Increasing production of corn-based ethanol to meet alternative fuel goals will worsen the "dead zone" that plagues the Gulf of Mexico, according to a new study that adds to the growing list of concerns over the fuel.
Each year, spring runoff washes nitrogen-rich fertilizers from farms in the Mississippi River basin and carries them into the river and the streams that feed it. The nitrogen eventually empties out of the mouth of the Mississippi and into the Gulf of Mexico, where tiny phytoplankton feed off of it and spread into an enormous bloom.
When these creatures die, they sink to the ocean floor, and their decomposition strips the water of oxygen. This condition, called hypoxia, prevents animals that depend on oxygen, such as fish or shrimp, from living in those waters. In recent years, this so-called "dead zone" has grown to the size of New Jersey—about 20,000 square kilometers (7,700 square miles)—each summer.
Previous research has shown that corn, one of the three staple crops grown on U.S. croplands, accounts for the bulk of the nitrogen pollution that fuels the dead zone, said study leader Simon Donner of the University of British Columbia.
The most recent U.S. Energy Bill set a target of 36 billion gallons of renewable fuels to be produced in the United States by 2022. Of this, 15 billion gallons can come from corn starch. Meeting this goal would require devoting more U.S. cropland to growing corn.
Donner and his team studied how the conversion of more and more U.S. cropland to corn would affect efforts to mitigate the growth of the Gulf dead zone, and the news isn't good.
"This biofuels policy, particularly the fact that they're stressing corn, is just a death knell for efforts to mitigate the Gulf of Mexico problem."
Donner's study, detailed in the March 10 issue of the journal Proceedings of the National Academy of Sciences, adds to the growing body of research on the potential ills of ethanol, particularly made from corn. Studies have shown that producing ethanol could consume more energy than the fuel creates, strain water resources, and possibly pose a threat to public health.
"I think the outcome of most of the recent analyses, including ours, is that corn is just a bad idea," Donner said. "It's just not an intelligent crop to be using to create fuel."
A spokesperson at the American Coalition for Ethanol, a non-profit group that promotes the use and production of ethanol, said the organization had not reviewed the study and could not yet comment.
The Corn Belt
More than 80 percent of U.S. corn and soybeans is grown in the Mississippi-Atchafalaya River Basin, also know as the "Corn Belt." Most of the corn grown there goes not to our dinner tables, at least not directly, but to make feed for livestock, which makes corn big business for farmers.
Corn and soybeans are usually grown in rotation from year to year. While soybeans require little nitrogen fertilizer, corn "responds to more nitrogen, and since it's a very valuable crop, and fertilizer isn't that expensive, it's worth applying a lot of fertilizer," Donner said.
Last year, rising corn prices and the growing demand for ethanol spurred U.S. farmers to plant more than 90 million acres of corn for the first time in 60 years. With more corn comes more nitrogen washing into the Mississippi and the Gulf.
In the 1990s, the EPA and several states created a policy aimed at reducing the Gulf hypoxic zone to less than 5,000 square kilometers (1,930 square miles) through voluntary measures. To reach this goal, the policy aimed at reducing nitrogen runoff by 30 percent, but subsequent research showed that the reduction would probably have to be closer to 50 percent, Donner told LiveScience. "But that doesn't gel with growing more corn," he added.
Donner and his team used U.S. Department of Agriculture data to create a model that looked at the effects on mitigation efforts of meeting the 15 billion gallon goal with corn ethanol under a range of planting scenarios. The study was not funded by any direct sources. Donner is supported by the High Meadows Leadership and Policy Fund and by the Princeton University Carbon Mitigation Initiative.
When incentives, such as the demand for corn-based ethanol, spur farmers to plant more corn, they stop their crop rotation, planting corn twice in a row on the same field instead of planting soybeans one year.
Planting corn, which is heavily fertilized, instead of soybeans, which are not, naturally means that more nitrogen runs off into streams and rivers in the basin. This would mean an even higher percentage reduction in nitrogen would be needed to reduce the area of the dead zone, and Donner isn't optimistic about that option because agriculture is more valuable to the U.S. economy than Gulf fisheries, he said.
"I look at this and it's hard to be optimistic because you really need to break a subsidy structure, basically, to see these things happen, and so the projection for the Gulf of Mexico is not good," Donner said.
Daniel Kammen of the University of California, Berkeley, agrees that the heavy subsidizing of corn prompts farmers to grow it instead of other potential biofuels crops for which they could not make as much money. Corn has only been used to make ethanol thus far because "we happen to grow a lot of it already," he said.
Kammen, who was not involved with the study says that the projected impact to the Gulf in Donner's study isn't a surprise and also agrees with Donner that the studies researchers have done in recent years show that corn isn't the direction to turn.
"Corn is an awful fuel for ethanol," Kammen said.
Bruce Dale of Michigan State University, who has worked on the development of ethanol from cellulose (for example, grasses, wood chips and crop waste ) for the past 30 years says that the industry is increasingly moving away from corn to cellulosic ethanol because it is more energy efficient and more environmentally-friendly, but that "without corn-based ethanol, we would have had a much more difficult time in moving cellulosic ethanol forward."
"There is a very large national (and international) effort to improve the economics of cellulosic ethanol, and it will probably eventually far surpass corn ethanol," Dale wrote in an e-mail.
Donner said that while his study doesn't advocate any particular approach to biofuels, the current U.S. policy isn't going to work.
"Our study is not, on its own, passing judgment on other biofuels choices, but what we can tell you is that if the U.S. pursues this energy policy, it will take what was an already pretty difficult challenge, of reducing nitrogen loading in to the Gulf of Mexico, and make it pretty much impossible," he said.
- What's Your Environmental Footprint?
- Power of the Future: 10 Ways to Run the 21st Century
- Ethanol: Energy Panacea or False Promise?
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Andrea Thompson is an associate editor at Scientific American, where she covers sustainability, energy and the environment. Prior to that, she was a senior writer covering climate science at Climate Central and a reporter and editor at Live Science, where she primarily covered Earth science and the environment. She holds a graduate degree in science health and environmental reporting from New York University, as well as a bachelor of science and and masters of science in atmospheric chemistry from the Georgia Institute of Technology.
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