We argue that evaluating the suitability and utility of biofuels or any alternative energy source within the limited framework of plus and minus carbon emissions is too narrow an approach. Biofuels have numerous impacts, and policy makers should seek compromises rather than relying solely on carbon emissions to determine policy.
Here, we estimate that cellulosic ethanol, despite having potentially higher life cycle CO2 emissions (including from land use) than gasoline, would still be cost-effective at a CO2 price of $80 per ton or less, well above estimated CO2 mitigation costs for many alternatives. As an example of the broader approach to biofuel policy, we suggest the possibility of using the potential cost reductions of cellulosic ethanol relative to gasoline to balance out additional carbon emissions resulting from indirect land use change as an example of ways in which policies could be used to arrive at workable solutions.