Wood Mackenzie Study Reveals Critical Risks of Europe's "Dunkelflaute" Renewable Energy Droughts

A comprehensive new study by Wood Mackenzie reveals the growing challenge of "dunkelflaute" – prolonged periods of low wind and solar generation – as Europe transitions to renewable-dominated power systems. The research shows these events are driving extreme price volatility and exposing critical vulnerabilities in energy security across the continent.

Dunkelflaute is an increasingly familiar concept in European power markets, especially following two widely covered events in November and December 2024.

According to the report “Weathering the lulls: the risks and opportunities of dunkelflaute,” On average, European markets will be exposed to 1.6 dunkelflaute events annually, although significant regional variation exists. Northern markets, especially those relying on offshore wind, suffer the greatest exposure, due to correlated wind fleets and limited spatial diversity. Southern European markets have less dunkelflaute risk, as midday solar remains strong even in winter, aligning more closely with peak demand and enabling effective load shifting via battery storage.

For example, Belgium experiences the highest frequency with 3 events per year, while Portugal records zero. Events are most prevalent between November and January, with 41% lasting longer than 3 days.

Extreme Market Consequences

According to the report, market consequences range from extreme prices to dramatic shifts in the power supply mix. In Germany, the prices observed during just two dunkelflaute events in 2024 were sufficient to generate over 50% of the wholesale revenues of gas peaker plants. During November 2024's event, German intraday prices spiked to €820/MWh. Gas and coal generation ramped up dramatically, with German imports averaging 10.5 GW over three days.

The Growing Challenge

"As Europe transitions to a power system dominated by variable wind and solar, understanding these extreme weather events is essential," said Matthew Campbell, Senior Research Analyst, European Power at Wood Mackenzie.

The study reveals three main drivers of dunkelflaute frequency:

1. Wind resource distribution – geographic concentration increases vulnerability
2. Solar irradiance levels – particularly winter availability in northern markets
3. Supply-demand synchronicity – misalignment between renewable generation and peak demand

“Our research shows that scarcity events will increasingly drive dispatchable asset revenues, with the business case for new flexible generation hinging on revenue opportunities during limited low-renewable periods each year,” said Campbell. “Despite declining utilisation rates, gas-fired generation remains system-critical, emphasizing its increasing value across many European markets.”

Looking Ahead to 2030

Wood Mackenzie's 2030 analysis of Germany shows that during dunkelflaute periods, thermal generation will remain essential, with gas and coal, in just one event, being called upon to supply 40% of load in Europe's largest market and net imports exceeding 20 GW.

"Energy policy, planning frameworks and market arrangements should explicitly prioritise spatial diversification over more blinkered progress-to-target led approaches, especially in markets with the highest exposure to these events,” said Campbell. “What should really focus policymakers’ minds is our finding that the coldest days are disproportionately associated with low wind output, raising the risk of tight supply during periods of increased demand and highlighting the increasingly essential role of targeted capacity mechanisms in market design.”

Caption: The highest 1% of demand days in Belgium experience an average wind capacity factor of only 15%.