On June 21, the U.S. Senate passed a new energy bill that includes a requirement to produce 36 billion gallons of ethanol a year by 2022, a sevenfold increase over 2006 production. To be sure, alternatives and supplements to gasoline have benefits, but requiring ethanol production may result in more harm than good. For one thing, that amount of ethanol requires a commensurate increase in our production of feedstocks.

The mandated ethanol would be made from corn and cellulosic sources such as prairie grass, wood chips, and agricultural residues. In the next five to ten years, however, the only viable feedstock for ethanol production on a large scale is corn.  Can the United States increase the availability of corn for ethanol several times over? 

There are two options for addressing this need. One is to convert land currently used for other crops or purposes into corn production, which would have consequences for both agricultural commodity diversity and for environmental health.  The other is to divert corn currently used for other purposes – notably food and feed – into corn for ethanol.  This diversion, already taking place, is having such far-reaching effects such as mass protests in Mexico over the rising cost of tortillas, a staple of the Mexican diet, especially among low-income households. 

Researchers are investigating numerous creative ways to increase ethanol yield from per-acre corn production, as well as conversion processes for other cellulose sources, but it will be years until those approaches have been adequately tested and validated. In the meantime we can expect disruptions in our food supply.

On that key issue, the use of cellulosic sources such as wood chips or switchgrass would be less problematic.  However, even if we had adequate supply of this feedstock for ethanol production, we are not yet quite able to convert efficiently those cellulose sources into fuel.  A number of significant, likely not insurmountable, technological and infrastructure hurdles remain before these sources can be used on a commercial scale to meet the required production volume. And we may be doing so at the expense of our natural resources. 

The potential environmental issues arising with significant increases in agricultural intensity are numerous.  Increases in soil erosion due to increases in cropland and in plant harvest residue is one.  Another is decreases in soil fertility, which leads to reductions in yield, due to continuous planting of the same crop. Increases in fertilizer and pesticide application are also likely, as a counteractive measure for some of the problems associated with continuous single-species cropping.  The impacts of increased fertilizer use on water quality are well known, including a growing hypoxic zone in the Gulf of Mexico largely related to agricultural production in the Mississippi River basin. 

Perhaps the biggest problem with the new renewable fuel standard is that it is, in fact, an ethanol standard.  There are many reasons to believe that ethanol is a promising fuel option, if the pitfalls can be overcome.  But there are also sound reasons to believe that other non-gasoline technologies may be equally or more promising than ethanol in the long run.  By focusing attention exclusively on one type of transportation-sector option, continued research and development of other alternatives will decrease.

Policies that address the fuel needs of the country are important but lawmakers should not be in the business of selecting some technologies and excluding others. When one considers the wide array of interconnected systems, it is an unwise course of action to mandate certain technologies which may not prove to be the best.