Looking for an alternative to a new furnace or air conditioning system for your home, building, campus, or community? Geothermal heating and cooling technologies are a great option.
What is a Geothermal Heat Pump?
Heat pumps move heat from one place to another using electricity. Air conditioners and refrigerators are two common examples of heat pumps. Heat pumps can also be used to heat and cool buildings.
Temperatures at about 30 feet below the surface remain relatively constant year-round—between about 50°F (10°C) and 59°F (15°C). For most areas in the United States, this means soil temperatures are usually warmer than the air in winter and cooler than the air in summer.
Geothermal heat pumps (GHPs) take advantage of these constant underground temperatures to efficiently exchange temperatures, heating homes in the winter and cooling homes in the summer.
What is in a Geothermal Heat Pump System?
A GHP system includes:
- An underground heat collector—A geothermal heat pump uses the earth as a heat source and sink (thermal storage), using a series of connected pipes buried in the ground near a building. The loop can be buried either vertically or horizontally. It circulates a fluid that absorbs or deposits heat to the surrounding soil, depending on whether the ambient (outside) air is colder or warmer than the soil.
- A heat pump—When ambient temperatures are colder than the ground, a geothermal heat pump removes heat from the collector’s fluids, concentrates it, and transfers it to the building. When ambient temperatures are warmer than the ground, the heat pump removes heat from the building and deposits it underground.
- A heat distribution subsystem—Conventional ductwork is generally used to distribute heated or cooled air from the geothermal heat pump throughout the building.
Where Can Geothermal Heat Pumps be Used?
GHPs can be:
- Used to heat and cool a single house, single business, or an entire community (college campus, neighborhood, etc.)
- Implemented as part of new construction or retroactively added for existing buildings
- Installed in urban or rural environments.
Some systems can supply homes and businesses with hot water.
Is a Geothermal Heat Pump the Same as an Air-Source Heat Pump?
No, geothermal heat pumps (GHPs) are different from air-source heat pumps. GHP systems exchange heat from the earth, while air-source heat pumps exchange heat from the air.
Compared to air-source systems, geothermal systems have been shown to be quieter, last longer, and require less maintenance, and they do not depend on the temperature of the outside air. Geothermal systems are typically more expensive than air-source systems, but the additional costs are often returned with energy savings.
Community Geothermal Heating and Cooling Design and Deployment
In April 2023, the U.S. Department of Energy (DOE) announced selections in the Community Geothermal Heating and Cooling Design and Deployment initiative. Projects will receive funding to help communities design and deploy geothermal district heating and cooling systems, create related workforce training, and identify and address environmental justice concerns. The initiative will also help expand community-scale geothermal by supporting new systems and developing case studies to be replicated throughout the country.
Grid Cost and Total Emissions Impacts from Mass Deployment of Geothermal Heat Pumps
In December 2023, DOE announced results of an analysis highlighting that, deployed at mass scale and coupled with building efficiency improvements, geothermal heat pumps could decarbonize heating and cooling and save energy in U.S. buildings, avoiding as much as 24,500 miles of new grid transmission lines by 2050—enough to cross the continental United States eight times. Learn more by reading the report.
To explore different types of geothermal heat pumps, visit DOE’s Energy Saver page.
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