Funding gives weight to Gravitricity’s idea for storing energy
Old mine shafts could be revived as storage sites for renewable energy under a scheme being prepared by a Scottish engineering company. Gravitricity has secured a £650,000 grant from Innovate UK, the government innovation agency, to explore the commercial viability of its idea, which involves using the force of gravity on huge weights to provide a novel storage method. The intermittent nature of some renewable energy generation methods, particularly wind power, means that it cannot be relied upon to provide a stable supply. The Edinburgh-based Gravitricity is alone in its ambitions. Companies around the world are pouring time and money into projects to develop large-scale batteries to store energy and release it when there is greater demand on the grid. Gravitricity is proposing to put a weight of up to 2,000 tonnes down a mine shaft, which would be held by cables attached to winches on the surface. On days when more electricity is being generated than is needed, the weight would be lifted to the top of the shaft. On days when demand was outstripping supply, it would be lowered and the movement of the winches would generate additional power. Charlie Blair, managing director of Gravitricity, said: “[The weight can] 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.” The company said that funding would allow it to start building a scale demonstration of the technology this year and it hopes to find a site to install a full-scale prototype by 2020. Mr Blair said that once the technology had been proven in old mines, there was the potential to dig new shafts. Each converted mine shaft or newly built site would provide construction jobs and then a small number of operational roles. The idea of using gravity to store energy is not new, Mr Blair said. Britain already has pumped-storage hydroelectric schemes. He added that the Gravitricity concept required less infrastructure and would be able to produce electricity more quickly. The company estimates that each of its sites would last for 50 years without any degradation in performance, which would be an advantage over batteries.