ABSTRACT
The term ‘geothermal energy’ refers to the energy stored in form of heat beneath the earth’s surface. It has been used since antique times for heating and for about 100 years also for electricity generation. The earth can offer a heat source (30°C-80°C) for direct uses: District heating, applications in agriculture… The earth offers also a steady and incredibly large heat source, heat sink and heat storage medium for thermal energetic uses, like for the geothermal heat pump. A steady underground temperature was first scientifically proven in 1778 in deep vaults beneath the Observatoire in Paris. It took until the middle of the 20th century before this steady heat reservoir was first used by a ground-source heat pump. Geothermal energy is also used for electricity generation. The first attempt at generating electricity from geothermal steam was made at Larderello, Italy in 1904. The success of this experiment indicated the industrial value of geothermal energy and marked the beginning of a form of exploitation that was to develop significantly from then on. After World War II, many countries were attracted by geothermal energy, considering it to be economically competitive with other forms of energy. It did not have to be imported and, in some cases, it was the only energy source available locally. 1
