Electricity Producing Condensing Furnace
The Electricity Producing Condensing Furnace[1][2][3] can be a cost-effective, fuel-saving, and lower carbon footprint replacement for natural gas and propane-fueled hot air furnaces. It is also recognized as Home Cogeneration Furnace. Cogeneration means producing two useful products from the same fuel. This module produces electricity as a co-product of home heating. It converts 20 % of the heat of combustion to electricity while recovering most of the remaining 80 % as useful space heat.
Original Motivations and Additional Motivations[edit]
This Home Cogeneration Furnace, better described as a Electricity Producing Condensing Furnace, was developed in the 1980s with funding by the United States Department of Energy. It was conceived to be a cost effective and fuel saving replacement for every natural gas or propane fueled furnace. It was a time when the leading concern was depletion of fossil fuels.
This major concern forty years later is climate change from the CO2 product from fossil fuels. A large portion of the CO2 from burning fossil fuels is remaining in the atmosphere causing global warming by what has been called the Greenhouse Effect. Atmospheric CO2 was 280 ppm prior to the 1700s Industrial Revolution at the beginning of extraction and burning of fossil fuels. It had increased up to 350 ppm in the 1980s. It has increased another 70 ppm to 420 ppm in the early 2020s.
The United Nations has been coordinated plans that depend on volunteer action along with various subsidies, incentives and legislation to replace fossil fueled electricity with wind and solar, along with electrification of transportation and space heating. The reality is that natural gas fueled heating will be necessary for the intermediate future. The Electricity Producing Condensing Furnace can produce electricity with a relatively low CO2 footprint.
Electricity Condensing Furnace also supplies surplus electricity to the grid during the coldest days and hours when it is most needed for homes and buildings that are relying on electricity for heat, that is also a time when the output of solar electricity is minimal because of shorter days and sun lower in sky.
The Electricity Producing Condensing Furnace or comparable systems should be considered as the next efficiency standard for space heating.
Fundamental Theory and Practice[edit]
Gas-fueled hot air furnaces became a preferred home heating method after World War II when natural gas became available with long-distance pipelines and distribution systems.[4]
The early gas hot air furnaces were thermostatically ON-OFF controlled with a pilot light, a circulating fan for space air, and a natural draft chimney. Elevated flue temperatures were required to exhaust the combustion products and prevent damaging acidic condensate to the chimney. Chimney energy loss also occurred when it was not hot operating. Efficiency which was defined as the fraction of the heat from combustion that was transferred to the heated space could range from 60% to 75%.
The “condensing furnace” that approached 100% efficiency became the next standard. An additional heat exchanger was added to extract heat from the combustion products down to near ambient temperature along with capturing the latent heat from condensing most of the water vapor. The chimney was replaced with a clothes drier-type vent to the side of the building and a condensate drain. Without the benefit of the buoyancy of a chimney, a small fan is used to force the exhaust of the combustion products.
It is noted that 100% efficiency is a 1st law efficiency but is not the best that can be achieved. The ideal efficiency would be an ideal fuel-burning engine[6] driving an ideal or Carnot heat pump.[7] An example would be a natural gas-fueled engine with a 25% efficiency with mechanical power driving a heat pump with a Coefficient of Performance of three and also recovery most of the 75% rejected engine heat for space heating. The resulting heating system would have a first law efficiency of 150%.
The subject Electricity Producing Condensing Furnace[5] is a method of getting the same overall benefit, but with a module compatible with the connections of an existing condensing furnace. The fuel is supplied to a single cylinder air-cooled engine driving a grid-connected induction generator that converts 20% of the fuel to electricity while recovering the remaining 80% as space heat from engine cooling and exhaust.
Simplicity results from a single module serving as a furnace and electric generator. The generator also serves as the starting motor. The electric grid provides starting power and then voltage and speed control. The engine serves as the combustion chamber and high-temperature heat exchanger. The exhaust stroke of the engine provides the required forced purging of combustion gas. The spark plug serves as the ignitor. The engine cooling fan also circulates the space air.
The United States Department of Energy provided funding for the initial development and demonstration.[8] It was also recognized as an Energy-Related Innovation of the Year by the American Society of Mechanical Engineers.
Operation[edit]
Electricity Producing Condensing Furnace is a cogeneration system since it produces both useful heat and electric power from a single fuel source. One problem with most cogeneration systems is they cannot match the production of heat and power with simultaneous need. Thus, either electricity or heat is wasted, or storage is required. The electricity condensing furnace operate in a manner which no heat nor electricity is wasted.
It is controlled by the heating requirement of the building at thermostat. Since it is reconnected and the excess electricity is provided to the grid which serves as virtual storage with no cost nor loss is associated with a charging and discharging of batteries.
It also increases the reliability of the electric power grid by producing electricity during the winter peak hours.
Comparing Carbon Footprints for Electricity Production[edit]
A measure of the carbon footprint from fossil fueled electricity is the ratio of CO2 emitted to electricity produced. It depends on the type of fuel in chemical composition and heat value and the efficiency of the thermodynamic cycles.
A coal fueled steam plant will emit 2.35 pound of CO2 per kwh. This assumes coal is pure carbon with a heat value of 14,000 Btu per pound and a 38 % plant efficiency.
A natural gas fueled combines cycle plant will emit 0.78 pound of CO2 per kWh. This assumes natural gas is pure CH4 with a heat value of 24,000 Btu per pound and a 50% combined cycle efficiency.
The Electricity Producing Condensing Furnace will emit 0.39 pound of CO2 per kWh. This also assumes natural gas is pure CH4. It also recognizes electricity is produced with a marginal efficiency of 100 % corresponding to the extra fuel required to produce the space heat and electricity relative to only space heat.
Examples for Home Use[edit]
A typical house has a furnace that produces 40,000 Btu/h of heat while it operates 1,200 hours a year. The Electricity Producing Condensing Furnace who has a fuel input of 50,000 Btu/h of which 10,000 Btu/h corresponding to about 3kW of electricity power, based on the conversion factor of 1kW equals 3412 Btu/h. The remaining 40,000 Btu/h is captured as useful heat by cooling the engine and generator and from the exhaust heat exchangers.
The result is a yearly energy production of 3,600 kWh per year. The corresponding average output over the 8760 hours of a year will be about 0.4kW or 400W.
The performance of a typical electric vehicle is 4 mi/kWh. Thus, this vehicle can travel 14,400 miles with the energy reduced in one home in one year by the Electricity Producing Condensing Furnace.
Initial Concerns and Resolution[edit]
While the potential of the Electricity Producing Condensing Furnace was recognized, there were significant concerns[by whom?] related to safety, maintenance, engine life, and noise. It was noted that each of these concerns has been resolved.[citation needed] The original team of Union College faculty and students built prototypes for demonstration and resolved some concerns.[citation needed]
Other concerns have been resolved by the introduction of a similar engine-driven home cogeneration system by Honda called Freewatt.[9] The Honda system has more features[which?] that also add cost and complexity, such as the ability to operate separately from the electric grid.[citation needed]
References[edit]
- ↑ Government of Canada, Innovation. "Canadian Patent Database / Base de données sur les brevets canadiens". www.ic.gc.ca. Retrieved 2022-07-19.
- ↑ CA1241203A, Wicks, Frank E., "Electricity producing ultra high efficiency furnace", issued 1988-08-30
- ↑ Jones, Stacy V. (1987-07-11). "Patents; Electricity From a Gas Furnace". The New York Times. ISSN 0362-4331. Retrieved 2022-07-19.
- ↑ Wicks, Frank (2016-07-01). "Pipelines for War and Peace". Mechanical Engineering. 138 (07): 40–45. doi:10.1115/1.2016-Jul-3. ISSN 0025-6501.
- ↑ 5.0 5.1 Gilmore, V. Elaine (March 1989). "Home-size Congenerator". Popular Science. 234. Bonnier Corporation. pp. 82–84. ISSN 0161-7370.
- ↑ Wicks, F. (August 1989). "Design and benefits of a non-electric air conditioner that combines compression and absorption cycles". Proceedings of the 24th Intersociety Energy Conversion Engineering Conference: 2561–2563 vol.5. doi:10.1109/IECEC.1989.74835.
- ↑ Wicks, Frank (2012-06-10). "Teaching the Theory and Realities of Second Law Heating Systems": 25.1260.1–25.1260.9.
- ↑ Wicks, F.; Dykstra, E.; Arnold, M.; DeBerardinis, D.; Leavitt, N. (August 1989). "Development of a residential size electricity producing condensing furnace". Proceedings of the 24th Intersociety Energy Conversion Engineering Conference: 1909–1914 vol.4. doi:10.1109/IECEC.1989.74732.
- ↑ "Honda and Climate Energy Begin Retail Sales of freewatt™ Micro-CHP Home Heating and Power System". Honda Newsroom. 2007-04-03. Retrieved 2022-07-19.
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