Geothermics

99% of the earth is hotter than 1000°C, only 0.1% is colder than 100°C. How can we use this energy? The heating sector is responsible for about half of the energy consumption in Austria. On a global average, the temperature increases by about 3°C per 100 m in depth. Three pillars fundamentally shape the research and use of geothermal energy.

The first pillar to be researched is the technology for the use of heat. There are several tasks to be solved here. From which depth can the heat be lifted with which method. We distinguish between near-surface and deep geothermal energy. In near-surface geothermal energy, depths of a few hundred meters are used. Here it is necessary that the temperature is raised additionally with electrical heat pumps for a use. In deep geothermal energy, hydrothermal utilization comes first. This means that hot water is extracted from greater depths of several thousand meters, used and fed back into the rock. The prerequisite for hydrothermal geothermal utilization, however, is that an aquifer (thermal aquifer) is present in the deep subsurface. Another method would be to inject cold water directly into a porous rock, heat it in the subsurface, and then extract it. The porosity of the rock can be technically produced and enhanced and this is called "enhanced geothermal systems" EGS.

The second pillar concerns the geologically favorable areas in which naturally porous aquifers are already present in the deep subsurface. In most cases, these are limestones, dolomites or sandstones. These rocks typically occur in Austria in our basin landscapes such as the Molasse zone, the Vienna Basin and also the Styrian Basin. Here it is necessary to investigate and describe the structures of the deep subsurface in mostly 2000 m - 5000 m by means of geophysical methods, such as seismic reflection. The results of these investigations can then be used to plan and drill geothermal wells. In Styria, we already have some showcase projects in the Fürstenfeld area. The vegetable producer Frutura uses thermal energy from about 3000 m with a temperature of 130°C. Geoscientific research is currently intensively searching for such geothermal favorable areas in order to be able to lift the heat treasure.

The third pillar is aimed at the consumers of thermal energy. On the one hand, there are industrial sites such as Frutura with its vegetable production, and on the other hand, there are the heating systems in our buildings. Thus, it makes sense that we find geothermal energy near metropolitan areas, preferably with already existing local and district heating networks. Interdisciplinary geoscientific research can make a significant contribution here to the decarbonization of the heat supply in Austria. Since thermal energy accounts for about half of total energy use, the energy transition is highly dependent on the heat transition. Let's use this opportunity for Austria, too!