Energy-Storage.news has heard from the founder and CEO of start-up Lumenion that the company’s technology, now being trialled in Germany by Vattenfall, can store energy in steel structures for up to 48 hours.

At the end of October, Lumenion announced that a 2.4MWh steel-based thermal energy storage system will go into operation in Berlin through Vattenfall Energy Solutions and Gewobag, a municipal housing company. The company claims it can provide low-cost energy storage on combined heat & power (CHP) principles, using steel as the medium. The steel modules store energy thermally at up to 650 degrees Celsius and the system is then capable on conversion of outputting around two parts heat to one part electricity.

The system will absorb power generated by local renewables plants, wind and solar, and store it at a claimed cost of less than €0.02 per kWh. While it could output all of the stored energy as heat, it can also be converted back into power and heat using steam engines.

CEO Alexander Voigt told Energy-Storage.news that Lumenion is producing a ‘bulk storage’ technology, developed with a “view to economically shift large amounts of renewable energy – and to integrate it effectively into our energy system. Voigt said it is “much simpler – and thus also cheaper than batteries.”

“Which is why we see it as a compliment to – rather than a replacement of – batteries,” he said.

“Steel storage is well suited for providing the ‘heavy lifting’, i.e. to quickly absorb large amounts of renewable energy when the production peaks occur, to store those peaks for two cents per kWh or less, and then provide the energy continuously for many hours or even days. Batteries, on the other hand, provide the precision round the edges – frequency regulation, voltage control, black start capability and the rest.”