Thermomineral Water and Geothermal Energy - Hydrogeology: Objectives, Methods, Applications - page 85

Figure 47 Geothermal resources in metropolitan France.
aquifers can have a very high mineral content; so the doublet procedure
can be used as well, where the cooled water is returned to the aquifer.
For medium energy resources, several systems are under development
at Los Alamos (United States), Rosemanowes (United Kingdom), and Hijiori
(Japan). Depending on the context, several terms are used: HDR (Hot Dry
Rock), HFR (Hot Fractured Rock), or HWR (Hot Wet Rock), the concept
being to inject cold water into a hot fractured rock mass, and then to pump
up the heated water.
In France, the HDR system is under construction in Soultz-sous-Forêts
(Bas Rhin). Experiments done since 1997 (Gentier & Genter, 2010) showed
that it was possible, by injecting pressurized water in 5,000 m deep boreholes
to stimulate natural fracturation, in order to enable artifi cial circulation of
water, heated to 200°C, between two deep boreholes. The site is located on