earth energy - technology
Geothermal Energy is heat (thermal) derived from the earth (geo). It is the thermal energy from the earth's core, which is stored in the rock in the earth's crust. This resource can be classified as low temperature (less than 90°C), moderate temperature (90°C - 150°C), and high temperature (greater than 150°C).
EarthEnergy Systems circulate water through pipes buried in the ground to extract the diffuse low temperature resource which is available everywhere. The average ground temperature just below the surface, in the UK is between 8ºC and 13ºC, this temperature remains constant throughout the year. The temperature of the water in the pipes is lower than the surrounding ground and so it warms up slightly. The returning water is chilled back down by a heat pump, where it is used to heat up a refrigerant. By compressing this 'warmed' refrigerant the temperature is further increased before being transferred to the building heating system. The heating water output from the heat pump is typically 45ºC - 55ºC.
This process can be reversed, using the ground as a heat sink, to provide cooling water for the building.
EarthEnergy Systems are suitable for almost any new building anywhere in the UK, and are compatible with underfloor heating, radiators, fan coils, ducted air, chilled beams and distributed water to air heat pumps. Heating, cooling and domestic hot water systems can be provided in conjunction with horizontal trenches, vertical boreholes or submerged pond loops.
The sizing of any ground source heat pump system is dependent on design day heat loss (kW) and/or peak cooling load (kW) and an assessment of monthly heating and/or cooling energy demand (kWh). Projects in excess of 200 kW in size may benefit from EarthEnergy undertaking an in situ thermal conductivity test to provide data to refine the ground loop heat exchanger design. This is not normally necessary for smaller schemes.
