On the link between weather regimes and energy shortfall during winter for 28 European countries

Increasing the proportion of energy generation from renewables is one of the necessary steps towards reducing greenhouse gas emissions. However, renewable energy sources such as wind and solar are highly weather sensitive, leading to a challenge when balancing energy demand and renewable energy production, and therefore in managing energy shortfall. Identifying periods of high shortfall, here defined as when electricity demand significantly exceeds production by renewables, and understanding how these periods are affected by weather, is therefore critical. We use a previously constructed energy dataset derived from reanalysis data for a fixed electricity system to analyse the link between weather regimes and periods of high shortfall during the boreal winter for 28 European countries. Building on previous work we provide a perspective spanning from the subcontinental scale to individual countries. For each country we identify days with critical energy conditions, focusing on those with high energy demand, low production from wind and solar, and high energy shortfall. We show that high shortfall is more driven by demand than by production in countries with colder climates or less installed wind generation capacity, and is more driven by production than by demand in countries with warmer climates or more installed wind generation capacity. Of the six North Atlantic weather regimes considered here, only a subset are found to favour the occurrence of high shortfall days. In particular, blocking-type weather regimes affect large parts of Europe, suggesting that shortfall days can occur across multiple countries simultaneously. Furthermore, if a subset of countries experience shortfall days, neighbouring countries have a higher likelihood of also experiencing shortfall days. Motivated by this result, we examine the hypothetical impact the coldest European winter of the 20th century, 1962/63, would have had on the present-day energy system. It is found that the persistent blocking conditions associated with that winter, if they occurred today, would lead to higher demand and shortfall across large parts of Europe during most of the winter, and would be extreme in this respect compared to other winters.