In the Federal Republic of Germany there were around 2.4 million solar thermal plants in 2018. These have mostly been installed on the roofs of private houses and contribute to the supply of local heat. However, due to the prevailing amount of radiation from the sun in Germany (approx. 1000-1200 kWh/m² per year), their potential is limited. The solar coverage ratio is usually between 5-50%. In the southern regions of Europe the irradiation is naturally higher, so that such plants can be operated at a higher temperatures with correspondingly greater efficiency. For example, parabolic trough power plants are already in use in southern Europe whose carrier medium drives a steam turbine at high temperatures.
Following the “High Performance Solar 2” research project in Evora, Portugal, a German consortium is now researching new ways of improving this tried-and-test technology. The MSOpera project aims to use molten salts for heat transfer. The difference to conventional systems is that operating temperatures of up to 565°C can be achieved instead of the standard 400°C of thermal oils. The advantages are obvious: the 20% higher operating temperature generates higher pressure, which results in a higher yield. In addition, as an operating medium, salt is cheaper than thermal oil. In addition to testing different salt mixtures in a solar thermal power plant, the project partners from industry and science are also working on optimising the components and increasing efficiency through tracking systems. The aim is to scale up the system to commercial plant size.
The solar research department of the German Aerospace Center and the solar thermal specialist TSK Flagsol GmbH from Cologne are involved in the project. The project will be funded by the Federal Ministry for Economic Affairs and Energy until 2021.