The high shares of fluctuating energy sources in a future energy system, which will be strongly based on renewable sources, require the widespread use of efficient technologies to store and convert energy in line with demand. DLR performs research and development both on electrochemical power storage ("batteries") as well as on thermal and thermochemical storage of heat. This is complemented by diverse activities on chemical storage using hydrogen and hydrocarbons, which are characterized by their high energy density and a high versatility in its use. For the production of hydrogen as the simplest chemical storage option, electrolysis is being optimized and different solar high-temperature processes are being investigated. By using fuel cells, hydrogen can be used to generate power and heat with high efficiency in line with demand.
The research activities are allocated at the DLR Institute of Technical Thermodynamics, partly in cooperation with the Institute of Materials Science, the Institute of Solar Research and the Institute of Combustion Technology.
DLR’s research activities on batteries are focused both on the further development of Lithium-ion technology as well as on the next generation of batteries like Lithium-Sulphur and metal-air batteries. In close cooperation with the Karlsruhe Institute of Technology (KIT), the Zentrum für Sonnenenergie- und Wasserstoffforschung Baden Württemberg (ZSW) and the university of Ulm, DLR especially takes over tasks of numerical simulation of the complex electrochemical processes. This is organised within the framework of the Helmholtz Institute Ulm (HIU). Besides that, extensive experimental investigations of batteries are performed and - jointly with the DLR branches of transport and aeronautics - the integration of batteries into complex systems is investigated.
Thermal and Thermochemical Storage
Heat may be stored physically in the form of sensible or latent heat (with phase change) or by using reversible chemical reactions. DLR investigates all three approaches. High temperature storage in the range of 100 to 1000 degrees Celsius is in focus, which is required for applications in industry and energy industry. We aim at the development of low-cost and durable technologies which may also be used on large scale to save energy in power plants and industrial processes and to allow for more flexible operations. The work on thermal storage is complemented by research on high-temperature heat-exchangers, a central system component.
Via an intelligent process management, thermochemical storage offers the special opportunity to perform a heat transformation, i.e. to raise the temperature level of heat. Here, interesting perspectives open up to make use of low-temperature waste heat.
Chemical Storage, Electrolysis and Fuel Cells
Due to the close technical relation, DLR in parallel uses its extensive electrochemical competencies to further develop fuels cells (PEFC and SOFC) and electrolysers. In both systems, efficient, robust, and low-cost practical solutions are needed. Within this research, in-situ diagnostic technologies play an important role to detect weak points during operations. Also of high importance are coating technologies to develop highly effective reactive surfaces. The work on fuel cells especially includes the integration into stationary systems (e.g. a combination of SOFC and gas turbine) as well as mobile systems in cars, trucks and airplanes.
Following a different approach, in close collaboration with DLR solar research high-temperature chemical reactors are being investigated which produce hydrogen using concentrated solar radiation via chemical cycles. This approach provides interesting long-term perspectives in sun-belt countries.
Finally, processes to generate liquid synthetic hydrocarbons from renewable power and CO2 are evaluated and optimized concerning their energetic and economic characteristics using simulation methods. In addition, the role and performance of different chemical storage technologies in a future energy system are evaluated.