Britain is turning to an age-old technology to stabilise its power grid as coal and gas plants are phased out and replaced with renewable energy. Grid operators are increasingly relying on heavy spinning devices called flywheels to provide the inertia once supplied by fossil-fuel power stations, in order to prevent large-scale blackouts.Flywheels, used for centuries in machinery from potters’ wheels to steam engines, can mimic the stabilising effect of turbines in coal and gas plants by responding to sudden fluctuations in electricity supply and demand. Without such rotating systems, “the system is more prone to fluctuations than it would be otherwise,” said David Brayshaw, professor of climate science at the University of Reading. “As we get to ever higher levels of renewables, we’re going to have to think about this more carefully,” he told AFP.The challenge was underscored in April, when Spain and Portugal were hit by a major outage after their renewable-heavy grid failed to absorb a sudden surge in voltage. A similar incident in 2019 plunged parts of Britain into darkness and prompted the National Energy System Operator (NESO) to begin contracting grid-stabilising projects.Among the solutions, flywheels and batteries are being deployed to create “synthetic inertia”. According to engineering professor Keith Pullen of City St George’s, University of London, steel flywheels could prove more cost-effective and longer-lasting than lithium-ion batteries. “I’m not saying that flywheels are the only technology, but they could be a very, very important one,” said Pullen, who also leads the startup Levistor.One of the flagship projects is Statkraft’s “Greener Grid Park” in Liverpool, operational since 2023. It uses two 40-ton flywheels attached to synchronous compensators to supply about one percent of Britain’s total grid inertia. “We are providing that inertia without burning any fossil fuels, without creating any carbon emissions,” said Guy Nicholson, Statkraft’s head of zero-carbon grid solutions. NESO reports that at least 11 similar projects are already operational across the UK, with more on the way.Despite this progress, concerns remain. “We aren’t building them fast enough to decarbonise the grid,” Nicholson warned, noting Britain’s target of 95 percent clean energy by 2030. “At the moment… we can’t even do it for one hour,” he added, pointing out that gas turbines are still required to keep the grid stable.The government insists it is working with industry to scale up new stabilisation technologies. A spokesperson for the Department for Energy Security and Net Zero said the UK is collaborating with partners to roll out “world-leading technology, including flywheels, static and synchronous compensators, as we overhaul the energy system.”Still, experts say Britain and Ireland remain ahead of continental Europe in adopting such measures. “In GB and Ireland, the system operators are leading by contracting these services,” Nicholson said. “On the continent, there hasn’t been the same drive for that. I think these things are driven by events. So, the Spanish blackout will drive change.”
