Heat Pumps - Geothermal Heat Pump Environmental/Energy Benefits Geothermal heat pumps are among the most energy- and cost-efficient heating and cooling systems available today. They use less electricity and produce fewer emissions than conventional systems, reduce air and water pollution, and provide a comfortable indoor environment for building occupants. About 500,000 geothermal heat pumps are being used today for heating and cooling throughout the United States in residential, commercial, and government buildings.
Geothermal heat pumps (GHPs) represent a major clean energy technology. As a commercially viable technology now, GHPs are well positioned to help our nation achieve the increasingly desirable benefits of more efficient, clean energy technologies. While the consumer benefits from the economic and comfort-related benefits of using GHPs, everyone benefits from the substantial environmental and energy benefits resulting from GHP use, especially as GHPs become more widespread in the market. The geothermal heat pump is ideal for residential, commercial, and government building applications. Understanding the environmental and energy benefits of GHPs helps broaden appreciation of the overall potential of this outstanding technology.
Achieving the present market penetration level of 400,000 GHP installations reduces U.S. greenhouse gas emissions by over 1 million metric tons of carbon dioxide each year. In a landmark technical report (source: "Space Conditioning: The Next Frontier," EPA 430-R-93-004, April 1993). the U.S. Environmental Protection Agency (EPA) found that GHPs are the most energy efficient, environmentally clean, and cost-effective space-conditioning systems available. The EPA also found that GHPs offer the lowest carbon dioxide emissions and lowest overall environmental cost of all the residential space-conditioning technology readily available today. The few emissions that are released occur at the power plant, where they are carefully monitored and controlled.
Energy Under Foot: Resource Conservation - Over two-thirds of the nation's electrical energy and over 40% of natural gas consumption is used in buildings. Space heating and cooling and water heating account for over 40% of the electric power used in residential and commercial buildings. By decreasing or offsetting the amount of energy needed for space conditioning and water heating, the nation has a major energy-saving opportunity.
GHPs, also known as GeoExchangeSM systems, move the heat from the earth (or a groundwater source) into the home in the winter, and pull the heat from the house and discharge it into the ground in the summer. The underground (or underwater) piping loops serve as a heat source in the winter and a heat sink in the summer. It's the same heat-exchanging process used by a refrigerator or air-conditioner.
While many parts of the country experience seasonal temperature extremes-from scorching heat in the summer to sub-zero cold in the winter-a few feet below the earth's surface the ground remains at a relatively constant temperature. Because a GHP system is so efficient, it uses a lot less energy to maintain comfortable indoor temperatures. This means that less energy-often created from burning fossil fuels-is needed to operate a GHP. According to the EPA, geothermal heat pumps can reduce energy consumption-and corresponding emissions-up to 44% compared to air-source heat pumps and up to 72% compared to electric resistance heating with standard air-conditioning equipment for residential applications.
Environmental Benefits: Greenhouse Gas Mitigation and Emissions Reductions - Nearly 40% of all U.S. emissions of carbon dioxide are the result of using energy to heat, cool, and provide hot water for buildings. This is about the same percentage that the transportation sector contributes. The EPA found that under most electricity generating scenarios, GHP systems have the lowest carbon dioxide emissions of all technologies analyzed, and the lowest overall environmental cost (source: "Space Conditioning: The Next Frontier").
Over an average 20-year lifespan, every 100,000 units of nominally sized residential GHPs will save more than 24 trillion BTUs of electrical energy, and save consumers approximately $500 million in heating and cooling costs at current prices. And over the same period, these 100,000 units reduce greenhouse gas emissions by almost 1.1 million metric tons of carbon equivalents.
Ozone Layer Damage: GHPs minimize ozone layer destruction by using factory-sealed refrigeration systems that will seldom or never have to be recharged. GHPs typically use less refrigerant than conventional air-conditioning systems. And using factory-sealed refrigeration systems also reduces leak potential from field connections and increases reliability.
Human Health and Comfort: GHPs are safe and clean because there are no combustion flames, no flues, and no odors; just safe, reliable operation year after year. And compared to most conventional HVAC systems, GHPs deliver constant comfort and improved humidity benefits, especially with 2-speed fan GHP systems. GHPs are quiet too; there's no noisy outdoor compressor.
GHP systems themselves are environmentally friendly-when properly installed, there is no danger of GHPs polluting ground water sources. The fluid in the ground-loop heat exchangers is typically an environmentally safe, water-based antifreeze solution. A recent EPA analysis ("Evaluation of Consequences of Anti- freeze Spills from Geothermal Heat Pumps," undated EPA report released in late 1998, GPO#1998-615-003/60624) found that the human health risk from ingesting groundwater contaminated by a GHP antifreeze leak is low.
A tremendous opportunity exists to reduce energy use and carbon emissions significantly by the accelerated and expanded deployment of GHP systems. |
