The U.S. Environmental Protection Agency’s (EPA’s) plan to regulate carbon emissions is just the latest challenge facing the U.S. electric power system. Technological innovation is disrupting old ways of doing business and accelerating grid modernization. Earlier this year, AEE released Advanced Energy Technologies for Greenhouse Gas Reduction, a report detailing the use, application, and benefits of 40 specific advanced energy technologies and services. This post is one in a series drawn from the technology profiles within that report.
A ground-source heat pump is a heating and cooling system that exchanges heat between the earth and the interior of a building. It relies on the fact that ground temperatures tend to be constant throughout the year – this allows it to achieve higher efficiencies than air-source heat pumps, and also makes it suitable for any climate. In the winter, it transfers heat stored in the ground into a building, and in the summer, the system works like an air conditioner, transferring heat out of a building and into the ground. Ground-source heat pumps require vertical wells or horizontal loop fields to be installed to enable the heat transfer to occur. Ground-source heat pumps can also provide domestic hot water from desuperheaters, one of the heat pump’s components, and heat water for free in the summer.
Air-source heat pumps (like the one pictured above) are used more commonly than ground-source heat pumps. They are another efficient heating and cooling technology and operate on the same principle as ground-source heat pumps, but exchange heat between indoor and outdoor air. Air-source heat pumps have predominately been utilized in warmer climates but advances in technology have recently made them more effective in cold climates.
Both technologies are currently used for cooling, space heating and water heating in residential and small- or medium-sized commercial buildings. For example, a net-zero school building in Irving, Texas, utilized geothermal heat pumps to meet its heating and cooling needs. Each year about 50,000 new geothermal heat pumps are installed across the United States, with over a million ground-source heat pumps currently installed. The U.S. market for geothermal heat pumps was estimated at $115 million in 2013, up 9% from 2012.
Although ground source heat pumps tend to have higher purchase and installation costs than traditional heating and cooling systems, they significantly reduce energy costs, typically 25 to 40%. Ground source heat pumps are particularly beneficial in the summer, as they can reduce peak electricity demand. Depending on available incentives and financing options, a residential or commercial user could recoup the initial cost of investment in two to 10 years.
 Navigant Research, Advanced Energy Now 2014 Market Report, http://info.aee.net/advanced-energy-now-2014-market-report