The highest temperature resources are typically used for electrical power generation. Uses for low and moderate temperature resources can be split into 2 classes : direct use and ground-source heat pumps. The point of a geothermal facility is to take the energy stored in the guts of the earth and use it for heating or to supply electricity from the steam generated. But this heat can only be removed if underground geological formations are permeable or cracked, so that hot water can rise to the surface. In a number of cases, rock discontinuities enable hot water to rise thru cracks at many thousands of litres an hour in a thermal spring. There are lots of sites of this sort in France, especially in Chaudes-Aiges, Southern Auvergne ( in the Cantal Dep. ), where water powers out at 82C. It's the hottest spring in Europe. Obviously , the problems in harnessing geothermal heat alter dependent on the geological context and depth.

Some regions are way more favourable than others and there are deposits of geothermal energy in a fairly similar way as there are oil deposits. Hot water can be discovered nearly everywhere, provided that we drill far enough, however it is definitely better to go looking for the best sites, where hot water is near to the surface. Steam or this water can then be employed in geothermal power stations to generate electrical power or offer a heating network for buildings. Geothermy is utilized in France for cooling and heating and there are numerous pilot projects. France is thought of as a front-runner in Europe. The sole Western european country that makes larger use of geothermal energy is Iceland, where the capital, Reykjavik, is 82% heated by geothermal. The contribution of geothermy to French energy generation is far greater than wind and sun generated energy.

It's estimated that there are six MTOE ( Million tons of Oil Equivalent ) every year of serviceable geothermal reserves in France. Worldwide , geothermal heat has been employed mainly in locations where hot water was discovered, which is a serious limitation. To develop geothermal energy for the future, ways are wanted to increase the quantity of engaging areas, as an example the 'hot dry rocks' strategy, as utilized in the Soultz-sous-Forts project in the Alsace area of France, which uses heat from rocks without the presence of hot water. This technique is composed of fracturing rocks between 2 boreholes and pumping in cold water from the surface, to heat it as it makes contact with deep rocks.

In France, sites with a calorific potential of more than 180C at a depth of 5,000m have been identified in the Languedoc-Roussillon area and in the Massif Central. According to expert guesses, the Earth's temperature at a depth of 40km is 1,000C. Thus we live on a nearly infinite stock of energy. All we want to do is to find out how to utilize it. Another expanding application is known as 'surface geothermy' and uses heat pumps. This makes usage of the least identifiable fraction of geothermal energy and can often be used to heat or air condition little buildings. Using resource temperatures of 4C to 38C, the heat pump, a gizmo which moves heat from one place to another, transfers heat from the soil to the house in winter and from the house to the soil in summer. These heat pumps open up novel opportunities and are possible just about anywhere.

The method consists of drilling 2 wells to a depth of 150m, so a heat exchanger composed from polyethylene tubes can be inserted.The liquid that circulates in these tubes collects heat from the rock to provision a heat pump on the surface. Direct use, as the name indicates, involves using the heat in the water without delay ( without a heat pump or power plant ), for such items as heating of buildings, economic processes, greenhouses, aquaculture ( growing of fish ) and resorts.Direct use projects generally use resource temperatures between 38C to 149C.