National Grid uses 'last resort' measures to keep UK lights on

Britain was forced to rely on new "last resort" measures to keep the lights on for the first time on Wednesday after coal power plants broke down and wind farms produced less than one per cent of required electricity.

National Grid used a new emergency scheme to pay large businesses to cut their electricity usage, resulting in dozens of large office buildings powering down their air conditioning and ventilation systems between 5pm and 6pm.

The scheme, which is paid for through levies on consumer energy bills, was introduced last year but had never been called upon before.

National Grid blamed the power crunch on “multiple plant break downs”. Several ageing coal-fired power plants had unexpected maintenance issues and temporarily shut down, experts said, reducing available supplies.

The problem was compounded by low wind speeds meaning most of Britain’s 6,500 onshore and offshore wind turbines were barely generating any power just as demand hit its highest.

UK wind farms have a theoretical maximum capacity of more than 13,000 megawatts, but produced less than 400 megawatts of power for much of the peak demand period – meeting less than one per cent of the UK’s electricity needs, published data suggests.

Britain's 8,000 megawatts of solar panel capacity would also have produced no power during the peak, because it was dark at the time.

• Electricity demand hits highest level - as wind power slumps to its lowest

National Grid first intervened in the market yesterday lunchtime, issuing an alert to power plants that more generation would needed between 4.30pm and 6.30pm.

The alert, called a Notification of Inadequate System Margin, (NISM), was the first to have been issued since 2012.

Short-term electricity prices spiked as a result, with analysts reporting that one power plant was paid £2,500 per megawatt-hour - about 50 times average power prices.

National Grid later announced that it had also had to use a scheme called “demand side balancing reserve” (DSBR) to reduce demand on the Grid by about 40 MW.

The scheme was one of two emergency schemes first introduced last year to help cope with Britain’s tightening power margins, as old coal plants are closed down and not replaced.

The second emergency measure, which has so far not been used, would see a reserve of old power plants fired up.

Businesses that volunteer to take part in the DSBR scheme are paid a retainer, in return for agreeing that they will receive additional payments to cut their demand if needed. National Grid has estimated the scheme will cost consumers about 50p a year.

National Grid had previously said that the schemes would only be used "as a last resort in the event that there is insufficient supply available in the market to meet demand". Until Wednesday it had never actually asked businesses taking part to cut their usage.

Flexitricity, one of the companies coordinating businesses to take part in the scheme, said commercial energy users had reduced power at 46 sites, mostly by “turning down building ventilation”. This was primarily air conditioning at offices, it said.

A spokesman for National Grid insisted that the measures taken on Wednesday did “not mean we were at risk of blackouts”, only that “we needed the safety cushion of power in reserve to be higher”.

Lisa Nandy, Labour’s shadow energy secretary, blamed Government policy for “creating an energy security crisis” while the GMB Union said Britain was in the “bonkers position… where National Grid is using consumer’s money to pay firms to stop work in order to avoid blackouts”.

The Department of Energy and Climate Change declined to comment.