Salt Water Batteries

Before it went bankrupt, Aquion had set up a sample semi-domestic installation in California for a 25kWh installation, with a potential charge/discharge rate of 30kW, to back up a 32kW PV system on a farm. So the technology was demonstrable at that stage. The claimed round-trip efficiency of their system was 85%

The batteries were designed for long duration storage, based on sodium, sodium sulphate and water. Low cost battery materials sound good. However, there has been no indication of deployment for any higher capacity or higher power systems, since the company was taken over by Titan, so possibly not yet suitable for grid-level storage.

Imperial College have published research into a new salt-water battery design.