Biofuels have moved front and center in a national debate over the best strategies for reducing U.S. dependence on imported oil and lowering the net amount of carbon dioxide released to the atmosphere from burning fuels in the transportation system. Recent policies pursued in the U.S. to promote the production of biofuels at the federal level include subsidies for domestic ethanol fuel production, tariffs on imported ethanol fuels, international agreements with Brazil to promote ethanol fuel production, credits toward corporate average fuel economy (CAFE) standards for production of dual-fueled vehicles, and accelerated research efforts to develop technologies for producing cellulosic ethanol. Various states have also enacted policies to promote the availability of ethanol-gasoline blends. These policies have stimulated a dramatic increase in capital invested in ethanol production - both large scale venture capital and investment by farmers in local refineries - and have resulted in an increase in the price of corn, the principal feedstock from which ethanol fuels are made in the U.S.

The discussion leaders for this question, Nathanael Greene of the Natural Resources Defense Council and Bruce E. Dale of Michigan State University, agreed on the desirability of pursuing biofuels, though they chose to emphasize somewhat different aspects of the issue. Both wrote about the potential of liquid biofuels to displace fossil fuels in the transportation system. Both saw the potential of corn-based ethanol fuels as limited, whether due to the small volume of fuel that could realistically be produced relative to the demand, or to the limited energy and environmental benefits compared with petroleum-based fuels. However, both believe that ethanol derived from cellulosic feedstocks such as switchgrass, wood chips, or crop residues has significant potential as a domestic, renewable transportation fuel.

While the discussion leaders focused primarily on bio-derived ethanol fuels to be used in transportation, the responders to this question took a considerably broader view of biofuels, whether in terms of sources, the types of fuels, and the end uses. Sources of fuels discussed included corn, sugarcane, cellulosic materials, sewage, municipal solid waste, compost, animal waste, forest products, oil-bearing nuts, and algae. Fuels discussed included: gases such as methane and hydrogen derived from biomass; liquids such as methanol, ethanol, butanol, vegetable oils, and oils from algae; and solids including hemp and trees. End uses discussed included transportation, electric power generation, and heating.

Within the diversity of the discussion several major categories of views could be distinguished: 59 percent of the responders were biofuel advocates (those who were clearly in favor of pursuing at least some form of biofuels); 20 percent were biofuel skeptics (those who felt that the costs outweighed the benefits, or that biofuels were a distraction from other promising avenues); and 21 percent were in a more cautious group of conditional supporters (those who believed that biofuels were at best transitional fuels or should only be developed if critical problems could be solved). The main threads of discussion for each of these categories of views are described below. Finally, despite the wide diversity of opinions expressed, there were several areas of agreement, and these are noted in the conclusion.