As the UK transitions towards a cleaner energy system, a new weather phenomenon has been making headlines, highlighting the urgent need for reliable low-carbon power. “Dunkelflaute,” a German term meaning “dark doldrums,” describes periods of cold, still, and overcast weather when wind and solar power output drops dramatically. Recent data from Electric Insights underscores the challenge Britain faces in securing energy supply during these periods, reinforcing the necessity for flexible and sustainable alternatives.
Over the past winter, the UK encountered two significant Dunkelflaute episodes. The first, in mid-December, saw wind generation—a major power source—plummet to just 6% of total supply. To compensate, gas-fired power plants surged to a record-high output, meeting over 73% of demand and driving electricity prices to extraordinary levels. A similar event occurred in early January, with power prices soaring to £2,900/MWh—forty times the average. These incidents illustrate the vulnerability of the current energy mix, which still leans heavily on fossil fuels when renewable output falls short.
This winter’s energy challenges underscore the obstacles on the path to a clean power system by 2030. The prolonged cold spell and diminished wind supply forced the UK to rely on gas and imported electricity, drawing down national gas reserves to critically low levels. Without additional investment in low-carbon flexibility solutions, Britain risks further price volatility and potential supply shortages. A robust approach—combining new and existing technologies—is imperative to enhance energy security and reduce dependence on fossil fuels.
Beyond gas, other power sources stepped in to bridge the gap during Dunkelflaute. Biomass and hydro plants increased output by 40% and 60%, respectively, on peak demand days. However, Britain’s relatively limited capacity in these areas restricted their overall impact. In previous years, coal would have supplemented supply, but with the last coal station closing in September, that option is no longer available. Pumped hydro and battery storage provided short-term relief, but their capacity remains insufficient for multi-day shortfalls.
International energy interconnections also fell short during the crisis. On December 12th, when Britain most needed imported electricity, cross-border supply dropped by 50% as neighbouring countries experienced the same wind drought. This highlights a fundamental challenge of relying on interconnection—when weather patterns affect entire regions, competition for limited electricity drives up costs and leaves gaps in supply.
Gas remains the only large-scale flexible energy source in Britain, posing significant risks. Economically, heavy dependence on gas exposes consumers to volatile price swings, as seen during the recent energy crisis. Britain’s electricity prices are disproportionately linked to gas prices compared to other European nations, due to limited alternatives like hydro and biomass. The result is that gas dictates the cost of power 98% of the time, despite only providing about one-third of total electricity.
Security of supply is another growing concern. The tight capacity margins in December and January led to the issuance of rare Capacity Market Notices, a mechanism designed to prevent blackouts. The retirement of coal plants, the ageing of nuclear reactors, and the uncertain future of biomass exacerbate the challenge, particularly as demand for electricity is set to rise with the adoption of electric vehicles, heat pumps, AI, and data centres. Without strategic expansion of generation capacity, such warnings will become more frequent.
The carbon challenge remains paramount. Gas is now the most polluting fuel in Britain’s power mix, and with the government’s goal of achieving a near-zero-carbon grid by 2030, its role must be significantly reduced. Current plans aim to limit fossil fuels to just 5% of electricity generation, down from 25% today. However, to ensure reliability, gas capacity is expected to remain in place for backup during periods of extreme low renewable output. This raises questions about market structures—whether gas plants will need to charge higher prices to remain viable or if the industry will shift towards capacity payments rather than purely output-based compensation.
Scaling up renewables alone will not be sufficient; the variability of wind and solar power demands a broader strategy. Both the Climate Change Committee (CCC) and National Electricity System Operator (NESO) acknowledge the need for a balanced approach, incorporating flexible low-carbon generation, long-duration energy storage, interconnectors, and limited but strategic gas use. Looking ahead, policy frameworks anticipate new technologies—such as carbon capture and storage (CCS), hydrogen, and long-duration storage—playing a key role from 2030 onwards. These solutions are not yet widely deployed, making it crucial to define clear pathways for scaling them up while managing costs for consumers.
By proactively planning for Britain’s future energy landscape, policymakers, industry leaders, and investors can break free from the cycle of expensive, volatile gas dependence. Instead, they can seize the opportunity to build a cleaner, more stable, and cost-effective power system that ensures both energy security and long-term sustainability.
Drax Group plc (LON:DRX), trading as Drax, is a power generation business. The principal downstream enterprises are based in the UK and include Drax Power Limited, which runs the biomass fuelled Drax power station, near Selby in North Yorkshire.
