Chesapeake is looking at natural gas as a potential energy source to fuel its rigs due to the cost benefits and the environment friendly nature of the fuel.

FORBES: Chesapeake Energy Gassed Up For Drive To $36

And conservative America, once solidly sceptical, is now split over the issue, as Christians concerned about mankind's stewardship of the Earth, neo-cons keen to reduce America's dependency on the Middle East and farmers who see alternative energy as a new potential source of energy come round to the idea of cutting down on carbon.

ECONOMIST: Climate change

Strong ocean winds are another potential source of energy.

FORBES: Mister Natural

Many venture capitalists and investment bankers see a carbon-trading regime and massive subsidies for renewable energy as a potential source of windfall profits.

FORBES: Magazine Article

It's a tantalizing prospect: Based on an estimate of the number of rivers around the world with suitable conditions, it's a potential source of 1, 700 terawatt hours a year of energy globally, according to estimates by Statkraft's scientists.

FORBES: Getting Power From Salty Water

It is true that Kazakhstan is potentially an alternative energy provider but in ten years' time it will probably still be only a potential source.

ECONOMIST: Charlemagne