In a residential area in Berlin-Tegel, the high-temperature steel storage by the start-up company Lumenion with around 2.5 megawatt hours is being tested in commercial operation and transferred to regular operation. For this purpose, the storage will be integrated with an existing gas-fired combined heat and power unit (CHP) by Vattenfall Energy Solutions GmbH into the district power and local heating supply of the Gewobag residential quarter. The storage will temporarily absorb unneeded power peaks and later on, if required, feed them into the heat supply.
Steel is a durable, inexpensive and effective storage medium. Thanks to its robustness and density, it can store very high temperatures and achieve a high temperature gradient. As a result, the overall efficiency for heat is up to 95%.
If required, in larger plants also a steam turbine can be used, which can reliably supply electricity from the stored heat. The residual heat of about 80-120°C remaining during the conversion of electricity can be fed into the local and district heating network to avoid losses.