Carbon capture and storage (CCS) is often promoted as a way for coal power to be made “clean”: Projects such as the in-progress Kemper power plant in Mississippi and the recently announced Petra Nova project in Texas aim to trap the carbon dioxide from burning coal and then store it into underground storage or into previously depleted wells to extract more oil. (See related story: “Clean Coal Test: Power Plants Prepare to Capture Carbon.”)

CCS is being applied to natural gas-fired electricity as well (just today a new effort in Scotland was announced), and a new project in the U.S. aims to produce fossil power with zero emissions and greater efficiency than other facilities have been able to