Micro cogen for homes: Honda, climate energy system under development for home heat and power;...

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

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.

The combined heat and power means that the fuel normally used to keep a home warm is used twice, first to produce electric power and then to heat the home. Electric power is generated whenever heat is produced to satisfy normal space or water heating demands in the home.

During the winter when the heating demand is at a peak, the engine's heat output is augmented by operating the furnace or boiler. The heating system has two stages, with the engine being stage one, and the furnace or boiler being stage two. The goal is to operate the engine, with its modest heat output, close to 100% of the time throughout the heating season in order to maximize electricity production.

When heat demand increases beyond what can be supplied by the engine, the larger capacity furnace or boiler kicks in to provide the balance. In essence, whenever there is a demand for heat, the engine runs as much as possible, and the furnace or boiler operates as little as possible and only when absolutely necessary:.

Initially the system is seen as being applicable for new and existing home construction, primarily in the Northeastern U.S. The Northeast is being targeted as the system makes the most sense in cold weather areas that need the heat the system can produce.

Also, as the system can interface with and sell power back to the utility, it works best in states with net metering for small-scale cogeneration. There are about 10 such states now, with several in the Northeast. The systems in Japan, an even more highly regulated market, were sold and installed through a natural gas utility.

More long term, beyond about 2009, the system is seen for both new home construction and retrofitting to existing homes in any area with moderate to high heating loads, essentially the northern half of the U.S.

Honda and Climate Energy stressed that the prototype systems being installed this year are needed to verify product safety/performance, as well as allowing time to train installers and supervise early installations for quality control.

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