They say displacing oil with domestically grown plants will offset over a million barrels of oil a day, and that's just under the current law. They also say biofuels emit far fewer greenhouse gasses than oil when the plant-growing process is taken into account.
But critics say biofuels are partly responsible for the surge in food prices, groundwater depletion and pollution, and pressure on topsoil. They also say it's perverse to put food in gas tanks when people are starving.
NEXT: Tapping the Strategic Petroleum Reserve