The UK's electricity grid operator has warned of a short supply over the next few days due to generator outages and a lull in autumn winds.
The National Grid said on Oct. 14 that it was exploring various measures to create a buffer to avoid potential outages, like the one last summer that left 1 million homes without power.
"We’re forecasting tight margins on the electricity system over the next few days owing to a number of factors including weather, import and export levels and availability of generators over periods of the day with higher demand," the National Grid said in a statement.
"Unusually low wind output coinciding with a number of generator outages means the cushion of spare capacity we operate the system with has been reduced."
Power outages in the UK are rare. The last blackout was over a year ago and lasted for only one hour.
In an update on Oct. 15, the National Grid said that margins are currently "adequate" and it will continue to monitor the situation through the weekend.
According to the National Grid, last month one-fifth of the power supply came from wind, "in spite of unusually calm British weather during the middle of September."
The latest announcement may fan concerns about over-reliance on wind power, which critics say is unreliable compared to gas or nuclear power.
Growth in Renewable Energy
Renewable energy has been a rapidly growing source of electricity in the UK. According to government data, 47 percent of UK electricity generation came from renewables in the first quarter of 2020, compared to 36 percent from the same time in the previous year.
The UK has the biggest offshore wind market. The government in March lifted a moratorium on onshore wind turbine subsidies, ahead of committing to a goal to reduce carbon emissions by 2050 to zero.
Last week, the prime minister announced a push to quadruple offshore wind capacity over the next decade.
In August last year, a single lightning strike (pdf) took out two power generators, causing the worst blackout in a decade that left more than 1 million people without power.
Dieter Helm, a University of Oxford professor and government adviser on energy policy, wrote at the time: "The power cut revealed just how fragile the system is becoming as it relies on more and more intermittent renewables generation. This may not have caused the power cuts, even if a wind farm drops off, the intermittency of the capacity on the system makes it harder to secure supplies. It is just a fact that a power system with lots of intermittent renewables is harder to manage."
He said that despite power cuts being rare, the outage also revealed the fragility of the system.
"If power cuts can happen when just two power generators drop off, then something fundamental has gone wrong."