Impacts of power plant emissions on air quality amplified by renewable energy droughts

Renewable energy droughts, characterized by prolonged periods of low winds and reduced solar irradiance, threaten the stability of electricity supply, with fossil fuel plants expected to cover much of the energy deficit. By integrating an electricity system model with a chemical transport model, here we quantify the effects of fossil fuel plant emissions on China’s air quality in the 2050s during renewable energy droughts. Our findings reveal that under scenarios of high renewable penetration, even with the best pollution-control technologies, fossil fuel plant emissions can boost PM_2.5 by 15–40% and O₃ by 10–20% during renewable energy shortages, raising the frequency of extreme pollution hours by 40–100% annually. Attribution analysis indicates that more stagnant weather and elevated pollutant emissions from fossil fuel plants contribute comparably to extreme pollution during renewable energy droughts. Incorporating health costs of elevated pollution into renewable capacity planning could reduce reliance on fossil fuel generation by ~50% in China by 2050, enabling a deeper clean energy transition.