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Previous studies on photovoltaic (PV) waste recycling in China have focused on predicting waste volumes and the technical and economic feasibilities of recycling. However, those studies lack an assessment of balance of system (BOS) waste in a PV system and a macro-level assessment of the variation in the net benefits of waste recovery. This paper establishes a multi-factor gray neural network model, combined with the Weibull distribution model, to predict the total PV waste, including modules and BOS. By considering the learning curve of recycling technology and the future projected share of three mainstream technologies (mechanical, chemical, and thermal treatment), we also analyze the changes in net PV recycling benefits across the industry. The results show that total cumulative PV waste is expected to reach about 100 million tons by 2050; of this, 56.13% may be PV modules and 43.87% may be BOS. Three metals, Fe (26%), Al (21%), and Cu (4%), are expected to account for the largest proportion of total metals. Compared with direct landfill disposal, by 2050, the recycling of PV waste could potentially reduce carbon dioxide (CO 2) emissions by 1.1E+11 kg, save 1.1E+12 kg of industrial water, and generate 3.6E+11 MJ for primary energy use. The change in net benefits indicates that the benefit could start to generate a positive return by 2026 and total net benefits are expected to reach 90 billion CNY by 2050. [Display omitted] • Forecasting PV waste with a multi-factor gray neural network model. • Analyzed 23 waste materials generated by PV modules and BOS. • China is expected to generate 214.68 GW–579.76 GW of PV waste by 2050. • Waste PV recovery can bring massive energy saving and emission reduction benefits. • Net benefits of waste PV recycling start to be positive in 2026. [ABSTRACT FROM AUTHOR]

A top-down approach was employed to estimate the influence of lockdown measures implemented during the COVID-19 pandemic on NO x emissions and subsequent influence on surface PM 2.5 and ozone in China. The nation-wide NO x emission reduction of 53.4% due to the lockdown in 2020 quarter one in China may represent the current upper limit of China's NO x emission control. During the Chinese New Year Holiday (P2), NO x emission intensity in China declined by 44.7% compared to the preceding 3 weeks (P1). NO x emission intensity increased by 20.3% during the 4 weeks after P2 (P3), despite the unchanged NO 2 column. It recovered to 2019 level at the end of March (P4). The East China (22°N - 42°N, 102°E - 122°E) received greater influence from COVID-19. Overall NO x emission from East China for 2020 first quarter is 40.5% lower than 2019, and in P4 it is still 22.9% below the same period in 2019. The 40.5% decrease of NO x emission in 2020 first quarter in East China lead to 36.5% increase of surface O 3 and 12.5% decrease of surface PM 2.5. The elevated O 3 promotes the secondary aerosol formation through heterogeneous pathways. We recommend that the complicated interaction between PM 2.5 and O 3 should be considered in the emission control strategy making process in the future. Unlabelled Image • NO x emission in the lockdown period is 53.4% lower than the same period in 2019. • East China experienced greater influence from COVID-19 than national mean level. • NO x decline leads to 36.5% O 3 increase and 12.5% PM 2.5 decrease over East China. • Elevated O 3 enhances secondary aerosols formation through heterogeneous pathway. [ABSTRACT FROM AUTHOR]