There's a new fad starting, which might eventually prove to be more a revolution than a fad: an efficient furnace that also generates electricity.

The "micro-combined-heat-and-power" units, or CHPs, turns natural gas into hot water and generates up to $800 a year in electricity, the Christian Science Monitor reported Tuesday.

Factories and other industrial facilities have used large CHP systems for years. Home heating systems producing 1 kilowatt of electricity, as well as bigger units that generate about 4 kilowatts are available in Europe and Japan and are expected to make their commercial U.S. debut next month, The Monitor said.

At least five companies are building micro-CHP systems worldwide. In the United States, Marathon Engine Systems of East Troy, Wis., plans to bring a 4-kilowatt hot-water system to the United States next year. Climate Energy of Medfield, Mass., has developed a forced-hot-air system that links a high-efficiency furnace with a Honda quiet generator.

The Micro-CHP units cost up to $20,000 including installation, with an estimated payback period on the initial investment of 3 to 7 years, the newspaper said.

Copyright 2006 by United Press International