Spells in which wind or solar output falls sharply and stays low could grow longer as the climate warms, according to a global modelling study. The largest projected increase occurs when both sources are affected together, leaving electricity systems with less renewable generation to draw on at the same time.
The researchers call these episodes flash energy droughts. The term combines a rapid decline in generation with a prolonged period of low output. When wind and solar droughts overlap, they form a compound event. During those overlaps, wind and solar are less able to compensate for each other's low output.
Even under SSP1-2.6, a scenario with low greenhouse-gas emissions, the study projects longer wind, solar and compound droughts. The largest increase is for compound events. This concerns the length of low-output episodes, not the proportion of electricity supply lost.
Longer episodes matter because other resources must cover the missing generation. In the study's power-system analysis, flash droughts were associated with more unserved energy, meaning electricity demand that could not be met, as well as higher costs. The analysis also found greater flexibility requirements: the system needed more ability to adjust its supply as renewable output changed.
Those results describe risks under modelled conditions. They do not give the probability that a particular grid will lose power, and a decline in renewable output does not by itself establish that an outage will occur.
The study also examined whether future wind and solar farms could avoid some of that exposure through their choice of location. Prioritizing sites with more favourable flash-drought trends reduced risk in some deployment pathways, with benefits depending on emissions and which sites could actually be developed. That brings the speed and duration of output losses into siting decisions alongside the amount of electricity a project can generate over a year.
Sources
- Nature Climate Change: Flash energy droughts in solar and wind resources under climate change
- Zenodo: Processed data and code supporting the study
- Representative wind-farm photograph by the U.S. Department of Energy, public domain. The image shows an offshore wind farm, not a drought event measured in the study.