ENERGY
Floating energy storage unlocks offshore renewables
Battery barges and subsea reservoirs smooth power from wind and solar throughout the floating economy.
Ocean Grazer Battery. Image by RenewableEnergyWorld.com
Floating energy storage is moving from concept to deployment. With offshore wind and solar scaling quickly, storage systems are needed to smooth variable output and deliver stable power to coastal grids. In 2025, barge-mounted batteries and subsea pumped hydro pilots are setting the pace.
Singapore tests floating battery barge. In 2025, Singapore launched the Floating Living Lab with a 7.5 MW/7.5 MWh battery energy storage system mounted on a barge. The project explores ways to overcome land scarcity by siting storage at sea.
Ocean Grazer pilots subsea “Ocean Battery”. Dutch startup Ocean Grazer, supported by Stantec, is developing the Ocean Battery to store offshore wind and solar power in pumped hydro-style subsea reservoirs. Pilots are under review in Europe.
Europe’s OESTER project targets offshore storage. In February 2025, the EU launched OESTER, a project exploring offshore storage solutions from monopile-integrated batteries to compressed air. The program addresses challenges in stabilizing large offshore wind farms.
DOE reviews floating battery barges. In April 2025, the U.S. Department of Energy published a draft environmental assessment for a project deploying three barges equipped with battery containers. The units would store offshore wind power and supply coastal grids.
That’s not all: floating storage is becoming central to the offshore energy transition. From barge-mounted BESS to subsea pumped hydro, analysts see these systems as critical to balancing renewable power at sea.
—TFI
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