Fuel Type Breakdown
Britain’s electricity generation in September 2025 was led by wind, which contributed 35% of the energy mix, its highest September share in the past five years. This represented a 9 percentage point increase compared to September 2024 and outpaced gas generation by 13 percentage points, reinforcing wind’s continued dominance as Britain’s leading power source.
Gas, meanwhile, supplied 22% of electricity in September 2025, marking its lowest September contribution in the past five years and half of the share recorded in September 2022. This decline highlights ongoing progress in reducing reliance on fossil fuels.
Electricity imports accounted for 15% of Britain’s generation mix, consistent with September 2024 but remaining substantially higher than in 2021 (10%), 2022 (2%), and 2023 (11%). This sustained level reflects continued dependence on cross-border electricity flows to balance domestic supply.
Nuclear power contributed 10% to the mix, down from 16% in September 2024 and below the levels seen in 2021 (16%), 2022 (15%), and 2023 (17%). This marks a continued period of reduced nuclear availability.
Solar generation delivered 7% of Britain’s electricity in September 2025, its highest September share in the past five years and 1 percentage point higher than in September 2024. This record contribution highlights solar’s growing role in supporting Britain’s late-summer energy demand.
Storage technologies supplied 2% of the mix, up 1 percentage point year-on-year and the highest September contribution in the last five years, signalling ongoing improvements in grid flexibility and battery capacity.
Biomass contributed 7% to the mix, 1 percentage point lower than in September 2024 but still representing its second-highest September share in the past five years. Hydropower remained steady at 2%, consistent with levels in 2023 and 2024, and 1 percentage point above those recorded in 2021 and 2022.
Coal remained absent from the generation mix, continuing Britain’s phase-out of coal-fired power.
Zero-Carbon Sources & Carbon Intensity
Zero-carbon sources, including wind, solar, nuclear, and hydro, delivered 67% of Britain’s electricity in September 2025, the highest share of any month on record and nearly 30 percentage points higher than in September 2021. This milestone reflects the steady structural shift toward a cleaner, more sustainable energy system.
Carbon intensity for September 2025 fell to 112 gCO₂/kWh, the lowest September figure in the past five years and 45% below the level recorded in September 2021, underscoring substantial progress in reducing emissions from electricity generation.
Over the longer term, the 12-month rolling average for zero-carbon generation remained at 52%, consistent with the previous period and indicating a short-term plateau in renewable expansion. In contrast, the rolling average carbon intensity rose by 8% to 133 gCO₂/kWh compared with the previous 12 months, signalling the importance of accelerating clean energy deployment to sustain downward momentum.
Concluding Remarks
September 2025 marked a strong month for Britain’s renewable generation, led by record wind output and growing solar capacity. Together, these sources helped deliver the highest September share of zero-carbon electricity in five years, driving carbon intensity to new lows.
However, the decline in nuclear generation and continued reliance on imports highlight the need for further investment in domestic clean energy infrastructure and flexible technologies. While progress in storage and renewable deployment is evident, maintaining long-term momentum will be essential to achieving sustained reductions in carbon intensity and strengthening Britain’s energy resilience.
Britain's Electricity Summary Charts
Monthly Statistics
12-Month Rolling (Average) Statistics
To explore more insights, visit our interactive renewables map
here.
Data source: National Grid ESO 2025
(https://www.nationalgrideso.com/electricity-explained/electricity-and-me/great-britains-monthly-electricity-stats)