Ever since Jules Verne wrote in 1864 about a trip to the Earth's interior, people have dreamed of bringing up heat from the centre of the planet. So far we have only scratched the surface, but researchers are now beginning to work down into the depths.

The fact is that 99 percent of the planet has a temperature above 1000°C. The heat is what’s left over from when the Earth was first formed, and there is more than enough of it for us to transform it into energy.

“If we can drill and recover just a fraction of the geothermal heat that exists, there will be enough to supply the entire planet with energy – energy that is clean and safe,” says Are Lund, senior researcher at SINTEF Materials and Chemistry.

Inexhaustible Source Geothermal heat offers incredible potential. It is an inexhaustible energy source that is nearly emission-free. Heat energy is found in the different rock types that make up the Earth’s surface, and deeper in the crust. The deeper you get, the hotter it is.

Around one-third of the heat flow comes from the original heat in the Earth's core and mantle (the layer closest to the Earth's crust). The remaining two-thirds originate in radioactivity in the Earth's crust, where radioactive substances continuously decay and generate heat. The heat is transported to rock layers that are nearer the Earth's surface. 

Different Depths Geothermal energy that comes from 150-200 metres below the surface is called low temperature geothermal energy. At these depths, temperatures hover between 6 and 8°C and can be extracted with heat pumps, combined with an energy well. This type of geothermal energy is exploited at a fairly large scale. 
 
(Renewable Energy World)

Read more