Geothermal energy, as a renewable resource is already used since more than 2000 years. Hence the rapidly increasing experience with this energy resource, new deep geothermal applications are still under debate in politics and public, especially in European countries. Investments are often missing or investors retract their financial support due to the unsecure political situation. Despite all debates, the quantity of geothermal applications is steadily increasing in e. g. Germany over the last

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... hree decades. Taking only German deep geothermal applications into account, a total of 31 systems were running, 34 more were still in the planning phase and a total of 34 were canceled due to various reasons. Of the canceled ones, the majority was shut down for missing investments, uneconomic operation or political reasons. Engineering issues and low discharge only summed up to approx. 21 % of the canceled operations, which leads to the assumption, that neither drilling nor geological exploration and planning is a main failure reason for such projects.