Cameron Bracken , Nathalie Voisin, Kendall Mongird, Casey Burleyson, Konstantinos Oikonomou

As variable renewable energy resources become a larger part of the generation mix in the United States (U.S.), so does the potential impact of prolonged periods of low wind and solar generation, known as variable renewable energy (VRE) droughts. In a future decarbonized or low-carbon grid, naturally occurring VRE droughts need to be evaluated for their potential impact on grid reliability. This study is the first of its kind to examine the impacts of compound VRE energy droughts in the Western U.S. across a range of climate change and future infrastructure scenarios. We find that compound VRE drought severity will increase significantly in the future, primarily due to the dramatic increase in wind and solar generation needed to meet decarbonization goals. Climate change is expected to increase the variability of energy drought severity, which has implications for sizing energy storage necessary for mitigating drought events. We also examine the spatial patterns of compound VRE drought events that effect multiple regions of the grid simultaneously. These co-occurring events have distinct spatial patterns depending on the season. We observed overall fewer connected events in the future with the combined effect of climate change and infrastructure growth, although in the fall we observe a climate change-induced shift toward events which impact more regions simultaneously.