The tewag team is continually working to advance knowledge in the field of geothermal energy. Its aims are to enhance understanding of the systems involved; to devise generally applicable rules for high-quality planning and professional execution and monitoring of geothermal systems; and to optimise geothermal energy supply concepts.

Cold Local Heat Supply

In recent years we have, among other projects, been carrying out research into centralised and decentralised geothermal heat supply systems. As part of those activities, we successfully completed a research project on "Cold local heat supply". With a cold local heat network it is possible to supply a complete settlement very efficiently with heat and cold by means of a central probe field and the distributed deployment of heat pumps at the individual consumer locations. The research project, financed by the German Federal Ministry of Economics and Technology, enhanced our knowledge of modelling, heat transfer, energy transport, the installation of distribution networks, and the use of appropriate materials and control components. The findings obtained and the experience gained, combined with the development of a special planning and design software, brought the innovative supply system to market maturity. The tewag team has already implemented cold local heat supply networks at the "Sonnenberg" construction site in Ludwigsburg and the "Grüne Höfe" site in Esslingen.

Quality Criteria for Geothermal Systems

Current research activities are focused on quality assurance in the planning, construction and operation of geothermal probe systems. We are drawing up recommendations as to how ground-water pollution can be avoided, detailing the essential aspects of sound planning, setting out the potential impact on drilling operations of geotechnical risks, and explaining what state-of-the-art execution of drilling and supply connection work means. Our objective is to set forth criteria for working with soil and ground-water which minimise the risks and safeguard sustainable management of the underground environment in order to preserve natural cycles.

New Systems

In an already completed project, we analysed and assessed a CO2 probe (thermosiphon heat pipe). We are at present analysing the use of a direct-evaporator probe (also termed: phase-change probe). This project is also investigating the possibilities for combining a solar energy plant with a ground-source heat pump system. The heat source for this is a cascaded solar energy store in a "geothermal cistern" with artificial freezing of the ground.


The highly interdisciplinary nature of the research projects, and the close cooperation between project partners, is making it increasingly easy to find satisfactory answers to complex, over-arching questions in research and development work.