Storage / Batteries / Stationary Storage / Redox-Flow-Technology

24 Sept 2018: An article from www.spectrum.de mentions giant Redox-Flow-Batteries projects. Redox-Flow-Batteries are based on a fluid, were the electrical energy is stored in two electrolyte fluids. One is the “brine4power” project for stationary power storage, which wants to use as tanks for storage caves deep in the underground in Northern Germany Jemgum, close to the Netherlands. Thus, to store (wind) energy and to feed it into the grid if necessary might be possible. Planned is to store about 700 MWh of energy, i.e. as much as is needed in one hour in 1,8 million households (as for a city of the size of Berlin). The technology is in the laboratory state, might work at 2025. However, the Redox-Flow-Accumulators there are dependent on the expensive element Vanadium. It seems to be better than Lithium technology or Lithium based batteries for storage of current’s energy, the problem here is the high cost. A lithium battery was built from TESLA, the Hornsdale Power Reserve in Australia with 129 MWh or another is planned by Siemens in California with 400 MWh. Redox-Flow-Technology until now is proven only in Japan with 60 MWh. EWE uses in Jemgum already eight caves for storing of gas, and wants to use two of them later to store wind power energy. Another group of researchers (university of Jena and company JenaBatteries) presented the liquid salt polymer battery in a contribution to journal “Nature” in 2015. No metal salts anymore. Here the electrolyte is based on common salt, water and special polymers. Survive these plastics for 20 years of battery operation – as  assumed under laboratory conditions - and can be produced below 50 Euro per KWh this seems the right way to help the redox-flow-technology to break through – as also RWTH Aachen’s Dirk Uwe Sauer is cited. The membrane is also inexpensive. It consists of material that is already produced in large quantities and is known from drinking water filtration and dialysis. How such a redox-flow-battery works please see: 
https://jenabatteries.com/products/how-does-it-work/