Statkraft looks into long-duration energy storage based on saltwater

Statkraft and Dutch startup Aquabattery have joined forces to develop the latter's long-duration storage solution based on saltwater.

The two companies will test the storage technology in a pilot project for six to 12 months in Delft, the Netherlands. The objective is to investigate the scalability of Aquabattery's technology and its commercial viability.

Aquabattery's patented storage technology uses saltwater as a storage medium. The tech is described as a flow battery that is able to independently amend power (kW) and energy (kWh) capacity. It is also said to be low-cost, highly scalable, and sustainable, as it uses only water and table salt, with its storage capacity being expandable by just adding water reservoirs or using larger tanks.

The battery system uses three storage tanks, one with fresh water, one with concentrated salt water and one with diluted salt water, and also relies on membrane stacks. During the charging phase, the diluted salt water is split into concentrated salt water and fresh water in the membrane stack and stored separately.

The separation is achieved through electrodialysis (ED), which is a separation process in which charged membranes and electrical potential differences are used to separate ionic species from an aqueous solution and other uncharged components.

In the discharging phase, the two streams are combined and the resulting energy is converted to electricity with the help of the membrane stack through reverse electrodialysis (RED), which is a technology to generate electricity from the salinity difference between two solutions, for example, seawater and river water.