Grist: When I first looked at the environmental impact of corn ethanol I thought it was simple: Grow an acre of corn for fuel and it means you have to grow another acre elsewhere for food, which ultimately means cutting down forests and releasing a lot of carbon into the atmosphere. Plus, even the EPA said it was worse than oil. Then I dug a little deeper, and realized it might not be as simple as it looked, and that the EPA estimates were rough and out of date. I promised to figure it out and report back....