One of the trial projects has been under way in Liverpool, run by Statkraft, a Norwegian company. It is adjacent to the site of the former coal-fired power station that once supplied much of Merseyside’s electricity.
Statkraft is also behind a similar £20m trial project at Keith, in Moray, Scotland, which also uses flywheels to store energy and stabilise the grid.
Such systems work by replicating the spinning turbines of a traditional power station but without the reliance on fossil fuels or the emissions associated with them.
The UK’s transmission networks were designed around a network of power stations fuelled originally by coal and later by gas and nuclear energy. These all work by generating heat to make steam that is then used to spin turbines.
The last coal-fired power station at Ratcliffe-on-Soar, Nottinghamshire, closed this week and eight of the nation’s nine remaining nuclear reactors will close by 2028, with gas also falling out of favour owing to its CO2 emissions.
The loss of such generators poses risks to the system because the power they produced was constant and therefore helped maintain the steady frequency needed to prevent outages.
An NESO spokesman said: “If there’s a sudden change in system frequency, the weight and inertia of generators means they carry on spinning – even if they have lost power. This avoids a sudden change of frequency, giving time for our control room to restore balance.”
The scale of the problem is shown by the number of contracts awarded for so-called “stability services” – expected to total more than 100 by the time all are operational, probably in 2026. NESO is now planning to open an entire new stability services market to encourage the construction of more flywheels or other services that back up the grid.
NESO said the schemes would save consumers money by cutting the need for maintaining backup power stations and importing power from overseas via interconnectors.
A spokesman said: “The pathfinders alone are expected to provide consumers with savings of £14.9bn between 2025 and 2035.”