Eos Energy zinc-bromide battery storage, 7.5 MW and 30 MWh, planned in Gaggenau, Germany for 2028

A large energy storage system based on zinc-bromide batteries is planned in Germany, according to ixbt.com. It is to deliver up to 7.5 MW and store up to 30 MWh of energy ixbt.comixbt.comixbt.comOpen source ↗. The project is run by the utility Stadtwerke Gaggenau and the energy company CAPAC AG, with technology supplied by the US company Eos Energy Enterprises. Construction is planned to begin in 2027, with launch scheduled for 2028.

Chemistry and design

The Eos Indensity system uses aqueous zinc-bromide chemistry, without lithium, cobalt, vanadium or rare earth elements. The electrolyte is non-flammable, which lowers the risk of fire and explosion, so battery modules can be placed more densely. The design resembles Lego: blocks can be stacked or placed side by side to save area. The system needs no active cooling and is rated for temperatures from -20 to 50 °C. The developers promise a service life of up to 25 years, with capacity loss over that period not exceeding 3.6%, by their estimate.

Operation and site

The plant will run in a four-hour mode: it will store surplus electricity during high output of solar and wind plants and feed it into the grid when demand rises. The technology itself supports storage durations of 4 to 16 hours. The project cost is estimated at about 15.2 million euros. It will be built on the grounds of a former liquefied gas storage facility of Stadtwerke Gaggenau. After launch, the site is expected to become one of the largest zinc-bromide energy storage complexes in Europe.