A study by the University of Oxford and University College London (UCL), published in Nature Sustainability, revealed that aerosols —small particles suspended in the air— reduced global solar energy production by 5.8% in 2023. This is equivalent to 111 TWh of lost energy, similar to the generation of 18 medium-sized coal power plants.
Interaction between coal and solar
The research analyzed more than 140,000 photovoltaic solar installations using satellite images and atmospheric models. The key finding: coal emissions scatter and absorb sunlight, reducing the amount that reaches the panels.
Between 2017 and 2023, new solar installations added an average of 246.6 TWh annually, but losses due to aerosols reached 74 TWh, nearly a third of those gains. This demonstrates a little-recognized interaction: fossil fuel emissions directly limit the performance of renewable energies.
The case of China
- Solar production: 793.5 TWh in 2023 (41.5% of the global total).
- Losses due to aerosols: reduction of 7.7%.
- Origin: around 29% of those losses come from coal power plants.
Interestingly, China showed sustained improvement: between 2013 and 2023, losses decreased by 1.4% annually, thanks to stricter regulations and ultra-low emission technologies.
Global impacts
Lead author Rui Song warned that the energy transition is less effective than assumed:
“Emissions alter the radiative environment and directly undermine solar generation performance.”
Moreover, air pollution not only blocks sunlight but also alters clouds, which could increase real losses beyond what is measured.
Analysis tools
The researchers combined:
- Global satellite images.
- Machine learning to map solar installations.
- Validated solar energy models to calculate losses.
Jan-Peter Muller highlighted that in the future, it will be possible to observe in real-time, every 10 minutes, the impact of dust and smoke particles on solar energy thanks to geostationary satellites.
Political implications
Co-author Chenchen Huang noted that ignoring these losses can lead to overestimating renewable production and diverting the Sustainable Development Goals. She proposed removing coal subsidies and strengthening emission control policies.
Professor Myles Allen, founder of Oxford Net Zero, added that all scenarios compatible with the Paris Agreement require a rapid transition away from coal, something that has not yet occurred because its energy remains “surprisingly cheap” by hiding its real costs.
The study shows that coal pollution not only affects health and the environment but also reduces the efficiency of solar energy, limiting the transition to a clean future. To move forward, it will be necessary to integrate stricter emission control policies and recognize that renewable energies cannot fully deploy their potential while coal continues to dominate.
