Disused mine shafts in South Africa have been identified as an ideal location to test UK-based energy start-up Gravitricity’s green energy technology.

The company announced plans to transform disused mine shafts into hi-tech green energy generation facilities through a system that uses gravity and massive weights.

Gravitricity received a £650, 000 ($907, 000) grant from Innovate UK, the British government’s innovation agency, to kick-start their plan to harness the power of gravity to store renewable energy.

South Africa identified for rollout

The technology uses a massive weight suspended in mine shafts to capture green energy, and then release it in seconds. Read more…

Should this plan by Gravitricity succeed, their technology could breathe new life into former mining communities and with it jobs and economic activity.

The UK grant will enable them to start building a scale demonstrator later this year, and find a site to install a full-scale prototype by 2020.

They are now on the look-out for investors, including those who can bring mining experience to the team and suitable shafts to trial their technology.

Gravitricity uses natural source of power

“So far there is a lot of focus on batteries, but our idea is quite different,” says Charlie Blair, the company’s managing director.

“As we rely more and more on renewable energy, there is an increasing need to find ways to store that energy – so we can produce quick bursts of power exactly when it is needed,” explains Blair.

Once the technology is proven in disused mine shafts, the plan is to sink new shafts to store green energy wherever it is required.

According to Gravitricity, the technology uses a heavy weight – up to 2,000 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,” Blair explains.

“It’s a simple case of ‘what goes up, must come down’,” he says.

Not new, but long-lasting

Unlike batteries, the system can operate for decades without any degradation or reduction in performance, Blair states.

Of course the idea of using gravity to store energy is not new. Britain and South Africa already relies on a number of pumped storage hydro schemes, where water is pumped uphill to be released when required.

“The difference is we don’t need a mountain with a loch or lake at the top, and we can react much faster,” says Blair.

He says the biggest single cost is the hole, and that is why the start-up is developing their technology using existing mine shafts, both in the UK and South Africa.

“We are keen to speak with mine operators in South Africa to understand how we might work together,” Blair says.

As the technology advances, the cost of drilling will reduce significantly and will allow them to sink purpose-built shafts wherever they are required, the company claims.

The start-up plans to build models from 1 to 20MW, and estimates each project will last up to 50 years.

Later this year they will build and test a part-scale demonstrator, and they are currently short-listing a number of disused mine shafts for their first full-scale working prototype in 2019/20.


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