Research for solar thermal power plants, for future solar fuels and CO2-free industrial processes
Solar researchers at DLR are testing new components and processes in Jülich to further develop solar tower power plants. The aim of the researchers is to reach higher temperatures and better efficiency in order to lower the electricity production costs. Their focus is on mirror systems for directing and concentrating solar radiation, solar absorber and energy storage systems and the effective use, as well as theoretical and computer-aided analyses and developments in the field of fluid mechanics and heat transfer. Depending on the development status and goal, individual components, functional groups or even a complete solar power plant system can be tested, evaluated and optimised.
In addition, the DLR Institute for Future Fuels is investigating manufacturing processes for solar fuels such as hydrogen and the use of high-temperature solar heat for industrial processes.
Two solar towers, four experimental levels
In front of the two Jülich solar towers, there are more than 2,000 adjustable mirrors (heliostats) on an area of around ten hectares. They catch the sunlight, bundle it and direct it to the two solar towers. The larger of the two towers is a functioning solar tower power plant, so it can actually produce electricity.
A volumetric solar radiation receiver at the top of the tower picks up the concentrated sunlight and heats the ambient air to up to 700 degrees Celsius. A steam generator inside the tower uses the high temperatures to convert water into water vapor, which drives a turbine that uses a generator to produce electricity without emitting CO2. The nominal electrical output of the system is 1.5 megawatts. Although the electricity generated can be fed into the local medium-voltage network, DLR does not use the system commercially for electricity production, but uses it exclusively for research purposes. The tower is 60 meters high and has a research level at halter height, on which different experimental setups can be set up. In the large-scale experiments carried out so far, the focus was on the further development of volumetric receivers and processes for the solar thermal production of hydrogen.
Since 2020, the solar tower power plant has been supported by the somewhat smaller so-called multifocus tower. There are three levels with special equipment for the installation of specific experiments. On the upper level, scientists from the Institute of Solar Research test a particle receiver with ceramic beads as a heat transfer, storage and transport medium. The middle level is specially equipped for process engineering applications. There, high-temperature processes for solar water splitting are tested. On the lower level, the focus is on molten salt as a carrier medium for high-temperature heat. This is also where the pump, tank and heat exchanger for this system are installed and used.
Control software developed at DLR can align subsets of the mirrors in such a way that several experiments can take place on the two solar towers at the same time.