Deep geothermal energy leads a shadowy existence among the renewable energies. Only now – in the course of the Russian war of aggression against the Ukraine and the gas crisis – is the heat from the earth’s interior experiencing a certain boom. Geothermal energy has immense potential, especially in Bavaria. Almost half of the heat that Bavaria needs could be covered by deep geothermal energy, says physicist and geothermal energy pioneer Erwin Knapek, for example. The state parliament SPD is now demanding that the Free State invest heavily in the technology. “We absolutely need a geothermal turbo,” says the parliamentary group leader and Bavarian SPD leader, Florian von Brunn. “The state government has neglected to expand geothermal energy for 20 years. Now we have to tackle it.”
Brunn’s Geothermie-Turbo is a mix of financial support and technological support for municipalities that want to invest in heat from below. A central point are state guarantees for cities and municipalities that want to convert their heat supply. This should make it easier for them to get the loans they need.
In addition, the SPD calls for the designation of preferred areas for geothermal energy, an improvement in the data basis on the geology in Bavaria and preliminary investigations by the Free State, for example exploratory drilling. And the state government should promote the acceptance of the technology. In the past, local residents had repeatedly feared that drilling deep into the earth’s interior could trigger earthquakes. According to experts, however, the technology is very safe. Overall, according to Brunn’s idea, the Free State should invest at least 100 million euros in deep geothermal energy in the coming years.
The warmth from the depths comes from the Malm. This is a jagged, water-bearing limestone layer up to 600 meters thick, which can be imagined as a water-saturated, hard sponge. North of the Danube, in the Franconian Jura, lies the Malm on the surface of the earth. South of it, in the so-called Molasse Basin, it disappears further and further into the globe until it reaches a depth of around 5000 meters in the foothills of the Alps. The deeper the Malm is, the hotter the thermal water is in it. While it is just 35 degrees near Straubing, the temperature near Erding in Upper Bavaria is already 65 degrees, south of Munich, in Holzkirchen, it even reaches 157 degrees. This geology is the reason why the Molasse Basin is so well suited for deep geothermal energy. 24 of the 42 geothermal plants in Germany are located there.
Deep geothermal energy produces heat and electricity in any weather and around the clock
Geothermal pioneer Knapek, who, as mayor of the Munich suburb of Unterhaching, had one of the first geothermal power plants built in Bavaria in 2004, supports the demands of the SPD in the state parliament. In his view, Bavaria’s technology must be “first choice” when it comes to the state government’s goal of becoming climate-neutral by 2040. Because deep geothermal energy is – apart from the construction of the power plants – CO₂-neutral. But that’s not their only asset. Unlike wind power and photovoltaics, which only supply energy when the wind is blowing and the sun is shining, it produces electricity and heat in all weather conditions and around the clock. And it is a domestic source of energy, every geothermal power plant that is built in Bavaria makes the Free State somewhat independent of energy imports.
All these advantages have been known for a long time. Prime Minister Markus Söder (CSU) and Economics Minister Hubert Aiwanger (FW) keep saying that by 2050 a quarter of the heat requirement should be covered by deep geothermal energy. That would be a gigantic amount, it would correspond to at least 500 new plants. Bavaria’s heat consumption is two and a half times greater than electricity consumption. In total, it amounts to around 210 billion kilowatt hours per year. Three quarters come from burning fossil fuels, mainly oil and natural gas. The proportion of geothermal energy has so far been negligibly small. It has been stagnating at 0.5 percent or one billion kilowatt hours for a long time.
The state government has also been committed to promoting deep geothermal energy for a long time. Economics Minister Aiwanger has repeatedly announced a “master plan for geothermal energy”. Its core should be grants for a local heating network in municipalities that rely on deep geothermal energy. Because the high costs for the network that brings the geothermal energy from the power plant to the consumers are a main reason why deep geothermal energy has not made any progress so far. According to Knapek, the rule of thumb is that one million euros must be estimated for the construction of one kilometer of heat pipe. Now, after a long back and forth, the federal government has launched a multi-billion dollar subsidy for efficient heating networks. He wants to invest three billion euros in efficient heating networks by 2026. Therefore, according to a spokeswoman for Aiwanger, there is “no more leeway” for a special Bavarian program.
Knapek appeals to the state government: “Now it’s time to deliver”
Drilling and power plants are also expensive. A well quickly devours ten million euros. At least two wells are required for each power plant: the production well, from which the hot deep groundwater is brought up, and the injection well, through which it returns to the earth’s interior after it has released its energy. In addition, there are heat exchangers, generators and other systems in the power plants. That quickly adds up to tens of millions of euros. So far, geothermal energy has only been for financially strong communities such as the Upper Bavarian town of Holzkirchen.
Knapek shares the SPD’s assessment that the state government should do more for geothermal energy. “So far there have only been confessions and announcements,” he says. “Now it’s time to deliver.” Especially since it is in the interest of the Bavarian economy to get away from Russian natural gas. There are now very strong signals from the chemical triangle in south-east Bavaria, but also from the food industry.