Ocean pumped hydro storage company Sizable Energy has raised $8 million. The company will use the money to accelerate commercial deployment.
Founded in 2022, the company makes an offshore pumped hydro system that stores energy by pumping saturated sea salt brine (heavier than seawater) from the seabed to a surface reservoir, leveraging the depth of the ocean for efficient energy storage. The company said its technology has minimum carbon intensity and avoids the need for scarce materials.
The company said its technology is invisible from the shore and is modular and scaleable fron one to hundreds of gigawatt hours of storage. It also said the technology combines readily available materials that can be manufactured, assembled, and installed at depths of 500 meters or more, using existing maritime infrastructure and offers the lowest Levelized Cost of Storage (LCOS) for Long Duration Energy Storage even when considering the most optimistic projections for Li-ion cost decreases.
Sizeable Energy is preparing for commercial project development in 2026 across multiple global sites, in partnership with local manufacturers, governments, and energy providers.
“Without cost-effective long-duration storage, the grid cannot keep up, regardless of energy source,” said Dr. Manuele Aufiero, CEO and Co-Founder of Sizable Energy. “Our ocean-based system stores gigawatt-scale power affordably, making the grid more stable, resilient, and ready for the future.”
The round was led by Playground Global. Other investors include Exa Ventures, Verve Ventures, Satgana, EDEN/IAG, and Unruly Capital which led a previous round.
“As a society, we’ve proven that wind and solar can deliver the cheapest electrons. Now we urgently need a long duration energy storage solution that can be economically deployed at massive scale,” said Bruce Leak, general partner at Playground Global and board member of Sizable Energy. “Ocean depth is a practically unlimited resource, and Sizable Energy is leveraging it to deliver long-duration energy storage at a fraction of the cost of batteries. Their gravity-based approach is the clear path to enabling energy abundance.
Sizable Energy has also begun deployment of its next sea trial off the coast of Reggio Calabria, Italy. This pilot will validate all key floating components, demonstrate the full-scale assembly and deployment process, setting the stage for a multi-MWh demonstration plant in the Mediterranean Sea off the coast of Italy.
