Sustainable Scotland: Scots firm goes global with ‘weight-drop’ energy storage innovation

An entrepreneurial Scottish firm is set to go global with a pioneering gravity-fed energy storage invention that was trialled in the Scottish capital.

Edinburgh-based start-up Gravitricity has been testing out its technology – which uses underground shafts and massive weights to store power and can deliver it back to the network at a moment’s notice – at the Prince Albert Dock in Leith. Now, thanks to £194,00 from the UK government, the company is heading to India to demonstrate how the invention can help the heavily coal-dependent and rapidly developing country cut its environmental footprint.

India is currently one of the world’s biggest climate-polluters – in third place after the US and China. But plans have been set out to install more than 500GW of renewable power by 2030, a fivefold increase on the 2021 target, and with that will come a massive need for energy storage.

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Analysts have calculated that Gravitricity’s system can store energy at half the cost of lithium-ion batteries, with an operational lifespan of 50 years. Green tech pioneers are already making moves to install the invention in decommissioned mineshafts and custom-built shafts across the UK and mainland Europe.

The Scottish company has now partnered with India energy specialists Panitek Power in a 12-month project to identify a shortlist of sites and suppliers with a view to constructing a demonstration scheme.

Chris Yendell, project development manager at Gravitricity, said: “India has very few fossil fuel resources and is committed to adopting renewables to fuel its economic growth. Solar power is extremely cheap in such a sunny country but brings with it a need for energy storage to meet peak morning and evening demand, both of which typically occur during the hours of darkness.

“With the introduction of renewable energy generation at this scale, new flexible storage services will be essential to ensure the grid continues to operate in a stable manner. Gravitricity's versatile technology is ideally placed to deliver the balancing services required to achieve this stability.

“It is also a relatively simple technology. It doesn’t rely on any rare earth metals and has a very long lifespan, meaning it can be manufactured and deployed locally alongside vast amounts of new grid infrastructure which will also be required to meet the rapid growth in demand.”

Chris Yendell, project development manager at Gravitricity, believes his firm's innovative energy storage technology -- which has been demonstrated at Edinburgh's Leith docks -- can help India reduce its climate emissions and move to renewable power. Picture: Peter Dibdin

Parag Vyas, chief commercial officer at Panitek Power, said: “India has an immediate and growing need for energy storage technologies. In many locations there is little or no grid, and it makes sense to integrate energy storage within their evolving infrastructure to cope with intermittent generation.

“In addition, as a country’s share of renewables rises, this can cause frequency and voltage disturbances in the existing grid due to mismatch of load demand and generation. Gravitricity’s technology has a response time of less than one second and can be cycled thousands of times, making it ideally suited to grid balancing and rapid frequency response services.”

The 250kW prototype seen in Leith was made up of a 15m-high tower, two 25-tonne weights suspended by steel cables, plus a pair of grid-connected generator units. The system works by winching the weights up to the top of the tower using excess renewable energy at times of low demand, then dropping them to generate electricity whenever needed.

This visualisation illustrates what a Gravitricity energy storage plant might look like in a rural setting. Picture: Tom Barnett
This diagram shows how a Gravitricity energy storage scheme works, using a heavy weight which is lifted up and dropped down an underground shaft to bank or release energy according to demand



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