Geothermal energy has been used for centuries, but its use has increased recently in an effort to offset global warming since it is considered to be a clean and renewable energy source. The use of geothermal hot dry rock, geothermal hot water, and geothermal heating are currently the most popular forms of geothermal energy. While geothermal energy does emit some greenhouse gases, they are considerably less than that of fossil fuels. Compared to fossil fuels, geothermal energy benefits the atmosphere and reduces global warming.
Geothermal energy has been used since the third century BCE to generate hot water for things like community baths. Geothermal hot water (hot springs) is created through fissures and pores in the earth's crust.
Geothermal hot water can be used in many ways. It can be pumped directly into an application for hot water or it can be used to heat buildings, grow greenhouse plants, used for pasteurization or for fish farming.
Geothermal hot dry rock can also be used to generate electricity. The energy from hot dry rock can be harnessed by creating extra down holes, which water is poured into. 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.
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 use of water at hot dry rock sites can damage surrounding land. It can create other fissures and stability issues. The use of water at a hot dry rock site can also release chemicals such as mercury, arsenic, and carbon dioxide into the atmosphere. It is theorized that this can be offset by injecting these fluids and gases back into the planet's core.
Geothermal energy is used in approximately 70 countries for heating. With the use of heat pumps, it is possible to heat many homes, as well as bodies of water, using underground pipes and loops which work with a heat exchanger and ductwork.
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