Status: 24/09/2023, 21:49 p.m.
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Markus Söder welcomed Chancellor Scholz and Research Minister Bettina Stark-Watzinger at the start of the Loop Geothermal Project in Geretsried, Bavaria. © Peter Kneffel/dpa
The first commercial geothermal power plant with innovative technology is to be built in Geretsried, Bavaria. However, a great deal of research is still needed for the widespread use of geothermal energy.
The potential is huge: Federal Chancellor Scholz recently visited a geothermal site in Geretsried, Bavaria, where the first commercial power plant with the new loop technology is to be built. But much more research is needed to tap into the energy source – and, above all, more efficient authorities, specialists and suitable instruments to reduce financial risks.
The heat from the earth's interior can make an important contribution to making the heat supply climate-friendly. So far, it has been based primarily on fossil fuels such as oil and gas. The share of renewable energies in this sector was only around 2022 percent in 17. The German government wants much more: by 2030, 50 percent of municipal heat is to come from climate-neutral sources. That's around 400 terawatt hours per year. Whether this will succeed is questionable.
More efficiency of the plants in depth – and more output
The renewables that have clearly dominated the heating market so far – wood and biomass – can only be expanded to a limited extent. The use of environmental heat and especially geothermal energy must therefore be promoted. In addition to near-surface geothermal energy – it is by definition limited to drilling depths of up to 400 meters and is usually found on single-family homes – deep geothermal energy is particularly in demand. Here, layers up to 5000 meters are developed, where the temperatures are sometimes well above 100 degrees Celsius. This increases the efficiency of plants and their output, so that entire districts can be supplied via a district heating network.
The geological conditions are often good. Experts estimate the heat potential of deep geothermal energy at a good 300 terawatt hours per year (TWh/a). "In order to achieve the 50% target of climate-neutral municipal heat (i.e. approx. 400 TWh/a), it is recommended to cover at least 2030 TWh/a from deep geothermal energy by 100 and to create the framework conditions for 20 to 25 GW of installed capacity," says the roadmap for deep geothermal energy in Germany. It was presented last year by Fraunhofer and Helmholtz experts.
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This analysis is IPPEN. MEDIA in the course of a cooperation with the Research.Table Professional Briefing – it was first published by Research.Table on September 19, 2023.
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By 2030, fifty times more plants will be needed than are currently in operation
However, there are currently just 40 such plants in operation, which together have a thermal output of 417 megawatts. By 2030, it would have to be around fifty times as much. In view of long lead times, economic risks and a lack of experts in business and public authorities, this is very ambitious.
Four regions are considered to be particularly suitable for this technology: the foothills of the Alps, the Upper Rhine Graben, the North German Basin and the Rhine-Ruhr region. There, the temperature in the subsoil is comparatively high and sufficient water circulates, which is favorable for heat transport. "Hydrothermal systems" say the experts, they are easy to develop. It takes two boreholes and a heat exchanger on the surface to create a cycle: cold water is pumped down via one borehole, where it heats up by geothermal energy, and via the second it comes upwards, where it releases the heat – and is then pushed back into the first.
Geothermal energy: Drilling costs up to 35 million euros
The greater Munich area is a leader in deep geothermal energy. This is where most of the facilities are located and correspondingly a lot of experience as well as data on the properties of the subsoil. This reduces the uncertainties associated with new projects and makes it more likely that the boreholes, which cost around 20 to 35 million euros, will find suitable layers and that they will be able to operate economically.
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"We also need this good level of knowledge in the other geothermal regions," says Ingo Sass from the German Research Centre for Geosciences (GFZ) in Potsdam. Financial input from politicians is needed, from the development to the integration of new plants. "Geothermal energy is dominated by medium-sized companies," he says. Often it is municipal utilities that are financially "tight" and do not have such resources as large energy companies. "If a borehole yields less than predicted, it can threaten the company's existence, which is why many municipalities are cautious."
There is still a lot to explore in NRW
But there is also a need for qualified personnel in the authorities, says Kosta Schinarakis from the Fraunhofer Research Institution for Energy Infrastructures and Geothermal Energy (IEG), which is involved in various projects in the Rhine-Ruhr region. "The approval procedures are time-consuming, it is not always clear which documents are required, and staff shortages quickly mean delays." There is also a lack of experts and data on the part of the Geological Surveys. In North Rhine-Westphalia, the layers of earth far below 1000 meters have so far hardly been interesting for use, little has been explored. "And if it does, it would be for the oil and gas industry, which didn't exactly want to produce near the cities – but that's where we need geothermal plants to supply the population with heat."
Skilled workers also in demand for geothermal projects
Also, the relevant data are not always available at the Geological Surveys: On the one hand, no one in the coal regions has been interested in the earth layers below 1000 meters, little has been explored. "And understandably, the oil and gas industry didn't want to extract and explore near the cities – but that's where we now need geothermal plants to supply the population with heat."
"Specialists are needed by the authorities as well as by the applicants and contractors," says Frank Schilling of the Karlsruhe Institute of Technology (KIT) and head of the State Research Center for Geothermal Energy. "Sometimes specialist departments in municipal utilities and engineering offices have little experience with this." Even the drilling companies lacked good people. "If geothermal energy is to grow – and there are good reasons for this – then we need well-trained and experienced personnel in many areas," says the KIT scientist. "This is also a challenge for the universities."
Research aims to make geothermal energy more economical
In addition, there are a number of research topics that need to be worked on in order to make the process more economical. This includes keeping the thermal water cycle stable for many years. In reality, it is a hot, salty brine that attacks boreholes and pumps. "Not only do we have to make the turbines more resilient, but we also have to develop methods to ensure that the boreholes and their shells last a long time," says GFZ researcher Sass. This is also important in order to protect groundwater horizons that are penetrated by deep boreholes.
Research on large-scale heat pumps must also be promoted, says Schinarakis of IEG. With such systems, the heat yield can be further increased. This helps if a hole delivers a little less than assumed. However, it can also help to use geothermal energy for industrial processes that have so far also been fossil-based.
Even more warmth in Geretsried: crystalline stones in a loop
Another major research topic is geothermal energy beyond hydrothermal systems. These are, for example, the crystalline rocks in the low mountain ranges. These provide even more heat, but there is too little circulating water underground to extract them. In Geretsried, Bavaria, a new process is currently being tested to develop a "petrothermal system". It works with two drilling rigs operated in parallel. These first drill vertically to a depth of 4.5 kilometers. There, the holes are fanned out horizontally. There are several parallel branches, each a good three kilometers long. The wells will be connected to each other to create underground thermal loops, explains the Canadian company Eavor.
According to the company, the project will receive a grant of 91.6 million euros from the European Innovation Fund. At the end of August, Federal Chancellor Olaf Scholz, Bavaria's Prime Minister Markus Söder and Federal Research Minister Bettina Stark-Watzinger arrived to find out more.
Loop technology still takes time
"Without exploration risk and regardless of location, Loop technology can be used to build geothermal power plants capable of electricity and heat anywhere in Germany and worldwide," Eavor advertises. Whether this can be maintained remains to be seen. KIT researcher Schilling sees "great challenges" in drilling such long distances cost-effectively, making the connections, and whether the underground heat exchanger will remain intact in the long term.
"If all this works out, it would be a big step forward, but it will take many years before the process could be used on a large scale," he says. "In order to quickly increase the share of geothermal energy in the heat supply, we should urgently focus on low-hanging fruits, i.e. expand hydrothermal systems." (Ralf Nestler)
