Solar thermal power plants
Solar thermal test system with liquid salt heat transfer medium inaugurated
The German Aerospace Center (DLR) and its partners in Portugal inaugurated one of the world's first parabolic trough plants operated with liquid salt. Its supporters in the HPS2 research project include the Federal Ministry for Economic Affairs and Climate Action (BMWK).
"The Évora Molten Salt Platform (EMSP) is an important step in advancing solar thermal energy as a technology for the global energy transition. The test system enables us to test the use of liquid salt on a power plant scale for its reliability and operational reliability. Both are imperative criteria for quickly moving from laboratory scale to industrial application and increasing competitiveness", explained Prof. Karsten Lemmer, member of the DLR Executive Board, at the inauguration on 28 April 2022 in Évora, Portugal.
Parabolic trough collectors - specially curved mirrors arranged in two rows behind each other - with a total length of almost 700 metres stand on the solar testing ground and focus the sun's rays onto a pipeline in the middle of the troughs. This contains the liquid salt. It absorbs the heat from the concentrated solar irradiation and transports it further. The heat is used to generate steam, which drives a generator via a turbine to produce electricity. The plant has an overall performance of 3.5 megawatts. A total of around 88 tonnes of salt circulate there.
Liquid salt as an alternative to thermal oil for cheaper electricity
Liquid salt is regarded as an attractive alternative to the conventional heat transfer medium thermal oil. The advantage: The salt can be used up to a temperature of 565 degrees Celsius (thermal oil 400 degrees Celsius). This enables higher efficiencies and thus lower electricity prices. The downside: The salt must be kept constantly in a liquid state at high temperatures of up to 250 degrees Celsius. Depending on the type, it solidifies again underneath, which can damage components and shut down the plant. The researchers from all three HPS2 project partners - DLR and the two companies TSK Flagsol Engineering and eltherm production - have therefore designed all components and the entire system specifically with this in mind. An electric heater also ensures that the salt does not solidify during initial filling and whilst the system is in operation.
German plant and component know-how is in demand worldwide
Solar thermal systems produce electricity in particularly sunny regions such as Spain, the USA or Chile. In Germany, on the other hand, they are not profitable due to insufficient solar irradiation. German plant and component know-how is however in demand worldwide. To ensure that the German industry remains one of the technology leaders on the global market, the Federal Ministry for Economic Affairs and Climate Action has funded the construction of the plant and supporting projects with a total of more than 10 million euros over several years. (it)