Ethanol May Not Beat Gas

An MIT researcher has found the fuel source to be neither cleaner nor cheaper to produce.
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A new report on ethanol is questioning whether the energy efficiency and environmental impact of the alternative fuel will leave consumers any better off than they are with existing motor gasoline.

The report, titled "Ethanol: A Look Ahead," was written by Tiffany Groode at the Laboratory for Energy and the Environment at the Massachusetts Institute of Technology.

Groode says that corn ethanol is not more energy-efficient than motor gasoline. She also argues that the overall impact of producing and burning corn ethanol could be as harmful to global warming as is producing and burning gasoline.

Regardless of the enormous government subsidies and investment dollars flowing into ethanol projects, should the findings gather traction or be supported by additional research, some of the positive sentiment for ethanol might be dampened.

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To calculate the energy efficiency of various ethanol and gasoline mixtures, Groode computed their net energy values, that is, the amount of energy that a fuel generates minus the amount of energy that was required to produce the fuels.

For corn ethanol, the amount of energy required to produce the fuel is dependent on, among other things, the quality of the farmland that supplied the corn. Growing corn in efficient farming states requires less fertilizer and irrigation than in other states because they have better growing conditions. For her research, Groode used Iowa as an example of a good farm state and Georgia as an example of a less-efficient state.

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The ethanol feedstock's place of origin is an important variable to consider, because if ethanol production was to increase from current levels, land-use restrictions and other market pressures would likely force ethanol producers to expand feedstock output to less-efficient geographic regions.

By comparing the net energy value of Iowa corn ethanol and motor gasoline, Groode found that the two fuels are equally efficient. However, when the ethanol feedstock's place of origin is moved to less-efficient farming regions, corn ethanol actually becomes less energy-efficient than gasoline.

The MIT report also shows that corn ethanol has no clear greenhouse gas benefit over gasoline unless alternate products that displace fossil fuel inputs are also considered.

Though burning ethanol releases no greenhouse gasses, the process of making ethanol demands natural gas, electricity and petroleum. This represents a major difference between ethanol and gasoline -- ethanol creates greenhouse gasses when it's being made, while gasoline produces them when it's burned as fuel.

Corn ethanol only starts to see a greenhouse gas advantage if one of its byproducts, dried distillers' grain with solubles (DDGS), used for livestock feed, is also manufactured and sold. If a market exists for DDGS, it's possible to allocate a share of the greenhouse gasses originally attributed to ethanol back to the DDGS.

The amount of greenhouse gasses reallocated to the DDGS byproduct depends on the value that DDGS garners in the market. Most models that employ a reallocation credit use a number between 20% and 40% of greenhouse gasses produced. The more gasses that are reallocated to the byproduct, the more competitive corn ethanol becomes relative to motor gasoline.

Currently, a parallel market for DDGS is by no means assured, Groode says. Thus, any model that assumes a greenhouse gas reallocation to an ethanol byproduct like DDGS is highly presumptuous.

The only clear benefit of corn ethanol production found in Groode's research is the amount of oil that ethanol displaces as its importance grows in the marketplace. Burning ethanol decreases petroleum consumption by 68% on a per-unit basis.

Since the U.S. must import most of its petroleum, higher ethanol use corresponds to a decreased reliance on oil imports. However, processing ethanol on an industrial scale would increase the need for natural gas as a feedstock. Natural gas is already imported in a liquefied form, and that amount would likely grow if ethanol use were to reach a level that made a dent on petroleum demand.

Groode's findings suggest that while corn-based ethanol will likely not be the white knight that energy conservationists are looking for, it could be a stepping stone to a more efficient and environmentally friendly alternative.

The next step toward making a mass-market biofuel, according to Groode, is cellulosic ethanol, derived from plants with cellulose, such as switchgrass. Cellulosic ethanol hasn't been perfected for industrial use yet. If it was to reach mass production, Groode predicts that cellulosic ethanol would have a 40% higher net energy value and 60% less greenhouse gas emissions than today's corn ethanol.

Regardless of its inefficiencies, Groode says that corn ethanol's expanding presence in the energy marketplace is good for U.S. consumers because they are growing accustomed to seeing it in their daily lives.

According to Groode, the more that people recognize ethanol as a common additive to existing gasoline blends, the more comfortable consumers will become with ethanol and other biofuels.

Land use restrictions will ultimately play a major role in any industrial-scale ethanol production program, according to Groode. In 2006, U.S. corn ethanol production demanded 20% of domestic corn acreage. Increasing ethanol production to a level that decreases petroleum demand could require the use of between 50% and 75% of the planted corn acreage in 2006.

The question that has to be asked, then, is if we were to ever reach the point where we could make our own motor fuel, would we still have the space to grow our own food?