Ethanol from corn is being hailed as a carbon-neutral fuel for automobiles. The CO2 emitted from from ethanol combustion is balanced by CO2 absorbed in growing the corn. Corn ethanol is also promoted as reducing US dependence on imported petroleum for gasoline.
It takes a lot of energy besides sunlight to produce ethanol. Energy is needed for transportation, fertilizers, fermentation, and refining. A Cornell University study by Professor David Pimentel claimed that the energy released by combustion of corn ethanol is less than the energy used to create it. The US Department of Agriculture is more optimistic, estimating that 100 BTU of energy is expended to create 134 BTU of corn ethanol.
This chart is from zfacts.com, which has summaries of many such studies, including a July 2006 report from the National Academy of Science.
To make ethanol without the foreign fossil fuel, nuclear power, and coal, one might use renewable ethanol energy instead. The production process would consume 3 of every 4 gallons produced. Let's compute the farmland to satisfy US transportation fuel needs with ethanol.
28 quadrillion [10^15] BTU annual US transportation fuelTotal US farmland is only 1 billion acres. About 10% is now used for corn. Already the increasing fuel demand for corn ethanol is raising prices for cattle feed and reducing exports.
divided by 76,000 BTU per gallon of ethanol
divided by 2.5 gallons of ethanol per bushel of corn
divided by 25% to account for production energy consumed
divided by 148 bushels of corn per acre
equals 4 billion acres of farmland.
Ethanol is not needed in gasoline for environmental reasons, either. The US had required 2% oxygen content in reformulated gasoline to reduce smog-causing NOX (nitrogen oxides) tailpipe emissions in heavily populated areas. The oxygen was supplied by supplementing gasoline with 11% MtBE (Methyl tertiary Butyl Ether) or 6% ethanol. MtBE use has ended after leakage from underground gasoline tanks into groundwater, and ethanol use has increased to replace MtBE. However NOX emissions are properly controlled by modern fuel injection engines, so the ethanol oxygenate is not needed, and the Energy Policy Act of 2005 eliminated this requirement.
Corn ethanol is subsidized at 51 cents/gallon by taxpayers. Corn ethanol is promoted very effectively by the corn lobby. Citizens and political leaders have been deluded into believing that corn ethanol is a solution to the US energy crisis, but it is not. It is expensive, displaces food crops from farmland, and continues fossil fuel use.
Cellulosic ethanol, derived from the abundant fibers of plants rather than the starches and sugars of seeds, may be much more productive of ethanol in the future. Research and development into this technology is ongoing, with funding from the US federal government, state governments, and venture capitalists. Success is not certain, and practical, economical, industrial-scale production of cellulosic ethanol is 15-20 years into the future.
Corn energy ethanol is an expensive, delusional diversion of US energy policy. It diverts public attention, money, and national resources away from solutions that can really address the issues of global warming, energy costs, and foreign oil addiction.
Pebble bed reactors can solve the problem that corn ethanol can not -- production of inexpensive, carbon-neutral vehicle fuels. Future posts will show how.