What is Ground Source Energy?
By Chris Bradshaw on June 8th, 2011
Ground source energy – sometimes also known as “geothermal energy” – is energy extracted from the uppermost 300′ or so of the Earth’s crust.
The temperature of the ground at a depth of just 5′ below the surface is typically between 8°C and 12°C and below 50′ the temperature is constantly 10°C, regardless of climatic conditions at the surface. This effectively means that there are unlimited reserves of free energy which can be exploited for 12 months a year beneath the surface of the Earth.
Ground source energy is typically extracted from the ground using a buried ground loop. This may, for example, be a loop of polyethylene pipe buried at a depth of 150′ to 200′ and containing a mixture of water and antifreeze. A ground source heat pump – not dissimilar to that employed by a standard domestic refrigerator – extracts heat energy from the ground which can subsequently be used for heating or hot water in your home.
Electricity is required to drive the pump and compressor components so efficiency is key to the successful capture of ground source energy. Most ground source heat pumps, however, are highly efficient and typically output three or four units of heat for each unit of electricity used to pump the heat. Ground source energy can therefore provide significant reductions in the costs of heating or cooling your home and in your carbon dioxide (CO2) emissions. Indeed even the most efficient condensing gas or oil boiler of equivalent output cannot compare in terms of CO2 emissions.