Geothermal power is the power extracted from the heat stored in the earth. This geothermal energy originates from the original formation of the planet, from radioactive decay, and from solar energy absorbed at the surface.
Geothermal power is cost-effective, reliable, sustainable, and environmentally friendly. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating.
Direct heating is far more efficient than electricity generation and places less demanding temperature requirements on the heat resource. Heat may come from co-generation via a geothermal electrical plant or from smaller wells or heat exchangers buried in shallow ground.
As a result, geothermal heating is economic at many more sites than geothermal electricity generation. Where natural hot springs are available, the heated water can be piped directly into radiators. If the ground is hot but dry, earth tubes or downhole heat exchangers can collect the heat. But even in areas where the ground is colder than room temperature, heat can still be extracted with a geothermal heat pump more cost-effectively and cleanly than by conventional furnaces. Geothermal heat pumps can be used for space heating essentially anywhere.
Economics
Geothermal power requires no fuel (except for pumps), and is therefore immune to fuel cost fluctuations. In very large scale (power plant construction for example), drilling typically accounts for over half the costs, and exploration of deep resources entails significant risks.
However, with direct heating applications like geothermal systems, units are far smaller with lower costs and the risks are far more feasible.
How much will I save with a Geothermal Heat Pump?
Resources
The Earth’s internal heat naturally flows to the surface by conduction at a rate of 44.2 terawatts (TW) and is replenished by radioactive decay of minerals at a rate of 30 TW.
These power rates are more than double humanity’s current energy consumption from all primary sources, but most of it is not recoverable. In addition to heat emanating from deep within the Earth, the top 10 meters (33 ft) of the ground accumulates solar energy (warms up) during the summer, and releases that energy (cools down) during the winter.
Beneath the seasonal variations, the geothermal gradient of temperatures through the crust is 25–30 °C (77–86 °F) per kilometer of depth in most of the world.
A geothermal heaters can extract enough heat from shallow ground anywhere in the world to provide home heating and cooling.
Sustainability
Geothermal power is considered to be sustainable because any projected heat extraction is small compared to the Earth’s heat content. Human extraction taps a minute fraction of the natural outflow, often without accelerating it.
The long-term sustainability of geothermal energy has been demonstrated at the Lardarello field in Italy since 1913, at the Wairakei field in New Zealand since 1958, and at The Geysers field in California since 1960.
