Geothermal energy is used in over 70 countries. With the use of heat pumps it is possible to heat many homes, as well as bodies of water. The system involved includes underground pipes and loops which work with a heat exchanger and ductwork within the structure. Geothermal heat pumps can use the Earth as a coolant or a heating source. The design of the geothermal heat pump takes advantage of moderate temperatures in the shallow ground to boost efficiency and reduce operational costs. Solar heating is often combined with geothermal energy to form a geosolar system with large efficiency rates.
Geothermal hot water (hot springs) can be found underground and have a variety of uses. Water from hot springs is heated by the geothermal heat from the interior of the earth. The temperature of the earth's rocks increases with depth (known as a geothermal gradient). If water reaches into the crust it comes in contact with these very hot rocks. The water from hot springs in non-volcanic areas is heated in this manner. Geothermal hot water can be used to heat buildings, grow greenhouse plants, for pasteurization or for fish farming.
Geothermal hot dry rock can be used to generate electricity. While geothermal energy itself is renewable, geothermal sites are not necessarily. An overworked site, or one with an excessively large energy plant, can quickly be depleted. The potential release of toxic elements also needs to be actively managed so as to minimize the impact on the surrounding environment.
When natural cracks and pores will not allow for positive flow rates of geothermal energy, high pressure cold water is pumped into the rock. This increases the rate of the geothermal energy, and the water captures the heat of the rock until it is forced out of the ground in the form of hot water. The water is then converted into electricity with either a steam turbine or a binary power plant system.
