How much extreme weather events have affected European power generation in the past three decades?

Extreme weather events (EWE) can affect energy supply, particularly when energy systems are significantly reliant on renewable energy sources, highly vulnerable to climate and weather conditions. We combine observational energy data from EUROSTAT with records of EWE, between 1990 and 2019, to evaluate European power plants capacity factors (CF) responses to those events. Using a statistical compositing analysis, we show that years with floods and storms increased annual European hydropower CF by 7 and 5.8%, respectively, compared to non-EWE years, while CF of fossil power plants decreased (-2.8%). Similar behaviours are found for Central and Mediterranean countries. From 1993 to 2004 to 2005-2016 European hydropower tripled during floods and quintupled during storms suggesting that the events are becoming more severe or there is more efficient water use. On the contrary, from 1993 to 2016, in every year with droughts/heatwaves the European hydropower decreased (-6.5%), with a subsequent increase of fossil CF (2.3%). Such behaviour is also observed across Central and Eastern Europe. Cold waves negatively affected solar photovoltaic output at the European level and Central Europe (-5%). Vulnerability of wind power plants to floods is increasing: from 1993 to 2004 to 2005-2016 there is 3-fold decrease in the European wind CF; from one flood year to the following, wind CF decreases in Central (- 1.9%yr- 1) and Eastern Europe (- 3.7%yr- 1). During droughts/heatwaves, wind CF increases in Central Europe (2%yr- 1), but decreases in Mediterranean (- 3%yr- 1). Shifting to renewable energy sources is key to decarbonization. It's crucial understanding the historical impacts of EWE in the power system towards its resilience and stability.