Scientific American: Editor’s Note: We are posting this feature from our September 2006 issue in light of the Obama administration’s renewed focus on how to use the most abundant–and dirtiest–fossil fuel, coal, without overloading the atmosphere with greenhouse gases. More than most people realize, dealing with climate change means addressing the problems posed by emissions from coal-fired power plants. Unless humanity takes prompt action to strictly limit the amount of carbon dioxide (CO2) released …