Introduction
The UK’s electricity sector has reached a historic milestone as the carbon intensity of its power generation fell below 100 grams of carbon dioxide per kilowatt-hour (gCO₂/kWh) between April and June 2025. This marks a monumental step forward in the United Kingdom’s decarbonisation journey. The achievement is attributed to a combination of extensive renewable energy deployment, the phasing out of coal, and smarter grid management, further positioning the UK as a leader in clean energy.
Understanding Carbon Intensity
Carbon intensity measures the amount of CO₂ emitted per unit of electricity produced, a critical metric in assessing the environmental footprint of power generation. Lower carbon intensity means cleaner electricity, which directly contributes to reducing national greenhouse gas emissions. Historically, the UK has made considerable strides in lowering carbon intensity by shifting away from fossil fuels towards renewables like wind, solar, and nuclear energy.
What Made This Achievement Possible?
Several factors converged to enable the carbon intensity to drop below 100 gCO₂/kWh for the first time:
- Record Renewable Output: During spring 2025, Britain experienced one of its sunniest seasons in decades, boosting solar generation significantly. Solar capacity exceeded 20 GW with additional installations adding to the grid’s clean energy supply.
- Coal Phase-Out: Britain fully retired coal power by late 2024, eliminating one of the dirtiest forms of electricity generation.
- Reduced Natural Gas Usage: Gas-fired power, though still vital for balancing, shrank in share as renewables scaled up and imports supplemented supply.
- Grid Flexibility: Advances in energy storage, demand-side response, and grid balancing enabled greater integration of variable renewables without compromising stability.
The Scale of Improvement
To place the achievement in perspective, carbon intensity stood at over 450 gCO₂/kWh just a decade prior. Now, up to 40% of Britain’s electricity demand at peak during May 2025 was met by solar alone on some days, with wind and nuclear adding substantially to the clean mix. On June 10th, the grid recorded an extraordinarily low average carbon intensity of 28 gCO₂/kWh— the cleanest day in British history.
This shift translates into real and immediate benefits for consumers and businesses, who now can power their electricity needs with a far smaller carbon footprint, effectively lowering the overall environmental impact of day-to-day electricity use.
Broader Implications for the UK’s Net Zero Goals
Achieving sub-100 gCO₂/kWh carbon intensity is a vital milestone on the path to net zero emissions, reflecting commitments under the UK’s Sixth Carbon Budget and progress towards a decarbonised power sector by 2035.
However, the system also faces new challenges. Higher electricity demand during hotter summers strains the grid, while grid operators confront the complexity of integrating ever-growing shares of variable renewable generation. Continued investments in storage, demand flexibility, and grid infrastructure remain essential to sustain and improve upon this performance year-round.
Role of Solar Power and Battery Storage
Solar energy’s rapid expansion plays a central role. The addition of over 3 GW of solar capacity in recent years has enabled unprecedented contributions to the grid, especially during sunny days in spring and early summer. Yet, matching solar output with consumption requires effective energy storage solutions.
Battery storage systems alleviate variability by storing excess solar energy during peak production and releasing it when demand spikes or solar output dips. Companies like Atlantic Renewables are helping homes and businesses install integrated solar plus storage systems that lower carbon footprints while providing reliable power.
Looking Ahead: Maintaining Momentum
Although the milestone is historic, maintaining carbon intensity below 100 gCO₂/kWh consistently requires ongoing effort. The UK must:
- Accelerate grid-scale storage and interconnectors
- Expand offshore wind and other renewables
- Continue electrification of transport and heating sectors
- Upgrade grid management for flexibility and resilience
Achieving these will help meet climate goals and boost energy security.
The UK’s electricity sector crossing the milestone of under 100 grams CO₂ per kilowatt-hour marks a powerful statement on how far clean energy has come. This progress is driven by policy, commitment to renewables, and innovation. Yet, with new challenges ahead, sustained focus on cleaner generation and smarter grid operation is crucial to keep Britain on the path to a net zero future.
Get in Touch
For those interested in reducing energy emissions through solar power and battery storage, Atlantic Renewables offers expert guidance and installation services to help achieve sustainability goals. Contact the team today on 0161 207 4044 for consultations and bespoke energy solutions.
