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More than ever before, automakers have been putting some serious creative thought into improving the efficiency of automobiles. Some are improving the combustion reaction with ideas like hydrogen injection, and others are attempting to recapture energy that is otherwise wasted, such as the idea of regenerative braking. BMW is working on a variation of the latter, but rather than trying to utilize “waste” momentum, they are aiming to put a conventional gasoline engine’s excess heat to good use. And they’re using some good-old-fashioned technology to accomplish it: steam power.

BMW’s design uses hot liquid from the coolant system as well as heat from the engine exhaust to heat a closed reservoir of water up to 550 degrees Celsius, evaporating the water into steam. The resulting pressure is then converted into mechanical energy in an expander, and transferred by pulleys to the engine’s crankshaft. The company says more than 80 percent of a car’s waste heat energy can be recycled using this technology. BMW calls this gas/steam hybrid a Turbosteamer.

According to tests performed on a 1.8-liter 4-cylinder engine, the prototype steam assist system provides an extra 14 horsepower and 15 foot-pounds of torque, resulting in an overall 15% improvement in efficiency. The components for this prototype drive system have been designed to fit in any existing and future models of BMWs, however the company doesn’t expect to have a production-ready design for about ten years. In the meantime, they’re working towards reducing the size and weight of the rig, which currently weighs in at about 220 pounds.

No word yet on whether the Turbosteamer removes tough stains from carpets.

Further reading:
Autoblog article