Lester Brown is the head of the Earth Policy Institute. He discusses themes from his book Plan B 2.0: Rescuing a Planet Under Stress and a Civilization in Trouble. He provides a great discussion on biofuels and how there is a brewing conflict between food users and fuel users in this Pop!Cast. There are limits to biofuel: the grain required to fill a 25 gallon SUV tank with ethanol will feed one person for a year.