AS THE United States searches for alternative ways to feed its addiction to petroleum, ethanol and other biofuels derived from organic material have been considered a miracle motor vehicle elixir. The energy bill signed by President Bush in December mandates that at least 36 billion gallons of biofuels a year be used by 2020. Yet separate studies released this month by Princeton University and the Nature Conservancy reveal that biofuels are not a silver bullet in the battle against global warming. In fact, they could make things worse.
Corn and sugar cane are common sources of ethanol. Aside from emitting fewer greenhouse gases than coal or oil when burned as fuel, these biofuel crops remove carbon from the atmosphere while they are growing -- thus making them nearly carbon-neutral. But the studies show that ethanol may be even more dangerous for the environment than fossil fuels are. As the Princeton study points out, clearing previously untouched land to grow biofuel crops releases long-sequestered carbon into the atmosphere. While planting corn and sugar cane in already tilled land is fine, a problem arises when farmers churn up new land to grow more fuel or the food and feed displaced by biofuel crops.