Plants consume carbon dioxide, so growing corn to produce ethanol should be at worst a zero-sum game, emissions-wise, right? Wrong, says the EPA. There's another factor involved: Turning food crops into fuel drives up their prices, which raises demand for farmland worldwide. In places like Brazil, that means chopping down the rainforest, which produces massive emissions, NPR reports.
Once it factored worldwide deforestation into its energy equations, the EPA found that the current biofuels standards might cause more harm than good—and is considering stricter regulations for ethanol plants that could curb the industry. "What I think this means for the industry is you need to innovate," says a UC Berkeley scientist.