Geothermal energy is the exploitation of heat from the earth. The obtained geothermal energy is used as heat or electricity. There are three kinds of geothermal energy:
– high temperature geothermal energy (electricity)
– low temperature geothermal energy (heat)
– very low temperature geothermal energy (geothermal heat pumps)
The science is booming in research organizations and enterprises faced with increasing demands for energy.
Deep geothermal energy has the distinction of providing abundant resources around the world (hence a high total potential). Environmental footprint is small and it has a reliable basis for the search for energy. Deep geothermal energy also has the advantage of not depending on weather conditions (rain, wind, sun …). In Norway, Rock Energy company is currently investigating the energy use in deep hot rock fractures. The principle of this operation process is to create the loop circulation of water from two wells after testing the geological and thermal characteristics of the site. One injection well is drilled vertically reaching the depth of 5000m. The second producing well is drilled obliquely. It reaches 3500m. Thus water is piped into the injection well. But the deeper you drill into the crust, the more temperature you get (on average, temperatures rising about 20-30 degrees per kilometer). The injected water will squeeze the pores of the rock where it is heated. The water will then go up by the producing well to fuel the plant and generate electricity.
The benefit for Rock Energy is that the company uses drilling techniques developed by the oil industry in the North Sea. It signed the first contract with Hafslund Fjernvarme to build a thermal power plant of 5 MW which can be connected to the heating system of Oslo and was also elected coordinator of Section Energi21 geothermal program.
This technology has a geothermal potential because, unlike the hydrothermal geothermal, it does not require the presence of deep aquifer. This technique can be applied everywhere. Thus, there would be 125 000 km2 in Europe with sufficient geological and thermal characteristics to implement such technology. Finally, this technology can be used for generating electricity, heating or air conditioning. No other deep geothermal technology is less dependent on subsurface conditions.