Gravitricity to Transform Disused Mines into Renewable Energy Hubs
With the goal of providing a stable supply of green electricity to the UK an Edinburgh-based start-up plans to bring renewable energy technology to market, that can capture, store and release energy rapidly using weight, gravity and disused mine shafts.
Having recently secured a grant of £650,000 from Innovate UK, Gravitricity is set to explore the commercial viability of their unique system of energy creation and storage. The ambitious company aims to trial the first full-scale prototype in 2019 or 2020 at a disused mine in the UK.
Using their patented technology, their system is based on the principle of raising and lowering a heavy weight to store energy. The conversion of these disused mine shafts and the operation of these systems will generate new jobs and improve economic activity in areas which struggled with the decline in the UK coal mining industry.
The Key Requirement is a Deep Hole in the Ground
Gravitricity explained that the energy is generated by the suspension of a cylindrical weight of up to 3000 tonnes in a deep shaft by several synthetic ropes each of which is engaged with a winch capable of lifting its share of the weight. Electrical power is then absorbed by raising or lowering the weight. The weight is guided by a system of tensioned guide wires to prevent it from swinging and damaging the shaft.
In practice, it has similar advantages to hydro-electric pumped storage for networks up to 33kV, without the need for a nearby mountain with a lake or loch at the top. The company estimates each unit could produce between 1MW and 20MW peak power, with an output duration of 15 minutes to 8 hours.
What Sets Gravitricity Apart?
While other forms of renewable energy are influenced by the weather and the need for large-scale batteries for storage, this system faces no such barriers. It is designed to permit the rapid switching between energy generation to power absorption, which means it can deliver reactive as well as resistive power, which will ultimately improve grid stability.
Charlie Blair, Gravitricity Managing Director said: “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.”
By eliminating the need for batteries, Gravitricity will not have the issue of disposal or dealing with battery degradation. The company estimates that each of its sites would last for up to 50 years without any decrease in performance and will thus reduce the requirement for redundancy in grid hardware.
Unlike existing wind, hydro and solar power systems which can have an impact on surrounding scenery and local wildlife the Gravitricity system would by default take advantage of brownfield locations such as disused mineshafts.
Scotland’s Renewable Energy Targets
It is exciting that a potentially game-changing renewable energy is being developed in Scotland, which already has the goal of decreasing its use of fossil fuel and nuclear output as an energy source.
The Scottish Government is pushing to have renewable sources generate the equivalent of 100% of Scotland’s gross annual electricity consumption and to provide 11% of its heat demand by 2020.
The amount of electricity generated by renewables energy in Scotland has increased fourfold since 2000, the largest renewable sector being onshore wind, followed by solar PV, and heat pumps.
In 2015, the amount of electricity generated in Scotland by renewable sources equated to 59.4% of the gross annual consumption of electricity in Scotland, compared with 12.2% in 2000. It will be interesting to see how Gravitricity’s system will impact the renewable energy market.