A study recently presented by the Internationl Geothermal Center, Bochum, Germany finds that by 2017, the number of ground-source heat pumps (GSHP) using geothermal and hydrothermal energy, sold annually in Germany will reach approx. 65.000. This number is a projection of the guidance given by the ministry for the environment in its own study ("Leitscenario").
By 2020, the stock would have reached approx. 800 000 ground-source units. On top of this, about the same amount of air-source heat pumps are expected to be sold. Mainly installed as air-water units, this variant of the technology will mainly be used for renovation.
The full report is available for download on the website of the International Geothermal Center.