A “Dunkelflaute” period of weather has sent wind power generation tumbling in the UK, Germany and other parts of northern Europe.
The phenomenon – which translates roughly as “dark wind lull” – describes periods when wind speeds plunge, leading to little to no generation from turbines.
On Tuesday, it meant wind farms were only able to meet 3-4pc of the UK’s electricity demand during the morning and evening peaks, with gas-fired plants instead fired up to meet around 60pc of demand.
The remainder was met by nuclear and biomass power plants, along with solar farms and imports via interconnectors, according to grid transparency data.
A similar phenomenon was seen in Germany, where low wind speeds left the country’s wind farms generating barely 7pc of their nameplate capacity.
There, grid operators had warmed up coal-fired power plants to meet 30pc of the morning’s demand, with another 18pc coming from gas and 12pc coming from solar farms.
Wind is created when two masses of air have a difference in pressure, which is in turn caused by differences in temperature.
Dunkelflautes are caused by static, high-pressure systems that cause weaker-than-normal winds in the areas they cover, along with cloudy weather.
Andrea Bishop, a spokesman for the Met Office, said: “At the moment, we have high pressure dominating the weather and this is helping to keep the wind quite gentle.
“This high pressure is centred to the east of the UK. Furthest away from the high pressure across Northern Ireland and western Scotland, there is slightly more of a southerly breeze blowing.”
Complete drops in wind generation are extremely rare, but sharp declines in output are a well-known issue and one of the central problems grid planners are grappling with as they switch over to weather-dependent renewables.