A gravity-based energy storage system has been developed by a Scottish startup which the company claims is ideal for storing renewable energy. The storage system developed by Gravitricity involves a 16 metre high rig utilising the clean power to lift a mass in a 150-1500 metre shaft, discharging the energy that it 'stores' by releasing the mass to rotate a generator.
Gravitricity energy storage
The company says the mass can be in the range of 500 to 5,000 tonnes and the discharged electricity would be able to provide power to 30,000 homes for two hours.
The technology uses winches and a control system to lower the mass quickly, making it flexible enough to stabilise energy networks at 50Hz, thus ensuring the system is able to respond to full electricity demand in under a second.
“Our technology has the fast response time of lithium-ion batteries,” the company said in a statement.
The startup also claims that its system will offer a 25-year service with zero degradation or loss of performance and can be located anywhere, even in city centres. At present, the tech is being used in disused mine shafts, which the company says are ideal locations and require no drilling.
Edinburgh-based Gravitricity is scheduled to start construction of a £1 million (€1.14 million) pilot project in Autumn 2020 on an industrial estate at Port of Leith, Scotland's largest enclosed deep-water port.
The pilot is due to be completed by December, connecting the 250 kW prototype to the port's energy network. The technology's response speed and grid stabilisation will then be assessed.
“The demonstrator at the Port of Leith will allow the technology to be trialled on a much smaller scale, utilising an above ground structure,” the company said.
The pilot system will use two 25-tonne weights suspended by steel cables. “This two-month test program will confirm our modelling and give us valuable data for our first full-scale, 4 MW project, which will commence in 2021,” said Gravitricity lead engineer Miles Franklin.
The lattice tower for the Port of Leith facility will be supplied by UK engineer Kelvin Power and the winches and control system will come from Huisman, a Dutch manufacturer of heavy lifting, drilling, pipe laying and mooring systems.
The project is being backed by government agency Innovate UK with a £640,000 (€729,680) grant.
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