By C. Kohn Agricultural Sciences Waterford, WI Unless specially cited, all information is taken from the Alternative Fuels and Advanced Vehicles Data Center and the Great Lakes Bioenergy Research Center, both of the US Department of Energy.Alternative Fuels and Advanced Vehicles Data CenterGreat Lakes Bioenergy Research Center

Ethanol Ethanol is a liquid produced by yeast through fermentation, or the conversion of sugars and other carbohydrates into ethanol and carbon dioxide in the absence of oxygen. Pure ethanol is a clear, colorless liquid that consists of 2 carbon atoms bonded to a hydroxyl (-OH) group Ethanol has the same molecular structure (CH 3 CH 2 OH) regardless its original source (corn, sugar cane, etc.)

Ethanol and Engines Ethanol works well in internal combustion engines. Henry Ford and other early automakers thought ethanol would be the world's primary fuel before gasoline became so readily available. Unfortunately, a gallon of pure ethanol (E100) contains 34% less energy than a gallon of gasoline. However, ethanol does have a higher octane rating, improving engine performance.

Ethanol as a Fuel Ethanol is a high-octane fuel. The octane rating is a measure of how efficiently a fuel combusts. Low-octane gasoline can be blended with 10% ethanol to attain the standard 87 octane requirement. Low-level blends of ethanol, such as E10 (10% ethanol, 90% gasoline), generally have a higher octane rating than unleaded gasoline.blends This means that the addition of ethanol to gasoline generally tends to improve engine performance by increasing the octane rating of the fuel.

Ethanol Benefits Ethanol is a renewable, largely domestic transportation fuel. Use of ethanol and other alternative fuels can displace a significant amount of imported petroleum. About two-thirds of U.S. petroleum demand is used for transportation. 60% of U.S. petroleum is currently imported. Ethanol use also supports the U.S. agricultural sector and improves the US economy by providing jobs and investment opportunities.

Reducing GHGs The carbon dioxide released when ethanol is burned is balanced by the carbon dioxide captured when the crops are grown to make ethanol. This differs from petroleum, which is made from plants that grew millions of years ago and obviously do not reabsorb CO2 after it is emitted. According to Argonne National Laboratory, on a life-cycle analysis basis, corn-based ethanol production and use reduces greenhouse gas emissions (GHGs) by up to 52% compared to gasoline production and use. Cellulosic ethanol use could reduce GHGs by as much as 86%.

Protecting the Environment Ethanol is biodegradable and, if spilled, poses much less of a threat than petroleum to surface and ground water. E.g. after the sinking of the Bow Mariner off the Virginia coast in February 2004, U.S. Coast Guard officials noted the cargo of 3.2 million gallons of industrial ethanol had dissipated quickly and did not pose an environmental threat to humans or marine life.sinking of the Bow Mariner Compare this to the 2010 oil spill in the Gulf of Mexico!

Sources of Ethanol Ethanol can be produced from a variety of sources. Ethanol produced in Brazil is made primarily from sugar cane. Ethanol produced in the US is made primarily from corn. The original source of ethanol, or its feedstock, is a major determining factor in its ease of production and sustainability.

Feedstock Comparison Sugar Cane (+) easiest to ferment into ethanol (-) cannot be grown in most of the US (not a domestic fuel) Corn (grain) (+) widely available; grown in all 50 states (-) competition for food; not enough corn grain to meet all US energy needs; choice of cultivation methods can have major impacts on the sustainability of this feedstock Cellulose (plant stalks, leaves, trunks, branches, and husks) (+) found everywhere we find plants; large supply; very sustainable; can be waste material from other crops or grown on marginal lands (-) most difficult to ferment into ethanol

Cellulosic Feedstocks Cellulosic feedstocks have many advantages over starch- and sugar-based feedstocks. They are much more abundant and thus can be used to produce more substantial amounts of ethanol to meet U.S. fuel demand. Cellulosic feedstocks are usually either waste products (such as the corn stover that remains after the corn cobs themselves are harvested) or can be grassy crops that are grown on low- quality land (such as prairie or switchgrass) Less fossil fuel energy is required to grow/collect them and convert them to ethanol, and they are not human food products (meaning they won’t raise food prices).

Cellulosic Feedstocks Cellulosic feedstocks suited to ethanol production include the following: Agricultural residue —crop residues such as wheat straw and corn stalks, leaves, and husks Forestry residue —logging and mill residues such as wood chips, sawdust, and pulping liquor Grasses —hardy, fast-growing grasses such as switchgrass grown specifically for ethanol production Municipal and other wastes—plant-derived wastes such as household garbage, paper products, paper pulp, and food- processing waste Trees—fast-growing trees such as poplar and willow grown specifically for ethanol production

Ethanol Myths and Facts True or False? Discuss in groups; be ready to present: 1. In terms of emissions, ethanol pollutes the same as gasoline or more. 2. Ethanol cannot be produced from corn in large enough quantities to make a real difference without disrupting food and feed supplies. 3. More energy goes into producing ethanol than it delivers as a fuel. 4. Ethanol-gasoline blends can lower fuel economy and may harm your engine. 5. Rainforests will be destroyed to create the new croplands required to meet food, feed, and biofuels needs, thus accelerating climate change and destroying valuable ecosystems.

In terms of emissions, ethanol pollutes the same as gasoline or more. Myth! Ethanol produced from corn results in about a 20% reduction in GHG emissions compared to gasoline Ethanol produced from cellulose has the potential to cut life cycle GHG emissions by up to 86 percent relative to gasoline.

Ethanol cannot be produced from corn in large enough quantities to make a real difference without disrupting food and feed supplies. ½ Myth, ½ Fact Corn grain ethanol, by itself, is not enough to meet US energy needs However, corn is not the only source of ethanol! Future ethanol will be produced increasingly from cellulose, energy crops (e.g., switchgrass, sorghum), and sorted municipal wastes. The Energy Independence and Security Act of 2007 (EISA) requires use of 36 billion gallons of renewable transportation fuels in the U.S. by Of that quantity, 16 billion gallons must be cellulosic biofuels. Ethanol from corn is capped at 15 billion gallons

More energy goes into producing ethanol than it delivers as a fuel. Myth! Ethanol has a positive energy balance – that is, the energy content of ethanol is greater than the fossil energy used to produce it Plus, this balance is constantly improving with new technologies.

Ethanol-gasoline blends can lower fuel economy and may harm your engine. ½ Myth, ½ Fact Flex-fuel vehicles designed to run on higher ethanol blends (E85 or 85 percent ethanol) do experience reduced miles per gallon. However, they also show a significant gain in horsepower. Ethanol enhances engine performance and adds oxygen, increasing the octane rating of fuel.

Rainforests will be destroyed to create the new croplands required to meet food, feed, and biofuels needs, thus accelerating climate change and destroying valuable ecosystems. Pending, but probably Myth Bottom-line: regulations and economic incentives will be necessary to ensure that a fuel adopted for reasons of sustainability will actually be sustainable. This hinges on whether we can continue to increase our use of cellulosic sources of ethanol and whether or not farmers can merge sustainable practices with new crops E.g. the planting and harvesting of diverse prairie could provide additional wildlife habitat while simultaneously providing a perennial feedstock for ethanol. A top focus of US energy research is sustainability (e.g. GLBRC)