摘要：Biofuel debates often focus heavily on carbon emissions, with parties arguing for (or
against) biofuels solely on the basis of whether the greenhouse gas emissions of biofuels are
less than (or greater than) those of gasoline. Recent studies argue that land use change
leads to significant greenhouse gas emissions, making some biofuels more carbon intensive
than gasoline. 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.
