Understanding Dunkelflaute and its Impact on Energy Supply

Turbines transform wind into energy, making good use of a breezy day. Likewise, during sunny spells, solar panels harness the sun's beams to produce power.
However, not every day is ideal for generating renewable energy. What happens in the absence of wind and sunlight?
Enter Dunkelflaute, a period marked by negligible wind or solar generation. The phenomenon has become more frequent in Europe, especially during the cold winter months, sometimes extending for several days or even weeks.
Deciphering Dunkelflaute
Authored by Anouk Honoré and Jack Sharples from the Oxford Institute for Energy Studies, a paper called 'Dunkelflaute: Driving Europe Gas Demand Volatility' delves into the repercussions of Dunkelflaute periods.
The study suggests significant shifts in energy supply dynamics as Europe increasingly leans on renewable sources. As renewables gain traction, conventional gas-fired plants are tasked with addressing power supply gaps due to their ability to quickly compensate for the intermittent nature of wind and solar power.
Dunkelflaute episodes occur predominantly during cold spells, putting additional pressure on the gas systems that need to manage abrupt fluctuations in heat and power demand.
The report adds that, because improved renewables availability is coupled with higher nuclear generation, fossil fuels have been pushed down the merit order most of the time, meaning gas plants are moving further away from providing baseload power.
Wind power introduces a new layer of unpredictability to gas demand, characterised by peaks whose size and duration are challenging to forecast. Although the linkage between total gas demand and prices isn't strongly correlated, the report asserts that "with limited short-term flexibility on the demand side — for now, this should improve in the future — flexible and rapidly available gas supply will be increasingly crucial to balance the system in Europe."
Insights from the Dunkelflaute report
Key messages from the report highlight ongoing reliance on gas-fired power stations, essential for ensuring energy flow when renewable sources fall short. The tendency for Dunkelflaute events to coincide with colder temperatures amplifies demand for heating, further straining gas supplies.
Four primary takeaways from the study are:
- Gas-fired power plants remain the primary source of flexibility in Europe’s power system: These facilities are crucial for managing irregularities in wind energy generation.
- The growing share of wind power in the energy mix creates unpredictable peaks in gas demand: Addressing these demands requires agile and strategic planning.
- The relationship between the power sector and gas demand has evolved: Gas use for power has become less predictable yet more vital during high-price periods.
- With reduced flexibility on the demand side, the European market demands flexible supply solutions: In 2024, this flexibility predominantly comes from gas storage and liquefied natural gas (LNG) imports.
Brian Marrs, Senior Director of Energy Markets at Microsoft, explains: "We need more clean firm generation, storage, grid infrastructure, demand response, et cetera, to tame Dunkelflaute — and today’s gas market has risen to the challenge.”
He also points out that seasonal gas flexibility must continue to adapt to match the weather-driven seasonality in GWs (gigawatts) of generation.
Industry perspective on Dunkelflaute
Criticism and concerns echo through the industry regarding the implications of Dunkelflaute.
Ebba Busch, Sweden's Deputy Prime Minister, comments: “When there is no wind, we get high electricity prices with this failed electricity system.
“Germany’s energy system isn’t right. It is a result of decommissioned nuclear power. When it’s not windy, we get high electricity prices.”
Ebba advocates for a more robust electric supply across Europe to help stabilise prices.
Amund Vik, Senior Advisor to Eurasia Group, stresses the importance of integration for a secure energy system amidst transitions.
And Gerald Kaendler, Director Asset Management at Amprion, highlights: “Dunkelflaute is the worst-case scenario for a renewables-based power system,” highlighting the challenges of periods with inadequate wind and solar power.
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