Due to the energy transition, weather plays an increasingly significant role in the European energy system. Wind and solar energy and hydropower are highly dependent on the weather, as is energy demand, which depends on temperature. Unfavorable weather can therefore lead to shortages of sustainable energy – also known as energy droughts. If multiple countries experience an energy drought simultaneously, problems can arise. In a new study, we investigate which large-scale weather patterns lead to such simultaneous energy droughts. Understanding this is essential for a reliable energy system, now and in the future.

Simultaneous Energy Droughts and Energy Exchange  

Unfavorable weather conditions can cause energy droughts. Energy droughts are expressed based on the residual demand: the electricity demand minus the sustainable generation from wind, solar, and hydropower. The duisterluwte – a period with little wind and sun – from last November led to an energy drought with high electricity prices.

The electricity system of the countries in Europe is strongly interconnected; there is a continuous trade of electricity. In the case of simultaneous energy droughts, there is less room for that trade. Other solutions are then needed, such as previously stored energy from batteries or reservoirs. Because energy droughts usually arise from large-scale weather patterns, simultaneous shortages in multiple countries are a real risk. To illustrate this, we show in Figure 1 a simultaneous energy drought in countries X and Y, while country Z has an energy drought at another time.  

Neighboring Countries with Different Sensitivities 

Neighboring countries do not always have the same sensitivities to the influence of weather on electricity demand and supply. For an energy drought, both local weather and the local energy system play a role. In Northwest Europe, there are many wind turbines, so wind speed plays a larger role than, for example, in Poland. In Poland, energy droughts mainly occur due to high demand driven by severe cold (Figure 2). In Germany, with a larger role for wind energy, energy droughts occur due to a combination of cold and little wind.   

This difference in weather sensitivity has direct consequences for the likelihood of simultaneous energy droughts: if Germany has an energy drought, there is a 50% chance that Poland will also experience it at the same time, and vice versa. Figure 3 shows the likelihood of simultaneous energy droughts between all neighboring countries in Europe. Blue lines between countries show that there are few simultaneous energy droughts, which is favorable for energy security. Red lines indicate a risk, as simultaneous energy droughts often occur.