If it weren't for that pesky climate-change problem, petroleum would remain a great source of power. It's energy-dense, portable and (relatively) cheap. Remove the carbon and it would be perfect which is essentially what researchers at Arizona State University (ASU) have been trying to do. Milton Sommerfeld and Qiang Hu have been working on raising algae to turn into a biofuel that would be virtually identical to gasoline. The fuel would actually be carbon-neutral, because algae consume carbon dioxide as they grow. Unlike traditional corn or sugarcane two plants used for most ethanol biofuels today algae can't be eaten, so using it for fuel doesn't cut into food supplies. ASU isn't alone. Start-ups like Sapphire Energy in San Diego are vying to bring the fuel to market and give oil back its good name.