Earth Energy

Geothermal energy refers to energy obtained from ground, water or air. It usually means energy obtained by means of a device called a heat pump, an electrical device that that moves heat from one place to another.

A heat pump can provide year-round climate control for your home - heating in winter and cooling and dehumidifying in summer. Refrigerators and air conditioners are common examples of the technology used in a cooling mode, and heat pumps are now being used in many places to heat and cool homes.

Heat pumps transfer heat by circulating a substance called a refrigerant through a cycle of evaporation and condensation . A compressor pumps the refrigerant between two heat exchanger coils. In one coil, the refrigerant is evaporated at low pressure and absorbs heat from its surroundings. The refrigerant is then compressed in the other coil, where it condenses. At this point, it releases the heat it absorbed earlier in the cycle. The process is fully reversible, so it can be used to heat or cool a home.

Refrigerators and air conditioners are examples of heat pumps operating in the cooling mode. A refrigerator is essentially an insulated box with a heat pump connected to it. The evaporator coil is located inside the box, where heat is absorbed and transferred outside, usually behind the unit where the condenser coil is located. Similarly, an air conditioner transfers heat from inside a house to the outdoors.

Since the ground, water or air always contains some heat, a heat pump can supply heat to a house even on cold winter days.

There are three forms of heat pump systems, depending on the source of heat: ground, water or air.

Copyright Real Energy Alternatives Limited 2009