A company aiming to use old mine shafts as batteries to store renewable energy is to build a demonstration project showcasing its technology in Scotland

Greig Cameron writes on the Times website about a demonstration project in Scotland that will use gravity-powered batteries. What are your views on this technology?


Gravity-powered batteries generate electricity when the wind dies down

A company aiming to use old mine shafts as batteries to store renewable energy is to build a demonstration project showcasing its technology in Scotland.

Gravitricity believes that it can use large weights on cables attached to winches on the surface to help to compensate for the intermittent nature of wind farms.

The company estimates that the cost of its technology would be lower than the large-scale lithium ion battery deployment being considered by many renewable energy producers.

The Gravitricity method means that on days when more electricity is being generated than is needed by the grid the weight would be lifted to the top of the mine shaft. Then when demand is outstripping supply the weight can be lowered, with the movement of the winches producing power.

The Edinburgh company secured more than £600,000 of funding from Innovate UK, a public agency, two years ago and has raised £750,000 through a crowdfunding drive.

Today it has announced plans to build a £1 million demonstration of its system in Leith.

It has signed a land rental agreement with Forth Ports and work is scheduled to begin in October, which could mean that the equipment is operating by the end of the year.

Instead of using a mine shaft a 16m-high tower will be used, with two 25-tonne weights capable of being hoisted to the top. The system will be hooked into the grid and is forecast to be capable of producing 250 kilowatts.

Miles Franklin, the chief engineer, said that a two-month test programme would take place and give the company vital data as it prepares to move on to larger projects.

He said: “In our first test we’ll drop the weights together to generate full power and verify our speed of response. We calculate we can go from zero to full power in less than a second, which can be extremely valuable in the frequency response and back-up power markets. We will then run tests with the two single weights, dropping one after the other to verify smooth energy output over a longer period.”

The company believes that its technology could eventually be used with weights of up 12,000 tonnes being released into deep mine shafts.

It is looking into the possibilities for the technology in South Africa after receiving a separate tranche of Innovate UK funding.

It is also assessing UK and European locations for a larger demonstration project, which could begin development next year with an attempt to generate four megawatts of power.

Stuart Wallace, chief operating officer at Forth Ports, said that the company was working with a range of renewable energy developers and operators as part of its work towards meeting net-zero emissions targets set by the Scottish government.

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