogen Association has been demonstrating these conversions. Other renewable energy sources, like biodiesel, are also practical for existing automobile conversions, but come with their own host of problems.

In 2005 an Israeli company claimed it succeeded in conquering most of the problems related to producing hydrogen by using a device called a metal-steam combustor that separates hydrogen out of heated water. A tip of a magnesium or aluminum coil is inserted into the small metal-steam combustor together with water where it is heated to very high temperatures. The metal atoms bond with the oxygen from the water, creating metal oxide. As a result, the hydrogen molecules become free, and are sent into the engine alongside the steam. The solid waste product of the process, in the form of metal oxide, will later be collected in the fuel station and recycled for further use by the metal industry. The problem is that it takes a lot of energy to make the magnesium or aluminum coils. [6]

Outside of specialty and small-scale uses, the primary target for the widespread application of fuel cells (hydrogen, zinc, other) is the transportation sector; however, to be economically and environmentally feasible, any fuel cell based engine would need to be more efficient from well head-to-wheel, than what currently exists. At the time of this writing, hydrogen fuel cells are roughly equivalent to gasoline combustion, in terms of energy efficiency and pollution; however, if the energy and pollution costs in the production of the fuel cell are considered, hydrogen is sorely behind. Other fuel cell technologies, like zinc-air, are currently ahead of gasoline combustion in energy efficiency, and hydrogen in terms of production costs and safety, but have been widely overlooked by the advocates of gasoline combustion alternatives.
[edit]

Related Patents

USP # 4,936,961 ~ Method for the Production of a Fuel Gas KeelyNet/Vangard Notes, USP # 4,826,581 ~ Controlled Process for the Production of Thermal Energy from Gases..., USP # 4,798,661 ~ Gas Generator Voltage Control Circuit, USP # 4,613,304 ~ Gas Electrical Hydrogen Generator, USP # 4,465,455 ~ Start-up/Shut-down for a Hydrogen Gas Burner, USP # 4,421,474 ~ Hydrogen Gas Burner, USP # 4,389,981 ~ Hydrogen Gas Injector System for Internal Combustion Engine
[edit]

Automobile and bus makers

For more details on this topic, see List of fuel cell vehicles.

Many companies are currently researching the feasibility of building hydrogen cars. Funding has come from both private and government sources. In addition to the BMW and Mazda examples cited above, many automobile manufacturers have begun developing cars. These include:
Hyundai Tucson FCEV in the background (on the left) and Toyota Highlander FCHV in the foreground (on the right) during UC Davis's Picnic Day activities
Enlarge
Hyundai Tucson FCEV in the background (on the left) and Toyota Highlander FCHV in the foreground (on the right) during UC Davis's Picnic Day activities

* BMW — The 750hL[7] is powered by a dual-fuel Internal Combustion Engine and with an Auxiliary power based on UTC Power fuel cell technology. The BMW H2R speed record car is also power by an ICE. Both models use Liquid Hydrogen as fuel.
* DaimlerChrysler — F-Cell, a hydrogen fuel cell vehicle based on the Mercedes-Benz A-Class.
* Ford Motor – Focus FCV, a hydrogen fuel cell modification of the Ford Focus
* General Motors — multiple models of fuel cell vehicles including the Hy-wire and the HydroGen3
* Honda – currently experimenting with a variety of alternative fuels and fuel cells with experimental vehicles based on the Honda EV Plus, most notable the Honda FCX.
* Hyundai — Tucson FCEV, based on UTC Power fuel cell technology
* Mazda - RX-8, with a dual-fuel (hydrogen or gasoline) rotary-engine [8]
* Nissan — X-TRAIL FCV, based on UTC Power fuel cell technology.
* Morgan Motor Company – LIFEcar, a performance-oriented hydrogen fuel cell vehicle with the aid of several other British companies
* Toyota – The Highlander FCHV and FCHV-BUS[9] are currently under development and in active testing.
* Volkswagen also has hydrogen fuel cell cars in development.

A few bus companies are also conducting hydrogen fuel cell research. These include:

* DaimlerChrysler, based on Ballard fuel cell technology
* Thor Industries (the largest maker of buses in the U.S.), based on UTC Power fuel cell technology
* Irisbus, based on UTC Power fuel cell technology
* Fuel Cell Bus Club

Supporting these automobile and bus manufacturers are fuel cell and hydrogen engine research and manufacturing companies. The largest of these is UTC Power, a division of United Technologies Corporation, currently in joint development with Hyundai, Nissan, and BMW, among other auto companies. Another major supplier is Ballard Power Systems. The Hydrogen Engine Center is a supplier of hydrogen-fueled engines.

Most, but not all, of these vehicles are currently only available in demonstration models and cost a large amount of money to make and run. They are not yet ready for general public use and are unlikely to be as feasible as plug in biodiesel hybrids.

There are, however, fuel cell powered buses currently active or in production, such as a fleet of Thor buses with UTC Power fuel cells in California, operated by SunLine Transit Agency.[10] Perth is also participating in the trial with three fuel cell powered buses now operating between Perth and the port city of Fremantle. The trial is to be extended to other Australian cities over the next three years.

Mazda leased two dual-fuel RX-8s to commercial customers in Japan in early 2006, becoming the first manufacturer to put a hydrogen vehicle in customer hands. BMW has recently released to the media information of a new car that has been manufactured and uses hydrogen or petrol and is completely clean. BMW also plans to release its first publicly available hydrogen vehicle in 2008.
[edit]

Fuel stations

For more details on this topic, see Hydrogen station.

Since the turn of the millennium, filling stations offering hydrogen have been opening worldwide, new are the home stations [2].
[edit]

Planes

For more details on this topic, see Hydrogen planes.

Many companies such as Boeing and Smartfish are pursuing hydrogen as fuel for planes.

Unmanned hydrogen planes have been tested and Boeing is currently planning a manned flight for 2007.


List of vegetable oils
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Plant oils
Types
Vegetable fats (list)
Essential oil (list)
Macerated (list)
Uses
Drying oil - Oil paint
Cooking oil
Fuel - Biodiesel
Aromatherapy
Components
Saturated fat
Monounsaturated fat
Polyunsaturated fat
Trans fat

The list of vegetable oils includes all vegetable oils that are extracted from plants by placing the relevant part of the plant under pressure, to squeeze the oil out. Although few plants are entirely without oil, the oil from a relatively small set of plants has become widely used and traded.

Oils may also be extracted from plants by dissolving parts of plants in water or another solvent, and distilling the oil (known as essential oils), or by infusing parts of plants in a base oil (a process known as maceration - see list of macerated oils). The distilled essential oils often have quite different properties and uses to vegetable oils, and are listed in the list of essential oils.

Vegetable oils can be classified in several ways, for example:

* By source: most, but not all vegetable oils are extracted from the fruits or seeds of plants, and the oils may be classified by grouping oils from similar plants, such as "nut oils".
* By use: oils from plants are used in cooking, for fuel, for cosmetics, for medical purposes, and for other industrial purposes.

The vegetable oils are grouped below in common classes of use.
Contents
[hide]

* 1 Edible oils
o 1.1 Major oils
o 1.2 Nut oils
o 1.3 Food supplements
o 1.4 Other edible oils
* 2 Oils used for biofuel
o 2.1 Edible oils used as biofuel
o 2.2 Inedible oils used only as biofuel
* 3 Drying oils
* 4 Other oils
* 5 See also
* 6 General references
* 7 Notes and references

[edit]

Edible oils
[edit]

Major oils
Sunflowers are the source of Sunflower oil.
Enlarge
Sunflowers are the source of Sunflower oil.

These oils account for a significant fraction of world-wide edible oil production. All are also used as fuel oils.

* Coconut oil, a cooking oil, high in saturated fats, particularly used in baking and cosmetics.[1]
* Corn oil, a common cooking oil with little odor or taste.[2]
* Cottonseed oil, used in manufacturing potato chips and other snack foods. Very low in trans-fats.[3]
* Canola oil (a variety of rapeseed oil), one of the most widely used cooking oils, from a (trademarked) cultivar of rapeseed.[4]
* Olive oil, used in cooking, cosmetics, soaps, and as a fuel for traditional oil lamps.[5]
* Palm oil, the most widely produced tropical oil. Also used to make biofuel.[6]
* Peanut oil (Ground nut oil), a clear oil used for dressing salads and, due to its high smoke point, especially used for frying.[7]
* Safflower oil, produced for export for over 50 years, first for use in paint industry, now mostly as a cooking oil.[8]
* Sesame oil, cold pressed as light cooking oil, hot pressed for a darker and stronger flavor.[9]
* Soybean oil, produced as a byproduct of processing soy meal.[10]
* Sunflower oil, a common cooking oil, also used to make biodiesel.[11]

[edit]

Nut oils
Hazelnuts from the Common Hazel, used to make Hazelnut oil.
Enlarge
Hazelnuts from the Common Hazel, used to make Hazelnut oil.

Nut oils are generally used in cooking, for their flavor. They are also quite costly, because of the difficulty of extracting the oil.

* Almond oil, used as an edible oil, but primarily in the manufacture of pharmaceuticals.[12]
* Cashew oil, somewhat comparable to olive oil. May have value for fighting cavities.[13]
* Hazelnut oil, mainly used for its flavor. Also used in skin care, because of its slight astringent nature.[14][15]
* Macadamia oil, strongly flavored, contains no trans-fats, and a good balance of omega-3 and omega-6.[16]
* Pecan oil, valued as a food oil, but requiring fresh pecans for good quality oil.[17]
* Pistachio oil, strongly flavored oil, particularly for use in salads.[18]
* Walnut oil, used for its flavor, also used by Renaissance painters in oil paints.[19][20]

[edit]

Food supplements

A number of oils are used as food supplements, for their nutrient content or medical effect.

* Acai oil, from the fruit of several species of the Açaí Palm (Euterpe). Grown in the Amazon region. Similar to grape seed oil. Used in cosmetics and as a food supplement.[21]
* Blackcurrant seed oil, used as a food supplement, because of high content of omega-3 and omega-6 fatty acids.[22]
* Borage seed oil, similar to blackcurrant seed oil, used primarily medicinally.[23]
* Evening primrose oil, used as a food supplement for its purported medicinal properties.[24]

[edit]

Other edible oils
Carob seed pods, used to make carob pod oil.
Enlarge
Carob seed pods, used to make carob pod oil.

* Amaranth oil, high in squalene and unsaturated fatty acids, used in food and cosmetic industries.[25]
* Apricot oil, similar to, but much cheaper than almond oil, which it resembles. Only obtained from certain cultivars.[26]
* Argan oil, a food oil from Morocco that has also attracted recent attention in Europe.[27]
* Avocado oil, used a substitute for olive oil.[28] Also used in cosmetics.[29] Unusually high smoke point of 510°F.[30]
* Babassu oil, similar to, and used as a substitute for, coconut oil.[31]
* Ben oil, extracted from the seeds of the moringa oleifera. High in behenic acid. Extremely stable edible oil. Also suitable for biofuel.[32]
* Carob pod oil (Algaroba oil), from carob, used medicinally.[33]
* Coriander seed oil, from coriander seeds, used medicinally. Also used as a flavoring agent in pharmaceutical and food industries.[34]
* False flax oil made of the seeds of Camelina sativa, available in Russia as рыжиковое масло. Considered promising as a food or fuel oil.[35]

Coriander seeds are the source of an edible pressed oil, Coriander seed oil.
Enlarge
Coriander seeds are the source of an edible pressed oil, Coriander seed oil.

* Grape seed oil, suitable for cooking at high temperatures. Also used as a salad oil, and in cosmetics.[36]
* Hemp oil, a high quality food oil.[37]
* Kapok seed oil, used as an edible oil, and in soap production.[38]
* Meadowfoam seed oil, highly stable oil, with over 98% long-chain fatty acids. Competes with rapeseed oil for industrial applications. [39]
* Mustard oil (pressed), used in India as a cooking oil. Also used as a massage oil.[40]
* Okra seed oil (Hibiscus seed oil), from the seed of the Hibiscus esculentus. Composed predominately of oleic and linoleic acids.[41]
* Perilla seed oil, high in omega-3 fatty acids. Used as an edible oil, for medicinal purposes, in skin care products and as a drying oil.[42]
* Pine nut oil. An expensive food oil, from pine nuts, used in salads and as a condiment. [43]
* Poppyseed oil, used for cooking,[44] moisturizing skin,[45] in paints and varnishes,[46] and in soaps.
* Prune kernel oil, marketed as a gourmet cooking oil.[47]
* Pumpkin seed oil, a specialty cooking oil, produced in Austria and Slovenia. Poor tolerance for high temperatures.[48]
* Quinoa oil, similar in composition and use to corn oil.[49]
* Ramtil oil, pressed from the seeds of the one of several species of genus Guizotia abyssinica (Niger pea) in India and Ethiopia. Used for both cooking and lighting.[50]
* Rice bran oil, suitable for high temperature cooking. Widely used in Asia.[51]
* Tea oil (Camellia oil), widely used in southern China as a cooking oil. Also used in making soaps, hair oils and a variety of other products.[52]
* Thistle oil, pressed from the seeds of Silybum marianum. Relatively unstable. Also used for skin care products.[53]
* Wheat germ oil, used as a food supplement, and for its "grainy" flavor. Also used medicinally. Highly unstable.[54]

[edit]

Oils used for biofuel

A number of the oils listed above are used for biofuel (biodiesel and Straight Vegetable Oil) in addition to having other uses. A number of oils are used only as biofuel.[55][56]

Although diesel engines were invented, in part, with vegetable oil in mind,[57] diesel fuel is almost exclusively petroleum-based. Rising oil prices have made biodiesel more attractive. Vegetable oils are evaluated for use as a biofuel based on:

1. Suitability as a fuel, based on flash point, energy content, viscosity, combustion products and other factors
2. Cost, based in part on yield, effort required to grow and harvest, and post-harvest processing cost

A flask of biodiesel.
Enlarge
A flask of biodiesel.
[edit]

Edible oils used as biofuel

The oils listed immediately below are all (primarily) used for other purposes - all but tung oil are edible - but have been considered for use as biofuel.

* Castor oil, lower cost than many candidates. Kinematic viscosity may be an issue.[58]
* Coconut oil (copra oil), promising for local use in places that produce coconuts.[59]
* Corn oil, appealing because of the abundance of maize as a crop.
* Cottonseed oil, shown in one study not to be cost effective when compared with standard diesel.[60]
* False flax oil, from Camelina sativa, used in Europe in oil lamps until the 18th century.[35]
* Hemp oil, relatively low in emissions. High flash point. Production is problematic in some countries because of its association with marijuana.[61]
* Mustard oil, shown to be comparable to Canola oil as a biofuel.[62]
* Palm oil, very popular for biofuel, but the environmental impact from growing large quantities of oil palms has recently called the use of palm oil into question.[63]
* Peanut oil, used in one of the first demonstrations of the Diesel engine in 1900.[57]
* Radish oil. Wild radish contains up to 48% oil, making it appealing as a fuel.[64]
* Rapeseed oil, the most common base oil used in Europe in biodiesel production.[56]
* Ramtil oil, used for lighting in India.
* Rice bran oil, appealing because of lower cost than many other vegetable oils. Widely grown in Asia.[65]
* Safflower oil, explored recently as a biofuel in Montana.[66]
* Soybean oil, not economical as a fuel crop, but appealing as a byproduct of soybean crops for other uses.[56]
* Sunflower oil, suitable as a fuel, but not necessarily cost effective.[67]

* Tung oil, referenced in several lists of vegetable oils that are suitable for biodiesel.[68][69]

[edit]

Inedible oils used only as biofuel

These oils are extracted from plants that are cultivated solely for producing oil-based biofuel.[70] These, plus the major oils described above, have received much more attention as fuel oils than other plant oils.

* Algae oil, recently developed by MIT scientist Isaac Berzin. Byproduct of a smokestack emission reduction system.[71][72]
* Honge oil, pioneered as a biofuel by Udipi Shrinivasa in Bangalore, India.[73]
* Jatropha oil, widely used in India as a fuel oil. Has attracted strong proponents for use as a biofuel.[74]
* Jojoba oil, from the Simmondsia chinensis, a desert shrub.[75]
* Milk bush, popularized by chemist Melvin Calvin in the 1950s. Researched in the 1980s by PetroBras, the Brazilian national petroleum company.[76]
* Petroleum nut oil, from the Petroleum nut native to the Philippines. The Philippine government once explored the use of the petroleum nut as a biofuel.[77]

[edit]

Drying oils

Drying oils are vegetable oils that dry to a hard finish at normal temperatures. Such oils are used as the basis of oil paints, and in other paint and wood finishing applications. In addition to the oils listed here, walnut, sunflower and safflower oil are also considered to be drying oils.[78]

* Dammar oil, from the Canarium strictum, used in paint as a drying agent.[79] Can also be used as in oil lamps.[80]
* Linseed oil, used in paints, also suitable for human consumption.[81]
* Poppyseed oil, similar in usage to linseed oil but with better color stability.[78]
* Tung oil, used in wood finishing.[82]
* Vernonia oil is produced from the seeds of the Vernonia galamensis. It is composed of 73-80% vernolic acid, which can be used to make epoxies for manufacturing adhesives, varnishes and paints, and industrial coatings.[83]

[edit]

Other oils

A number of pressed vegetable oils are either not edible, or not used as an edible oil.
Castor beans are the source of castor oil
Enlarge
Castor beans are the source of castor oil

* Amur cork tree fruit oil, pressed from the fruit of the Phellodendron amurense, used medicinally and as an insecticide.[84]
* Apple seed oil, used in cosmetics for its hydrating properties.[85]
* Balanos oil, pressed from the seeds of the Balanites aegyptiaca, was used in ancient Egypt as the base for perfumes.[32]
* Burdock oil (Bur oil) extracted from the root of the burdock. Used medicinally in scalp treatment.[86]
* Candlenut oil (Kukui nut oil), produced in Hawai'i, used primarily for skin care products.[87]
* Carrot seed oil (pressed), from carrot seeds, used in skin care products.[88][89]
* Castor oil, with many industrial and medicinal uses. Castor beans are also a source of the toxin ricin.[90]
* Crambe oil, extracted from the seeds of the Crambe abyssinica, is used as an industrial lubricant, a corrosion inhibitor, and as an ingredient in the manufacture of synthetic rubber.[91]
* Cuphea oil, from a number of species of genre Cuphea. Of interest as sources of medium chain triglycerides.[92]
* Jojoba oil, used in cosmetics as an alternative to whale oil spermaceti.[93]
* Lemon oil, similar in fragrance to the fruit. One of a small number of cold pressed essential oils. Used medicinally, as an antiseptic, and in cosmetics.[94]
* Mango oil, pressed from the stones of the mango fruit, is high in stearic acid, and can be used for making soap.[95]
* Neem oil, used in cosmetics, for medicinal purposes, and as an insecticide.
* Orange oil, like lemon oil, cold pressed rather than distilled. Consists of 90% d-Limonene. Used as a fragrance, in cleaning products and in flavoring foods.[96]
The fruit of the sea buckthorn
Enlarge
The fruit of the sea buckthorn
* Palm kernel oil, extracted from the kernel of the palm fruit. High in saturated fats. Popular in West African and Brazilian cuisine.[97]
* Rosehip seed oil, used primarily in skin care products, particularly for aging or damaged skin. Produced in Chile.[98]
* Sea buckthorn oil, derived from Hippophae rhamnoides, produced in northern China, used primarily medicinally.[99]
* Shea butter, used primarily in skin care products.[100]
* Snowball seed oil (Viburnum oil), from Viburnum opulus seeds. High in tocopherol, carotinoides and unsaturated fatty acids. Used medicinally.[101]
* Tall oil, produced as a byproduct of wood pulp manufacture. A further byproduct called tall oil fatty acid (TOFA) is a cheap source of oleic acid.[102]
* Tamanu oil, originates in Tahiti, from the Calophyllum tacamahaca, used for skin care and medicinally.[103]
* Tonka bean oil (Cumaru oil), used for flavoring tobacco and snuff.[104]

[edit]

See also

* Carrier oil discusses the use of (pressed) vegetable oils, mixed with essential oils
* Complementary and alternative medicine
* INCI explains naming conventions for oils used in cosmetics and soaps
* Fatty acids discusses the components of most vegetable oils

[edit]

General references

* Bulk Oil Trading. Retrieved on 2006-07-25. This site was very helpful in making this list more comprehensive.
* R.O. Adlof and G. Duchateau. Seed oil translations (PDF). Lists seed oil names in English, French, German, Italian, Spanish, Turkish and Portuguese.
* Hormel Foods: Other Oils and Fats Cooking Guide. Retrieved on 2006-07-25. Lists smoke points of various oils.
* Vegetable Oil Yields and Characteristics. Retrieved on 2006-07-21. Compiles useful information on vegetable oils from a number of sources.
* Yokayo Biofuels: History of Biodiesel. Retrieved on 2006-07-25. Gives a good overview of biodiesel and the oils that are used to produce it. Yokayo is a California-based company that sells biofuel.
* Castor Oil. Retrieved on 2006-07-25. The site contains a large set of resources on castor oil and many other oils, particularly those used to make biodiesel.



Biomass to Plastics and Fuels
Published by jcwinnie July 3rd, 2006 in analysis, design, complexity, politics, economics, security, transportation, development, energy, environment, policy, recycle, model, manufacturing, agriculture, chemistry, conservation Tags: agriculture, analysis, biofuel, chemistry, combustion, complexity, conservation, design, development, economics, emissions, energy, environment, fleets, manufacturing, model, policy, politics, recycle, security, thermodynamics, transportation.

Bio Energy Cycle
Enough waste biomass is being generated by farming, by lumbering, and as urban waste to meet 10 percent of current U.S. transportation needs.

Green Car Congress1 seem enamored with systems that will facilitate the conversion of biomass polysaccharides to liquid alkanes and oxyalkanes for fuel applications. Mineral fuels have been soaring in cost, so biofuels may seem to be a good alternative. Is cheaper also cleaner?

Should, and more importantly, can transportation policies change? Especially, when it would seem that “the oilies” are deciding the policy for the policy makers to make.

Yet, even in the best of times, such policy analysis remains complex. As the GCC and Wired2 articles suggest, while such biotechnology can yield biofuel, the conversion of biomass also can yield co-products that 1) generate more income, making a bio-refinery more profitable, and 2) utilize lignocellulose resources more fully, which also has an impact on the bottom line by reducing waste and waste handling. Lignin, for instance, has many industrial uses, not the least of which are lightweight, carbon-fiber composites, that, when utilized in the production of vehicles, can reduce fuel consumption.

Certainly, a biomass model is complex because of production factors. The resultant policy analysis is complex for another reason. Biomass conversion practices can extend and become established across various sectors, i.e., agricultural waste, lumber waste, and municipal solid waste. (And, if you insist on referring to the last one as MSW, I may have to chastise you since, as everyone knows, the acronym stands for Master of Saving the World.) There are environmental consequences to each pathway to sleek, biofuel-powered plastic cars.

In other words, we need to give greater consideration to the Patzek paradigm — using less rather than just using different — and to “the birkie chant” — reduce, reuse, recycle. It is not enough that, as World Changing3 puts it: Professor James Dumesic and his team have broken new ground in terms of creating a process that can compete economically with the more conventional models.

Certainly, different could be a good thing, too. The transportation sector now accounts for two-thirds of U.S. oil consumption and is 98 percent dependent on petroleum. Our oil addiction requires intervention, at the very least from a security viewpoint.

Yet, while changing suppliers rather than trying to control a dwindling supply is better foreign policy, it nevertheless is an insufficient energy policy. According to a new report from the Environmental Defense Fund4, the US has 30% of the world’s cars, but because our cars are less efficient and we drive them more, they account for nearly half (45%) of the world’s automotive CO2 emissions. As an elementary school classmate of a Woody Allen character relates, “I used to be a heroin addict, now I’m a methadone addict.”

The famous Entropy Production - After Gutenberg debate (”What do you mean it wasn’t on the evening news”) made clear that we need to maintain perspective even as we consider incremental improvements in processes. Switching to a biodiesel blend may not be all to the good, yet, on the other hand, it could make things a bit better, whether economically, i.e., three-quarters of a billion dollars leaves the U.S. each day in exchange for imported oil, or otherwise, e.g., in terms of energy production, environmental impact and “cradle to grave” manufacturing.

In other words, while current biodiesel applications do less well with some emissions, could changes be made, other than after treatment, that would reduce emissions due to greater efficiency? Unfortunately, automotive engineers seem more focused upon incremental changes in combustion rather than forgoing the dominance of internal combustion. Direct injection, dual turbochargers, and inter cooling may be insufficient to make biodiesel a suitable, alternative fuel. And, no matter the engine chosen to drive the generator — combustion ignition, spark ignition, homogeneous charge catalytic compression ignition, or some other, non-combustible hybridization — studies seem to indicate that on board and life cycle energy consumption is reduced by the addition of electric drive.

Yet, electric drives may be unsuitable for some applications. Medium to heavy-duty vehicles have a very important part to play when it comes to transportation, energy and environmental policy.

How best to lower emissions and energy consumption, plus improve our health and global climate is a matter of intense debate, which may get hotter still as more of the movie going public learns that they were taken for a ride they can’t buy an electric car conversion of biomass to electric power is the most efficient, cost-effective and environmentally sound option for most forms of ground transportation going forward to a 2020 horizon.
Biomass to Plastics and Fuels
Published by jcwinnie July 3rd, 2006 in analysis, design, complexity, politics, economics, security, transportation, development, energy, environment, policy, recycle, model, manufacturing, agriculture, chemistry, conservation Tags: agriculture, analysis, biofuel, chemistry, combustion, complexity, conservation, design, development, economics, emissions, energy, environment, fleets, manufacturing, model, policy, politics, recycle, security, thermodynamics, transportation.

Bio Energy Cycle
Enough waste biomass is being generated by farming, by lumbering, and as urban waste to meet 10 percent of current U.S. transportation needs.

Green Car Congress1 seem enamored with systems that will facilitate the conversion of biomass polysaccharides to liquid alkanes and oxyalkanes for fuel applications. Mineral fuels have been soaring in cost, so biofuels may seem to be a good alternative. Is cheaper also cleaner?

Should, and more importantly, can transportation policies change? Especially, when it would seem that “the oilies” are deciding the policy for the policy makers to make.

Yet, even in the best of times, such policy analysis remains complex. As the GCC and Wired2 articles suggest, while such biotechnology can yield biofuel, the conversion of biomass also can yield co-products that 1) generate more income, making a bio-refinery more profitable, and 2) utilize lignocellulose resources more fully, which also has an impact on the bottom line by reducing waste and waste handling. Lignin, for instance, has many industrial uses, not the least of which are lightweight, carbon-fiber composites, that, when utilized in the production of vehicles, can reduce fuel consumption.

Certainly, a biomass model is complex because of production factors. The resultant policy analysis is complex for another reason. Biomass conversion practices can extend and become established across various sectors, i.e., agricultural waste, lumber waste, and municipal solid waste. (And, if you insist on referring to the last one as MSW, I may have to chastise you since, as everyone knows, the acronym stands for Master of Saving the World.) There are environmental consequences to each pathway to sleek, biofuel-powered plastic cars.

In other words, we need to give greater consideration to the Patzek paradigm — using less rather than just using different — and to “the birkie chant” — reduce, reuse, recycle. It is not enough that, as World Changing3 puts it: Professor James Dumesic and his team have broken new ground in terms of creating a process that can compete economically with the more conventional models.

Certainly, different could be a good thing, too. The transportation sector now accounts for two-thirds of U.S. oil consumption and is 98 percent dependent on petroleum. Our oil addiction requires intervention, at the very least from a security viewpoint.

Yet, while changing suppliers rather than trying to control a dwindling supply is better foreign policy, it nevertheless is an insufficient energy policy. According to a new report from the Environmental Defense Fund4, the US has 30% of the world’s cars, but because our cars are less efficient and we drive them more, they account for nearly half (45%) of the world’s automotive CO2 emissions. As an elementary school classmate of a Woody Allen character relates, “I used to be a heroin addict, now I’m a methadone addict.”

The famous Entropy Production - After Gutenberg debate (”What do you mean it wasn’t on the evening news”) made clear that we need to maintain perspective even as we consider incremental improvements in processes. Switching to a biodiesel blend may not be all to the good, yet, on the other hand, it could make things a bit better, whether economically, i.e., three-quarters of a billion dollars leaves the U.S. each day in exchange for imported oil, or otherwise, e.g., in terms of energy production, environmental impact and “cradle to grave” manufacturing.

In other words, while current biodiesel applications do less well with some emissions, could changes be made, other than after treatment, that would reduce emissions due to greater efficiency? Unfortunately, automotive engineers seem more focused upon incremental changes in combustion rather than forgoing the dominance of internal combustion. Direct injection, dual turbochargers, and inter cooling may be insufficient to make biodiesel a suitable, alternative fuel. And, no matter the engine chosen to drive the generator — combustion ignition, spark ignition, homogeneous charge catalytic compression ignition, or some other, non-combustible hybridization — studies seem to indicate that on board and life cycle energy consumption is reduced by the addition of electric drive.

Yet, electric drives may be unsuitable for some applications. Medium to heavy-duty vehicles have a very important part to play when it comes to transportation, energy and environmental policy.

How best to lower emissions and energy consumption, plus improve our health and global climate is a matter of intense debate, which may get hotter still as more of the movie going public learns that they were taken for a ride they can’t buy an electric car conversion of biomass to electric power is the most efficient, cost-effective and environmentally sound option for most forms of ground transportation going forward to a 2020 horizon.