Ethanol
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Bioenergy > Biofuels > Liquid biofuels > Ethanol
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| Energy density: | 19.6 MJ/l1 |
|---|---|
| Air-fuel ratio: | 9.01 |
| Specific energy: | 3.0 MJ/kg air1 |
| Heat of Vaporization: | 0.92 MJ/kg1 |
| Research Octane Number (RON): | 1301 |
| Motor Octane Number (MON): | 961 |
| Pump Octane Number (PON): | ??? |
| Feedstocks: | Temperate: corn, sorghum, sugar beets Tropical: sugar cane, sweet potatoes, coconut, cassava, milo Second-generation: cellulose, miscanthus, prairie grass, switchgrass |
| 1Wikipedia: biobutanol | |
Ethanol (C2H5OH) (shorthand designation EtOH), also known as ethyl alcohol or grain alcohol, is a colorless, flammable, toxic chemical compound. It is the alcohol that is consumed in alcoholic beverages. Ethanol has been used as a fuel since the early days of the automobile. It can be blended with gasoline for use in flex-fuel engines, making it a gasoline additive and substitute for petroleum-derived gasoline.
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Advantages/disadvantages
- One liter of ethanol contains 66% of the energy content (typically expressed as British Thermal Units, or BTUs as one liter of gasoline, which means that cars that use ethanol require one third more fuel by volume to travel the same distance.1
- "However, pure ethanol has a high octane value, which improves the performance of gasoline by reducing the likelihood that engine knock problems will occur."1
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Emissions
- Ethanol is an oxygenate because it contains oxygen, unlike gasoline.1
- Oxygenates can improve the fuel combustion process reducing the emission of pollutants.1
- However, ethanol combustion products also react with more atmospheric nitrogen, which can marginally increase emissions of ozone-forming nitrogen oxide (NOx) gases.1
- Ethanol contains less sulfur than gasoline and as a result lowers emissions of sulfur oxides (SOx).1
- The carbon dioxide released by burning bioethanol is the same CO2 that was fixed by the plant it was produced from, and therefore net emissions of carbon are zero.1
- However, fossil fuels are used in the production of the feedstocks and in the processing of ethanol, and these must be considered when evaluating the impact of ethanol on emissions of greenhouse gases contributing to climate change.1
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Ethanol production
- The simplest way to produce ethanol is through the fermentation of simple sugars, such as those found in sugar cane, sugar beet and sweet sorghum.1
- "Starch crops such as corn, wheat, and cassava can also be hydrolyzed into sugar, which can then be fermented into ethanol".1
- Sugars naturally ferment into acids and alcohols, including ethanol, but yeast and other enzymes can be used to speed up the process.1
- Cellulosic ethanol - Ethanol can also be produced from cellulose, which makes up the fibrous and woody parts of the plant. Cellulose is mostly inedible, except to termites and ruminants, such as cows.
- Producing cellulosic ethanol is far more challenging then normal ethanol, requring the use of special enzymes or the use of gasification and biomass-to-liquids technologies.
- The much greater amounts and lower cost of cellulosic feedstocks means that there is great potential for producing cellulosic ethanol.
- However, the technology has not yet been fully commercialized, with only small scale plants currently in operation.
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Brazilian ethanol
- Brazil is the largest producer of ethanol in the world.
- "The fermentation units are usually integrated into existing sugar mills, where the co-products of refining sugar cane include various grades of sugar, molasses, CO2, and the fibrous residue of crushed sugar cane stalks, called bagasse.1
- The bagasse residue is often used as a direct-firing biofuel to produce steam, which is used to provide heat and often to generate electricity for use in the ethanol production process. The excess electricity is often sold to the electric grid. (This process is known as co-firing.)1
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US ethanol
- Miscanthus can meet U.S. biofuels goal using less land than corn or switchgrass, 30 July 2008 press release by University of Illinois at Champaign-Urbana: "Using corn or switchgrass to produce enough ethanol to offset 20 percent of gasoline use – a current White House goal – would take 25 percent of current U.S. cropland out of food production, the researchers report. Getting the same amount of ethanol from Miscanthus would require only 9.3 percent of current agricultural acreage."[1]
- Tropical maize could become biofuel supercrop in the US, similar to sugarcane. "Scientists from the University of Illinois who are studying tropical maize have found that when the crop is grown in the US, it does not produce grain, but stores far more sugar in its stalks instead."
- The United States is the second largest producer of ethanol in the world. (Citation needed)
- Ethanol in the United States is mostly produced from corn. (Citation needed)
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News
- Uprising Against the Ethanol Mandate, 23 July 2008 by the New York Times: "The ethanol industry, until recently a golden child that got favorable treatment from Washington, is facing a critical decision on its future."
- "Gov. Rick Perry of Texas is asking the Environmental Protection Agency to temporarily waive regulations requiring the oil industry to blend ever-increasing amounts of ethanol into gasoline. A decision is expected in the next few weeks."
- "His request for an emergency waiver cutting the ethanol mandate to 4.5 billion gallons, from the 9 billion gallons required this year and the 10.5 billion required in 2009, is backed by a coalition of food, livestock and environmental groups."
- "In ethanol’s home ground of the Midwest, where much of the corn is grown and the additive is made, Mr. Perry’s petition was opposed by 12 governors. Senator Charles Grassley, Republican of Iowa, accused the Grocery Manufacturers Association, the group leading the public relations fight against ethanol, of 'treasonous' acts."[2]
- Shell boosts stake in Iogen cellulosic ethanol, 15 July 2008 by Reuters: "Oil major Royal Dutch Shell Plc said on Tuesday it will make a 'significant investment' in a venture it has with Canadian cellulosic ethanol maker Iogen Corp."
- "Iogen, which is also backed by Goldman Sachs Group Inc, has run a demonstration plant in Ottawa since 2004 that can produce about 2.5 million liters of ethanol a year from the plant stalks that are left behind after farmers harvest crops."
- "It is planning to open a C$500-million ($500 million) commercial-scale plant in Saskatchewan, Canada's largest wheat-producing province, in 2011. That plant would produce about 90 million liters (23.78 million U.S. gallons) of ethanol a year.
- "Cellulosic ethanol costs about twice as much to produce as corn-based ethanol, and has not yet been produced on a commercial scale."[3]
- Biofuels Battle: Tear Down The Brazilian Wall, 1 July 2008 in the Wall Street Journal's Environmental Capital blog: "Biofuels have few friends lately. But Brazil’s biofuel industry found a big one —- U.S. Senator Richard Lugar."
- Food-related industries launch anti-biofuel campaign, 10 June 2008 by Bloomberg.com, in the Houston Chronicle: In the United States, the "Grocery Manufacturers Association, the American Meat Institute, the National Restaurant Association and other groups say rising corn-based ethanol production is pushing food costs higher." Their new lobbying alliance, "Food Before Fuel", is "calling on Congress to step back and re-evaluate our biofuels policy, which is distorting the marketplace and harming the environment and consumers."[4]
- Grass biofuels 'cut CO2 by 94%', 8 January 2008, by BBC News: A new report by US researchers has found that fast-growing "switchgrass-derived ethanol produced 540% more energy than was required to manufacture the fuel" and "delivers vast savings of carbon dioxide emissions compared with petrol." The paper, "Net energy of cellulosic ethanol from switchgrass (PDF file)" in the Proceedings of the National Academy of Sciences, analyzed all of the energy input factors, including "nitrogen fertiliser, herbicides, diesel and seed production."
- Hillary Clinton outlines ambitious biofuels plan: 60 billion gallons by 2030, From Biopact, Clinton outlined her plan to dramatically increase biofuels production in the United States.
- Brazil case accents need for new biofuels rules. Brazil is preparing to finally take their case against US ethanol tariffs before the WTO. It is expected that regardless of the results of the case, the WTO will be prompted to develop new rules for the regulation of biofuels.
- USDA report looks at ethanol transportation and logistics. According to Biopact, the USDA is looking at the requirements for transporting ethanol around the United States, for example dedicated pipelines for corn ethanol.
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Publications
See books, reports, scientific papers, position papers and websites for additional useful resources.
- U.S. Ethanol Policy—Possibilities for the Future (pdf) by Wallace E. Tyner; Department of Agricultural Economics, Purdue University, January 2007.
- Ethanol and Energy Policy (pdf) by Otto Doering; Department of Agricultural Economics, Purdue University, December 2006.
- Economics of Ethanol (pdf) by Chris Hurt, Wally Tyner, Otto Doering; Department of Agricultural Economics, Purdue University, December 2006.
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Organizations
- American Coalition for Ethanol - "A non-profit membership association devoted to promoting the increased production and use of ethanol."[5]
- Renewable Fuels Association
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References
1Biofuels for Transportation (draft) (2006, Worldwatch Institute), p.10-12. Used with permission.
| Ethanol | edit | |
| Bioethanol - Corn ethanol Ethanol producers by country | Ethanol feedstocks: Cellulosic ethanol (Microbe research) | Ethanol policies: Ethanol subsidies | ||
| Bioenergy feedstocks | edit | |
|
Biodiesel feedstocks: Ethanol feedstocks: | ||
| Types of bioenergy | edit | |
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Gases: Biopropane | Biogas | Synthetic natural gas | Syngas | ||
