Investors commit $8m to Italian offshore-pumped-hydro storage

An Italian start-up claiming to offer the world’s lowest-cost LDES technology is aiming for commercial operation of its offshore pumped hydro systems next year.

Announcing an $8 million funding round led by Californian “deep technology” venture capital (VC) investor Playground Global, Milan-based Sizable Energy said it is prepping its next sea trial off the coast of Reggio Calabria, in Italy.

Sizable issued a press release yesterday to announce the funding round and reveal successful testing last month in the wave basin at the Maritime Research Institute Netherlands (Marin).

That will pave the way for the Calabria test to validate key floating components of the system and demonstrate full-scale assembly and deployment.

The Sizable system stores energy by using excess electricity to pump a saturated sea brine solution which is heavier than seawater from depths of at least 500 m to a reservoir at the surface. The battery is discharged by releasing the solution back down to the bottom of the system, releasing energy.

Sizable said the Calabrian sea test will be followed by a multi-megawatt-hour demonstrator in the Mediterranean, off the coast of Italy. The company said it is preparing for commercial deployment of the technology “across multiple global sites” next year, working with unspecified local manufacturers, governments and energy companies.

The Italian startup says its technology, which it says is invisible from the shore, offers the lowest levelized cost of storage available for LDES; is modular and scalable from 1 GW to hundreds of gigawatts; and can be deployed at depths of 500 m or more using existing maritime infrastructure and readily available materials.

Bruce Leak, general partner at Playground Global and a Sizable Energy board member said, “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 said other backers of the company include London-based VC and private equity investors Exa Ventures and Unruly Group; Milanese peer Eden, which is backed by Milan-based VC network IAG; and climate technology VC Satgana, based in Luxembourg.