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Sizable Energy is raising $25 million to store and generate electricity at sea.

Why it matters: Investors are looking to ever more ambitious technologies to power grids and data centers. 

How it works: Sizable Energy is riffing on one of the oldest forms of energy storage: pumped hydro.

Conventional systems use excess electricity to push water into an uphill reservoir whenever power prices are low, then release the water through turbines to generate electricity when grid prices are high.

Sizable Energy is developing such a system for the ocean, piping seawater back and forth from the surface to the seafloor.

Zoom in: It aims to store eight to 24 hours of electricity, per Canary Media, which reported on the company's $8 million seed raise in October. Conventional lithium batteries hold just a few hours of energy. 

Yes, but: Ocean-based systems have historically faced intense technical and cost hurdles, from seawater that quickly corrodes equipment to limited places on-shore to connect to the grid.

What's next: The Italian startup is also expanding into electricity generation and cooling for off-grid data centers, a source tells Axios Pro, citing insatiable energy demand from the AI hubs. 

State of play: Such power consumption has unleashed a tide of investment in unconventional energy and storage technologies, including systems harnessing gravity, compressed air, and heat.

Follow the money: Deep-tech investor Playground Global led Sizable Energy's seed round, joined by Exa Ventures, Verve Ventures, Satgana, Eden/IAG, and Unruly Capital.

Sizable Energy did not return requests for comment.

Scoop: Sizable Energy raising $25M for offshore energy storage

It's developing ocean-based pumped hydro.

Illustration of Benjamin Franklin with his head almost under water

Sizable Energy is raising $25 million to store and generate electricity at sea.Why it matters: Investors are looking to ever more ambitious technologies to power grids and data centers.

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Scoop: Sizable Energy raising $25M for offshore energy storage

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