S. Hu, H. Qi, Z. Wang et al.
Environmental Science and Ecotechnology 30 (2026) 100682
Therefore, assessments of the potential of solar power generation for PPPs must explicitly account for regional variations in solar resource availability across plant locations. The annual total solar radiation at the locations of PPPs consistently exceeded 4000 MJ m − 2 year − 1 (Supplementary Fig. S6), with most values concentrated between 5000 and 6000 MJ m − 2 year − 1 . This distri- bution indicates substantial potential for PV power generation across most PPP locations. According to the calculation framework described in Section 2.6 and the GSA of potential CER due to PV power generation (Supplementary Fig. S7), only the first-order and total sensitivity indices for PV panel length exceeded the 0.1 threshold. Both were substantially higher than those for all other variables. This in- dicates that panel length is the dominant factor influencing CER outcomes. Accordingly, we further evaluated the rooftop PV power-generation potential of PPPs across four scenarios repre- senting different installation densities. In these scenarios, all model parameters were held constant, whereas the PV panel lengths ( L p ) were set to 0.5, 1.0, 1.5, and 2.0 m, respectively. As the panel length increased, the CER potential consistently declined across all plant types (Fig. 8a). The greatest carbon- reduction benefits were observed when the panel length was set to 0.5 m, with some facilities achieving potential reductions exceeding 35%. According to this optimal scenario, LPPMPs and SPPMPs had particularly high CER potential at the individual level, with most plants exceeding 20%. The CER potential of individual RFPP and HPPMP plants was relatively low across all scenarios, generally below 10%, and in some plants, the potential approached 0% for 1.5 and 2.0 m panel lengths.
Fig. 6. Distribution of carbon emissions from pulping and papermaking plants in China (2022). a, Provincial distribution of carbon emissions. b, Comparison of total carbon emissions between coastal and inland provinces. c, Total carbon emissions of different plant types, showing the contribution of each plant category to overall emissions. PFPP: primary fiber pulp plant, RFPP: recovered fiber pulp plant, HPPMP: heavyweight paper product manufacturing plant, SPPMP: specialty paper product manufacturing plant, LPPMP: lightweight paper product manufacturing plant.
carbon emissions. In contrast, nearly 75% of PPPs exhibited carbon emissions below the sectoral average, suggesting that most oper- ated with relatively low emission intensities. These findings un- derscore the importance of adopting a differentiated approach to CER. While maintaining sector-wide coordination, regulatory ef- forts, and technical upgrades should be prioritized for a small subset of high-emission plants to support more efficient and cost- effective decarbonization. Fig. 7. Carbon emissions from pulping and papermaking plants producing different products. Violin plots represent the distribution of carbon emissions for each plant, scattered points indicate individual data points, and black circles indicate the median values. For primary fiber pulp plant (PFPP), recovered fiber pulp plant (RFPP), heavyweight paper product manufacturing plant (HPPMP), lightweight paper product manufacturing plant (LPPMP), and specialty paper product manufacturing plant (SPPMP), the minimum – maximum carbon emissions were (4.36 – 450.70) × 10 4 , (2.33 – 375.34) × 10 4 , (0.34 – 202.38) × 10 4 , (0.32 – 38.48) × 10 4 , and (0.30 – 75.84) × 10 4 t CO 2 , respectively.
Fig. 8. Carbon emission reduction potential under different photovoltaic panel lengths. a, Box plots show the distribution of carbon-emission-reduction potential for different plant types at varying photovoltaic (PV) panel lengths. The boxes represent the interquartile range, the central line indicates the median value, and the error bars denote the minimum and maximum values. The inset figures show magnified views of the recovered fiber pulp plant (RFPP) and heavyweight paper product manufacturing plant (HPPMP) at PV panel lengths of 1.5 m and 2.0 m, to better illustrate their differences in the low-value range. b, Total carbon emission reduction of different plant types under different PV panel lengths. PFPP: primary fiber pulp plant, SPPMP: specialty paper product manufacturing plant, LPPMP: lightweight pa- per product manufacturing plant.
4. Results for CER potential in the PPI
China is a vast country with complex terrain, resulting in sig- nificant variations in solar energy resources across regions (Supplementary Fig. S5). In general, solar radiation levels are higher in western regions than in central and eastern regions.
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