The United Kingdom narrowly avoided blackouts during a recent heatwave, with whistleblowers claiming the national energy grid failed to meet necessary security standards. The incident, which occurred on June 23 when temperatures reached 34 degrees Celsius (93.2 degrees Fahrenheit), has raised concerns about the UK's increasing reliance on renewable energy sources, particularly wind power, and its impact on national energy security.
Shadow energy secretary Claire Coutinho revealed the allegations, stating that operators claimed the grid did not meet standards designed to prevent blackouts. She also alleged that the corporate affairs team at the National Energy Systems Operator (Neso) attempted to cover up the crisis and interfered with operational decisions, potentially prioritizing the operator's reputation over security of supply. These allegations, she noted, were not denied by the energy minister.
During the heatwave, a 'heat dome' trapped warm air over the UK, leading to slowed wind speeds and a significant drop in renewable energy generation. On June 23, wind power accounted for only 13 to 15 percent of the UK's electricity, roughly half of the average for June in the previous year. Simultaneously, five gas plants reduced their output by approximately 2.5 gigawatts due to the high temperatures, which also made nuclear power plants and their cooling systems less efficient.
In response to a forecasted shortfall, Neso issued an 'emergency margin call,' requesting increased supplies from generators. The operator secured about 1.7 gigawatts of extra electricity capacity from continental Europe to meet the evening peak demand, incurring costs of approximately £1,400 per megawatt-hour, nearly 20 times the average market price for June. Neso confirmed at the time that extra capacity was needed due to the "impact of extremely high temperatures affecting Great Britain and the continent, and low wind."
Experts have voiced concerns about the vulnerability of the energy system under such conditions. Dr. John Constable, director of the Renewable Energy Foundation, stated that the incident highlights the risks of relying on weather-dependent generation. "Experts have warned for over 20 years that betting Britain's electricity system on weather-dependent generation such as wind and solar would make the network intrinsically less robust, far harder to manage and vastly more expensive for consumers," Constable said. He added that Neso's concession about low wind power output driving the margin notice indicates that increased spending on the problem is not a viable solution.
Kathryn Porter, an independent energy consultant, echoed these concerns, noting that low wind speeds during periods of high heat or cold place collective stress on interconnected grids. She pointed out that the UK experienced grid frequency issues requiring exports to neighbors to be cut off at times, which could jeopardize future energy imports during winter. "We need sensible energy policies and to stop gambling on the weather and praying other countries can bail us out," Porter stated.
However, some experts dispute the severity of the incident. One unnamed energy expert who analyzed the margin notice described it as a normal market operation, noting that it was issued the day before, reissued the morning of, and then canceled mid-afternoon. They explained that energy notices are often issued with lead times for gas units to start, and can be canceled if conditions change, suggesting the event was not cause for alarm.
Energy Minister Michael Shanks has stated that electricity supplies were maintained throughout the heatwave and no customers lost power. Neso has since commissioned an independent investigation into the whistleblower allegations, with a report expected from the legal firm conducting the inquiry in the coming weeks.
This event brings to mind past power disruptions, including a major blackout in 2019 caused by simultaneous failures of a gas power station and a wind farm, and a widespread outage in Spain and Portugal last year. A Neso spokesman stated that their initial analysis shows the electricity system operated securely during the heatwave, with no customer demand disconnected and all parameters within statutory limits. They confirmed an independent investigation into allegations of operational decision-making and record-keeping is underway.