By Shawn Allee, the Environment Report
Chicago – Carbon dioxide emissions that cause global warming are driving power companies to a decision.
They can move away from burning coal altogether or they can work on technology to eliminate their CO2 emissions someday.
While they're making that decision, some of the nation's oldest, dirtiest coal-burning power plants still run.
In the final part of our series on the future of coal, Shawn Allee looks at why they billow dangerous air pollution- stuff most people think we cleaned up long ago.