The Federal State Ministry of Economy of Thuringia intended to allow and support an explorative drilling for a Deep Geothermal (petrothermal/EGS) Electricity and Heat Utility. Plans were made public in January 2013 by the ministry and led to massive and swift protests. Internal planing however began much earlier, in 2007.
The project is part of the so called “deep geothermal energy”. That are drillings deeper than a few hundred meters, usually reaching a depth of well beyond a thousand meters. In contrast to that, small “heath pumps”
in family homes operate only in depths of around 100 meter.
The drilling in Meiningen was intended to reach a depth of 4000 meters. Hot water from the underground was supposed to be pumped to the surface. There it would have powered a steam turbine to produce 4,5 - 5 megawatt electricity. That equals approximately the electricity output of two medium size wind turbines (app. 2 - 3 million Euro each). Wind fluctuates and geothermal power delivers a permanent flow of power. Additionally, the plant would have provided between 10.000 and 40.000 MW heath in a central heating grid. The electricity of deep geothermal plants is sold via the renewable energy feed-in-tariff for 25cent per kilowatt, plus 4 cent extra for unconventional/enhanced/petrothermal plants. 29 cent per KWh is is a much higher tariff than granted to other renewable energies (solar, wind etc.). Geothermal heath is supported with 3 c/KWh.
The costs were estimated to be 57 million Euro. The lion´s share was to be granted by government support programmes. Only 100.000 euro were to be invested by the local utility (which is in public ownership). The largest share was due for the drilling that is in such depths a complex industrial process. Thus the project was, like all deep geothermal drillings, a large scale, industrial size technology, with regard to costs and effort (and also risks).
Meiningen would have been one of the few (worldwide) operating “petrothermal” systems. In contrast to hydrothermal systems, petrothermal methods (also called enhanced geothermal systems – EGS; or: “hot dry rock systems”) is applied in locations that are not naturally suitable. Naturally suitable places offer a geological underground that is porose and contains a flow of hot ground water. The technique of petrothermal power is to generate artificial cracks in massive rock formations, like the granite under Meiningen. Those allow water that is pumped down (in an open systems) to penetrate into the hot and dry rocks. Rocks are hot in that depth everywhere on earth. They warm up the water, that is pumped up by a second pipe, inside a second bore hole. If petrothermal worked commercially, deep geothermal power was possible nearly every on earth. The water from EGS has higher temperatures than the water from conventional hydrothermal systems. It can thus power not only a central heating but a steam turbine. EGS is said to be the key to the breakthrough of geothermal electricity production. Presently it is far away from commercial viability and operates in Research and Development schemes.
The artificial fissures in massive rock formations (that are naturally unsuitable for conventional geothermal systems) like those in Meiningen are created by injecting water with high pressure, usually mixed with chemicals. Project operators and some scientists call that “hydraulic stimulation” or in German “Rissstimulation” (stimulation of cracks). Opponents call it “fracking”.
The minister for economy declared that only a “fracking” method with fluids non-harmful to water would be used (Drucksache 5/6924, 19.11.2013).
Like the hydraulic stimulation/fracking used to exploit gas and oil, the risk of earthquakes and other detrimental seismic events cannot be excluded. The petrothermal project Deep-Heath-Mining Basel was very likely responsible for a series of minor earthquakes up to a magnitude of 3,5 in 2006 and 2007. Another Swiss geothermal project in St.Gallen has very likely caused an earthquake of magnitude 3,6 in 2013 after an accident occurred (Swiss earthquake service SED). In the German city Landau, a conventional geothermal systems has induced an elevation of the surface soil in 2013 and 2014, damaging roads and houses, according to various studies.
The drilling in Meiningen was supposed to be a scientific project to test the possibility for a subsequent petrothermal power plant. Supporters stressed the openness of the choice, that would have still allowed not to install a permanently running system. Opponents argued that the high financial investments in the first drilling would justify the second and finally the whole development because otherwise the invested means would have been lost.
Neither the power plant nor the explorative drilling materialised. A local citizen initiative was set up in 2013 and lobbied to stop all activities. It mainly feared earthquakes that would damage houses and also argued with possible exposure to radioactive gases and ground water pollution caused by accidents in the drilling process. A second actor was the lively anti-fracking-movement of the region that supported the local initiative.
In may 2014 the city council, after supporting the project for 3/4 of a year, gave in to popular pressure and voted with a majority to abandon the project. The decision is valid for 2 years. However it is not very likely at the time being that the project will be started again.
The plan for the petrothermal power plant was supported by the local public utility that would have been the owner of the plant, the ministry of economy of the Land, the public energy agency Thuega, and a public financing and planing body LEG (Landesentwicklungsgesellschaft).