The German Aerospace Centre (Deutsches Zentrum für Luft- und Raumfahrt; DLR) has commissioned MAN Energy Solutions to build a molten-salt circuit for its solar-research facility in Jülich, Germany. The plant is intended to help to further improve the process of generating and storing solar energy at very high temperatures. 

The DLR has already conducted research in Jülich for ten years on concentrated solar power (CSP) and runs Germany's only solar tower for this purpose. A second solar tower has now been built in which MAN Energy Solutions, among others, will install the molten-salt circuit. 

Norbert Anger, site manager of MAN Energy Solutions in Deggendorf, said: “Already today, renewable sources supply almost 50% of the German electricity mix, with this set to rise to at least 65% by 2030. Storage solutions will therefore play an increasingly central role in ensuring a reliable and efficient energy-supply. Molten-salt circuits already have large storage capacities and can store energy … for a particularly long time and at low cost”. 

In use as a storage medium, the salt is first heated to a temperature of, typically, 565°C and then fed into a hot storage tank. The thermal energy can be stored in the tank for several days and – if required at a later date – can be converted back into electricity, for example by means of a steam turbine. During this process, the salt is cooled to around 290°C and is then available for further storage processes in the cold storage tank. 

“We analyse how liquid salts behave at even higher temperatures. Our goal is to raise the salt temperature to 600°C. In doing so, we are striving to further increase efficiency and also reduce the cost of electricity production,” said Miriam Ebert, project manager at the Centre ́s Institute for Solar Research. “On a small scale, the molten-salt circuit in our pilot plant works almost like a larger, solar-thermal power plant. This means that our findings can be scaled up to an industrial level.” 

MAN Energy Solutions and DLR have worked together on various contracts since 2001, including engine test stands for Ariane rocket engines at the Lampoldshausen site.