Whats the best biofuel to rely on to ensure a realistic greener America in the future?
Philpott: Well, they’re all problematic. What tends to be lost in discussions of “renewable” biofuels is the factors related to their production. For instance, soil is not a renewable resource. It takes centuries under natural conditions to replace an inch of topsoil lost to erosion. We’re already leaning hard on the world’s arable land to feed a growing global population. How hard do we really want to push it to fuel our cars? One answer has been to open up new sources of land by clear-cutting tropical rainforests and planting soybeans and palm trees for biodiesel production. This seems a colossal error, given that those rainforests are what’s known as natural “carbon sinks”—they slow climate change by trapping atmospheric carbon. Any wise biofuel policy will proceed with great respect for soil conservation and for existing carbon sinks. Cellulosic ethanol made from switchgrass is potentially one such solution, although claims made for it tend to be over-hyped. Biodiesel made from was
