Towering city skyscrapers could become the green batteries of the future.

Edinburgh start-up Gravitricity claims its new, patented form of energy storage could help make this a reality – the innovative solution works by lifting a number of heavy weights in a deep shaft using excess power and releasing them when energy is required.

The combined total weight can reach up to 12,000 tonnes – the firm says the technology could store energy at half the levelised cost of lithium-ion batteries.

Gravitricity suggests by building storage infrastructure in the heart of cities it can “massively reduce” the requirement for costly and disruptive grid upgrades.

Gravitricity Managing Director Charlie Blair said: “Our idea is very simple. We use excess green energy to lift massive weights to the top of a shaft. These can then be stacked and released when required, delivering energy rapidly back to the grid.

“In the early years, we will install our technology in disused mineshafts as this will help keep the cost down. But in the future, we will be able to sink purpose-built shafts wherever they are required – and the foundations of city buildings could be ideal.”