Geothermal energy

Question

what is underground that could provide so much heat that we can use it as energy source?

Answer 1

Sophia,

Another way to think of geothermal energy, is in terms of "heat value". For example, in Pennsylvania, we have multiple homes that are heated through "geothermal energy". In essence, a well is drilled several hundred feet into the ground and into- typically- an water reservoir. The well in then connected to pipes in the house, as well as a water pump- which is also located inside the house. At the end of the day, you have what is called a "closed loop" system. The water comes out of the ground at a specific temperature, is circulated though the house, and then returned to the ground. Any temperature increase (summer heat) or temperature drop (winter cold) in the water- while it is in the house- will be adjusted once the water is recycled back into the ground. (Hence the term, "closed loop"). This type of system is unique in that it allows the home owner to utilize the earth as a heating/cooling base (geothermal), and the energy put into the system by the homeowner is to run the water pump.

 

Finally, there are occasions when this type of system must be supplemented. Examples of this would include a power outage (you can't run the water pump with electricity) or in prolonged periods of VERY cold weather. In this case, methods outside of geothermal heating would be used.

Answer 2

The Earth has a core of molten Iron. This core is somewhere close to 6000 degrees celsius (that's far more than enough to melt strong steel). That's far more than enough to serve as a decent energy source. At places which are good for geothermal energy, heat from the core (ie lava) is closer to the surface. There are a lot of different explanations for how, why, when and where this heat reaches close to the surface in certain locations. But the basic concept is that at some geological locations it becomes possible to harness this energy. There can be other explanations as well, but often geothermal plants are built in areas where volcanic/geothermal activity is common.