The key element in this process, however, is not water. It's fire.

Underground Coal Gasification (UCG)—an old idea once embraced by Soviet leader Vladimir Lenin—is gaining new enthusiasts who say it can transform abundant but difficult-to-mine coal reserves into a cleaner fuel: synthetic natural gas. Instead of mining the coal, the companies propose to drill into the coal seam, ignite it, and capture the "syngas"—a combination of hydrogen, carbon dioxide, and methane—produced by the oxidation underground.

The syngas could be used just like natural gas to produce power, making it a potential solution for China, seeking an alternative to the coal-fired electricity that chokes its cities, and for Europe, eager to replace its own declining North Sea natural gas stores and reduce