A subsidiary of German utility EWE has unveiled proposals to build “the world’s largest redox flow battery” in the country’s underground former salt mines.
EWE Gasspeicher has teamed up with researchers at Germany’s Friedrich Schiller University in Jena to work on the Brine for Power (B4P) project that involves deploying an electrolyte solution pioneered by the university team.
The project will use recyclable plastics dissolved in salt water as an electrolyte, instead of electrolytes previously used “including environmentally-polluting salts of heavy metals such as vanadium dissolved in sulfuric acid”, EWE said.
EWE said it will not be using the salt mines – or caverns – initially, but “enormous plastic containers” set up at the utility’s gas storage facility in Jemgum, in East Frisia – “probably in the fourth quarter of this year”.
B4P project head Ralf Riekenberg said: “We need to carry out some more tests and clarify several issues before we can use the storage principle indicated by the University of Jena in underground caverns. However, I expect that we will have an operating cavern battery by about the end of 2023.”
EWE Gasspeicher managing director Peter Schmidt said: “If everything works, this may fundamentally change the storage market. The amount of electricity this kind of storage facility contains – consisting of two medium-sized caverns – is sufficient to supply a major city such as Berlin with electricity for an hour. It means that we will have built the world’s largest battery. In contrast to other energy storage facilities that convert the electrical current into other energy carriers – for example into compressed air – we are storing the electricity directly with B4P.”
EWE currently operates eight caverns in Jemgum in an underground salt dome for storing natural gas.