Intro to EthanolBy C. Kohn

Agricultural SciencesWaterford, 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.

EthanolEthanol 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 (CH3CH2OH) regardless its original source (corn, sugar cane, etc.)

Ethanol and EnginesEthanol 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 FuelEthanol 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.

This means that the addition of ethanol to gasoline generally tends to improve engine performance by increasing the octane rating of the fuel.

Ethanol BenefitsEthanol 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 GHGsThe 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 EnvironmentEthanol 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.Compare this to the 2010 oil spill in the

Gulf of Mexico!

Sources of EthanolEthanol 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 ComparisonSugar 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

Source: donhavey.com

Cellulosic FeedstocksCellulosic 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).

Source: donhavey.com

Cellulosic FeedstocksCellulosic feedstocks suited to ethanol production

include the following:Agricultural residue —crop residues such as wheat straw

and corn stalks, leaves, and husksForestry residue —logging and mill residues such as

wood chips, sawdust, and pulping liquorGrasses —hardy, fast-growing grasses such as

switchgrass grown specifically for ethanol productionMunicipal 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

Source: donhavey.com

Ethanol Myths and FactsTrue 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 FactCorn grain ethanol, by itself, is not enough to meet US

energy needsHowever, 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 2022. 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 FactFlex-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 MythBottom-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 cropsE.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)