Is it true that converting crops like corn into ethanol actually uses more energy than is produced?
—Leslie Foster, Eau Claire, WI
Recent revelations by Berkeley researcher Tad Patzek have fueled vigorous debate about the wisdom of using fuels such as ethanol to reduce our reliance on oil and our contribution to global warming. Patzek’s research concluded that producing ethanol actually uses more energy than the resulting fuel can generate.
“Ethanol production using corn grain required 29 percent more fossil energy than the ethanol fuel produced,” reported Patzek in the journal Natural Resources Research last winter. He added that ethanol produced from other common sources, such as biomass (wood products and agricultural waste), requires 50 percent or more fossil fuel derived energy than the ethanol that results can produce.
“People tend to think of ethanol and see an endless cycle: Corn is used to produce ethanol, ethanol is burned and gives off carbon dioxide, and corn uses the carbon dioxide as it grows,” says Patzek. “But that isn’t the case. Fossil fuel actually drives the whole cycle.”
Ethanol is primarily in use today as an octane-boosting fuel additive, but it can also be used as a primary fuel in some engines. Most gasoline sold in North America today contains about five percent ethanol, but some vehicles—such as the Ford Explorer and Chevy Silverado—can run on blends of up to 85 percent ethanol. In order to stimulate production, the U.S. offers generous tax-based subsidies to farmers who grow crops for ethanol.
While Patzek’s evidence may be compelling, his views on ethanol are not popular. Critics point out that his findings are based on farming and production practices that are fast becoming obsolete, and that newer techniques and machinery can make the ethanol production process much more energy efficient.
Hosein Shapouri, an economist at the U.S. Department of Agriculture, estimates that ethanol fuel can actually generate 67 percent more energy than it takes to produce it. He points out that scientists are experimenting with using alternative sources like solid waste, grass and wood to make the ethanol production process that much more energy efficient.
While the jury may still be out as to whether ethanol production can generate a positive or negative “energy balance,” there are also some potential hazards with ethanol production. For instance, the nitrogen fertilizer needed to grow corn and other crops ends up in waterways, causing “algae blooms” that can choke out other life in affected areas. And while ethanol produces fewer carbon monoxide emissions than regular gasoline, it does contribute significantly to low-lying smog.
Doubts about ethanol underscore a fundamental problem in getting many types of renewable energy sources, including hydrogen, into mainstream usage: Until fuel sources like solar or wind power can provide clean ways to make clean fuel, the processes must rely on coal, oil, gas and nuclear energy. Indeed, while we may be able to see a clean energy future, we are still wrangling with how to get there.
CONTACT: U.S. Department of Energy Ethanol Facts, www.eere.energy.gov/biomass/ethanol.html.