Earth Heat Pumps and Underground Thermal Energy Storage in Germany

Abstract

In the last years, the technical development of Earth Heat Pumps (Ground Source Heat Pumps, GSHP) in Mid Europe has advanced substantially, together with an increase in experience and knowledge. The paper gives an overview of the existing technology. The technological and market evolution from the first European plants in the early 70's is described shortly, and the state-of-the-art is shown using examples of the two largest plants with earth heat pumps in Germany. An important feature for applications of earth heat pumps in the commercial field in Europe now is space cooling, which has not been in demand in the past. Direct cooling from ground heat exchangers ("cold storage") is a new approach, sometimes combined with heat pumps in the cooling mode. Ecological and environmental calculations show the advantages of such "cold storage" plants. The latest example of this technology, the project for an Aquifer Thermal Energy Store (ATES) for the Reichstag Building, Berlin, is presented.