Geothermal energy – the thermal energy derived from the heat contained in the Earth, which is recognised as essentially limitless, its use being only restricted by technology and the associated costs.

It is environmentally clean, renewable, sustainable and is the largest energy source available to mankind. Geothermal energy can be used directly as a heat source with a range of industrial applications, or indirectly in a thermal power plant to produce electricity. The Earth’s heat is a combination of radioactive decay of uranium, thorium, and potassium in the Crust and Mantle, and primordial heat left over from the planet’s formation.

“The amount of heat that flows annually from the earth to the atmosphere is enormous – more than needed to power all nations of the world – if it could be harnessed… If only 1% of the thermal energy contained in the uppermost 10Km of our planet could be tapped this amount would be 500 times that contained in all oil and gas resources of the world” Geothermal Energy – Clean power from the Earth’s heat – US Geological Survey ’08

Geothermal targets must currently be sufficiently hot (>circa 130°C) and sufficiently close to surface (<4 Km) to justify commercial development. Exploitable targets have hitherto been associated with areas of recent volcanic activity – Pacific Rim (including western seaboard of America), Italian Alps, Iceland and the East African Rift System, which are largely high enthalpy. However, there are a larger number of low enthalpy geothermal systems that also have the potential to produce power and it is these that may provide the energy for the majority of globally produced geothermal power in the future.

Geothermal power production is already a reality in Africa with current production in Kenya at 676MW.

“Geothermal energy is potentially the largest – and presently the most misunderstood – source of energy in the world today” Al Gore “Our Choice”