How Plug-in Hybrid Cars Work

Pure Plug-in Hybrid Concepts

While Vue will be able to run on its gas engine after the battery's power is exhausted, the Chevrolet Volt Concept's motor will solely get its power from the electric battery. This concept car is most notable for what it doesn't have than for what it does. Not a hybrid in the conventional sense, the Volt's gasoline engine never powers the vehicle's wheels. Instead, in the event that the car's plug-in charge is depleted, a small gasoline engine is used to power a generator that supplies back-up electricity. As the gasoline engine never provides power directly to the drive wheels, Volt does not require a conventional transmission.

Relatively light and compact, Volt's three-cylinder engine weighs less than a long-range battery pack might, and consumes less space. The gas backup provides an added dimension of range as well as flexibility, providing immediate power when time for a full battery charge may not be available.

Though displayed only with the gasoline engine at the 2007 North American International Auto Show in Detroit, Chevrolet says that Volt's backup power could also be provided by a diesel engine or a hydrogen fuel cell.

While the stylized two-seat Volt is not a likely candidate for production, its gas-assisted electric drivetrain may someday find its way into Chevrolet's lineup.

While more conventional in appearance, the Ford Edge with HySeries Drive Concept showcases technology very similar to Volt. Introduced at the 2007 Washington Auto Show, the Edge HySeries features electric drive with power coming from either a plug-in charged battery, or a hydrogen fuel cell.

Unlike the Volt Concept, which uses another power source to supplement the plug-in charge, Edge HySeries uses plug-in charging as a backup for the fuel cell.

Fuel cells, like the one in HySeries, create electricity-using hydrogen as fuel. Because hydrogen-filling facilities are scarce, the plug-in electric backup power source adds a much-needed dimension of range and safety.

While Volt is purely a concept vehicle, the Edge HySeries is completely functional, though a similar regular-production vehicle is unlikely in the near future.

These concepts from Chevrolet and Ford look down the road at another generation, one working toward the end goal of fossil-fuel independence. In time, they may be able to bridge the gap between gasoline and electric powered cars; making the goal of an automotive landscape virtually independent of fossil fuels a reality.

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