Encyclopedia
Ethanol can be used as
fuel for
automobiles either alone in a special engine or as an additive to
gasoline for
petroleum engines. In the United States, the color yellow has become associated with the fuel and is commonly used on fuel pumps and labels.
Ethanol can be blended with gasoline in varying quantities to reduce the consumption of petroleum fuels, as well as to reduce
air pollution. The resulting fuel is known in the
United States as
gasohol, or gasoline type C in
Brazil. Two common mixtures in the United States are
E10 and
E85 which contain 10% and 85% ethanol, respectively, while the common mixtures in Brazil are gasoline type C and its high octane variants, which contain 20% to 25% ethanol .
Ethanol is increasingly used as an oxygenate additive for standard gasoline, as a replacement for
methyl t-butyl ether , the latter chemical being responsible for considerable groundwater and soil contamination .
Ethanol can also be used to power
fuel cells.
Ethanol derived from crops is a demonstrably
sustainable energy resource that may offer environmental and long-term economic advantages over
fossil fuel . It is readily obtained from the
sugar or starch in crops such as
maize,
miscanthus and
sugarcane. Ethanol made from maize, however, was found to use a significant amount of energy compared to the energy value of the produced fuel. On the other hand, sugarcane has enough energy not only for completely sustained ethanol production, but also for generating surplus , that may be sold to utilities. Sustainability of ethanol production is not only a matter of energy balance, but of availability of land area and soil and
biodiversity preservation.
Sources
Bioethanol is the result of conversion of feedstock. Agricultural feedstocks such as
switchgrass are considered renewable because they get energy from the
sun using
photosynthesis.
Ethanol as a substitute for
gasoline is often created by harvesting a crop such as
switchgrass and processing it for less money than it costs to pump oil and refine it into gasoline. Unfortunately, the technology does not yet exist to make ethanol from agricultural feedstock economically viable in comparison with gasoline.
Much of the ethanol produced in the world is actually a petroleum product.
It is made by the catalytic hydration of ethylene with
sulfuric acid as the
catalyst.
This process is cheaper than the traditional fermentation associated with
alcoholic beverages.
It can also be obtained via
ethylene or
acetylene, from
calcium carbide,
coal, oil gas,
and other sources. Two million tons of petroleum-derived ethanol are produced annually. The
principal suppliers are from South America, but there are also large plants in the
United States, Europe and Japan. Petroleum derived ethanol is a widely used
industrial solvent and has a considerable variety of other applications, Including use as fuel additive.
Four countries have developed significant bioethanol fuel programs:
Brazil,
Colombia,
China and the
United States. Ethanol can be produced from a variety of feedstocks, such as
sugar cane,
miscanthus,
sugar beet,
sorghum,
switchgrass,
barley,
hemp,
kenaf,
potatoes,
sweet potatoes,
cassava,
sunflower,
fruit, molasses, whey or
skim milk,
corn, corn cobs,
grain,
wheat,
wood,
paper,
straw,
cotton, grain
sorghum,
barley, other
biomass, well as many types of
cellulose waste. One result of increased use of ethanol is increased demand for the feedstocks such as corn, sugarcane, or
switchgrass. Large-scale production of agricultural alcohol for fuel may require substantial amounts of cultivable land with fertile soils and water. This may lead to environmental damage such as deforestation. Ethanol's energy comes from the carbon-based feedstocks which get their energy from sunlight, water, and
photosynthesis.
Production
Ethanol can be produced in different ways, using a variety of feedstocks.
Brazil uses sugarcane as primary feedstock, but a large variety of feedstocks are possible. For information on Brazil's method of ethanol production, see
ethanol fuel in Brazil. More than 90% of the ethanol produced in the U.S. comes from corn .
Crops with higher yields of energy, such as
switchgrass and
sugar cane, are more effective in producing ethanol than
corn[]. Ethanol can also be produced from
sweet sorghum, a dryland crop that uses much less water than sugarcane and produces food, and fodder in addition to fuel.
Basic steps for dry mill production of ethanol are: refining into starch, liquification and saccharification , fermentation,
distillation, dehydration, and denaturing .
Carbon dioxide, a potentially harmful
greenhouse gas, is emitted during fermentation. However, the net effect is more than offset by the uptake of carbon gases by the plants grown to produce ethanol.
The net result of using ethanol as a fuel is to reduce green house gases.
Ethanol is not typically transported by pipeline for three reasons. Current production levels will not support a dedicated pipeline. The costs of building and maintaining a pipeline from Midwestern United States to either coast are prohibitive. Any water which penetrates the pipeline will be absorbed by the ethanol, diluting the mixture.
Ethanol produced by fermentation results in a solution of ethanol in water. During
ethanol fermentation, glucose is evolved into ethanol and carbon dioxide. The equation is:
C
6H
12O
6 ? 2 CH
3CH
2OH + 2 CO
2For the ethanol to be usable as a fuel, water must be removed. The oldest method is
distillation, but the purity is limited to 95-96 % due to the formation of a low-boiling water-ethanol
azeotrope. The 96% ethanol, 4% water mixture may be used as a fuel, and it's called
hydrated ethyl alcohol fuel . In 2002, almost 5 billion liters of hydrated ethyl alcohol fuel were produced in Brazil, to be used in ethanol powered vehicles.
It is not possible to obtain ethanol of purity > 96 % by distilling any more dilute solution - ethanol and water form an
azeotrope. For blending with gasoline, purities of 99.5 to 99.9% are required, depending on temperature, to avoid separation.
Currently, the most widely used purification method is a physical adsorption process using molecular sieves. Another method, azeotropic distillation, is achieved by adding the hydrocarbon
benzene which also denatures the ethanol . However, benzene is a powerful carcinogen and so will probably be illegal for this purpose soon.
In the past, when farmers distilled their own ethanol, they sometimes used radiators as part of the
still. The radiators often contained
lead, which would get into the ethanol. Lead entered the air during the burning of contaminated fuel, possibly leading to neural damage. However this was a relatively minor source of lead since at the time
tetraethyl lead was used as a mainstream gasoline additive. Today, ethanol for fuel use is produced almost exclusively from purpose-built plants, avoiding any lead presence.
Biotechnology can help to improve the energetic productions of bioethanol.
Ethanol fuel mixtures
Generally, the higher the ethanol component of a gasohol blend, the lower its suitability for gasoline-powered car engines. Pure ethanol reacts with or dissolves certain
rubber and
plastic materials and must not be used in unmodified engines. Additionally, pure ethanol has a much higher
octane rating than ordinary
gasoline , requiring changes to the compression ratio or spark timing to obtain maximum benefit. To change a pure-gasoline-fueled car into a pure-ethanol-fueled car, larger
carburetor jets , or fuel injectors are needed. Ethanol engines also need a cold-starting system to ensure sufficient vaporization for temperatures below 13 °C to maximize combustion and minimize uncombusted nonvaporized ethanol. On the other hand, if 10 to 30% ethanol is mixed with gasoline, no engine modification is typically needed. Many modern cars can run on these mixtures very reliably.
In many countries cars are mandated to run on mixtures of ethanol. Brazil requires cars be suitable for a 25% ethanol blend, and has required various mixtures between 22% and 25% ethanol, as of February 2006 20% is required. The United States allows up to 10% blends, and some states require this in all gasoline sold. Other countries have adopted their own requirements. Because of this requirement it is speculated that all cars can run blends up to about 30% , but it is not known if this is true.
Beginning with the model year 1999, an increasing number of vehicles in the world are manufactured with engines which can run on any gasoline from 0% ethanol up to 100% ethanol without modification. Many light trucks are designed to be dual fuel or flexible fuel vehicles, since they can automatically detect the type of fuel and change the engine's behavior, principally air-to-fuel ratio and ignition timing to compensate for the different octane levels of the fuel in the engine cylinders.
Some of the problems experienced with ethanol include:
- Ethanol-based fuels are not compatible with some fuel system components. Examples of extreme corrosion of ferrous components, the formation of salt deposits, jelly-like deposits on fuel strainer screens, and internal separation of portions of rubber fuel tanks have been observed in some vehicles using ethanol fuels.
- The use of ethanol-based fuels can negatively affect electric fuel pumps by increasing internal wear and undesirable spark generation.
- E-85 is not compatible with capacitance fuel level gauging indicators and may cause erroneous fuel quantity indications in vehicles that employ that system.
- Ethanol will mix with either water or gasoline, but not both. For water levels below approximately 0.5% to 1.0% contained in the ethanol, there is no problem. For contamination with 1% or more water in the ethanol, phase separation occurs, and the ethanol-water mixture will separate from the gasoline.
- E-85 experiences heavy evaporation losses.
Fuel Economy
Fuel economy is directly proportional to energy content . Ethanol contains approx. 34% less energy per gallon than gasoline, and therefore will get 34% fewer miles per gallon . For E10 , the effect is small when compared to conventional gasoline, and even smaller when compared to oxygenated and reformulated blends . However, for E85 , the effect becomes significant. E85 will produce approximately 27% lower mileage than gasoline, and will require more frequent refueling. Actual performance may vary depending on the vehicle. For the EPA-rated mileage of current USA flex-fuel vehicles, see .
This reduced fuel economy should be considered when making price comparisons. For example, if regular gasoline costs $3.00 per gallon, and E85 costs $2.19 per gallon, the prices are essentially equivalent. If the discount for E85 is less than 27%, it actually costs more per mile to use. For USA price comparisons, see .
Some researchers are working to increase fuel efficiency by optimizing engines for ethanol-based fuels. Ethanol's higher octane allows an increase of an engine's compression ratio for increased thermal efficiency . In one study, complex engine controls and increased exhaust gas recirculation allowed a compression ratio of 19.5 with fuels ranging from neat ethanol to E50. Thermal efficiency up to approximately that for a diesel was achieved. . This would result in the mpg of a dedicated ethanol vehicle to be about the same as one burning gasoline. There are currently no commercially-available vehicles that make significant use of ethanol-optimizing technologies, but this may change in the future.
Local production and use of ethanol
Pakistan,
India,
China,
Thailand and
Japan have now launched their national gasohol policies. Thailand started blending 10% ethanol for its ULG95 in 1985; now there are more than 4000 stations serving E10. The blending of 10% ethanol into 95
RON gasoline will be mandated by the end of 2006 and into 91 RON gasoline by the end of 2010. It is expected that once the production of ethanol from
cassava and sugar cane molasses can be ramped up, a higher blending ratio like E20 or E85 or even Flexible Fuel Vehicles will be introduced to Thailand. Similarly, Pakistan has started ethanol blending with motor gasoline as a part of an experimental project called The Pilot Project. The blended fuel is 10 percent ethanol and 90 percent gasoline. It is initially available in
Karachi,
Lahore and
Islamabad through state-run
Pakistan State Oil petrol pumps but eventually will be made available to the rest of the country.
General Motors of
Canada are preparing the launch of E85 flex-fuel vehicles, and will be sold at the same price as their gasoline-only versions. Most of these new vehicles are being produced in
Oshawa, Ontario.
General Motors in the
United States states they have over 2 million vehicles on the road in all 50 states that are capable of running under a 85% ethanol-15% gasoline blend known as
E85. In 2006, GM will produce more than 400,000 flexible fuel vehicles annually -- vehicles that can also operate on gasoline or E85 ethanol without any modifications or special switches. According to many observers, automotive manufacturers in the United States are increasingly offering flex fuel vehicles in order to sell more gas-guzzlers without being penalized under the federal Corporate Average Fuel Economy standards.
Nearly every ethanol fuel plan is sponsored and/or subsidized by local governments. The 2006 U.S. subsidy is 51 cents per gallon. . This is based on current market conditions that prevent ethanol fuel from being competitive with the more popular
gasoline or
Diesel fuels.
Ethanol fuel in Brazil
As of 2004, Brazil was the largest producer and consumer of ethanol fuel in the world. Since the 1970s,
Brazil has developed an extensive domestic ethanol fuel industry upon
sugarcane production and refining. Brazil produces approximately 4 billion gallons of ethanol per year. Ethanol factories in Brazil maintain a positive energy balance by burning the non-sugar waste from sugarcane. The development of ethanol in Brazil was sponsored by its government. All gasoline in Brazil must be at least 20%~25% alcohol. Brazil can make ethanol for about $1.00 per gallon. Newer cars in Brazil are flexible fuel vehicles, capable of using fuels containing any proportion of pure ethanol and/or gasoline.
In the year 1988, cars using ethanol accounted for 66% of the car production. In 1997, only 1117 cars based on ethanol were produced in the country and almost zero in 2000. By 2005, rising oil prices and the availability of new flexible fuel technology made ethanol an increasingly popular choice among Brazilian consumers.
As of 2006, rising exportation of ethanol to the United States and rising prices of sugar in the international market is leading to rises in the price of the fuel.
Ethanol proponents say that
ethanol fuel in Brazil has decreased the country's dependence on oil, increased air quality, and provided useful byproducts to generate electricity. Critics suggest that Brazil's example is not applicable in the U.S. for a variety of reasons.
Ethanol fuel in Colombia
Colombia’s fuel ethanol program got a start in 2002 when the government passed a law which mandates oxygen enrichment of gasoline. This was initially done to reduce carbon monoxide emissions from cars. Later regulations exempted biomass-derived ethanol from some taxes on gasoline, thus making ethanol cheaper than gasoline. This trend was reinforced when petroleum prices went up starting in 2004 and with it the interest in renewable fuels . In Colombia the price of both gasoline and ethanol are controlled by the government. Complementing this ethanol program is a biodiesel program to oxygenate diesel fuel and produce a renewable fuel from vegetable oil.
Initially all the interest in ethanol production has come from the existing sugar industry, as it is relatively easy to add an ethanol back end to a sugar mill and the energy usage is similar to that needed to produce sugar. The government aims to gradually convert the nation’s auto fuel supplies to a mixture of 10 percent ethanol and 90 percent gasoline. Ethanol plants are being encouraged by tax breaks. There has been interest in ethanol plants from yuca and from new sugar cane plantations, but producing inexpensive carbohydrates has not been achieved.
The first fuel ethanol plant in Colombia began production in October 2005, with output of 300,000 liters a day in the Cauca region. By March 2006 five plants, all in the Cauca Valley, are operational with a combined capacity of 1,050,000 liters per day or 357 million liters per year. In the Cauca Valley of Colombia sugar is harvested year round and the new distilleries have very high availability. The total investment in these plants is $100 million. By 2007, Colombia hopes to have a capacity of 2,500,000 liters per day, which is the requirement for adding 10% ethanol to the gasoline. The ethanol fuel produced is currently used in the main cities close to the Cauca Valley, such as Bogota, Cali, and Pereira. There is not enough production for the rest of the country.
Ethanol fuel in the United States
Ethanol use and production in the United States is steadily increasing.
Archer Daniels Midland claims to be the largest producer of fuel ethanol in the US, with about 25% of the nation's ethanol production. Roughly 685 gas stations, out of a total of 165,000 carry
E85 pumps. Ethanol is predominantly only available in the
Midwest and
California, where most ethanol is refined. As of September 18, 2006 in the US, there are 4.93 billion gallons per year capacity for ethanol production with capacity of 2.92 billion gallons per year under construction.
For example, the U.S. company is currently building more ethanol facilities in the western U.S.
The estimate ethanol from corn cost $1.03-1.05/gallon in 2003-05, compared with forecasts of $1.27 from molasses, $2.35 from US beet and $2.40 from US sugarcane. The price of sugarcane in the U.S. is influenced by strict import quotas and federal price supports .
Regulations and subsidies
In
Brazil,
Colombia and the
United States, the use of ethanol from
sugar cane and grain as automotive fuel has been heavily promoted by government programs. Some individual
U.S. states in the
corn belt began subsidizing ethanol from corn after the Arab
oil embargo of 1973. The Energy Tax Act of 1978 authorized an excise tax exemption for
biofuels, chiefly gasohol. The excise tax exemption alone has been estimated as worth
US$1.4 billion per year. Another U.S. federal program guaranteed loans for the construction of ethanol plants, and in 1986 the U.S. even gave ethanol producers free corn. Colombia's ethanol program was started by a law which would exempt biomass-derived ethanol from some taxes on gasoline.
In August 2005,
President Bush signed a comprehensive energy bill which included a requirement to increase the production of ethanol and
biodiesel from 4 to 7.5 billion US gallons within the next ten years. It is expected that in the short term the majority of this increase will come from ethanol produced from corn.
Directive 2003/30/EC of the
European Parliament promotes the replacement of fossil fuels by biofuels: amongst them bio-ethanol to be blended into petrol. The United Kingdom has adopted a national policy of encouraging the use of
biofuels including ethanol, although the taxation of alternative fuels like
biodiesel is almost as onerous as that on conventional fossil fuels.
Ethanol and hydrogen
Hydrogen is being analyzed as an alternative fuel, creating a
hydrogen economy. Because hydrogen in its gaseous state takes up a very large volume when compared to other fuels,
logistics becomes a difficult problem. One possible solution is to use ethanol to transport the hydrogen, then liberate the hydrogen from its associated carbon in a hydrogen reformer and feed the hydrogen into a
fuel cell. Alternatively, some fuel cells can be directly fed by ethanol or methanol.
As of 2005, fuel cells are able to process methanol more efficiently than ethanol.
In early 2004, researchers at the
University of Minnesota announced the invention of a simple ethanol reactor that would feed ethanol through a stack of
catalysts, and output hydrogen suitable for a fuel cell. The device uses a
rhodium-
cerium catalyst for the initial reaction, which occurs at a temperature of about 700 °C . This initial reaction mixes ethanol, water vapor, and oxygen and produces good quantities of hydrogen. Unfortunately, it also results in the formation of carbon monoxide, a substance that "chokes" most fuel cells and must be passed through another catalyst to be converted into carbon dioxide. The ultimate products of the simple device are roughly 50% hydrogen gas and 30% nitrogen, with the remaining 20% mostly composed of carbon dioxide. Both the nitrogen and carbon dioxide are fairly inert when the mixture is pumped into an appropriate fuel cell. The carbon dioxide is released back into the atmosphere, where it can be reabsorbed by plant life. No net carbon dioxide is released, though it could be argued that while it is in the atmosphere, it does act as a greenhouse gas.
EEI has developed a new method for producing
butanol from biomass. This process involves the use of two separate micro-organisms in sequence to minimize production of acetone and ethanol byproducts. Interestingly, this process produces significant amounts of hydrogen as well as butanol.
Energy balance
For ethanol to contribute significantly to transportation fuel needs, it would need to have a positive net energy balance - and the federal government has long claimed that it does.
Quote: "...The most official study of the issue, which also reviews other studies, concludes that the "net energy balance" of making fuel ethanol from corn grain is 1.34...For
cellulosic bioethanol—the focus of the Biomass Program—that study projects an energy balance of 2.62...A Biomass Program life-cycle analysis of producing ethanol from stover, now underway, is expected to show a very impressive net energy ratio of more than 5..."
Meanwhile, some academic scientists argue that the energy balance is negative. The arguments advanced by these critics are highly flawed, since they assume energy used for distillation must be provided by petroleum, whereas the Brazil experience shows such energy can be provided by combustion of agricultural wastes from the source crop itself. In addition these critics argue that the same pesticide dose must be used on ethanol crops as crops destined for human consumption, a condition clearly contrary to fact.
To evaluate the net energy of ethanol, five variables must be considered: the amount of energy contained in the final ethanol product, the energy value of byproducts generated during the ethanol production process , the amount of energy directly consumed to make the ethanol , the quality of the resulting ethanol compared to the quality of refined gasoline, and the energy indirectly consumed . Although a topic of debate, some research that ignores energy quality suggests it takes as much or more fossil fuel energy to create an equivalent amount of energy in the form of ethanol. In other words, the energy needed to run the tractors, produce the
fertilizer, process the ethanol, and the energy associated with the wear and tear on all of the equipment used in the process may be more than the energy derived from burning ethanol. Two important flaws are cited in response to that argument. First, the energy quality is ignored, the economic effects of which are large. Principal economic effects of energy quality comparison are the cleanup costs of
soil contamination stemming from gasoline releases to the environment and medical costs from
air pollution resulting from refining and burning gasoline. Ethanol's higher octane rating may also allow for more thermally efficient conversion of chemical energy into mechanical energy. The second point is that the inclusion of development of ethanol plants instills a bias against that product based strictly upon the pre-existence of gasoline refining capacity. The real decision should be based upon the long-term economic and social returns. The first counter-argument, however, is contested. Burning a gallon of cleaner ethanol is still pointless if it implicitly requires burning two gallons of dirty gasoline to create that ethanol in the first place. New techniques for producing ethanol from plant cellulose create more ethanol per unit of energy input, and may fundamentally shift production to a positive energy balance when they reach economies of scale. Cellulosic ethanol can also be created from farm residue such as wheat straw, further defraying the energy costs of production.
Environmental effects
Air pollution
Compared with conventional unleaded gasoline, ethanol is a clean burning fuel source that combusts cleanly with oxygen to form carbon dioxide and water:
- C2H6O + 3 O2 ? 2 CO2 + 3 H2O
The Clean Air Act requires the addition of oxygenates to reduce carbon monoxide emissions in the United States. The additive
MTBE is currently being phased out due to ground water contamination, hence ethanol becomes an attractive alternative additive. As a fuel additive, ethanol being more volatile, carries with it gasoline as it evaporates, thus releasing more Volatile organic compounds .
Pure usage of ethanol rather than gasoline in your vehicle reduces its total carbon dioxide emissions, mile for mile, by about 13%. This is in part due to the agricultural processing needed to create the biofuel itself produces certain CO
2 emissions.
Ethanol is however considered to be a carbon neutral fuel meaning that if the sugar cane were left to rot it would produce the same amount of CO2 emissions as burning the ethanol used from it.
In considering the potential for pollution reduction with ethanol, however, it is equally important to consider the potential for environmental contamination stemming from the manufacture of ethanol. In 2002, monitoring of ethanol plants revealed that they released VOCs at a much higher rate than had previously been disclosed . The
Environmental Protection Agency subsequently reached settlement with
Archer Daniels Midland and
Cargill, two of the largest producers of ethanol, to reduce emission of these VOCs. VOCs are produced when fermented corn mash is dried for sale as a supplement for livestock feed. Devices known as thermal oxidizers or catalytic oxidizers can be attached to the plants to burn off the hazardous gases.
Effects of ethanol on agriculture
Environmentalists have
objections to many modern farming practices, including some practices useful for making bioethanol more competitive . If more third-world land were to be converted to agriculture to feed ethanol fuel demand, there is the possibility of trading today's automotive pollution for tomorrow's farm pollution.
There is some potential that through irresponsible farming methods some rainforest areas could be cleared to make land available for growing crops for commercial commodities such as palm oil for the generation of biodiesels.
Renewable resource
Ethanol is considered "renewable" because it is primarily the result of conversion of the sun's energy into usable energy. Oil production, however, is predicted to peak between 2021 and 2112 . Creation of ethanol starts with
photosynthesis causing the feedstocks such as
switchgrass,
sugar cane, or
corn to grow. These feedstocks are processed into ethanol . However, Brazil is the only country in the world where farming and production of ethanol is a profitable and widespread substitute for gasoline.
However, using current farming and production methods, ethanol from corn may not be fully sustainable as a replacement for fossil fuels. The amount of energy needed to produce it is a concern, especially if that energy is derived from fossil sources. For example, one study critical of ethanol assumes massive use of pesticides and fertilizers, which consume fossil fuels and damage the farming environment. However, corn grown for fuel would not need the same pesticide usage as corn grown for food, since consumer reaction is a major contributor to prolific pesticide applications. Moreover, the amount of ethanol that could be produced from corn or sugarcane, given the amount of farmland that is available, is likely limited to an amount below what would be needed to replace global petroleum consumption.
Economics
Some economists have argued that using bioalcohol as a petroleum substitute is economically infeasible because the energy required to grow and process the corn and other crops used as fuel is greater than the amount ultimately produced. They argue that government programs that mandate the use of bioalcohol are agricultural subsidies. The
United States Department of Energy, however, finds that for every unit of energy put towards ethanol production, 1.3 units are returned.
As yields improve or different feedstocks are introduced, ethanol production may become more economically feasible in the US. Currently, research on improving ethanol yields from each unit of corn is underway using biotechnology. By utilizing hybrids designed specifically with higher extractable starch levels, the energy balance is dramatically improved. Also, as long as oil prices remain high, the economical use of other feedstocks, such as cellulose, become viable. By-products such as straw or wood chips can be converted to ethanol. Fast growing species like switchgrass can be grown on land not suitable for other cash crops and yield high levels of ethanol per acre.
Dependence on foreign oil
A related argument is that developed regions like the
United States and
Europe, and increasingly the developing nations of Asia, mainly India and China, consume much more fossil fuels than they can extract from their territory, becoming dependent upon foreign suppliers as a result. As of 2006 the
energy policy of the United Kingdom recognizes it has become a net primary energy importer and is seeking increased foreign sources; near term targets are
natural gas import from
Norway. Even if the energy balance is negative, US production involves mostly domestic fuels such as natural gas and coal, so the impact on oil importation is still positive.
Notes
See also
...
- liquid fuels
- oil crisis
- Timeline of Alcohol Fuel
- cellulosic ethanol
External links
- Ethanol from Sweet Sorghum:
- Ethanol fuel for rural households;
- U.S. Department of Energy: .
-
- Farm Industry News: . Article about converting ethanol to hydrogen.
- Clean Fuels Development Coalition
- and
- Henry Ford, Charles Kettering and the Fuel of the Future
- survey article * . Published in Science, January 27, 2006
- David Cohn, "
