Energy droughts and climate change risks in renewable energy systems: A critical global review of compound risks, system vulnerability and mitigation strategies

Extreme weather events and climate change increasingly affect the performance and reliability of renewable energy systems, posing significant challenges to the global clean energy transition. Despite the growing body of research on climate impacts across individual renewable-energy technologies, current knowledge remains fragmented across regions, technologies, and assessment methodologies, highlighting the need for a comprehensive synthesis of renewable-energy droughts and their future evolution under climate change. This critical review examines how climate variability and extreme events influence solar, wind, and hydropower systems, with particular emphasis on renewable-energy droughts and the indicators used to assess them, including the standardized renewable energy production index and capacity factor-based thresholds (e.g., 10% and 5%). Regionally, Europe experiences frequent winter wind droughts, with extreme events reducing energy production by more than 50% in southern regions, while solar droughts may affect up to 24% of days annually in northern Europe. In China, autumn wind droughts can persist for up to 15 days, and solar shortages may affect up to 63% of winter periods, increasing risks to grid stability. North Africa also exhibits pronounced wind and solar drought vulnerability, whereas hydropower systems worldwide are increasingly affected by hydrological droughts and altered river-flow regimes. Hybrid renewable-energy systems, energy storage, and stronger grid interconnections can substantially improve resilience to renewable-energy droughts. The review further shows that renewable-energy drought risks generally intensify under higher-emission climate scenarios, underscoring the need for standardized assessment frameworks, integrated climate-resilient planning, and greater consideration of socio-economic factors to support adaptation and future energy-system resilience.