Britain could see its greenest-ever Christmas Day as renewables dominate power mix

Britain could be heading for its greenest Christmas Day on record, with the electricity system set to run at historically low carbon intensity levels if mild and windy conditions persist through the festive period.

The forecast comes from the National Energy System Operator, which said the grid could beat its previous best performance for 25 December as new renewable capacity continues to come online.

Craig Dyke, a director at Neso, said there was a real possibility that Christmas Day 2025 would record the lowest carbon intensity ever seen on the network. Earlier this year, on 1 April, the grid ran at a record peak of 97.7 per cent zero-carbon electricity, highlighting how quickly Britain’s energy mix is changing.

The current benchmark for the greenest Christmas Day was set in 2023, when the system recorded a carbon intensity of 30 grams of carbon dioxide per kilowatt hour — around five times lower than the level seen in 2018. By comparison, renewables accounted for more than 40 per cent of electricity generation on Christmas Day last year, up sharply from just 1.7 per cent in 2009.

Neso said Britain added an extra 2GW of wind power and 3GW of solar capacity during 2025, taking total renewable generation capacity to a record 53GW. Combined with lower-than-average electricity demand during the festive period, that additional capacity is expected to help push emissions even lower on 25 December.

Earlier this month, strong winds meant turbines were producing enough electricity at one point to power the equivalent of nearly three billion strings of 100-bulb LED fairy lights, underlining the growing role of renewables during winter peaks.

However, while electricity generation may be cleaner this Christmas, environmental groups continue to warn about the wider impact of festive consumption. Research by Material Focus suggests UK households have already thrown away an estimated 168 million light-up Christmas items and other “fast tech” gifts over the past year, while separate studies estimate that 1.1 billion electrical products and 450 million batteries are disposed of irresponsibly each year.

The prospect of a greener Christmas comes as the government pushes ahead with its ambition to reach net zero by 2050. Earlier analysis by Neso found that the UK already spends around 10 per cent of GDP on net-zero-related investment, with costs expected to rise further through the late 2020s before gradually declining in the following decades.

Under Neso’s most ambitious transition scenario, annual costs could peak at about £460 billion by 2029 before falling to around 5 per cent of GDP by mid-century. While a slower transition might reduce near-term spending, Neso has warned that delaying action would leave Britain exposed to far higher long-term costs from climate damage.