Kemiwatt

It was founded in 2014 as a spin-off from the Institute of Chemical Sciences in Rennes, and in 2017 built one of the first organic flow battery prototypes. Its electrolyte is an alkaline, water-based solution of organic molecules, free of heavy metals, rare earths and PFAS, and its systems are sized for 4 to 12 hours of storage. Kemiwatt's approach is to convert existing liquid storage tanks into batteries; it gives two 10,000 m3 tanks as an example of a 35 MW / 140 MWh system.

The 2025 Battery Report lists Kemiwatt among Europe's metal-air and flow battery players.