Al Jazeera: When President Barack Obama gave a major policy speech on reducing greenhouse gases last June, he didn't once mention ethanol, an alcohol-based fuel distilled from fermented corn. Biofuels in general which are extracted from plant or animal matter received a brief, passing reference. But when the Iowa political caucuses were on the horizon in 2007, thenpresidential candidate Obama made homegrown corn a centerpiece of his plan to slow global warming. And when former President George W. Bush...