The next generation of solar thermal parabolic trough power plants
Parabolic trough power plants convert solar energy into heat and then into electricity. To do this, they concentrate the sunlight with long mirror troughs arranged in rows. With the energy of the Sun, they heat thermal oil, which is located in a pipe positioned along the focal line of the mirror trough. This oil can absorb heat up to 400 degrees Celsius and transports it to a steam turbine to generate electricity or to a heat storage facility for later use. To increase the efficiency of parabolic trough power plants and reduce costs, the thermal oil can be replaced by other heat transfer media. These enable higher process temperatures.
A promising candidate for this is molten salt. Its maximum process temperature is 565 degrees Celsius. It is also cheaper, less flammable and more environmentally friendly than thermal oil. Solar thermal power plants already use salt for heat storage. This makes it possible to flexibly generate electricity when it is needed. If molten salt is also used in the solar field, higher temperatures are possible here and in the storage tank. Since the storage tank can then be made smaller and no heat exchanger is needed to transfer the heat to the salt in the storage tank, the capital costs are also lower.
The Évora Molten Salt Platform (EMSP) was designed and built to test molten salt as a heat transfer medium on a power plant scale for reliability and operational safety. From the collectors to the steam generator and condenser, it has the essential elements of a solar thermal power plant. The unique test plant includes parabolic troughs with a total length of 700 metres and has a total output of 3.5 megawatts. Thus, the transfer of results from research to industrial application is only a small step.
DLR developed and constructed the facility together with the University of Évora and European industrial partners. The plant began operating in autumn 2021.
German Aerospace Center (DLR)
Institute of Solar Research
Dr.-Ing. Jana Stengler | Email Jana.Stengler@dlr.de
