MechChem Africa March 2018

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New technology uses gravity to store green energy

F ormermining communities couldfindanew leaseof life –with oldmine shafts turned into hi-tech green energy stores. This is the plan of energy start-up Gravitricity, which has just received a £650 000 grant from Innovate UK, the UK Government’s innovation agency, for its plan to harness the power of gravity to store renewable energy. Ina caseof ‘what goesup,must comedown’, this technology uses a massive weight suspended in mine shafts to capture greenpower, for later releasewithin secondswhen theenergy is needed. If Gravitricity’s plan succeeds, its technology could breathe new life into former mining communities, and with it jobs and economic activity. The UK funds will enable the company to start building a scale demonstrator later this year, and to find a site to install a full-scale prototype by 2020. Gravitricity is now on the look out for investors, including those who can bring mining experience to the team, along with suitable shafts to trial the technology. And once the technology is proven in old mines, the plan is to sink new shafts to store energy wherever it is required. “As we rely more and more on renewable energy, there is an

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Gravitricity managing director, Charlie Blair, at Newtongrange Mining Museum, Scotland.

increasing need to find ways to store that energy so that we can produce quick bursts of power exactly when it is needed,” explains companymanaging director, Charlie Blair. “So far there is a lot of focus on bat- teries, but our idea is quite different. Gravitricity uses a heavy weight – up to 2 000 t – 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. The 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,” Blair explains. “It’s a simple case of ‘what goes up must come down,’” he adds. Unlike batteries, the Gravitricity system can operate for decades with- out any degradation or reduction in performance. “Of course, the idea of using gravity to store energy is not new. Britain already relies on numer- ous pumped storage hydro schemes, such as Ben Cruachan, where water is pumped uphill to be released when required,” he says. “The difference is we don’t need a mountain with a loch or lake at the top, and we can react much faster,” adds Blair. He says the biggest single cost is the hole, and that is why the start-up is developing the technology utilising existing mine shafts, both in the UK and well as in South Africa. As the

Gravitricity’s technology uses a massive weight suspended in mine shafts to capture green power, to be released within seconds when needed.

Pint of Science 2018 14-16 May 2018, Cape Town, South Africa The annual three-night global Pint of Science festival aims to create spaces and moments for interaction between scientists and the public by providing a valuable opportunity to ‘bring the lab’ to the public and foster conversation – over a pint – on latest research and findings. Event topics will include: The Beautiful Mind; Atoms to Galaxies; Our Body; Planet Earth; Tech Me Out; and Our Society. “As South Africa moves to the forefront of research in a number of STEM (Science, Technology,Engineering,Mathematics)arenas,it is important to get everyone involved in science, from young to old, because the best ideas come from the most unlikely of people,” says Taime Sylvester of Stellenbosch University. www.pintofscience.co.za

36 ¦ MechChem Africa • March 2018