National Geographic: New Energy Frontier: Drilling Into Coal for Gas
With their sights on stores of low-grade coal beneath the coasts of England, the ranches of Wyoming, and the fields of Inner Mongolia, entrepreneurs around the world are touting the promise of yet another "unconventional" approach to energy extraction.
The technique resembles the hydraulic fracturing technology that has produced an oil and gas boom across North America. 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.