OPTES® stands for Optimized Pumped Thermal Energy Storage – Battery and combines the advantages of low investment costs with very good power-to-power efficiency. In 2020 the OPTES® Battery was presented for the first time at the IRES (International Renewable Energy Storage Conference). The publication on this can now be read under


For lower power classes, the OPTES battery has been further developed into the OPTES GT. The OPTES-GT Battery is based on an open Brayton Cycle.

The basic engineering has just been completed for the VHTTES (Very High Temperature Thermal Energy Storage) shown in the figure. The storage systems are to be used in a solar power plant and in a thermal battery for storing electricity. The two storage tanks shown are flowed through with 1000 ° C hot air and have a usable storage capacity of 10 MWh each.

Iron silicate with a grain size of 1.8-2.4 mm was tested as a new storage medium in our TESS 3A test storage facility. The first measurement results show very successful tests with an approx. 15-20% higher energy density compared to silica sand.

STORENERGY took place for the third time on the 12th and 13th of November 2019 at the Offenburg fair. The topics of the congress are storage technology, grid integration and the path to decentralized power production in order to use the energy sources economically.

TESS 3A up to 640 °C

Our new HTTES test stand TESS 3A was operated with temperatures of 640 °C. The charging and discharging characteristics were investigated.