Constraint payments for Scotland’s electricity generators have reached a record £1.2 billion in the last 12 months, from August 2024 through July 2025 — the equivalent of over £140,000 every hour – according to Nuclear Industry Association analysis of National Energy System Operator (NESO) data. It marks an eight-fold increase in five years, from £147 million in the year from August 2019 to July 2020, adding to soaring grid balancing costs. These costs are spread across all UK billpayers, and amount to about £15 for every household in Scotland.
Constraint payments are made when electricity generators are asked to reduce output because the grid does not need or cannot transport the power to where it is needed. This record figure reflects the growing gap between the pronounced variability of Scotland’s power output and its lack of firm low-carbon power to back up its renewable power capacity.
Constraint payments have increased as Scotland’s nuclear capacity has shrunk since the closure of Hunterston B (above) in 2022. The plant provided reliable, low-carbon power directly to the Scottish grid for 46 years, helping to stabilise supply and reduce the need for constraint payments and other system costs. Without the station, Scotland has become more reliant on intermittent sources of power and imports from England during periods of low wind.
Balancing costs across have spiralled in recent years with the latest data from NESO showing that consumers across Britain paid £1.5 billion in the first six months of this year, the third highest ever after 2022 and 2023.
Tom Greatrex, Chief Executive of the Nuclear Industry Association, said, “The Scottish Government needs to look at the facts and back new nuclear so it can have more clean reliable power on the grid to contain ballooning system costs. Consumers are paying the price of not having a healthy mix of intermittent and firm power sources to prop up the grid. More nuclear means a more price-predictable, more secure and cleaner energy system so it’s vital that we commit to new projects.”
