A geothermal cooling system is one of the simplest forms of sustainable energy transfer, both in terms of conceptualization and installation. This type of cooling system does not rely on electrically-cooled air as with an air conditioning unit. Rather, it is designed to tap into the cool, stable temperatures found just below the surface of the earth. With the device installed, warm air from a home or building environment is replaced with air cooled naturally by the earth through a process of geothermal transfer.
How a Geothermal Cooling System Works
To harness the cool underground temperatures of the earth, a pump is installed at a sub-ground level, such as in a basement. To this pump is attached a pipe loop that is buried in the ground and extends for a distance away from and back to the pump. The pipe can be either copper or synthetic polyethylene. Continually cycled through this loop is a refrigerant that carries warm air from the building away and brings air back that has been cooled by the earth. This transfer process is constant when cooling the home, but it does not require anything to keep the temperature stable, such as freon. It requires some electricity or natural gas to run the pump, but other than that the system is self sustaining.
Types of Temperature Transfer Methods
There are two basic methods when using geothermal cooling. The first is called water to air, which is used as a substitute for central air conditioning. The liquid refrigerant transfers warm air into cool air, which is then blown back into the building. The other method is called water to water and works by pumping water cooled by the earth throughout a structure. This helps to maintain a cool temperature without blowing air through vents.
The pipe, whether copper or polyethylene, is buried below the frost line within the first 10 feet below the surface. At this level temperatures are kept very stable, between 50 and 60 degrees Fahrenheit. The loop leads out from the pump, away from the home, and zig zags around an area before returning back to the pump. Once the cooled refrigerant is returned, it is used to either cool air or is sent to various areas of the home in cool water form.
Open vs. Closed Loop
The system that pumps a refrigerant through the pipes to remove hot air and return cool air is called a closed loop system, which continually uses the same liquid to transfer the heat. An open loop system taps into nearby wells, the water of which, too, is kept at a stable, cool temperature by the earth. Once the water is used to transfer cool air to the structure it is returned to the well completely unpolluted. Open systems only work where there is plentiful ground water.
Geothermal cooling systems, once installed, can replace central air conditioning systems. They not only eliminate chemical use and potential pollution, but reduce energy expenditures by transferring the naturally cool temperatures found just below the surface of the earth into the structure, thereby replacing any hot air that amasses there.