China is the largest worldwide consumer of solar generated electricity, with 130 gigawatts of installed capacity as of 2017. China’s capacity is expected to reach at least 400 GW by 2030, supplying 10% of its primary energy needs.

Global dimming

The researchers observed a ‘dimming’ trend, or an ongoing reduction in the amount of solar radiation reaching the earth’s surface, and thereby the amount harvestable by solar panels. Their findings show that air pollution accumulation in China since the 1960s (when China embarked on an intensive campaign of industrialisation) has decreased solar energy potential by 13%. The strong correlation and absence of obvious alternative explanations indicates that the majority of observed dimming in China is due to emissions caused by human activities. However, high-quality data was needed to back the research team’s conclusions.

Making sense of the data

Until recently, the extent and cause of observed radiation trends in China remained unclear due to uncertainties over data quality, resulting from changes in the use of instruments and observational schedules. Research team member Su Yang standardised a dataset covering 119 measurement stations in China by referencing radiation observations to a larger quantity of sunshine-duration data from nearby stations. The team also factored in data on the angle of panels, or how they are tilted to collect solar radiation. Their findings have significant implications for Chinese climate policy.

‘Economic benefits could amount to 1.9 billion USD per year’

‘Reverting back to 1960s radiation levels in China could yield a 12–13% increase in electricity generation, equivalent to an additional 14-Terawatt hours when produced using the capacity available in 2016’, says Bart Sweerts, lead author of the paper and recent graduate of the Earth Sciences Master’s programme at the UvA. ‘The corresponding economic benefits could amount to 1.9 billion USD per year. China is on track to realise its Paris Climate Agreement goal of obtaining 20% of its primary energy from renewable energy sources6 by 2030. By that time, the economic benefits would range somewhere between 4.6 – 6.7 billion USD per year.’

China is actively pursuing strategies to combat air pollution resulting from using coal as its major energy source. In a rapidly expanding solar energy sector, this data-driven research demonstrates a clear link between air pollution and global dimming, underscoring the importance of gaining a better understanding of the impact of man-made changes on surface solar radiation.

References

Bart Sweerts, Stefan Pfenninger, Su Yang, Doris Folini, Bob van der Zwaan & Martin Wild: 'Estimation of losses in solar energy production from air pollution in China since 1960 using surface radiation data', in Nature Energy (8 July 2019).