Geothermal is where geothermal heat below the surface of the Earth is used to create electricity. Geothermal comes from the Greek “geo” and “therme”, meaning Earth heat.
The heat used is the natural heat of the Earth. A few kilometres down, the temperature is 250C. Roughly, for every 30-40 metres you go down, the temperature rises 1C. In some areas, like volcanic ones, there is molten rock very near to the surface.
Geothermal energy works because below the surface of the Earth there are is a lot of radioactive stuff reacting and giving off alpha rays, beta rays and gamma rays. This gives off incredible heat and this is how the Earth is heated.
Because of this we can use this thermal energy to good effect. We drill holes down to the level where there is enough heat to boil water. Then water is pumped down, and steam and hot water comes up the other hole into a generating station. In here, the steam is used to turn turbines and they dive generators.
- The generating station doesn’t take up much room
- There is no fuel needed
- It is almost free, except for the pumps which take water down and bring steam up.