Extreme weather “energy droughts” in renewable-heavy power systems can cause severe supply shortfalls, requiring rarely used but essential backup capacities to ensure long-term and short-term energy resilience.
If Europe’s future power grid is going to be clean, reliable, and affordable, it needs to do more than just generate green electricity — it has to survive the worst weather nature can throw at it 🌨❄️.
In a fossil-fuel era, sudden changes in supply or demand could be met by ramping up gas or coal plants. But in a net-zero future dominated by wind and solar, there’s no “emergency coal button.” Instead, the grid has to rely on flexibility, backup, and smart planning.
A recent research takes a deep dive into how extreme weather impacts energy systems, using 80 years of historical weather data (1941–2021) and advanced European power system modeling. The key focus? Energy resources adequacy — making sure the grid has enough capacity to meet demand — even during “energy droughts” when renewable output plummets.
In a highly renewable power system, the most dangerous scenario isn’t a hot summer — it’s a cold, still winter week.
Between November and February, Europe can experience low wind, minimal sunlight, and high heating demand at the same time. These “energy droughts” are rare — making up less than 1% of all hours in a year — but they can bring the grid to its knees.
During these periods, wind generation can drop from its normal 50% winter share to just 15–30%. Solar? Almost negligible in deep winter. Meanwhile, electricity demand surges due to heating. This creates net load spikes — the amount of demand left after renewables — reaching up to 540 GW (with total load peaking under 700 GW).
💡 Fun fact: The study found that these severe events, called System-Defining Events (SDEs), happen about every two years — meaning every major piece of infrastructure will likely face one during its lifetime.
The team breaks down flexibility into three layers:
Includes nuclear, biomass, hydropower, and pumped hydro storage — about 300 GW in total. These workhorse plants can handle much of the regular balancing but fall short for ~1000 hours per year in extreme cases.
Batteries — providing 100–230 GW of short-term balancing power — are perfect for smoothing daily fluctuations. But their limited energy storage means they can’t cover multi-day droughts.
The “last line of defense” — fuel cells or hydrogen turbines — run only during the toughest 50–100 hours per year. These are expensive to keep ready, with annual capacity factors as low as 4%, but they can make the difference between lights on and blackouts.
The mix changes depending on the weather year — some years need almost no backup; others require up to 77 GW of resilience capacity.
Not all extreme events are created equal. The study classifies SDEs into four main types:
One might think expanding transmission would solve the problem — moving surplus power from one region to another. The study tested a 25% increase in transmission and even doubling capacity.
The result? It helps reduce overall system costs, but doesn’t stop the worst events — because during these SDEs, the lack of wind is often continental-scale, especially around the North Sea where much of Europe’s wind capacity sits.
Similarly, enforcing national self-sufficiency (requiring countries to produce 70–90% of their own electricity) had little effect on the type or frequency of SDEs.
Resilience back-ups — like hydrogen turbines or gas plants (in scenarios with limited CO₂ allowances) — are rarely used but essential. This creates a big problem:
In fact, the study found that in none of the 80 years modeled did backup plants recover their capital costs purely from market prices.
The research draws a crucial distinction:
The kicker? The most extreme short-term events did not occur in the same years as the toughest long-term years — meaning planners need to prepare for both types.
The authors suggest several ways forward:
This study is a wake-up call for anyone designing net-zero power systems. Weather isn’t just a short-term operational headache — it’s a structural planning challenge that can dictate billions in infrastructure spending.
Europe’s energy future will depend not only on building more wind and solar, but on making the whole system weather-proof — with the right mix of storage, backup, and smart market design.
Because when the next cold, windless week hits — and it will — the grid can’t afford to be caught shivering.
🌬 Energy Drought - A period when renewable power generation (like wind and solar) is unusually low — often during cold, still winter days — making it harder to meet demand.
⚡ Net Load - The electricity demand left over after subtracting the power produced by renewables — basically, what the rest of the grid still needs to supply.
🛡 Resource Adequacy - The ability of an energy system to have enough generation and storage capacity to meet demand at all times, even during extreme conditions.
🔋 Daily Balancing - Using short-term storage, like batteries, to smooth out the ups and downs of renewable generation over hours or a single day.
🏭 Dispatchable Capacity - Power plants (like nuclear, biomass, or gas) that can be turned on or ramped up whenever needed to match demand.
🚨 Resilience Back-Up - Rarely used but crucial power sources — like hydrogen turbines — kept on standby to handle extreme weather shortages.
💰 Shadow Price - A model-based indicator showing how much it would cost to meet one more unit of demand — spikes here signal stress on the system.
📆 Long-Term Resilience - The system’s ability to handle tough weather years with low renewable output and high demand over months.
⏳ Short-Term Resilience - The system’s ability to cope with sudden, severe shortages lasting days or weeks.
🔄 Cascading Event - When several smaller energy shortage events happen close together, straining reserves over time.
Source: Aleksander Grochowicz, Hannah C. Bloomfield, Marta Victoria. Preparing for the worst: Long-term and short-term weather extremes in resource adequacy assessment. https://doi.org/10.48550/arXiv.2508.05163
From: Technical University of Denmark; Newcastle University.
