Dunkelflaute – a German term that translates to ‘dark doldrums’, also used to describe a period of low wind and solar output. Weather conditions familiar to UK residents eagerly anticipating the first days of Spring in – we can only hope – 8 weeks’ time.
Northern Europe experiences between two and ten dunkelflaute events a year; on average 50 and 150 hours per month during the peak winter months of November, December, and January.
Nuclear power is one of the few technologies capable of delivering reliable, low-carbon base-load energy in answer to how the UK can ensure it keeps the lights during these weather events, or extreme cold snaps, without relying solely on gas or imported electricity.
The UK is now faced with the challenge of maintaining base-load capacity as older nuclear power stations begin to decommission, and decisions made in the year ahead will be crucial to delivering the government’s Clean Power 2030 target.
The importance of a broad approach to nuclear
Whitehall discourse surrounding Small Modular Reactors (SMRs) has grown in recent years, and there is no doubt that SMRs bring unique strengths: lower upfront costs, faster construction due to modular design, and the ability to deploy closer to sites of demand, such as industrial clusters or data centres. They also offer flexibility for localised energy solutions and grid resilience, particularly in areas with limited infrastructure. However, while SMRs are promising, they cannot replace the scale of output delivered by gigawatt plants.
Gigawatt-scale nuclear power remains fundamental for the UK’s base-load energy requirements — ensuring reliable power when renewable sources such as wind and solar falter. Yet, the National Energy System Operator’s (NESO) Clean Power 2030 report highlights a looming reduction in nuclear capacity from 6.1 GW in 2023 to between 3.5-4.1 GW by 2030, at a time when it is crucial to mission delivery to scale up base-load capacity.
The same report states that achieving the 2030 clean power goals will require up to 220 GW of installed generation and storage capacity. Achieving this goal without a clear commitment to large-scale nuclear appears unrealistic.
Whilst the long-term output and reliability of large gigawatt nuclear provides a bedrock for clean energy transition, it demands significant upfront investment and planning. Furthermore, NESO’s Clean Power 2030 report stresses the importance of scalable solutions to meet the dual challenges of industrial decarbonisation and growing energy demand.
The only way forward, therefore, requires a mixed approach that leverages both technologies, balancing innovation and scale. While SMRs enable innovative decentralised, cost-effective deployment on the one hand, gigawatt nuclear remains irreplaceable in providing energy output at scale on the other. As the government responds to NESO’s recommendations, investment in smaller-scale nuclear solutions mustn’t detract from the critical role of gigawatt nuclear in meeting long-term energy demands.
The task ahead in 2025
The government faces critical decisions in the nuclear space in the year ahead and there are numerous rewards available if they get this right, from advancing towards clean power targets and boosting investor confidence in the UK, to reaping growth and productivity rewards outside of economic centres.
Government must determine the most effective approach to funding and deploying Small Modular Reactors (SMRs) to complement the UK’s energy mix; advance the development of Hinkley Point C and secure financing for Sizewell C; boost investor confidence in nuclear infrastructure by finalising funding mechanisms like the Regulated Asset Base (RAB) model; integrate new nuclear assets within the power grid and ensure workforce and supply chain readiness to meet the nuclear challenge.
The Government’s £410 million investment of R&D funding to secure the UK’s fusion programme in 2025 to 2026 announced this month will be welcome news, advancing innovations that will support the long-term viability of nuclear energy in the UK.
A partnership approach
Businesses can play a crucial role in supporting the UK government in this mission. From committing to long-term Power Purchase Agreements (PPAs) and collaborating with NESO to promote nuclear infrastructure to supporting R&I, advocating for grid reforms and investing in the workforce to address the talent gap, businesses can help support nuclear roll-out and contribute to a secure, low-carbon energy future.
With bold, coordinated action in 2025, the UK can lay the groundwork for a cleaner energy future. By combining innovation, scale, and strategic investment, the UK can ensure its lights stay on – regardless of the weather.
