In the first quarter of 2025, Great Britain significantly altered its electricity mix compared to the same period the previous year, increasing the share of natural gas at the expense of wind energy while maintaining a high level of electricity imports, based on official data published by the National Energy System Operator (NESO) in its Monthly Electricity Reports for Q1 2025.

In January 2025, gas accounted for 38.3% of total generation, up 2.6 percentage points from January 2024. This trend held through the quarter, with gas contributing 32.6% in February and 30.7% in March. By contrast, the same quarter in 2024 recorded lower figures: 35.7%, 26.6% and 24.3%, respectively.

Sustained Drop in Wind Power Output

Conversely, wind power saw a marked decline. In January 2024, wind contributed 33.3% to total electricity generation, but this dropped to 26.7% a year later. In February, the decline was 3.3 points (from 34.8% to 31.5%), and in March, it was even steeper: from 32.9% to 26.2%.

Despite reduced wind output, the share of zero carbon electricity sources remained relatively stable. January 2025 recorded 43% from zero carbon sources, compared to 47% the previous year. February and March stood at 48% and 45%, respectively, versus 51% in the same months of 2024.

Carbon Intensity Continues to Improve Despite Gas Uptick

Carbon intensity decreased further during the first quarter of 2025. January saw an average of 168 gCO₂/kWh, close to the 166 gCO₂/kWh in January 2024. February showed clearer progress: 147 gCO₂/kWh in 2025 versus 133 gCO₂/kWh in 2024. In March, carbon intensity reached one of its lowest readings: 146 gCO₂/kWh compared to 127 gCO₂/kWh a year prior.

The system also recorded notable peaks in low-carbon generation, such as 35 gCO₂/kWh at 11:00 on 1 January and 37 gCO₂/kWh at 10:00 on 30 March, showcasing improved efficiency and decarbonisation at optimal moments.

Storage Rises and Solar Power Gains Momentum

Energy storage showed a modest rise, increasing from 0.9–1% during the first three months of 2024 to 1.3–1.5% in 2025—a subtle but steady development, especially in light of growing renewable intermittency.

Solar energy saw a strong surge in March 2025, reaching 6.5% of electricity generation compared to 4.1% in March 2024. While gains in January and February were less pronounced, year-on-year growth was still evident.

Imports Remain Crucial to the Power System

The country’s dependence on electricity imports remained high. In March 2025, imports made up 17.6% of the mix—slightly higher than the 17.2% from March 2024. In January, imports increased from 9.2% to 11.7%, while in February, they remained relatively unchanged: 11.6% in 2025 versus 13.9% in 2024.

These levels highlight a structure still reliant on external energy, particularly in periods of lower domestic renewable output.

Nuclear Remains Stable; Biomass Sees Fluctuations

Nuclear energy remained steady, contributing close to 11% across both years. It continues to serve as the backbone of Britain’s low-emission system.

Biomass, on the other hand, displayed more variation: It peaked at 7% in February 2025—up from 6.6% in February 2024—but dipped to 4.8% in March 2025, compared to 5.3% a year earlier.

A Complex Transition in Motion

Between 25 and 28 TWh were transmitted through the national grid each month in Q1 2025, similar to the same period in 2024. However, the system operated with improved carbon efficiency and increased use of gas and solar power.

Thus, Great Britain’s energy outlook reveals a nuanced transition: greater reliance on fossil-based gas, yet a continuing decrease in carbon intensity, thanks to efficient solar use during key hours, steady nuclear output, and an overall more efficient grid.

The ongoing challenge will be to sustain environmental progress without sacrificing energy independence or reverting to higher fossil intensity, particularly during low-wind seasons.