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It heats. It powers. Is it the future of home energy?

Residential 'micro-combined-heat-and-power' units are efficient furnaces that create electricity.

By Staff writer of The Christian Science Monitor / November 14, 2006



Down in Bernard Malin's basement is a softly thrumming metal box that turns natural gas into hot water and generates $600 to $800 worth of electricity a year – a bonus byproduct of heating his home.

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"It's like printing money," says Mr. Malin, the first person in Massachusetts – perhaps in the nation – to own a residential "micro combined-heat-and-power" system, also known as micro-CHP.

But he's not likely to be the last.

Since Malin changed his home heating system to micro-CHP in February, 18 other families in the Boston area also have adopted the technology, which squeezes about 90 percent of the useful energy from the fuel. That's triple the efficiency of power delivered over the grid.

Factories and other industrial facilities have used large CHP systems for years. But until the US debut of micro-systems in greater Boston, the units had not been small enough, cheap enough, and quiet enough for American homes. Add to that the public's rising concern about electric-power reliability – seen in a sales boom of backup generators in the past couple of years – and some experts see in micro-CHP a power-to-the-people energy revolution.

"Right now these residential micro-CHP systems are just a blip," says Nicholas Lenssen of Energy Insights, a technology advisory firm in Framingham, Mass. "But it's a ... technology that ... could have a big impact as it's adopted more widely over the next five to 10 years."

The Japanese are early adopters

Home heating systems that produce a kilowatt of electricity – like Malin's – and bigger units that pump out about 4 kilowatts are already available in Europe and Japan. They'll make their commercial US debut in New England in January.

Of course, other home-based power-supply options – solar panels and wind generators – have preceded micro-CHP, with varying degrees of acceptance. Both can be costly and hard to site. Fuel cells are another much-anticipated option, but remain too costly for commercialization. Micro-CHP, by contrast, is an advanced hybrid of existing technologies: an internal-combustion engine generator married to a high-efficiency home furnace.

In Japan, more than 30,000 homeowners have installed micro-CHP systems driven by quiet, efficient internal-combustion engines, each housed in a sleek metal box made by Honda. Japan is ahead because gas utilities have been subsidizing and promoting the systems. In Britain, where the systems look like dishwashers and sit under kitchen counters, 80,000 systems made by a New Zealand company are on order.

At least five companies are building micro-CHP systems worldwide. Two are trying to enter the US market: Marathon Engine Systems of East Troy, Wis., plans to bring a 4-kilowatt hot-water system it sells in Europe to the US early in 2007. Climate Energy of Medfield, Mass., has developed a forced-hot-air system that marries a high-efficiency furnace to a superquiet Honda generator. That system has been deployed as a pilot to several US homes, including Malin's.

Such systems help people like Lynn Denoy insulate themselves from high electricity prices because they draw power from the commercial grid much less often in winter.

"I feel good about money we're saving – and the environment – because we're using less gas [than the old furnace] and creating our own heat and electricity," says the speech therapist from Braintree, Mass. Ms. Denoy's family will buy some power this winter – and all spring and summer when the furnace system is not running.

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