Geothermal energy is a clean, renewable energy source harnessed by extracting heat from underneath the Earth’s surface. Depending on the size and location of the system, heat can be extracted from hundreds to thousands of feet below the surface. Residential systems typically function by transferring heat to and from the Earth via a heat pump. Because the Earth’s temperature is virtually constant underground, homes can cool down by transferring heat into the ground, or warm up by transferring heat from the ground into the home. Utility-scale geothermal electricity plants operate slightly differently in that they typically take advantage of reservoirs or steam or hot water to spin electricity turbines. The Authority’s Community Geothermal Planning + Pilots grants provide funding for community-scale projects that provide heating and cooling to 100+ households. Below are some case studies from the US Department of Energy that show the systems in action.