When burned, coal produces three times its own weight in carbon dioxide (CO2) -- making it far dirtier than any other energy source, per unit of usable energy. Carbon dioxide is the main human contributor to global warming, so as more people worry about the future of human civilization in a hothouse world, new coal plants are being canceled across the country.

To protect its enormous investment in land, equipment, politicians and environmental groups, the coal industry has bet its future on an untried technology called "carbon capture and storage" (CCS). The idea is to capture the carbon dioxide emitted by burning coal, compress it into a liquid and bury it a mile below ground, hoping it will stay there forever.

The coal industry's fanciful name for this is "clean coal," a.k.a. carbon sequestration. And even though clean coal does not actually exist anywhere on Earth, the industry has sold the idea so effectively that more than 60 percent of Americans say they favor it.

To gain permission to build new coal plants, the coal and electric power industries are now promising the moon: "This new coal plant will be 'capture-ready.' Just let us build this plant now, and we'll add a CCS unit onto the back end as soon as CCS technology has matured and is affordable."