City skyscrapers could become green batteries of the future – thanks to a new form of energy storage patented by a UK firm.
Edinburgh start-up Gravitricity has developed an innovative energy battery which works by raising multiple heavy weights – totalling up to 12,000 tonnes – in a deep shaft and then releasing them when energy is required.
Analysts predict the system could store energy at half the levelised cost of lithium-ion batteries – and already the greentech pioneers are planning to install their invention in disused mineshafts across Europe.
They now believe they can install their technology in the foundations of new skyscrapers – turning the buildings into green energy stores.
“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,” says Gravitricity Managing Director Charlie Blair [pictured below].
“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.
“New skyscrapers bring substantial new electricity demand, and by building storage in the heart of cities we can massively reduce the requirement for very costly and disruptive grid upgrades.
“At the same time, our system means that future skyscrapers could reduce their environmental footprint and help cities decarbonise their energy needs.”
Blair says their 24MWh system – which comprises 24 weights of 500 tonnes – could power 63,000 homes for one hour. The total weight is equivalent to 84 blue whales.
The energy innovators have already received a £640,000 grant from Innovate UK, the UK Government’s innovation agency, and have teamed up with Dutch winch specialists Huisman to build a 250kW scale prototype of their idea.
They have now launched a crowdfunding campaign with CrowdCube to support their development plans, and have already raised more than double their minimum fundraising target.
This leaves the firm ideally placed to tap into the growing energy storage market, which Bloomberg New Energy Finance estimates will be worth $620 billion globally up to 2040.
“The climate emergency means we need to find new ways to capture and store green energy so we can use it when we need it,” Blair says.
“We think city skyscrapers could be an exciting part of that future,” Blair concludes.
Gravitricity uses heavy weights – totalling up to 12,000 tonnes – suspended in a deep shaft by cables attached to winches. When there is excess electricity, for example on a windy day, the weight is winched to the top of the shaft ready to generate power.
This weight can then be released when required – in less than a second – and the winches become generators, producing either a large burst of electricity quickly, or releasing it more slowly depending on what is needed.
Unlike batteries, the Gravitricity system can operate for decades without any reduction in performance.
Gravitricity has submitted four patents; two have been accepted for grant and two are in examination.
The idea of using gravity to store energy is not new. Britain already relies on a number of pumped storage hydro schemes, such as Ben Cruachan, where water is pumped uphill to be released when required.
The start-up plans to build models from 1 to 20MW, and is designing each Gravitricity Energy Storage System to last over 25 and up to 50 years. They are currently short-listing a number of disused mine shafts for their first full-scale working prototype in 2020. (Feasibility work in 2020, construction not until 2022.)
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Neil Davidson, PR consultant to Gravitricty
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