As more renewable energy arrays come online across the globe, and with battery prices plummeting, energy storage is widely regarded as one of the essential technologies for decarbonising the power sector. But with concerns about the technical capabilities of lithium-ion batteries – and the ethical and environmental impacts of the metals used to make them – innovators are now beginning to explore a range of alternatives, from silicon siloes and liquid air facilities to ammonia-based storage.

Continuing this trend, Swedish energy giant Vattenfall has teamed up with technology firm SaltX to pilot a 10MWh “salt battery” at one of its facilities in Berlin. The device contains nano-coated salt crystals, which are heated using renewable electricity. The heat from the charged salt is kept in using insulation until the user chooses to release it, either as hot air or steam.

SaltX claims that, during previous trials of the system, it was found to store up to ten times as much energy as comparable water-based storage arrays. It additionally claims that the battery can be charged several thousand times without damage and store energy for months with minimal losses.

The move from Vattenfall, which will see the device fitted as part of its project to convert the Reuter thermal coal power plant in Spandau into a power-to-heat plant, will mark the first real-world trial of a full-scale battery. Vattenfall will measure the amount of salt used, how quickly the storage medium reacts and how easily it can be controlled before deciding whether to use salt batteries in other projects.