Combined Heat and Power as Small as Your Dishwasher

Posted on Thu Feb 15 2007

By: Jen Lukenbill in Alternative Energy, Environment

Comments: 1

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Recent abnormal weather patterns have taught us to expect the unexpected. All over the country, people have had to deal with freezing ice, snow, and weeks-long power outages. Utility companies have responded by increasing rates (ours increased twice in five months).

It's seemingly hopeless: we have no control over energy costs that have steadily increased for several years. When faced with obstacles that seem insurmountable, we're forced to either fight back or surrender.

November 2006's Christian Science Monitor featured a fighter: Massachusetts resident Bernard Malin and the softly thrumming metal box in his basement that turns natural gas into hot water and generates $600 to $800 worth of electricity annually, a bonus byproduct of heating his home.

Mr. Malin was the first person in Massachusetts to own a residential micro- combined-heat-and-power system, or micro-CHP. Since then, 18 other Boston-area families have become micro-CHP owners.

These units have been around for years in industrial facilities, but were too large, noisy and expensive for a residence; finally, a smaller version was introduced in Boston.

Home heating systems that produce one kilowatt of energy (such as Malin's) and larger units that put out up to four kilowatts have been widely available in Europe and Japan for years.

In Japan, over 30,000 homeowners have installed micro-CHP systems driven by quiet, efficient internal-combustion engines in sleek metal boxes 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 in Wisconsin plans to bring a 4-kilowatt hot-water system it sells in Europe to the US in 2007. Climate Energy of Medfield, Mass., developed a forced-hot-air system combining a high-efficiency furnace and ultra-quiet Honda generator. That system was deployed as a pilot to several US homes, including Malin's.

Often referred to as cogeneration, the accepted term is "combined heat and power" or CHP. This means the simultaneous production and use of heat and electric power from the same device or system. Micro-CHP is simply CHP sized for the individual home.

Making heat and power together in the same place, when technically practical, is a far more efficient use of limited and increasingly expensive fuel supplies. While the combined heat and power concept is old and widely practiced on the industrial scale, it's the "technically practical" part where Climate Energy contributes for individual homeowners. Technically practical implies that the equipment used must be affordable, reliable, quiet, safe, and maintainable. Until recently, the technically practical requirements for Micro-CHP systems could not be met.

How does Climate Energy Micro-CHP work?

The Climate Energy Micro-CHP System combines Climate Energy's state-of-the art, high-efficiency gas furnace/boiler with a natural gas engine/generator module designed and manufactured by Honda Motor Company of Japan. This combination provides unrivaled total energy efficiency in combined heat and power delivery.

Working with the electric grid, Climate Energy's Micro-CHP System generates electric power as a by-product of operating a home heating system. The Honda engine produces 11,000 Btu's per hour of heat to heat the house. Potable hot water can also be produced. The generator simultaneously produces 1.2 kilowatts of high-quality electric power for home consumption. Essentially, combined heat and power means that the fuel normally used to keep a home warm is used twice, first to heat the home and then to produce electric power. The Climate Energy Micro-CHP System is heat-led, and electric power is generated whenever heat is produced to satisfy normal space or water heating demands in the home.

During winter when the heating demand peaks, the engine's heat output is augmented by operating the furnace or boiler. Now the heating system has two stages; stage one, the engine; stage two, the furnace or boiler. The goal: operating the engine, with its modest heat output, close to 100% of the time throughout the heating season to maximize electricity production. When heat demand increases beyond the engine's capacity, the larger-capacity furnace/boiler kicks in to provide the balance. Electric power is produced continuously in both stages of operation. In essence, whenever there is a demand for heat, the engine runs as much as possible, and the furnace or boiler operates only when absolutely necessary.

Power Savings and Net Metering

The 1.2 kilowatts is power that homeowners previously purchased from their electric utility. Converting means saving energy, conserving natural resources, and reducing emissions. Although it won't supply all of the electrical demand in the average US home (8,000 to 10,000 kilowatt-hours annually), it will provide a significant percentage, as much as 4,000 to 5,000 kilowatt-hours per year or more in the northern half of the country. Power production increases in colder climates as the system runs more to provide needed heat. During occupied morning and evening hours, homes are expected to consume more power than the Micro-CHP's 1.2 kilowatts. Therefore, the electric power produced is completely absorbed in the home, reducing the amount of electricity purchased from the utility and lowering the homeowner's electric bill. During nighttime hours, when the home consumption falls lower than 1.2 kilowatts, the excess power is sent to the grid and the electric meter spins backward as the system produces more electricity than required in the home. A "net-metering" agreement with the electric utility allows customers to draw power from the grid or supply power to the grid during billing periods; the customer pays for the net amount of power consumed during the period. Massachusetts and nine other states mandate that net-metering be provided for qualified small power producers. The meter is read at the end of the billing period and the indicated kilowatt-hours are used to assess the bill.

Our Micro-CHP system will produce electric power nearly continuously during the heating season. The Climate Energy Micro-CHP System produces enough electricity to pay back the additional capital cost over a conventional heating system in as little as 4 to 5 years. The actual payback time varies depending on the size and location of the home, and on the per kilowatt-hour cost of electricity. The higher the electricity cost and the longer and colder the heating season, the faster the payback.

Protecting the Environment

The heat and power produced by Climate Energy's Micro-CHP System is generated at a very high-net efficiency. 83% to 93% of the energy content of the fuel consumed is transformed into useful energy, as compared to the 30 to 40% of conventional power plants. Why the disparity? Central power plants convert fuel to heat, then only a portion of heat to electricity. The portion of the heat not converted at central power plants to electricity is dissipated without value into the environment.

We can do better. A system that has been in use for years in other countries can just as easily be used in the U.S. Let's put the pressure on I, for one, am sick of accepting the letters telling me I have no choice in controlling my electric rates.

Sources

It heats. It powers. Is it the future of home energy? http://www.csmonitor.com/2006/1114/p01s02-usec.html

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Photo from http://kelcroft.com.hk/img/cogeneration_whisperGen.jpg

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