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"Fuelling Animals or Fuelling Cars": the U.S. Energy Policy and the Gulf of Mexico
17 Mar, 2008 08:25 am
Recently, the U.S. Senate announced its energy policy aims of generating 36 billion gallons annually of ethanol by the year 2022, of which 15 billion gallons can be produced from corn starch. The corn-ethanol goal represents more than three times than triple the production in 2006. Scitizen interviews Simon Donner, whose recent study with Chris Kucharik in PNAS quantified the effect of biofuel production on the problem of nutrient pollution in a waterway.
Previous work by myself and a number of other scientists has shown that nitrogen fertilizer applied to corn in the Midwest helps fuel the development of the "Dead Zone" each summer in the Gulf of Mexico. The new US Energy Policy calls for a large increase in the production of ethanol from corn. So my colleague Chris Kucharik and I decided to examine how meeting the goals in the Energy Policy might affect the Gulf of Mexico.
2. What is the "Dead Zone", and how would it be affected by an increase of corn-based ethanol production?
The same nitrogen that fertilizes crops like corn on land can fertilize the growth of aquatic plants like algae. Nitrogen pollution in the Mississippi River promotes large blooms of algae in the northern Gulf of Mexico. The algae eventually dies, sinks, and decomposes, consuming much of the oxygen in the bottom waters along the continental shelf. The area of hypoxia has reached over 20 000 km2 in recent years, roughly the area of the state of New Jersey. A number of studies report that shrinking the Dead Zone to less than 5000 km2 in size, as has been recommended in federal policy, will require reducing nitrogen levels by up to 55%. Our study found that if that ethanol production will drive nitrogen levels in the other direction. For example, if the US produces 15 billion gallons of corn-based ethanol by the year 2022, the nitrogen output of the Mississippi River would increase by 10-18%.
3. There has been criticism on the feasibility of meeting these production values, as well as ethanol being the cure-all to the energy problem. Does your study address the possibility of the U.S. meeting its goals: what are the limitations, if any?
The one limitation that our study finds is the availability of highly productive cropland. The majority of the productive croplands in the Midwest and Central US are devoted to growing corn and soybeans, most of which is sold as animal feed. As the US devotes more and more of the productive croplands to producing fuels, trade-offs will emerge. For example, our study found that freeing up the productive croplands required to reach the biofuels targets may require reducing the production of animal feed. Unless the US can produce biofuels on marginal lands or from agricultural waste, it will eventually face a choice between fuelling animals and fuelling cars.
4. What is the policy of implementation that your research would suggest?
Our results indicate that meeting the biofuel targets in the Energy Policy Act will make the already difficult challenge of reducing the Dead Zone in the Gulf of Mexico practically impossible without radical changes in agricultural management and food production. First, the US would be better served looking to unfertilized grass crops, rather than energy and fertilizer intensive corn, to produce biofuels.
Interview by Audrey Wang
Simon Donner and Christopher Kucharik, "," PNAS, March 10, 2008. Abstract available here.