Geothermal energy is a type of heat that can be taken directly from the ground. It is a clean form of energy and it is sustainable. There are many different resources of this type of energy including from shallow earth, hot water, hot rock, and magma.
In most places in the world, the top 10 feet of the ground surface is a consistent temperature. This is usually between 10°C and 16°C. The use of a geothermal heat pump can draw out this heat and then use it to heat buildings or to provide an energy source to keep a building cool.
A system for using geothermal heat includes the heat pump itself, ductwork and a heat exchanger. The heat exchanger is a series of pipes that are buried in the ground close to the building. During the winter months, the pump will take the heat within the heat exchanger and moves it into the delivery system in the building. During the summer, the pump works differently. It removes heat from the building and sends it into the heat exchanger. However, there is also the option to use the heat removed in the summer to heat up hot water systems.
In the US there are a number of hot water geothermal reservoirs. These are located underground and it is possible to drill wells into them in order to harness the natural energy. A geothermal power plant can also be built and this will use the steam generated by the reservoir to provide the power for a generator.
Hot dry rock can be found much deeper in the Earth. Usually, it is a minimum of 3 miles down but anything up to 5 miles down. In order to access this source of heat, it is necessary to send cold water down one well, allow it to circulate and heat up as it goes, then bringing it back up another well when it is warmed. However, this type of technology is not commercially available and therefore it is unlikely that this can be used within the near future to produce the energy that millions of people need to heat their homes. The resources required to draw energy from magma are also extremely limited, although it can be done. Magma is even deeper below the Earth’s surface.