Is wind power partly to blame for near-blackouts? Experts say increasing reliance on Net Zero energy could leave UK's energy security at risk

By MARK DUELL, DEPUTY CHIEF REPORTER (DIGITAL) Published: 13:54, 17 July 2026 | Updated: 13:55, 17 July 2026 An increasing reliance on wind in the Net Zero push could be partly responsible for putting the UK's energy security at risk, experts suggested today after whistleblowers claimed Britain came close to blackouts during last month's heatwave.  Shadow energy secretary Claire Coutinho has revealed operators claimed the grid failed to meet necessary standards as temperatures reached 34C on June 23. She also told MPs on Wednesday that whistleblowers alleged the Neso (National Energy Systems Operator) corporate affairs team had tried to cover up the crisis. The second heatwave of 2026 happened when a 'heat dome' trapped warm air over the UK and slowed wind speeds, causing a drop in renewable energy generation. Wind power made up between 13 and 15 per cent of the UK's electricity on the day in question, which is around half of the average of 30 per cent in June last year. At the same time five gas plants said they would have to reduce output because of the heatwave, which saw them cut about 2.5 gigawatts (GW) from production. Nuclear power plants and water-cooling systems are impacted by extreme heat which puts pressure on the electricity system by making processes less efficient. In the run-up to the incident last month, Neso issued a so-called 'emergency margin call' - a request to generators to increase supplies - after forecasting a shortfall. Neso secured around 1.7GW of extra electricity capacity from the continent to meet the evening peak, but ended up paying about £1,400 per megawatt-hour (MWh). This was nearly 20 times the average electricity market price in June 2025. The output of one of the UK's five nuclear power stations is around 1.0GW to 1.2GW. The Little Cheyne Court Wind Farm among electricity pylons at Romney Marsh in Kent in 2017 Neso confirmed at the time that it needed extra capacity due to the 'impact of extremely high temperatures affecting Great Britain and the continent, and low wind'. Dr John Constable, director of the Renewable Energy Foundation charity, said the margin notice showed that the UK's reliance on wind was becoming a problem when conditions were not windy enough. He told the Daily Mail: '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. Successive governments pressed on regardless.  'But Neso itself now concedes that unexpectedly low wind power output helped drive a recent margin notice - and, with grid balancing costs already eye-wateringly high, it is clear that throwing yet more consumer money at the problem is not an option. The chickens are coming home to roost.' Kathryn Porter, an independent energy consultant at Watt-Logic, added that the recent incident was concerning for the UK's energy security given low wind speeds impacted both Britain and Europe. She told the Mail: 'As Britain and many of its near neighbours increasingly rely on weather-based forms of electricity generation, our electricity grids collectively experience stress during periods of low wind which are either accompanied by high heat or significant cold. 'High heat causes output from all types of electricity generation to fall for a variety of reasons, while high cold increases demand. Both make balancing the grid more difficult. 'At the end of June, we experienced periods when the frequency of the electricity grid went outside its safe operational limit for extended periods, with exports being cut off to our neighbours - at times without notice - in order to support the British grid. 'This is worrying since Britain is heavily reliant on imports in winter, so cutting off our neighbours when they need us risks them deciding not to send electricity to us when we need it in winter.' It comes after Ms Porter said on X last week that 'we need sensible energy policies and to stop gambling on the weather and praying other countries can bail us out'.  But a leading energy expert, who has analysed the margin notice and did not wish to be named, told the Mail that the incident was a normal market operation, which raised no concerns. They pointed out that the notice was issued at 9pm the day before, and reissued at 7am – then cancelled at 1.20pm on the day. Shadow energy secretary Claire Coutinho (pictured in the Commons) revealed operators said the grid failed to meet necessary standards as temperatures reached 34C on June 23 The expert explained that a key timeline is four hours ahead, given this is the lead time for starting up large gas units – specifically combined cycle gas turbines. They added that sometimes notices might in principle even be cancelled without any action being taken – such as if there is a possibility 12 hours ahead of wind generation being a long way from the central forecast, but it turns out not to be. The expert therefore concluded that the notice should not be a cause for concern. Energy minister Michael Shanks insisted in Parliament on Wednesday that electricity supplies were maintained and that no customers lost power.  However, he said Neso - a government body - had now ordered an independent investigation into the claims. In her urgent question, Ms Coutinho told MPs that whistleblowers had warned that the country was close to blackouts. 'I've been approached by multiple whistleblowers within our grid operator,' she said. 'The allegations are that first, on June 23, the operator failed to meet the grid security standards put in place to prevent blackouts. 'Second, that the corporate affairs team interfered with operation decisions. That is not something that the minister denied - putting the reputation of the operator above security of supply. 'And third, that operational decisions are being recorded in live documents with no audit trail. Again, something the minister did not deny.' She previously accused grid bosses of 'risking blackouts to protect Neso's reputation'. Government departments were warned about the risk of power cuts. Mr Shanks replied that there had been no blackouts last month and said that there was no kind of 'emergency situation'. 'Electricity supplies were maintained throughout the June heatwave. No customer demand was disconnected,' he said. 'It did not indicate any kind of emergency situation. Demand was met, and those are the facts.' He later added that although the electricity demand had been met, 'I don't for a second doubt that it was difficult on some of those days, as it was across all of Europe.' Neso instructed a legal firm to conduct an independent investigation into the claims of the whistleblowers, he said, with a report to be delivered to the operator and to regulator Ofgem 'in the coming weeks'. Britain has not suffered a major blackout since 2019 when the Little Barford gas-fired power station in Bedfordshire and the Hornsea windfarm in the North Sea failed at the same time, causing large parts of the grid to automatically shut down. An unprecedented blackout left Spain and Portugal without electricity for several hours last year, leading to questions about the reliability of the electricity supplies in times of stress. A Neso spokesman told the Daily Mail: 'Our interim analysis, as published on our website, show that during an unprecedented period of extreme heat and tight margins across Great Britain and Europe, the electricity system operated securely.  'No customer demand was disconnected, frequency and voltage remained within statutory limits, and no lines or cables were overloaded. 'As is routine following significant operational events, Neso is undertaking analysis of system and market operations and will publish its findings.  'Neso has also commissioned an independent investigation into allegations regarding operational decision-making and record-keeping.'