Rising summer temperatures pose a blackout threat to the UK’s electrical grid, with crucial equipment such as transformers and cabling ill-equipped to cope with the climate of the future. In a worst-case scenario, extreme heat could cause multiple equipment failures across the country, triggering widespread power outages similar to those seen last month in Spain and Portugal.
The UK’s Met Office predicts temperatures of 40°C (104°F) or more could be recorded in the country every three to four years by the end of the century unless urgent action is taken globally to reduce emissions. The UK’s energy infrastructure is largely not equipped to handle such extreme temperatures, by the consultancy Ricardo, produced in partnership with the UK government.
The analysis rates crucial elements of the power sector network – including underground cabling, transformers, service lines and circuit breakers – as among the most vulnerable parts of the system to extreme heat. UK transformers, for example, are designed for ambient temperatures of up to only 40°C before they lose capacity and become vulnerable to failure.
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The report warns of the potential of “high impact” failures of energy assets at warming levels of 2°C, particularly in East Anglia and the South East, where future summer temperatures are expected to be the most extreme. “Some of these components, when there are faults, they can cause blackouts,” says at Ricardo. Others will be able to only operate at reduced capacity, curtailing the amount of power available to consumers, he says.
The UK’s electricity system is designed to operate effectively within designated temperature ranges that cover the winter and summer seasons. But recent years have brought sharp spikes in temperatures that are well outside the bounds of what meteorologists would consider normal for the country’s climate. For example, in July 2022 the UK experienced a severe heat wave, with temperatures exceeding 40°C for the first time in the country’s history. At the time, the heat wave put the power grid under considerable strain, with the network running at reduced capacity because of the high temperatures while trying to meet increased demand for cooling. Analysts at Cornwall Insight .
Managing such extreme heat is expected to become even more difficult in the UK, as more people install cooling systems such as air conditioning in their homes and offices. That makes the system more vulnerable to serious impacts if extreme heat causes equipment failure, says at Newcastle University, UK. “At the moment, if you get potential for damage on the system, it’s not too problematic,” she says. “We can do some curtailment, we can do some adjustment. But in the future, when we’ve got higher air conditioning demand, there’s going to be quite a lot of strain on the grid if we have a heat wave.”
Last month Spain and Portugal suffered a widespread power blackout, the largest in Europe for two decades. The causes are still unclear, but it looks likely to have been triggered by generation loss from multiple electricity generators simultaneously that caused a collapse of the wider system, demonstrating the potential damage this kind of cascade effect could inflict.
The Ricardo study looked only at the vulnerability of individual grid components to extreme heat. But if multiple pieces of equipment fail at the same time, that could trigger a widespread power failure, warns at the University of Strathclyde, UK. “If you’re in a hot condition, one thing has gone out because things are hotter, and you don’t know what the hell is actually going on. You’re vulnerable to something else coming out before you have had a chance to correct the first thing,” he says, potentially leading to a situation like that seen in Spain and Portugal. “It is the combination of outages that you’re most worried about.”
