When General Motors, the world's largest automaker, attempts to reinvent the world's energy infrastructure-even rethinking notions of the car itself-it's not exactly research as usual. But in recent months, Detroit-based General Motors has integrated and expanded several existing research programs in a concerted effort to provide an alternative to the internal combustion engine. The plan is to use hydrogen to power cars, to tap into the vehicles' idle time to supply residential energy, and eventually to supply the nation's electric grid.

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