Geothermal cooling is a process by which shallow ground is utilized within a system to regulate temperature. The upper 10 feet of the earth's surface holds a stable temperature between 50° to 61°F (10° to 16°C). This stable temperature is harnessed, using a geothermal device, to draw heat energy out of a system and thus transfer the cool temperatures into a warmer area.
Surface temperature has almost no effect on the ground underneath the frost line. Using this knowledge, a pump can be placed under the ground, in an area such as a basement, that effectively pulls the cool sustaining temperature from the ground. This device is connected to a loop of copper tubing or high-density polyethylene, which is literally buried underneath the earth's surface. This loop contains a refrigerant that is pumped through the tubing, exchanging the warm energy in the building with cooler energy in the ground and acting almost like a heat sink. This process is known as direct exchange and is very effective at keeping a location at a stable cool temperature.
Geothermal cooling uses two different methods to implement the cooling process: water-to-air systems or water-to-water systems. Water-to-air systems replace central air conditioning systems by using a liquid coolant to transfer the energy into the air that can then be blown throughout a structure. Water-to-water systems use a large system of liquid spread throughout the building that is cooled, keeping the area at a stable temperature. The water-to-water system has the bonus of working very effectively at heating as well.
The U.S. Department of Energy estimates that approximately 50,000 geothermal cooling devices are installed in homes and businesses each year. The cost per ton of capacity averages $2,500 US Dollars (USD). A three-ton appliance is needed for the average home. The energy savings equates to the device paying for itself in approximately five to ten years. The components inside the geothermal cooling pump last for roughly 25 years, while the copper or polyethylene loop placed in the ground has a lifespan of 50 years.
The main advantage of using geothermal cooling is that it does not use fuel or chemicals to regulate the temperature. Central air conditioning devices use materials that can be harmful to the environment. They also create carbon emissions that pollute the atmosphere. With the average home producing 5,550 tons of emissions each year according to the U.S. Energy Information Administration, geothermal cooling is a viable option to cut greenhouse gas emissions while maintaining a comfortable home environment.