Because geothermal heating and cooling systems use the earth’s energy, no flame or gas is required — which means it is a completely clean method. Geothermal systems do not produce any emissions, which means that they do not pollute the air or contribute to global warming. The EPA has found that geothermal systems reduce energy consumption (as well as its corresponding emissions) by more than 40% compared to air source heat pumps and by more than 70% when compared to traditional air conditioning systems. This makes them the most cost effective, energy efficient, and environmentally clean space conditioning systems available.
References: Environmental Protection Agency, Space Conditioning: The Next Frontier, Office of Air and Radia