Waste Heat Replaced by Geothermal Energy


RWTH professor Peter Kukla is leading the development of Fraunhofer IEG at the Aachen site.


The transformation of energy supply from the large central structures of lignite and hard coal combustion to decentralized and climate-neutral systems poses major challenges. The decision to phase out coal-fired power supply will result in structural change in the affected regions and the question of the use of alternative energy sources. RWTH Aachen University and the Fraunhofer Institute for Energy Infrastructures and Geothermal Energy IEG, founded in early 2020, are jointly researching the exploration and sustainable use of georesources. Besides the integration of the International Geothermal Energy Centre Bochum (GZB) in Bochum into the Fraunhofer-Gesellschaft and the establishment of further institute units in Cottbus and Jülich, Fraunhofer IEG is also carrying out research at the branch offices in Aachen/Weisweiler and Zittau. These locations help build a bridge between the regions that are particularly affected by structural change in western and eastern Germany. To this end, Professor Peter Kukla, Head of the Department of Geology and Dean of the Faculty of Georesources and Materials Engineering at RWTH Aachen University, was given responsibility for the development of the Aachen site with the departments for georesources and storage technologies.

The aim of the cooperation between RWTH and Fraunhofer IEG is to create future-oriented alternatives for the upcoming system change in electricity and heating in the regions affected by the coal phase-out. In addition to electricity, power plants also feed process heat into the system as district heating, which covers the needs of entire regions. In the Rhineland, the cities of Aachen and Weisweiler and the institution Forschungszentrum Jülich are currently still using waste heat from the coal-fired power plant in Weisweiler. This is set to be replaced with geothermal energy in the future, with the future Fraunhofer IEG large-scale laboratory for deep geothermal technologies for heating, cooling, and power generation at the Weisweiler site also playing an important role. “The energy and heating market is facing radical change and we bear the responsibility for shaping a new, sustainable path. Geothermal energy in particular has great potential," explains Kukla.

Research on “Georesources”

Even after the end of the fossil energy age, the underground space will continue to be of particular importance for the extraction and storage of thermal energy and energy raw materials. In the Georesources department, the Fraunhofer IEG is conducting research on topics such as deep geothermal energy, hydrogen storage, and the extraction of raw materials from geofluids. Some of the key topics of the projects are the exploration methods of surface and borehole geophysics, modern reservoir simulation and management methods, estimations of sustainable heat performance in reservoirs, and the optimization of underground storage and extraction processes for heat and resources. The hydraulic, thermal, and seismic effects of deep boreholes will also be tested in pilot plants with the aim of obtaining data on extraction, safety, and damage prevention in the use of georesources in mining and natural ground.

"The underground remains a central element of future networked energy infrastructures. There are only a few universities in the whole world where the expertise for using them is as concentrated as it is here at RWTH. This is why the Aachen branch of Fraunhofer IEG will support a large number of companies from the traditional energy sector in converting their technology portfolios to low CO2 processes," explains Institute Director Professor Rolf Bracke.