During braking, it becomes a generator, recapturing energy normally lost as frictional heat.

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Heat from the sun boils water to run a steam turbine generator, which delivers power to the grid.

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Their compounds, along with those of wealthier Afghans, constitute the emergent generator-class rich enough to cool (or heat) their offices and homes with big diesel-powered generators.

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Ivanpah is a solar concentrator project, using fields of mirrors, known as heliostats, to concentrate sunlight onto a solar receiver on top of a tower. (This project when finished will include 173, 000 heliostats.) The concentrated sunlight is used to heat water, generating steam which is used to turn a traditional turbine and generator to produce electricity.

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PITTSBURGH, Pennsylvania (CNN) -- An expert said Wednesday that oxygen generator bottles should be safe to ship as cargo, but admitted they heat up to 1200 degrees inside the canister when activated.

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IMechE says this process is only 25% efficient but it is massively improved by co-siting the cryo-generator next to an industrial plant or power station producing low-grade heat that is currently vented and being released into the atmosphere.

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Whiting Bay Hall and Auchrannie Spa and Country House, in Brodick on Arran, are open for residents with power, heat and refreshments, while Lamlash fire station is also open all day with power available through a local generator.

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