With the focus on increasing the yield and energy efficiency of existing renewable energy plants, the German Aerospace Centre’s (DLR) Institute of Solar Research has teamed up with industrial partners to develop a new type of solar radiation receiver and circuit for “tower power plants” that uses low-cost liquid salt as the heat transfer medium. The new system will enable these plants to reach far higher operating temperatures and efficiencies.

In a pilot conducted between April and October 2022 at the DLR’s Multifocus Solar Tower, some 790 mirrors directed concentrated solar radiation to the tower-receiver, simulating conditions to those in a typical solar thermal plant. The receiver was integrated into a salt circuit for transporting the heat, which then powered a steam turbine to generate electricity.

Over the course of the pilot, a maximum temperature of 550°C was measured on the receiver tubes, which allowed it to generate a thermal output of 515 kw and maintain a temperature in the circuit pipes of over 500°C. Speaking for project partner MAN Energy Solutions Deggendorf, their head of new technology Christian Schuhbauer commented, “[We are] very pleased with the initial results. For us, the trials are an important step towards market launch.”

DLR’s project manager Cathy Frantz explains in a press release: “Next spring, we will continue irradiating the receiver in order to reach the target value of 600°C for the liquid salt in the pipes. This allows a 35°C higher process temperature compared to the state of the art, which noticeably increases the overall efficiency of the plant.” The project High Performance Molten Salt II was funded by the Federal Ministry for Economic Affairs and Climate Action as well as the Ministry for Economic Affairs, Innovation, Digitalisation and Energy for North Rhine-Westphalia.