GRAVITICITY What goes up, must come down

tO MAKE more electricity, companies are exploring ways to generate power from unconventional sources, while complementing the drive towards renewables.

The coal-mining industry is dying and it will never come back. But a new start-up is breathing life into mining communities with an ingenious design that uses old mine shafts to generate energy.

A development from the UK is making it possible for cheap energy to be generated by dropping weights down old mine shafts –which is good news for South Africa.

Gravitricity, an energy start-up based in Edinburgh, has drafted designs for a winch and hoist system that would drop 12 000 ton weights down disused mine shafts. Similar to pumped hydro, the concept works by converting electrical energy to gravitational potential energy, according to a report by the BBC.

Managing director of Gravitricity Charlie Blair said the company has devised a giant weight system that drops into disused mine shafts using gravity to create power on demand.

The patented technology is based on a simple principle – raising and lowering a heavy weight to store energy –the same principle used to run pendulum clocks, with a weight acting as a power generator to

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Part of what makes Gravitricity’s design so great is that it doesn’trely on sun or wind

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keep the clock running.

A weight of up to 3 000 tons is suspended in a mine shaft and energy is generated or expended by lowering and raising the weight.

The concept uses winches to hoist weights to the top of the mineshaft when energy is plentiful.

When there’s a dip in supply, the weights are dropped hundreds of metres down vertical shafts to generate electricity.

“It’s a simple case of

‘what goes up must come down’,” said Blair.

The system is capable of generating up to 20MW of power in shafts varying from 150m to 1 500m. It can last 50 years without degradation, and it’s cost effective because it uses existing infrastructure.

In areas where mine shafts don’t exist and solar or wind isn’t effective, a hole could be dug for the system.

Part of what makes Gravitricity’s design so great is that it doesn’t rely on sun or wind.

When you need energy, the weight can drop in a second for power on tap or be released slowly for sustained energy.

And because it doesn’t use a battery for energy storage, you don’t have the problems of disposal and degradation inherent in batteries.

If the energy comes from renewable sources, it could be a completely green form of energy storage and a way to repurpose abandoned infrastructure. – Compiled by Terry van der Walt