Scottish wind farms paid not to generate nearly 40% of potential electricity
Data highlights concerns over the increasing cost of curtailment for consumers
Scottish wind farms were paid not to produce 37 per cent of their planned output during the first half of this year, as the electricity could not be used locally or moved to where it was needed.
The four terawatt hours of curtailed output in northern Scotland would have been enough to power all of Scotland’s households for the entire six-month period, according to research from energy analytics firm Montel.
Wind farms in the area accounted for 86 per cent of the total 4.6 terawatt hours of electricity curtailed across Britain — 15 per cent higher than in the same period last year.
The figures are likely to fuel concern about inefficiencies in the design of Britain’s rapidly evolving electricity system and the impact on all consumers’ energy bills.
Rising wind farm curtailment volumes in recent years have sparked criticism among some industry leaders and raised questions for politicians.
“Curtailed volumes of electricity are rising on average and may continue to do so as more renewable capacity comes online,” said Fintan Devenney, senior analyst at Montel, urging government and industry to work together to try and solve the problem.
The increase comes as more wind farms have been developed in remote areas in Scotland, including in the Moray Firth off the north-east coast, where there is little demand for electricity and not yet enough cable capacity to move their output to consumers further south.
Power stations can agree to sell their output into the wholesale market regardless of where they are located, which in the case of wind farms often means they are planning to produce more than can actually be used given grid constraints.
The government’s National Energy System Operator (Neso) steps in throughout the day to make sure generators are not producing more than the local grid can manage and that users receive what they have ordered.
The operator frequently has to pay wind farms in remote areas to switch off, while at the same time paying gas-fired generators in other parts of the country to increase their output.
“Chronic under-investment in the grid over the past few decades has resulted in these constraint payments,” said one industry executive. “Grid upgrades will provide the capacity to help transport the power to demand in the south.”
Proposals to erect large pylons across rural Scotland have sparked resistance in local communities, some of which argue against new rural energy infrastructure when Scotland has sufficient generation capacity for its domestic needs.
Neso spent almost £117mn on getting the wind farms in northern Scotland to switch off during the six months, according to Montel, mostly making up for subsidies they would have received if they had generated. Its costs for balancing the network are charged to all consumers’ bills.
Neso added that it was determined to play its part in keeping the costs of balancing the system as low as possible for customers, and that it had “saved consumers at least £1.2bn over the past two years across the costs within our control”.
The report, shared with the Financial Times, noted that almost 30 gigawatts of additional wind generation capacity was set to be built in Scottish waters following the major ScotWind seabed leasing auction in 2022, potentially worsening the curtailment problem.
However, subsidy arrangements are being tightened up in a way that may encourage developers to switch off of their own accord during periods of oversupply.
The Department for Energy Security and Net Zero said Neso’s analysis had shown it was possible to produce clean and cheaper power by 2030 even when factoring in constraint payments.
It added it was “delivering the biggest upgrade in Great Britain’s electricity network in decades, which will minimise constraint costs”.
Scottish energy secretary Gillian Martin said. “I have been clear that the current UK energy system is not fit for purpose. Significant investment is required to achieve a clean power system.”