Karlsruhe Institute of Technology: Geothermal energy indispensable for a heat transition
Half of the municipal heat is to come from climate-neutral sources by 2030. Deep geothermal energy can make a major contribution to this goal of the federal government because it supplies local energy constantly and regardless of the weather and takes up little space in settlements. A joint roadmap by institutions of the Helmholtz Association, including the Karlsruhe Institute of Technology (KIT), and the Fraunhofer Society shows that deep geothermal energy has market potential in Germany, with expansion targets of more than a quarter of the annual German heat requirement (over 300 TWh) opened. The paper provides recommendations for action to achieve this goal – clear expansion targets, large-scale geological exploration, investments in key technologies and the development of skilled workers are needed.
“In order to be able to achieve the expansion target of more than 300 terawatt hours, we need technological development,” says Prof. Thomas Kohl from the Institute for Applied Geosciences at KIT. He coordinates the future underground research laboratory GeoLaB, a joint initiative of the KIT with the Helmholtz Center Potsdam – German Research Center for Geosciences (GFZ) and the Helmholtz Center for Environmental Research (UFZ). “The application and development of state-of-the-art monitoring and analysis tools in the future underground research laboratory GeoLaB will provide the knowledge that is of great importance for the safe and ecologically sustainable use of geothermal energy and other underground resources. The transparent interaction with the public and the decision-makers is also very important,” explains Kohl.
“Without geothermal energy, decarbonization of the heat sector in Germany will not be possible. The natural heat potentials underground are available for this in most urban areas. The sustainable expansion of geothermal energy is an investment in the cities of our future,” says Professor Ingo Sass, head of the “Geoenergy” section at the GFZ. “With their strategically aligned work programs and their unique research infrastructures, such as the future underground research laboratory GeoLaB, the research institutions of the Helmholtz Association are making a significant contribution to the success of the transformation,” Sass continued.
According to Sass, underground research laboratories such as the GeoLaB are of central importance because they illuminate the basic physical-chemical-biological understanding of sites with similar geological properties. Ingo Sass adds: “We implement our research results in applied, industrial and demonstrative projects and thus show society the safe and large-scale applicability of geothermal energy supply”.
There are local heat sources and storage options underground in large areas of Germany. “For the urban space, we have to coordinate demand and local supply. KIT is currently developing the required storage technology in its Helmholtz research infrastructure DeepStor,” says Professor Eva Schill from the KIT Institute for Nuclear Waste Management, who heads DeepStor. “An essential element is the regional heating concept, which we are developing together with the citizens.”
“The contributions of the UFZ focus in particular on the digitization process and geothermal system analyses,” says Professor Olaf Kolditz, who heads the Department of Environmental Informatics at the UFZ. “Among other things, we are pursuing concepts of ‘digital twins’ and virtualization in order to digitally reproduce natural and technical systems (real laboratories) as realistically as possible. In this way, geothermal systems can be technically optimized, their efficient integration into the entire energy system can be simulated and long-term environmental impacts can be estimated.”
The GFZ developed the roadmap together with colleagues from the KIT and the UFZ as well as from the Fraunhofer Society. The GFZ researcher Professor Ernst Huenges, co-editor alongside Professor Rolf Bracke from the Fraunhofer Institute for Energy Infrastructures and Geothermal Energy (IEG), says: “Reaching the climate neutrality of the heating market is a huge challenge and requires a whole bundle of measures. The market players such as energy suppliers, industrial companies, the housing industry, the financial sector, politics, administration, trainers and municipalities need new instruments for this complex implementation task.”
The strategy paper is intended to provide all stakeholders with the necessary information on the geothermal heat supply, the versatility of the heat market and the technological realization of the heat transition. The aim is to provide recommendations for action in order to implement the potential of geothermal energy in terms of climate-neutral heat supply.
The roadmap identifies five recommendations for action to promptly expand geothermal energy for the heating market in Germany:
Clear expansion goals: Parliament and local councils should formulate clear expansion goals and flank them with appropriate legislation and statutes, from the Federal Mining Act to municipal spatial planning.
Risikoausgleich für Unternehmen und Kommunen: Im Wärmemarkt sind kleine und mittlere Unternehmen wie Stadtwerke aktiv, die wirtschaftliche Risiken wie die Exploration von Tiefer Geothermie nur begrenzt tragen können. Daher braucht es Finanzinstrumente zum interkommunalen Risikoausgleich wie staatliche Versicherungen oder revolvierende Fonds, die sich an Projekten finanziell beteiligen. Zudem sollten die Länder ein flächendeckendes geowissenschaftliches Erkundungsprogramm aufsetzen, um das Fündigkeitsrisiko für Kommunen und Unternehmen zu senken.
Investment in key technologies: In order for a few dozen deep geothermal plants in Germany to grow into thousands, investments in key technologies are needed in order to achieve large-scale industrial standards. The key technologies are drilling methods, reservoir management, borehole water pumps, high-temperature heat pumps, large-scale heat storage, trans-municipal combined heat networks and cross-sector system integration.
Training and further education of specialists: The growing geothermal industry creates regional jobs in technology development, planning and production as well as in the construction and operation of the plants. One can assume around five to ten full-time equivalent jobs per megawatt of installed capacity. Academic training and supplementary curricula to the existing offers of the chambers of crafts, industry and commerce are needed to train thousands of skilled workers.
Dialogue with citizens: Solving social challenges requires social acceptance. The municipal actors therefore not only need business management and plant engineering strategies. It is necessary to involve all local interest groups on the way to the regional heat transition with community energy models, municipal communication strategies and transparent projects.
The heating sector accounts for 56 percent of the national energy demand. Only 15 percent of the heat is regenerative. The roadmap now presented discusses the contribution of geothermal energy to the heat transition. The focus is on the hydrothermal reservoirs, i.e. thermal water-bearing rocks at depths between 400 meters and 5,000 meters. Geothermal water can be extracted from such deep wells at temperatures between 15 and 180 degrees Celsius. They are available independent of the season and time of day and can be used in particular for local and district heating and even for low-temperature processes in industry. The technology is mature and has been used in many European cities, such as Paris and Munich, for decades.
According to estimates in the roadmap, hydrothermal geothermal energy – combined with large heat pumps – as a heat source for district heating networks could cover around a quarter of Germany’s total heat requirements, theoretically around 300 terawatt hours of annual work with 70 gigawatts of installed capacity. For comparison: in 2020, 42 systems nationwide delivered 359 megawatts of installed thermal output and 45 megawatts of electrical output.