Geothermal

Firstly what exactly does the word "geothermal" mean?

It comes from the Greek words geo meaning earth and therme meaning heat. Therefore geothermal means earth heat.

Beneath our feet lies a totally renewable energy resource. Our earths interior, like the sun, provides heat energy from natural sources, which produces warmth and power that we can use without polluting the environment.

The heat originates some 4,000 miles away at the earths core, where the temperatures can reach over 9,000 degrees Farenheit. As the heat is conducted outward through the various layers of the earth the temperatures and pressures increase sufficiently to melt mantle rock into a less dense substance call magma.

The magma moves slowly up towards the earth?s crust carrying the heat from below, heating nearby rock and water that is trapped in cracks and porous rock. This natural collection of water is called a geothermal reservoir. Sometimes this water escapes through faults and cracks in the surface producing natural hot springs and geysers.

There are a number of ways in which we can "tap in" to this resource. One of the methods utilised in schemes designed by enconsult is by drilling a borehole into an old mine, pumping the ground water through a heat pump, where it transfers its heat to the water that is piped through buildings in the scheme.

The ground water is returned down a well back into the reservoir to be heated and used again. In this open loop cycle, there are no emissions to the air.

The geothermal energy helps to conserve non-renewable fossil fuels, therefore decreasing the use of these fuels and reducing the emissions that harm our atmosphere, as heat pumps have a coefficient of performance (COP) between 4 and 5 (i.e. for every 1kW of electricity utilised, 4-5kW of heat is produced).

The benefits of using this type of energy are self-explanatory:

• It is clean ~ reducing emissions that can harm our atmosphere.

• Reliable ~ it is designed to run 24 hours a day, all year.

• More economic ~ utilises less electricity than conventional systems.