Underwater storage for clean energy

The flexible design could provide reliable energy storage for offshore wind

Spotted: Off-shore wind is a promising form of sustainable energy, but in order to scale it up sufficiently, it is necessary to develop effective methods for short- to medium-term energy storage. Conventional battery technologies are not ideal for the type of charging-discharging cycles associated with wind power, particularly in offshore applications.

Startup FLASC is working to make offshore wind scalable with a storage technology based on a hydro-pneumatic liquid piston. Generated electricity is stored by using it to pump seawater into a closed chamber to compress a fixed volume of air. By allowing the compressed air to push the water back out through a hydraulic turbine generator, the energy can then be recovered later on.

The Hydro-Pneumatic Energy Storage (HPES) system uses a pre-charged, dual-chamber design that is tailored for offshore applications, using the ocean itself as a natural heatsink. Because of this, the system can reach very high thermodynamic efficiencies of greater than 95 per cent.

During discharge, the energy conversion system can provide a combination of electricity and cold, pressurised seawater. This makes it potentially useful for applications such as the liquefaction of natural gas, reverse osmosis desalination, offshore green hydrogen production, and enhanced oil recovery using water injection.

In 2023, FLASC was selected for a grant under the European Innovation Council Accelerator. Previously, the company was awarded a grant from the UK government’s Department for Business, Energy and Industrial Strategy (BEIS) to further develop an innovative offshore energy storage system. The funding has been awarded as part of the Longer Duration Energy Storage (LODES) Competition.

Written By: Lisa Magloff