Geothermal Power (heat from the earth): The energy crisis of the mid-1970s drew particular attention to research into renewable energies ( alternative energy sources), including geothermal energy. In Austria, hot subsoil bodies of water with temperatures between 40 and 100°C are found in the Upper Austrian alpine foreland, the Vienna Basin and the Styrian/ South Burgenland Basin, where geothermal energy can be put to use as an environmentally friendly alternative energy. Prerequisites for practical use are a high temperature gradient and the presence of subsoil watercourses in the rock formations. In areas offering favourable conditions exploratory drilling has been performed on a major scale since the 1990s. In many cases hot springs are used for both balneological purposes and energy production. The technology of heat pumps for the use of shallow ground water is another important application of G. These systems utilize the lower temperatures of groundwater with about 10°C. A significant feature of both methods is the re-injection of low-energy water into the ground to avoid permanently affecting the ecological balance of groundwater.