Answer:
What is geothermal energy?
Geothermal energy is a type of renewable energy taken from the Earth’s core. It comes from heat generated during the original formation of the planet and the radioactive decay of materials. This thermal energy is stored in rocks and fluids in the centre of the earth.
Geothermal Energy - Geyser EruptingThe difference between the temperature in the earth’s core and the surface drives a continuous conduction of thermal energy from the centre to the exterior of the planet.
High temperatures of over 4000°C cause some of the rock in the centre of the Earth to melt and form hot molten rocks called magma. These heats also cause the mantle to behave plastically and portions of it to convect upwards, since it is lighter than the surrounding rock.
The rock and water in the Earth’s crust can reach heats of around 370°C.
Thermal energy contained in the rocks and fluids can be found from shallow depths right down to several miles below the Earth’s surface.
First used in Italy in 1904, geothermal has been a consistent – and expanding – source of energy in recent years. According to the International Renewable Energy Agency (IRENA), geothermal energy has grown steadily from around 10GW worldwide in 2010 to 13.3GW in 2018.
Where does geothermal energy come from?
Geothermal energy is the heat that comes from the sub-surface of the earth. It is contained in the rocks and fluids beneath the earth’s crust and can be found as far down to the earth’s hot molten rock, magma.
To produce power from geothermal energy, wells are dug a mile deep into underground reservoirs to access the steam and hot water there, which can then be used to drive turbines connected to electricity generators. There are three types of geothermal power plants; dry steam, flash and binary.
Dry steam is the oldest form of geothermal technology and takes steam out of the ground and uses it to directly drive a turbine. Flash plants use high-pressure hot water into cool, low-pressure water whilst binary plants pass hot water through a secondary liquid with a lower boiling point, which turns to vapour to drive the turbine.
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