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Geothermal power

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Geothermal power is the process of generating electricity from the heat found within the Earth. This energy source is considered renewable and sustainable. This is because the amount of heat humans extract is very small compared to the Earth's total heat content.

Puhagan geothermal plant
Puhagan geothermal plant

Using this heat is also cleaner for the atmosphere. Geothermal electric stations produce an average of 45 grams of carbon dioxide per kilowatt-hour. This is less than 5% of the emissions produced by conventional coal-fired plants. As of 2019, the total worldwide geothermal power capacity reached 15.4 gigawatts (GW).

World geothermal generation 2021
World geothermal generation 2021

The mechanism of geothermal power relies on transferring heat from the Earth to a working fluid. This fluid is used to turn a turbine, which then powers a generator to create electricity. The Earth's crust acts like a thick insulating blanket. To release the heat underneath, we must pierce this blanket with fluid conduits like magma or water. Heat naturally flows to the surface through conduction at a rate of 44.2 terawatts (TW). It is also replenished by radioactive decay at a rate of 30 TW. This heat must be carried to the surface through circulation. This can happen naturally through hot springs or by drilling wells into hot aquifers.

EGS diagram
EGS diagram

Engineers use different technologies to capture this heat depending on the available resources. Dry steam power stations are the simplest and oldest design. They require a resource that produces only dry steam. In these stations, geothermal steam of 150°C or higher is used directly to turn turbines. After the steam turns the turbine, it enters a condenser. There, it turns back into a liquid and is sent back into deep wells to be reheated. Flash steam power stations are another type used to harness high-temperature resources.

NesjavellirPowerPlant edit2
NesjavellirPowerPlant edit2

A third method is the binary cycle power station. This technology allows for the use of much lower temperature resources. It was first demonstrated in the Soviet Union in 1967. In these systems, an organic fluid is used to carry the heat. This fluid is heated by the geothermal water, turns into a gas, and spins the turbine. A binary cycle station in Chena Hot Springs, Alaska, produced electricity from a record low fluid temperature in 2006. This technology is vital because it expands the areas where we can generate power.

Central Geotérmica de Berlín 05
Central Geotérmica de Berlín 05

The history of geothermal energy began in the early 20th century. Prince Piero Ginori Conti tested the first geothermal power generator on July 4, 1904, in Larderello, Italy. That successful test lit four light bulbs. The world's first commercial geothermal power station was built in Larderello in 1911. Italy remained the only industrial producer of geothermal electricity until 1958. In that year, New Zealand became the second major producer when the Wairakei station opened. Wairakei was notable for being the first station to use flash steam technology.

Top 5 Geothermal-Electric Countries
Top 5 Geothermal-Electric Countries

Today, geothermal energy is a significant global resource. Geothermal electricity is currently used in 26 countries, while geothermal heating is used in 70 countries. The United States holds 23.9% of the world's installed capacity, which is 3.68 GW. Some countries, like El Salvador, Kenya, the Philippines, Iceland, New Zealand, and Costa Rica, generate more than 15% of their electricity from geothermal sources. Indonesia has the largest estimated potential in the world at 29 GW. In 2017, Indonesia's installed capacity was 1.8 GW.

geothermal capacity
geothermal capacity

Future developments may focus on enhanced geothermal systems (EGS). This approach is used in ground that is hot but dry or lacks water pressure. Developers bore two holes into a site and fracture the rock between them. They then pump water or liquefied carbon dioxide down one hole so it comes up the other as a gas. This could unlock much more energy than tapping natural aquifers. While the thermal efficiency of these stations is relatively low, around 7% to 10%, they are very reliable. Unlike wind or solar, geothermal power does not rely on variable sources. This allows for a high capacity factor, which reached a global average of 74.5% in 2008.

Installed energy capacity (geothermal)
Installed energy capacity (geothermal)
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🖼️ Images & Media (10)
File:Top 5 Geothermal-Electric Countries.png
Top 5 Geothermal-Electric Countries.png
File:geothermal capacity.svg
geothermal capacity.svg
File:EGS diagram.svg
EGS diagram.svg
File:Installed energy capacity (geothermal).png
Installed energy capacity (geothermal).png
File:Staufen.Cracks.jpg
Staufen.Cracks.jpg
File:Puhagan geothermal plant.jpg
Puhagan geothermal plant.jpg
File:Central Geotérmica de Berlín 05.JPG
Central Geotérmica de Berlín 05.JPG
File:World geo generation yearly.png
World geo generation yearly.png
File:World geothermal generation 2021.png
World geothermal generation 2021.png
File:NesjavellirPowerPlant edit2.jpg
NesjavellirPowerPlant edit2.jpg
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