November 7, 2025
Salt Wars: The Deep-End Debate
A startup’s quest to store electricity in the ocean
Ocean 'battery' plan reels in cash—and a tidal wave of hot takes
TLDR: Sizable Energy snagged $8M to test an offshore “hourglass” that stores power by pumping extra-salty water up and letting it fall to spin turbines. Comments split between ‘leave the ocean alone’ fears and efficiency hype, with a chorus noting it’s a closed-loop design that shouldn’t mingle with sea life.
A childhood fascination with “water batteries” just turned into a splashy startup bet: Sizable Energy raised $8 million to stash power in the sea, using two flexible reservoirs and extra-salty water to act like a giant hourglass. When energy is cheap, they pump brine up; when it’s needed, the heavy saltwater rushes down, spinning turbines. The pitch: mass-produce offshore units, pair with wind farms, and hit around €20 per kilowatt-hour—far below big lithium batteries, with pilots now and commercial projects by 2026. So why is the internet frothing?
Because the ocean is a character in this story. The top comments split fast: environmental guardians warn, “don’t mess with the sea,” with one user even fearing local weather shifts from temperature mixing. Tech optimists counter that pumped systems can top 80% efficiency, asking what the catch is. A calmer voice chimes in: it’s a closed loop, folks—no constant water swapping. Cue comic relief: “Is the salt… table salt?” sparked jokes about “Gordon Ramsay’s grid” and “Poseidon’s hourglass.”
Meanwhile, skeptics imagine leaky brine balloons and confused whales; fans see resilient, long-duration storage to back up wind and solar. The verdict? It’s a classic internet cliffhanger: bold idea, money, bigger questions—served extra salty.
Key Points
- •Sizable Energy is developing an offshore pumped-storage system using dense brine in flexible reservoirs connected by turbines.
- •The startup raised $8 million led by Playground Global with multiple venture participants.
- •Tests have been conducted in wave tanks and off Reggio Calabria, Italy; a pilot of floating components is underway toward a full demonstration.
- •Commercial deployments are targeted by 2026, with each turbine producing about 6–7 MW and one turbine per 100 meters of pipe.
- •Sizable aims to deliver storage at ~€20/kWh (~$23), envisions pairing with offshore wind, and requires water depths of at least 500 meters near grid access.