As the Washington Post explains, the U.S. mandate to create 36 billion gallons of biodiesel by 2020 will have terrible consequences for the environment.
The impact of these land-use changes is enormous. As the study from the Nature Conservancy warns, "converting rainforests, peatlands, savannas, or grasslands to produce biofuels in Brazil, Southeast Asia and the United States creates a 'biofuel carbon debt' by releasing 17 to 420 times more carbon dioxide than the fossil fuels they replace." There are other negative effects. Massive amounts of water are needed to irrigate cornfields, setting up potential competition between farms and homes. The runoff of pesticides and nitrogen-based fertilizers used by farmers could lead to increased pollution and oxygen-depleted waterways. The natural gas used to make the fertilizer adds to the carbon deficit created by biofuels.