Ocean battery, the new utility-scale offshore energy storage

March 1, 2022

The transition towards renewable power generation is a huge challenge. The fast-growing offshore wind power production results in an exponential demand for large-scale energy storage.

At CES 2022, Dutch startup Ocean Grazer has launched a new design for an energy storage system that functions a bit like a hydroelectric dam at the bottom of the sea.

The “Ocean Battery” installed at the seabed is a modular utility-scale energy storage system that is produced by renewable sources such as wind turbines, floating solar farms, tidal and wave energy systems. The battery is pumped hydro system in a box that provides eco-friendly utility-scale energy storage up to GigaWatt hours (GWh) scale. It is efficient, has low maintenance costs and is designed with a sustainable planet in mind, and enhances marine life.

The Ocean Battery is based on hydro dam technology that has proven itself for over a century as highly reliable and efficient. The technology does not require rare earth materials and uses clean water as the energy carrier.

The concrete reservoir buried in the seabed holds up to 20 million liters of freshwater stored at low pressure. To store energy, the system pumps water from the rigid reservoirs into the flexible bladder on the seabed. Now the energy is stored as potential energy in the form of water under high pressure. When there is demand for power, water flows back from the flexible bladders to the rigid low-pressure reservoirs, driving multiple hydro turbines to generate electricity.

According to the company, the system has an efficiency of about 80% and should be able to run an unlimited number of cycles over an operation lifetime of more than 20 years. Yet deploying systems like the “ocean battery” on the scale needed to work as part of an electricity grid is still years away. The company aims to have an offshore system in place by 2025, though one will be deployed onshore in the northern Netherlands by 2023.