Geothermal heat pumps have the potential to substantially reduce carbon dioxide emissions while also lowering the need for new transmission lines, according to the Department of Energy’s Oak Ridge National Laboratory.
The study, Grid Cost and Total Emissions Reductions Through Mass Deployment of Geothermal Heat Pumps for Building Heating and Cooling Electrification in the United States, found that, coupled with building envelope improvements, retrofitting around 70 percent of buildings in the United States with geothermal heat pumps could reduce electricity demand by as much as 13 percent by 2050 while avoiding as much as 24,500 miles of new grid transmission lines by 2050.
A geothermal heat pump uses an electric motor to use the relatively constant temperature of the ground – between 50 and 59 degrees Fahrenheit – to either cool or heat a building.
The study analyzed geothermal heat pump impact in three scenarios: a base case in which the grid is operated in its current configuration, a scenario in which measures to reach 95 percent grid emissions reductions by 2035 and 100 percent clean electricity by 2050 are implemented, and a scenario in which the grid decarbonization scenario is expanded to include the electrification of wide portions of the economy, including the heating of buildings.
The study was an impact analysis only, the authors noted, adding that installed costs and available land areas for installing geothermal heat pumps were not accounted for in determining their estimated deployment.
The researchers modeled each of the three scenarios with and without geothermal heat pump deployment to a large percentage of U.S. building floor space. In all cases, deployment of approximately 5 million geothermal heat pumps per year demonstrated system cost savings on the grid, consumer fuel cost savings through eliminated fuel combustion for space heating, and CO2 emission reductions from avoided on-site fuel combustion, they said.
“GHPs have traditionally been viewed as a building energy technology,” the researchers wrote. “The most notable result of this study, however, is the demonstration that GHPs coupled with weatherization in [single family homes] are primarily a grid-cost reduction tool and technology that, when deployed at a national scale, also substantially reduces CO2 emissions, even in the absence of any other decarbonization policy.”
The study also found that wholesale payments for electric grid services were reduced by 10 percent or $316 billion in the base case scenario, 13 percent or $557 billion in the grid decarbonization scenario, and by 11 percent or $607 billion in the full electrification scenario. Geothermal heat pumps could also reduce the cost of meeting the grid decarbonization objective by 47 percent and reduce consumer payments for heating fuels, resulting in savings of $19 billion per year by 2050, the study found.
