In particular aviation planners are focusing on ways of cutting the amount of time planes spend queuing to take off and land, in the process burning large and unnecessary amounts of fuel (IATA estimates that airlines could cut their annual CO2 emissions by 12 percent if air-traffic control operations were more efficient).

CNN: Green wing:?can technology make flying more environmentally friendly?

By contrast, two other recent telecom IPOs, Clearwire and Vonage, are pursuing far more ambitious plans--and burning serious amounts of money in the process.

FORBES: MetroPCS Dials Up IPO

If, however, they are subjected instead to pyrolysis a process of controlled burning in a low-oxygen atmosphere the result is charcoal, a substance that is mostly elemental carbon.

ECONOMIST: Biochar could enrich soils and cut greenhouse gases as well

The concept of heating underground coal to a combustion point may lead one to recall Centralia, PA, an abandoned town in Pennsylvania sitting on a coal seam which has been burning for 50 years, but the UCG controlled process makes that outcome highly unlikely.

FORBES: Underground Coal Gasification: A Trend Worth Watching