18 May 2017
Already in prehistoric times humans took advantage of the steady temperature inside the earth, by using caves or
holes in the ground to store food or to live inside, both in cold and warm climates. However, making active use
of this thermal energy reservoir in the underground required a tool for changing temperature, the heat pump.
Practical application of the heat pump process was already done in the 19th century, with the example of the
steam generation in Ebensee salt works in Austria by Peter von Rittinger, and the first claims on a heat pump
extracting heat from the earth were made by H. Zoelly in a Swiss patent as early as 1912. However, the first
documented Ground Source Heat Pump (GSHP) application in practice dates from 1945, in Indianapolis, USA,
and in Europe the first reports on ground-source heat pumps are from the 1960s.
R&D on geothermal heat pumps had a first boom in the 1950s in USA and Canada, and after the first oil price
crisis in 1973, it started in Europe and Japan, and resumed in North America. The paper gives some details on
the R&D-activities from the 1980s on and on the related work in IEA-cooperation. Some findings from that time
are highlighted, as well as steps towards guidelines and standards, and examples of milestones in practical
application are given. An assessment of the current status, both in technical development and market, and some
cautious expectations for future development will complete the presentation.