An abundant and global primary resource
Over the next few decades, global energy needs will increase slowly but surely and slowly disappearing fossil fuels will no longer be the universal answer to these new needs. It is therefore important to find new sources of energy, preferably non-polluting and renewable. Geothermal energy from hot fractured rocks could be one of the solutions to this global challenge. Underground rock is permanently heated by heat flows inside the Earth. 40 km below our continent, temperatures reach about 1,000°C.
Use of rocks in the subsoil as heat exchangers
The Soultz-sous-Forêts subsoil consists of naturally fractured rocks. However, these fractures have almost always been rectified over thousands of years. In order to use these rocks as heat exchangers, these fractures must be reopened. This can be achieved by injecting water at high pressure. Water allows the rocks to move slightly along the fracture planes. When the pressure is released, the fractures no longer fit together perfectly and there is enough space to allow the water to circulate and heat.
Since the 1990s, international teams of scientists have been working in Soultz-sous-Forêts – from France, Germany and Italy as well as from Switzerland, Great Britain, Sweden, Japan and America. In 1996, a European Economic Interest Grouping (E.E.E.I.I.E.) called “Heat Mining” was created, bringing together some of the largest international players in the energy sector, including Electricité de France, Electricité de Strasbourg, Pfalzwerke (Germany). The objective of this group is to test the process of extracting heat from deep hot rocks for commercial electricity production. By 2006, this facility should be able to produce about 6 MW of electricity.