UK start-up builds gravity-based storage system at Scottish port


Scottish start-up Gravitricity has begun construction of a £1 million ($1.38 million) gravity energy storage system on an industrial site at Port of Leith, Scotland’s largest enclosed deepwater port.

The 250 kW demonstration project, which is supported by a £640,000 grant from U.K. government funder Innovate UK and is scheduled for completion by the end of April, is being built with a 15m high lattice tower, two 25-ton weights suspended by steel cables, and two grid-connected generator units.

“Our full scale projects will operate underground–but for this scale demonstrator, we’ve built an above-ground structure,” said the company's engineering project manager, Frances Tierney. “This two-month test program will confirm our modeling and give us valuable data for our first full scale, 4-8 MW project, which will commence later this year.”

The company said the lattice tower was built by English engineering firm ESL, based in Hull, and the base frame and weight baskets were made by AJS Fabrication, which is a steel fabrication company based in Fife, Scotland. The winches and control modules were provided by Huisman, a Dutch manufacturer of heavy lifting, drilling, pipe laying, and mooring systems. Glasgow-based Industrial Systems and Control (ISC) supported Gravitricity with controls and simulations.

A tower uses renewable energy to raise a mass in a 150-1,500m shaft and discharges the electricity thus ‘stored’ by releasing the mass to rotate the two power generators. According to the company, the mass in similar facilities can range from 500 to 5,000 tons.

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The technology is claimed to have a faster response time than lithium-ion storage technology and to be able to help stabilize electricity networks at 50Hz by responding to full power demand in less than a second. The demonstrator will be linked to the port’s electricity grid.

The system is also said to have a 25-year life cycle without loss of performance or cyclical degradation. The company said it can be, potentially, located anywhere, although disused mine shafts were indicated as ideal locations.

Gravity storage has begun to raise interest in the renewable energy industry in recent years. U.S. company Energy Vault unveiled, in 2019, gravity-based storage technology relying on a crane and 35-ton concrete blocks. Austrian research organization the International Institute for Applied Systems Analysis (IIASA) recently suggested gravitational energy storage for low-energy-demand locations.

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