Micro cogen for homes: Honda, climate energy system under development for home heat and power; 15,000 in Japan

Diesel Progress North American Edition, August, 2005 by Mike Osenga

Smaller combined heat and power (CHP) cogeneration systems have long fallen under the good idea category, but have never found widespread use, at least in North America.

For many years proposals have been floated and plans developed to place these types of cogeneration systems in everything from hotels to fast food restaurants, small retail operations and even residential applications from apartment complexes to individual homes. But the market penetration of these smaller output sets has never quite realized the potential or the volumes predicted for them.

A technology widely used globally in large reciprocating engine markets with diesel or natural gas engines and especially gas turbines, the smaller CHP systems moved down the horsepower chart, the less practical the technology has seemed.

Now, however, a new effort is being mounted for development of a small CHP system that comes to the U.S. with something different--a real world track record; 15,000 applications of a similar system in Japan over the last three years.

American Honda Motor Co., Alpharetta, Ga., said it will work with Medfield, Mass.-based Climate Energy LLC to develop a new form of home heat and power technology. The system, which is still being developed, uses micro combined heat and power (MCHP) cogeneration technology with natural gas to provide residential heat more efficiently, with the added benefit of producing electric power.

The agreement between the two companies calls for Honda to supply its compact home-use cogeneration package to Climate Energy, which will combine it with a furnace or boiler and market the entire system as an alternative to conventional space heating and electric power in new, and eventually, existing homes.

Working in coordination with state and local authorities as well as energy utilities, limited in-home field test installations will occur by late 2005, with more widespread distribution planned from late 2006.

"MCHP technology will provide residential consumers with new levels of comfort and energy efficiency, while reducing their utility bills," said Wade Terry, vice president of Honda Power Equipment. "Ultimately, we think that this technology might set a new direction for the future of home heat and power"

The design of the Honda MCHP module consists of a small single-cylinder natural gas engine and a small electrical generation system that utilizes Honda's sine wave inverter technology.

Designed primarily for detached single-family homes, the unit will cogenerate up to 3.0 kW of thermal output per hour and 1.0 kW of electricity, while delivering what Honda said is ultra-quiet operation with minimal vibration. The heat output of the MCHP module is augmented, as needed, by up to 30 kW, by gas burners in the Climate Energy system.

The complete Climate Energy Micro--CHP system, powered by the Honda MCHP unit, results in more than 85% efficiency in converting fuel energy into useful heat and electric power, Honda said. The system is also expected to yield a 30% reduction in harmful carbon dioxide emissions as compared with conventional heating appliances and grid-supplied electricity.

A similar version of Honda's cogeneration unit has been available for general use in Japan since March 2003, and is now installed in more than 15,000 homes.

A complete system will include a high efficiency warm--air furnace, the Honda MCHP unit, the cogen heat module, and the system controller. The tightly packaged Honda MCHP system is built around a single-cylinder vertical crankshaft gas engine that Honda developed specifically for this use. The engine, which can operate on natural gas or propane, drives a newly developed 27-pole generator.

The engine system includes an intake air silencer, oil filter, large oil reservoir, a triple construction rubber engine mount, an air filter box, exhaust muffler and a three-way catalytic converter, all packaged in a 34.6 in. high, 22.8 in. wide, 15 in. deep enclosure.

The enclosure also includes the electrical portion of the system, an interconnection inverter, an electronic control unit, starter/generator driver and power supply unit.

As the system is designed to be housed inside, combustion products are vented to the outdoors, with multiple heat exchangers used for reclaiming heat from the engine block, oil and the catalytic converter and transferring it into the building air.

The Climate Energy Micro-CHP system combines a 95% efficient natural gas furnace or boiler designed and manufactured by ECR International with the 85% efficient Honda natural gas engine/generator module.

Working with the electric grid, Climate Energy's Micro-CHP system generates electric power as a by-product of the normal operation of a home heating system. The Honda engine produces heat in the form of heated coolant, which is used to heat the home, either by circulating warm air or hot water. Potable hot water can also be produced. The generator simultaneously produces 1 kW of electric power for home consumption, reducing overall electrical costs.