These could be among the first full-scale power plants in the nation to turn powdered coal into a synthetic natural gas that is burned in a gas turbine whose exhaust gas powers a steam turbine.

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To supply the extra juice, utilities turn on inefficient single-cycle gas turbines, which turn 25% of the fuel's energy into electricity, as opposed to 45% for combined-cycle plants that use turbine exhaust to make steam to run a second generator.

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Combined-cycle gas turbines, which use hot exhaust gases from one turbine to generate steam to turn a second one, can transform 6, 800 Btu of gas into a kilowatt-hour of electricity, enough to light one lightbulb for ten hours.

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