• Curriculum that teaches high school students about ethanol and its effect on vehicle performance, the environment, and the economy.
  
• The power of corn: E85 ethanol and the world’s increasing demands for energy. (middle school)
  
• Automobile Choices and Alternative Fuels (high school)
  
• Statistical Analysis of Corn Plants and Ethanol Production (high school)
  
• Make your own ethanol fuel
  
• Backyard ethanol production
  
• Fermenting waste fruit to fuel ethanol
  

Information on pump, California.

Ethanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages. It can be used as a fuel, mainly as a biofuel alternative to gasoline, and is widely used in cars in Brazil. Because it is easy to manufacture and process, and can be made from very common materials, such as sugar cane, it is steadily becoming a promising alternative to gasoline throughout much of the world.

Anhydrous ethanol (ethanol with less than 1% water) can be blended with gasoline in varying quantities up to pure ethanol (E100), and most spark-ignited gasoline style engines will operate well with mixtures of 10% ethanol (E10).^[1] Most cars on the road today in the U.S. can run on blends of up to 10% ethanol,^[2] and the use of 10% ethanol gasoline is mandated in some cities where harmful levels of auto emissions are possible.^[3]

Ethanol can be mass-produced by fermentation of sugar or by hydration of ethylene from petroleum and other sources. Current interest in ethanol mainly lies in bio-ethanol, produced from the starch or sugar in a wide variety of crops, but there has been considerable debate about how useful bio-ethanol will be in replacing fossil fuels in vehicles. Concerns relate to the large amount of arable land required for crops,^[4] as well as the energy and pollution balance of the whole cycle of ethanol production.^[5][6] Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns.^[7]

According to the International Energy Agency, cellulosic ethanol could allow ethanol fuels to play a much bigger role in the future than previously thought.^[8] Cellulosic ethanol offers promise as resistant cellulose fibers, a major component in plant cells walls, can be used to generate ethanol. Dedicated energy crops, such as switchgrass, are also promising cellulose sources that can be produced in many regions of the United States.^[9]

Chemistry

In this 3-d diagram of ethanol, the lines represent single bonds.

During ethanol fermentation, glucose is decomposed into ethanol and carbon dioxide.

C₆H₁₂O₆ → 2C₂H₆O + 2CO₂

During combustion ethanol reacts with oxygen to produce carbon dioxide, water, and heat: (other air pollutants are also produced when ethanol is burned in the atmosphere rather than in pure oxygen)

C₂H₆O + 3O₂ → 2CO₂ + 3H₂O

Together, they add up to:

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + heat

This is the reverse of the photosynthesis reaction, which shows that the three reactions completely cancel each other out, only converting light into heat without leaving any byproducts:

6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂

Sources

Main article: Energy crop

Sugar cane harvest

Cornfield in South Africa

Switchgrass

Ethanol is considered "renewable" because it is primarily the result of conversion of the sun's energy into usable energy. Creation of ethanol starts with photosynthesis causing the feedstocks such as switchgrass, sugar cane, or corn to grow. These feedstocks are processed into ethanol

About 5% of the ethanol produced in the world in 2003 was actually a petroleum product.^[10] It is made by the catalytic hydration of ethylene with sulfuric acid as the catalyst. 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 plants in the United States, Europe, and South Africa.^[11] Petroleum derived ethanol (synthetic ethanol) is chemically identical to bio-ethanol and can be differentiated only by radiocarbon dating.^[12]

Bio-ethanol is obtained from the conversion of carbon based feedstock. Agricultural feedstocks are considered renewable because they get energy from the sun using photosynthesis, provided that all minerals required for growth (such as nitrogen and phosphorus) are returned to the land. Ethanol can be produced from a variety of feedstocks such as sugar cane, bagasse, miscanthus, sugar beet, sorghum, grain sorghum, switchgrass, barley, hemp, kenaf, potatoes, sweet potatoes, cassava, sunflower, fruit, molasses, corn, stover, grain, wheat, straw, cotton, other biomass, as well as many types of cellulose waste and harvestings, whichever has the best well-to-wheel assessment.

Current, first generation processes for the production of ethanol from corn use only a small part of the corn plant: the corn kernels are taken from the corn plant and only the starch, which represents about 50% of the dry kernel mass, is transformed into ethanol. Two types of second generation processes are under development. The first type uses enzymes to convert the plant cellulose into ethanol while the second type uses pyrolysis to convert the whole plant to either a liquid bio-oil or a syngas. Second generation processes can also be used with plants such as grasses, wood or agricultural waste material such as straw.

Production process

The basic steps for large scale production of ethanol are: microbial (yeast) fermentation of sugars, distillation, dehydration (requirements vary, see Ethanol fuel mixtures, below), and denaturing (optional). Prior to fermentation, some crops require saccharification or hydrolysis of carbohydrates such as cellulose and starch into sugars. Saccharification of cellulose is called cellulolysis (see cellulosic ethanol). Enzymes are used to convert starch into sugar.^[13]

Fermentation

Main article: Ethanol fermentation

Ethanol is produced by microbial fermentation of the sugar. Production of ethanol from sugarcane (sugarcane requires a tropical climate to grow productively) returns about 8 units of energy for each unit expended compared to corn which only returns about 1.34 units of fuel energy for each unit of energy expended.^[14]

Carbon dioxide, a greenhouse gas, is emitted during fermentation and combustion. However, this is canceled out by the greater uptake of carbon dioxide by the plants as they grow to produce the biomass.^[15] When compared to gasoline, depending on the production method, ethanol releases less or even no greenhouse gases.^[16][17]

Distillation

Ethanol plant in West Burlington, Iowa

Ethanol plant in Sertãozinho, Brazil.

For the ethanol to be usable as a fuel, water must be removed. Most of the water is removed by distillation, but the purity is limited to 95-96% due to the formation of a low-boiling water-ethanol azeotrope. The 95.6% m/m (96.5% v/v) ethanol, 4.4% m/m (3.5% v/v) water mixture may be used as a fuel alone, but unlike anhydrous ethanol, is immiscible in gasoline, so the water fraction is typically removed in further treatment in order to burn with in combination with gasoline in gasoline engines.

Dehydration

Currently, the most widely used purification method is a physical absorption process using a molecular sieve, for example, ZEOCHEM Z3-03 (a special 3A molecular sieve for EtOH dehydration). Another method, azeotropic distillation, is achieved by adding the hydrocarbon benzene which also denatures the ethanol (to render it undrinkable for duty purposes). A third method involves use of calcium oxide as a desiccant.

Technology

Ethanol-based engines

Ethanol is most commonly used to power automobiles, though it may be used to power other vehicles, such as farm tractors and airplanes. Ethanol (E100) consumption in an engine is approximately 34% higher than that of gasoline (the energy per volume unit is 34% lower).^[18][19] However, higher compression ratios in an ethanol-only engine allow for increased power output and better fuel economy than would be obtained with the lower compression ratio.^[20][21] In general, ethanol-only engines are tuned to give slightly better power and torque output to gasoline-powered engines. In flexible fuel vehicles, the lower compression ratio requires tunings that give the same output when using either gasoline or hydrated ethanol. For maximum use of ethanol's benefits, a much higher compression ratio should be used,^[22] which would render that engine unsuitable for gasoline usage. When ethanol fuel availability allows high-compression ethanol-only vehicles to be practical, the fuel efficiency of such engines should be equal or greater than current gasoline engines. However, since the energy content (by volume) of ethanol fuel is less than gasoline, a larger volume of ethanol fuel (151%) would still be required to produce the same amount of energy.^[23]

A 2004 MIT study,^[24] and an earlier paper published by the Society of Automotive Engineers,^[25] describing tests, identify a method to exploit the characteristics of fuel ethanol that is substantially better than mixing it with gasoline. The method presents the possibility of leveraging the use of alcohol to even achieve definite improvement over the cost-effectiveness of hybrid electric. The improvement consists of using dual-fuel direct-injection of pure alcohol (or the azeotrope or E85) and gasoline, in any ratio up to 100% of either, in a turbocharged, high compression-ratio, small-displacement engine having performance similar to an engine having twice the displacement. Each fuel is carried separately, with a much smaller tank for alcohol. The high-compression (which increases efficiency) engine will run fine on ordinary gasoline under low-power cruise conditions. Alcohol is directly injected into the cylinders (and the gasoline injection simultaneously reduced) only when necessary to suppress ‘knock’ such as when significantly accelerating. Direct cylinder injection raises the already high octane rating of ethanol up to an effective 130. The calculated over-all reduction of gasoline use and CO2 emission is 30%. The consumer cost payback time shows a 4:1 improvement over turbo-diesel and a 5:1 improvement over hybrid. In addition, the problems of water absorption into pre-mixed gasoline (causing phase separation), supply issues of multiple mix ratios and cold-weather starting are avoided.

Ethanol's higher octane allows an increase of an engine's compression ratio for increased thermal efficiency.^[26] 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.^[27] This would result in the MPG (miles per gallon) of a dedicated ethanol vehicle to be about the same as one burning gasoline.

Engines using fuel with from 30% to 100% ethanol also need a cold-starting system. For E85 fuel at temperatures below 11 °C (52 °F) a cold-starting system is required for reliable starting and to meet EPA emissions standards.^[28]

Ethanol fuel mixtures

For more details on this topic, see Common ethanol fuel mixtures.

Hydrated ethanol × gasoline type C price table for use in Brazil

To avoid engine stall, the fuel must exist as a single phase. The fraction of water that an ethanol-gasoline fuel can contain without phase separation increases with the percentage of ethanol.^[29]. This shows, for example, that E30 can have up to about 2% water. If there is more than about 71% ethanol, the remainder can be any proportion of water or gasoline and phase separation will not occur. However, the fuel mileage declines with increased water content. The increased solubility of water with higher ethanol content permits E30 and hydrated ethanol to be put in the same tank since any combination of them always results in a single phase. Somewhat less water is tolerated at lower temperatures. For E10 it is about 0.5% v/v at 70 F and decreases to about 0.23% v/v at -30 F.^[30]

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 October 2006 23% is required. The United States allows up to 10% blends, and some states require this (or a smaller amount) in all gasoline sold. Other countries have adopted their own requirements. Beginning with the model year 1999, an increasing number of vehicles in the world are manufactured with engines which can run on any fuel from 0% ethanol up to 100% ethanol without modification. Many cars and light trucks (a class containing minivans, SUVs and pickup trucks) are designed to be flexible-fuel vehicles (also called dual-fuel vehicles). Their engine systems contain alcohol sensors in the fuel and/or oxygen sensors in the exhaust that provide input to the engine control computer to adjust the fuel injection to achieve stochiometric (no residual fuel or free oxygen in the exhaust) air-to-fuel ratio for any fuel mix. The engine control computer can also adjust (advance) the ignition timing to achieve a higher output without pre-ignition when higher alcohol percentages are present in the fuel being burned.

Fuel economy

All fuel-driven vehicles have a fuel economy (measured as miles per US gallon -MPG-, or liters per 100 km) that is directly proportional to the fuel's energy content.^[31] Ethanol contains approx. 34% less energy per unit volume than gasoline, and therefore will result in a 34% reduction in miles per US gallon, given the same fuel economy.^[18][19] For E10 (10% ethanol and 90% gasoline), the effect is small (~3%) when compared to conventional gasoline,^[32] and even smaller (1-2%) when compared to oxygenated and reformulated blends.^[33] However, for E85 (85% ethanol), the effect becomes significant. E85 will produce lower mileage than gasoline, and will require more frequent refueling. Actual performance may vary depending on the vehicle. The EPA-rated mileage of current USA flex-fuel vehicles^[34] should be considered when making price comparisons, but it must be noted that E85 is a high performance fuel and should be compared to premium. In one estimate^[35] the US retail price for E85 ethanol is 2.62 US dollar per gallon or 3.71 dollar corrected for energy equivalency compared to a gallon of gasoline priced at 3.03 dollar. Brazilian cane ethanol (100%)is priced at 3.88 dollar against 4.91 dollar for E25 (figures July 2007).

Use by country

The top five ethanol producers in 2006 were the United States (4.855 billion US gallons per year (bgy)), Brazil (4.491 bgy), China (1.017 bgy), India (0.502 bgy) and France (0.251 bgy).^[36] Brazil and the United States accounted for 90 percent of all ethanol production. Also, it should be noted that the United States, now producing at a rate of about 4.6 billion US gallons per year, is widely considered the world’s largest ethanol producer. Strong incentives, coupled with other industry development initiatives, are giving rise to fledgling ethanol industries in countries such as Thailand, the Philippines, Colombia, the Dominican Republic and Malawi. Nevertheless, ethanol has yet to make a dent in world oil consumption.^[37]

Distribution

The number of bioethanol stations in Europe is highest in Sweden (792). In the USA there are currently 1441 stations, although most stations are in the corn belt area.^[38].^[39] One of the debated methods for distribution in the US is using existing oil pipelines,^[40] which raises concerns over corrosion.

Brazil

Main article: Ethanol fuel in Brazil

Gasoline on the left, alcohol on the right at a filling station in Brazil.

Brazil has the largest bio-fuel programs in the world, involving production of ethanol fuel from sugar cane, and ethanol now provides 30% of the country's automotive fuel.^[41] As a result of this, together with the exploitation of domestic deep water oil sources, Brazil, which years ago had to import a large share of the petroleum needed for domestic consumption, recently reached complete self-sufficiency in oil.^[42][43][44]

Brazil produced around 16.4 billion liters of ethanol in 2004 and used 2.7 million hectares of land area for this production (4.5% of the Brazilian land area used for crop production in 2005^[45]). Of this, around 12.4 billion liters were produced as fuel for ethanol-powered vehicles in the domestic market. The ethanol-powered and flexible-fuel vehicles are manufactured to tolerate hydrated ethanol, an azeotrope comprised of 95.6% ethanol and 4.4% water.

Almost all new cars sold in Brazil can be fueled with ethanol and/or gasoline (the percentage of the mixture being irrelevant).

Production and use of ethanol has been stimulated through:

• Low-interest loans for the construction of ethanol distilleries
• Guaranteed purchase of ethanol by the state-owned oil company at a reasonable price
• Retail pricing of neat ethanol so it is competitive if not slightly favorable to the gasoline-ethanol blend
• Tax incentives provided during the 1980s to stimulate the purchase of neat ethanol vehicles.^[46]

Guaranteed purchase and price regulation were ended some years ago, with relatively positive results. In addition to these other policies, ethanol producers in the state of São Paulo established a research and technology transfer center that has been effective in improving sugar cane and ethanol yields.^[46]

United States

A Ford Taurus "fueled by clean burning ethanol" owned by New York City.

Main article: Ethanol fuel in the United States

Most cars on the road today in the U.S. can run on blends of up to 10% ethanol, and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends. In 2007, Portland, Oregon, recently became the first city in the United States to require all gasoline sold within city limits to contain at least 10% ethanol.^[47][48] As of January 2008, three states — Missouri, Minnesota, and Hawaii — require ethanol to be blended with gasoline motor fuel. Many cities are also required to use an ethanol blend due to non-attainment of federal air quality goals.^[49]

Several motor vehicle manufacturers, including Ford, DaimlerChrysler, and GM, sell flexible-fuel vehicles that can use gasoline and ethanol blends ranging from pure gasoline up to 85% ethanol (E85). By mid-2006, there were approximately six million E85-compatible vehicles on U.S. roads.^[50]

Fuel ethanol as it is currently produced in the United States is variously criticized for its dependence on high subsidies, its consumption of more energy than is contained in the resulting fuel, and its (usually) consuming a food crop to produce fuel.^[35] The subsidies have resulted in the conversion of considerable land to corn (maize) production, which generally consumes more fertilizers and pesticides than many other land uses.^[35] Recent developments with cellulosic ethanol production and commercialization may allay some of these concerns.^[51]

Europe

The consumption of bioethanol is largest in Europe in Germany, Sweden, France and Spain. Europe produces equivalent to 90% of its consumption (2006). Germany produced ca 70% of its consumption, Spain 60% and Sweden 50% (2006). In Sweden there are 792 E85 filling stations and in France 131 E85 service stations with 550 more under construction.^[53]

On Monday, September 17, 2007 the first ethanol fuel pump was opened in Reykjavik, Iceland. This pump is the only one of its kind in Iceland. The fuel is imported by Brimborg, a Volvo dealer, as a pilot to see how ethanol fueled cars work in Iceland. In a few weeks, the pump will be opened for public use.

In The Netherlands regular petrol with no bio-additives is slowly outphased, since EU-legislation has been passed that requires the fraction of nonmineral origin to become minimum 5,75% of the total fuel consumption volume in 2010. This can be realised by substitutions in diesel or in petrol of any biological source; or fuel sold in the form of pure biofuel. (2007:) There are only a few gas stations where E85 is sold, which is an 85% ethanol, 15% petrol mix.^[54] Directly neighbouring country Germany is reported to have a much better biofuel infrastructure and offers both E85 and E50. Biofuel is taxed equally as regular fuel. However, fuel tanked abroad cannot be taxed and a recent payment receipt will in most cases suffice to prevent fines if customs check tank contents. (Authorities are aware of high taxation on fuels and cross-border fuel refilling is a well-known practice.)

Main article: Ethanol fuel in Sweden

All Swedish gas stations are required by an act of parliament to offer at least one alternative fuel, and every fifth car in Stockholm now drives at least partially on alternative fuels, mostly ethanol.^[55]

Stockholm will introduce a fleet of Swedish-made electric hybrid buses in its public transport system on a trial basis in 2008. These buses will use ethanol-powered internal-combustion engines and electric motors. The vehicles’ diesel engines will use ethanol.^[56]

Asia and Oceania

China is promoting ethanol-based fuel on a pilot basis in five cities in its central and northeastern region, a move designed to create a new market for its surplus grain and reduce consumption of petroleum. The cities include Zhengzhou, Luoyang and Nanyang in central China's Henan province, and Harbin and Zhaodong in Heilongjiang province, northeast China. Under the program, Henan will promote ethanol-based fuel across the province by the end of this year. Officials say the move is of great importance in helping to stabilize grain prices, raise farmers' income and reducing petrol- induced air pollution.^[57]

Main article: Ethanol fuel in Australia

Legislation in Australia imposes a 10% cap on the concentration of fuel ethanol blends. Blends of 90% unleaded petrol and 10% fuel ethanol are commonly referred to as E10. E10 is available through service stations operating under the BP, Caltex, Shell and United brands as well as those of a number of smaller independents. Not surprisingly, E10 is most widely available closer to the sources of production in Queensland and New South Wales. E10 is most commonly blended with 91 RON "regular unleaded" fuel. There is a requirement that retailers label blends containing fuel ethanol on the dispenser.

Environment

Energy balance

Main article: Ethanol fuel energy balance

All biomass goes through at least some of these steps: it needs to be grown, collected, dried, fermented, and burned. All of these steps require resources and an infrastructure. The total amount of energy input into the process compared to the energy released by burning the resulting ethanol fuel is known as the energy balance. Figures compiled in a 2007 National Geographic Magazine article^[35] point to modest results for corn ethanol produced in the US: one unit of fossil-fuel energy is required to create 1.3 energy units from the resulting ethanol. The energy balance for ethanol produced in Brazil is more favorable per the accompanying chart. Energy balance estimates are not easily produced, thus numerous such reports have been generated that are contradictory.

Air pollution

Compared with conventional unleaded gasoline, ethanol is a particulate-free burning fuel source that combusts cleanly with oxygen to form carbon dioxide and water. Gasoline produces 2.44 CO2 equivalent kg/l and ethanol 1.94 (this is -21% CO2). 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. Use of ethanol, produced from current (2006) methods, emits a similar net amount of carbon dioxide but less carbon monoxide than gasoline. Current production methods includes air pollution from the manufacturer of macronutrient fertilizers such as ammonia.

A study by atmospheric scientists at Stanford University found that E85 fuel would increase the risk of air pollution deaths relative to gasoline.^[58] Ozone levels are significantly increased, thereby increasing photochemical smog and aggravating medical problems such as asthma.^[59][60]

Manufacture

In 2002, monitoring of ethanol plants revealed that they released VOCs (volatile organic compounds) at a higher rate than had previously been disclosed.^[61] The Environmental Protection Agency (EPA) 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. Smog causing pollutants are also increased by using ethanol fuel in comparison to gasoline.

Greenhouse gas abatement

Graph of UK figures for the Carbon Intensity of Bioethanol and fossil fuels. This graph assumes that all bioethanols are burnt in their country of origin^[62]

The calculation of exactly how much Carbon Dioxide is produced in burning bioethanol is a complex and inexact process, and is highly dependant on the method by which the ethanol is produced and the assumptions made in the calculation. A calculation should include:

• The cost of growing the feedstock
• The cost of transporting the feedstock to the factory
• The cost of processing the feedstock into bioethanol

Such a calculation may or may not consider the following effects:

• The cost of the change in land use of the area where the fuel feedstock is grown.
• The cost of transportation of the bioethanol from the factory to its point of use
• The efficiency of the bioethnol compared with standard gasoline
• The amount of Carbon Dioxide produced at the tail pipe.
• The benefits due to the production of useful bi-products, such as cattle feed

The graph on the right shows figures calculated by the UK government for the purposes of the Renewable transport fuel obligation^[62]

The January 2006 Science article from UC Berkeley's ERG, estimated reduction from corn ethanol in GHG to be 13% after reviewing a large number of studies. However, in a correction to that article released shortly after publication, they reduce the estimated value to 7.4%. A National Geographic Magazine overview article (2007)^[35] puts the figures at 22% less CO₂ emissions in production and use for corn ethanol compared to gasoline and a 56% reduction for cane ethanol. Carmaker Ford reports a 70% reduction in CO₂ emissions with bioethanol compared to petrol for one of their flexible-fuel vehicles.^[53]

An additional complication is that production requires tilling new soil^[63] which produces a one-off release of GHG that it can take decades or centuries of production reductions in GHG emissions to equalize.^[64] As an example, converting grass lands to corn production for ethanol takes about a century of annual savings to make up for the GHG released from the initial tilling.^[65]

Land use

Large-scale farming is necessary to produce agricultural alcohol and this requires substantial amounts of cultivated land. University of Minnesota researchers report that if all corn grown in the U.S. were used to make ethanol it would displace 12% of current U.S. gasoline consumption.^[66] There are claims that land for ethanol production is acquired through deforestation, while others have observed that areas currently supporting forests are usually not suitable for growing crops.^[67][68] In any case, farming may involve a decline in soil fertility due to reduction of organic matter,^[69] a decrease in water availability and quality, an increase in the use of pesticides and fertilizers, and potential dislocation of local communities.^[70] However, new technology enables farmers and processors to increasingly produce the same output using less inputs.^[66]

There is a concern that as demand for ethanol fuel increases, food crops are replaced by fuel crops, driving food supply down and food prices up. Growing demand for ethanol in the United States has been discussed as a factor in the increased corn prices in Mexico.^[71] Average barley prices in the United States rose 17% from January to June 2007 to the highest in 11 years. However, some commentators suggest that recent food price increases mainly reflect high oil prices in recent years, not specific pressures associated with ethanol production.^[72]

Cellulosic ethanol production is a new approach which may alleviate land use and related concerns. Cellulosic ethanol can be produced from any plant material, potentially doubling yields, in an effort to minimize conflict between food needs versus fuel needs. Instead of utilizing only the starch by-products from grinding wheat and other crops, cellulosic ethanol production maximizes the use of all plant materials, including gluten. This approach would have a smaller carbon footprint because the amount of energy-intensive fertilisers and fungicides remain the same for higher output of usable material. The technology for producing cellulosic ethanol is currently in the commercialization stage.^[73][74]

Many analysts suggest that, whichever ethanol fuel production strategy is used, fuel conservation efforts are also needed to make a large impact on reducing petroleum fuel use.^[75]

Efficiency of common crops

As ethanol 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. 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 unit area.^[35]

Reduced petroleum import

One rationale given for extensive ethanol production in the U.S. is its benefit to energy security, by shifting the need for some foreign-produced oil to domestically-produced energy sources.^[80] Production of ethanol requires significant energy, but current U.S. production derives most of that energy from coal, natural gas and other sources, rather than oil.^[81] Because 66% of oil consumed in the U.S. is imported, compared to a net surplus of coal and just 16% of natural gas (2006 figures),^[82] the displacement of oil-based fuels to ethanol produces a net shift from foreign to domestic U.S. energy sources.

Recent patents

In 2006-2-23, Veridium Corporation announced the technology to convert exhaust carbon dioxide from the fermentation stage of ethanol production facilities back into new ethanol and biodiesel. The bioreactor process is based on a new strain of iron-loving blue-green algae discovered thriving in a hot stream at Yellowstone National Park.^[83]

In 2006-11-14, US Patent Office approved Patent 7135308, a process for the production of ethanol by harvesting starch-accumulating filament-forming or colony-forming algae to form a biomass, initiating cellular decay of the biomass in a dark and anaerobic environment, fermenting the biomass in the presence of a yeast, and the isolating the ethanol produced.^[84]

Criticism and controversy

Main article: Food vs fuel

In 2007, biofuels consumed one third of America's corn (maize) harvest. Filling up one U.S. SUV fuel tank one time with ethanol uses enough corn to feed one person for a year. 30m tonnes of U.S. corn going to ethanol in 2007 greatly reduces the world's overall supply of grain.^[85]

Jean Ziegler (United Nations expert on the Right To Food) called for a five-year moratorium on biofuel production to halt the increasing catastrophe for the poor. He proclaimed that the rising practice of converting food crops into biofuel is "A Crime Against Humanity," saying it is creating food shortages and price jumps that cause millions of poor people to go hungry.^[86]

The European Organisation for Economic Co-operation and Development warns that “the current push to expand the use of biofuels is creating unsustainable tensions that will disrupt markets without generating significant environmental benefits.”^[87]

When all 200 American ethanol subsidies are considered, they cost about $7 billion USD per year (equal to roughly $1.90 USD total for each a gallon of ethanol). When the price of one agricultural commodity increases, farmers are motivated to quickly shift finite land and water resources to it, away from traditional food crops.^[88]

The 2007-12-19 U.S. Energy Independence and Security Act of 2007 requires American “fuel producers to use at least 36 billion gallons of biofuel in 2022. This is nearly a fivefold increase over current levels.”^[89]

When cellulosic ethanol is produced from feedstock like switchgrass and sawgrass, the nutrients required to grow the cellulose are removed and cannot decay and replenish the soil. The soil is of poorer quality, and unsustainable soil erosion occurs.

Sugar cane ethanol works in Brazil because they have an equatorial year-round growing season, and the Amazon River – world’s largest fresh water supply. Locations with snow on the ground part of the year, short growing seasons, and limited fresh water supplies are less effective. Growing crops like thirsty genetically-engineered corn can require significant irrigation.

Ethanol production consumes large quantities of unsustainable petroleum and natural gas. Even with the most-optimistic energy return on investment claims, in order to use 100% solar energy to grow corn and produce ethanol (fueling farm-and-transportation machinery with ethanol, distilling with heat from burning crop residues, using NO fossil fuels), the consumption of ethanol to replace current U.S. petroleum use alone would require about 75% of all cultivated land on the face of the Earth, with no ethanol for other countries, or sufficient food for humans and animals.^[90]

Fuel system problems

Several of the outstanding ethanol fuel issues are linked specifically to fuel systems. Fuels with more than 10% ethanol are not compatible with non E85-ready fuel system components and may cause corrosion of ferrous components.^[91].^[92] Ethanol fuel can negatively affect electric fuel pumps by increasing internal wear^[92] and undesirable spark generation.^[93], is not compatible with capacitance fuel level gauging indicators and may cause erroneous fuel quantity indications in vehicles that employ that system.^[94] and is not always compatible with marine craft, especially those that use fiberglass tanks.^[95].^[96]

Ethanol fuel decreases fuel-economy by 15-30%; this can be avoided using certain modifications that would, however, render the engine inoperable on regular petrol without the addition of an adjustable ECU, or use of multiple ECUs to run the engine on multiple fuel types.^[97] Tough materials are needed to accommodate a higher compression ratio to make an ethanol engine as efficient as it would be on petrol; these would be similar to those used in diesel engines which typically run at a CR of 20:1,^[98] versus about 8-12:1 for petrol engines.^[99]

References