Corn ethanol is not the answer to the critical energy challenges facing the world today. Current efforts to develop corn ethanol risk devoting scarce resources towards an energy approach that offers marginal returns. Instead of pandering to interest politics and focusing on energy independence to the exclusion of climate change issues, we need to devote our energy investments towards more promising options.
Corn ethanol suffers from at least three critical shortcomings. The first is that it offers a limited, at best, return on energy investment due to the costs of growing, transporting, and processing corn. Whether ethanol offers any return at all is a current topic of debate. Recent review articles in Science and Environmental Science and Technology find that on the whole, most research reveals that ethanol contains a slight return on investment—a range of 1.29 to 1.64 is cited by the latter article. The one researcher consistently reporting negative values is David Pimentel, who argues the energy return of ethanol is 0.84. The variety of numbers reflects the authors’ varied assumptions. Pimentel includes more energy inputs in his equation, such as energy used by workers to travel and in the manufacture of capital equipment. His critics, however, contend that he uses old data that over-inflates certain energy costs and that he does not include the energy-value of the by-products of ethanol production. Regardless of the exact value, the important point to keep in mind is that the energy return is at best mediocre. Corn ethanol requires too many fossil fuel inputs to be the basis of a renewable energy system.
Second, ethanol does not address the issue of greenhouse gas (GHG) emissions, which is arguably the greatest energy challenge we are facing at present. While fossil fuels are depleting, the more immediate energy problem the world faces is climate change, which has the potential to seriously disrupt ecosystems and devastate poor, low-lying countries. Estimates of the GHG emissions associated with the production of corn ethanol vary depending on how it is produced and used, but the authors of the Science article find a range varying from a 32% decrease to a 20% increase in GHGs, with an average saving of around 13%. Just like the modest returns of energy from ethanol, its benefits for alleviating the perils of global warming are mediocre as well.
A third consideration is the land needed to grow corn. There are natural limits to the extent we can expand corn production in order to increase ethanol output based on land availability. It is not clear that it will be possible to dramatically increase the total supply of ethanol given competing demands on agricultural land. In addition, there are serious questions about whether this is good idea. It may create environmental impacts on the land that is brought under cultivation. The best land is already under cultivation, so the additional fields planted will likely yield an even lower return on energy investment. More seriously, it brings into question whether land that could be growing food to feed people around the world would be devoted to ethanol instead.
The news is not completely bleak for ethanol, however, if we look past corn. The most intriguing possibilities in the ethanol world come from cellulosic ethanol. Whereas corn ethanol produces fuel only from the kernels of corn, cellulosic ethanol transforms entire plants, including leaves, stems, and stalks into fuel. The main benefit of this approach is that the lignin within plant cell walls includes energy that can be used to break down the plant materials and generate ethanol. This energy savings has resulted in studies promising an energy return of 4.40 to 6.61, while some suggest values over 10 might be achieved. However, such technology is at the early stages of development and cellulosic ethanol cannot be manufactured in significant quantities. Supporting this technology would be a much wiser policy than feeding more pork to Midwestern corn farmers.
Given all the problems with corn ethanol and the limited upside, why does it continue to garner such attention? The first reason is that people are not accustomed to viewing energy cycles holistically and asking questions about the energy required in the production of ethanol. The second reason is that energy independence is often discussed separately from climate change and sustainability. Corn ethanol can help us reduce imports of oil, which is certainly a desirable goal. However, energy independence that does not address the issue of climate change is not a wise policy, as it leads us out of the frying pan and into the fire. Finally, and perhaps most importantly, corn ethanol is being driven by Midwestern politicians who see it as an opportunity to bring money and industries to their states. While politicians have always sought to serve their constituents by attracting funding to their regions, we cannot allow such approaches to determine energy policy. Instead, we need to identify energy solutions that are sustainable, environmentally-friendly, and economically promising instead of pandering to interest politics.
So what should the future of ethanol be? Well, to quote a familiar phrase, it depends. If the government is truly committed to pursuing solutions to the pressing problems of energy, then ethanol should continue to receive some support. It can help us achieve a bit of energy independence and support Midwestern agriculturalists. However, in the current political environment where there are limited funds available for the development of new technologies, scarce resources should be shifted away from ethanol and towards technologies that offer greater promise, such as wind and solar power. By drawing money and attention away from more promising approaches, ethanol might actually make our energy problems worse.
 A value of 1 implies that there is no energy gain or loss in the production of ethanol. A value above 1 indicates a net positive gain and a value below 1 indicates a net energy loss. Alexander E. Farrell et al., "Ethanol Can Contribute to Energy and Environmental Goals," Science 311, no. 5760 (2006), Roel Hammerschlag, "Ethanol's Energy Return on Investment: A Survey of the Literature 1990-Present," Environmental Science and Technology 40 (2006).
 David Pimentel and Tad Patzek, "Ethanol Producting Using Corn, Switchgrass, and Wood; Biodiesel Production Using Soybean and Sunflower," Natural Resources Research 14, no. 1 (2005).
 Farrell et al., "Ethanol Can Contribute to Energy and Environmental Goals.", Roel Hammerschlag, "Ethanol: Energy Well Spent," (National Resources Defense Council, 2006).
 Farrell et al., "Ethanol Can Contribute to Energy and Environmental Goals," 506.
 Hammerschlag, "Ethanol's Energy Return on Investment: A Survey of the Literature 1990-Present."