One startup’s quest to store electricity in the ocean

When Manuel Aufiero was a child, his parents would take him hiking to a reservoir in northern Italy. This was no ordinary reservoir though. It is a drain and constantly refilled, with pumps raising the water level when electricity was cheap When nearby towns needed electricity, the pumps were reversed and turned into generators as the water drained from the reservoir.

known as technology Pumped-storage hydropoweror pumped hydro for short has been around for over a century. Such facilities are the largest “batteries” ever created by man. Globally, pumped hydro reservoirs store 8,500 gigawatt-hours of electricity, According to to the International Energy Agency.

Pumped hydro can generate electricity for hours, and power plants have occasionally become important as a source of energy. air And solar has become more widespread. But there are many places in the world with suitable topography to host pumped hydro reservoirs.

“I fell in love with pumped hydro,” Aufiero told TechCrunch. “It’s not enough to keep up with renewables.”

So Aufiero decided to solve that problem by moving the technology to sea. He co-founded a startup, great powerTo make his idea a reality.

Sizeable recently raised $8 million in a funding round led by Playground Global with participation from EDEN/IAG, Exa Ventures, Satgana, Unruly Capital, and Verve Ventures, the company exclusively told TechCrunch.

The startup’s power plant looks like a clockwork. The concept of sizable specifies two sealed, flexible reservoirs, one that floats on top and another that sits below the seabed. They are connected by a plastic tube and some turbines.

When energy is cheap, turbines will pump super-salty water from the reservoir below. When the grid needs power, Sizable will open a valve, and since the reservoir water has more salt than the surrounding seawater, it will be heavier and flow down into the reservoir below. As it flows through the pipes, it turns turbines, which act as generators.

“From an energy balance perspective, what we’re doing is lifting blocks of salt. But instead of using cranes, we dissolve it and pump it because it’s simple, simple,” Aufiero said. “Other than that, we’re just extracting a lot of salt.”

By transporting pumped hydro to the ocean, Sizable hopes to scale the technology to mass production, which isn’t really possible on land.

“Every time you build pumped hydro on shore, you have to design a concrete dam for that particular site and you have to adapt the technology there,” Aufiero said. “Making offshore allows us to streamline production and make everything we do the same, regardless of the final deployment location.”

Tested a small scale model of reservoirs in sizable wave tanks and off the coast of Reggio Calabria, Italy. It is now deploying a pilot of floating components ahead of a full demonstration plant. By 2026, it hopes to deploy several commercial projects at sites around the world.

At full scale, the turbines will generate about 6 to 7 MW of electricity and there will be one for every 100 meters of pipe. Deeper sites will have greater storage potential and each commercial site will host multiple reservoirs. Big hopes to offer energy storage for €20 (about $23) per kilowatt-hour one tenth How much does a grid-scale battery cost?

The technology would be well suited to offshore wind projects as the cost of sharing electrical connections on shore would be reduced. But Aufiero says Sizable’s reservoirs can connect to any grid in water at least 500 meters (1,640 feet) deep.

“We believe that long-term energy storage is necessary not only for renewable integration, but also for making the grid resilient,” he said. “We can’t sustain this with traditional pumped hydro or batteries. We need something new.”