UK power mix shifts as renewables surge but gas use edges up

5 January 2026

Renewable energy supplied a record share of the UK’s electricity in 2025, but gas-fired generation also increased as demand rose and nuclear output fell, according to analysis by Carbon Brief.

Wind, solar and biomass together provided 47% of electricity supplies, the highest level on record. Gas accounted for 28%, while nuclear dropped to 11%, its lowest share in around 50 years. Total electricity demand rose by 1% to 322 terawatt hours, marking the second consecutive annual increase after two decades of decline. The figures indicate that demand growth was driven by rising numbers of electric vehicles, greater use of heat pumps and expanding data centres.

Carbon Brief attributes the rise in gas generation, which increased by 5% to 91TWh, to several shifts in the power system. The UK completed its first full year without coal power following the closure of its last coal-fired plant in 2024. At the same time, nuclear output fell by 12% as much of the remaining fleet was offline for refuelling and outages. Net electricity imports also declined slightly as exports increased.

Renewable generation reached a combined 152TWh, up 6% on the year. Wind output rose to 87TWh as new capacity was added, while solar generation climbed by nearly a third to 19TWh, helped by a particularly sunny year and an expansion in installed capacity. Biomass generation rose modestly to 41TWh, although output is expected to fall later in the decade as government support for some plants is reduced.

Despite the record contribution from renewables, the carbon intensity of UK electricity increased slightly. Average emissions rose to 126 grams of carbon dioxide per kilowatt hour, up 2% from the record low set in 2024, reflecting the higher use of gas.

The National Energy System Operator recorded a new high for low-carbon operation of the transmission grid, reaching 97.7% for half an hour in April. However, it did not meet its target of running the system without any fossil fuels for a full 30 minutes during the year.