Geothermal energy use, harnessing the natural geothermal energy in the Earth, has been a part of human existence for centuries, with documented examples of geothermal energy use dating back to Greek and Roman times and being seen in Ancient China and Egypt. There are a number of ways in which this energy can be used, and it attracted a great deal of interest from alternative energy advocates in the early 21st century as people and governments sought out sources of renewable energy.
The most common geothermal energy use is direct use, in which heated water and steam from inside the Earth is used for heating, cooking, and bathing. Direct use is also the oldest use; the Greeks and Romans, for example, used geothermal springs for bathing and also attached beliefs about healing powers to deposits of naturally warmed water. This use can be seen in over 70 countries around the world, and is especially common in geologically active regions such as Iceland, where there is ample geothermal energy available.
Another form of geothermal energy use can be found in geothermal power plants, which use geothermal energy to generate electricity. The advantage of such facilities is that they can generate energy in a remote location and transfer it elsewhere, allowing people in regions without sources of geothermal energy to enjoy geothermal power. Efficiency rates for geothermal power plants can be very high, depending on the technology they use, how well they are maintained, and where the power is being sent.
There is an additional option for geothermal energy use known as a heat pump. With a heat pump, geothermal energy is used to push heat into buildings in the winter, and to pull heat out of buildings in the summer. This technique achieves climate control, often at very low cost. It relies on the natural warmth of the Earth near the surface, and does not require access to deep geothermal deposits. This geothermal energy use may be known as geoexchange so that people do not confuse it with the deep deposits of geothermal energy used in geothermal power plants and direct use systems.
This type of alternative energy has both advantages and disadvantages, as with every type of energy used by people to heat, fuel vehicles, cook, generate electricity, and perform other tasks. Many advocates for alternative energy have suggested that the solution to energy problems probably lies in a happy medium, with people combining energy sources and technologies to meet their needs, rather than relying on a single technology.
