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This study aimed to quantitatively estimate and compare the environmental sustainability of docked and dockless bike-sharing promotions. The greenhouse gas (GHG) emission reduction effect and potential of different bike-sharing modes in the five cities of Beijing, Guangzhou, Hangzhou, Nanjing, and Shanghai in China were compared and analyzed using the life-cycle assessment (LCA) approach. The empirical analysis of current data showed that compared with that by the small-scale traditional docked bike-sharing (DBS), the promotion of large-scale dockless bike-sharing (DLBS) has increased the amount of urban green travel; however, it has reduced the operating efficiency of the urban bike-sharing system. On average, the life-cycle mileage of DLBS bikes was only approximately one-third that of DBS bikes, and the corresponding GHG emission intensity of DLBS was approximately twice that of DBS. The GHG emission reduction benefit per kilometer of DLBS trips was lower than that of DBS trips in the same city. In particular, the promotion of DLBS has exerted significant negative effects in Beijing, Shanghai, and Hangzhou. Notably, the environmental sustainability of bike-sharing depends on the utilization of shared bikes. When the life-cycle mileage of the shared-bike was less than 8000 km, DLBS was more environmentally friendly than DBS; otherwise, DBS was more environmentally friendly. Under the current modal shift structures, the maximum GHG emission reduction potential of the DLBS was approximately 25 % lower than that of the DBS. Significant differences in the development status of DBS and DLBS systems in different cities significantly affected their corresponding environmental impacts. Hence, city managers and planners should consider the scale and efficiency of a city's bike-sharing system according to its actual situation and seek an optimal balance point. To ensure complete utilization of the emission reduction potential of bike-sharing, the government and enterprises should strive to shift from car travel to bike-sharing travel and increase the utilization of shared bikes. • Environment friendliness of dockless and docked bike-sharing in Chinese cities was compared. • Environmental impact of bike-sharing showed significant geographical differences. • Dockless mode was less environmentally friendly owing to low operating efficiency. • Increasing bike utilization can significantly improve the sustainability of dockless mode. • The maximum GHG reduction potential of bike-sharing travel could reach 30–40 g CO 2 -eq/km. [ABSTRACT FROM AUTHOR]

China has started to focus on the reduction in pollutants from diesel vehicles with high emission intensities in recent years. Therefore, it is essential and valuable to conduct a deep and detailed exploration of the reduction potential from diesel vehicles and compare the abatement effect from different control measures in upcoming decades. This study attempted to estimate the present emissions of four conventional pollutants from diesel vehicles by applying the Computer Program to Calculate Emissions from Road Transport (COPERT) model, and to predict the future emission trends under different scenarios during 2019–2030, taking the Beijing–Tianjin–Hebei (BTH) region as the case study area. In addition, we analyzed the emission reduction potential of diesel vehicles and compared the reduction effects from different control measures. The results showed that the CO and NOX emissions from diesel vehicles in this region could increase by 104.8% and 83.9%, respectively, given no any additional control measures adopted over the next decade. The largest emission reduction effect could be achieved under the comprehensive scenario, which means that vehicular diesel emissions in 2030 could decrease by 74.8–94.0% compared to values in 2018. The effect of emission reduction under the emission standards' upgrade scenario could cause a gradual increase and achieve a 19.8–82.6% reduction for the four pollutants in 2030. Furthermore, the new energy vehicle promotion scenario could achieve a considerable reduction effect. It could also offer better emission reduction effects under the highway to railway scenario for Tianjin and Hebei provinces. The old vehicle elimination scenario could have a considerable reduction effect, but only in the short term. Furthermore, emission reductions could be mainly influenced by heavy diesel trucks. These results can provide scientific support to formulate effective reduction measures to diesel vehicles for policy makers. [ABSTRACT FROM AUTHOR]

The current top-down method for calculating carbon emissions in the building sector erroneously includes carbon emissions from charging new energy vehicles (NEVs). This error is particularly concerning as the number of NEVs is expected to rise significantly in the future, thereby exacerbating the negative impact on the formulation of effective carbon reduction policies. This study analyzes carbon emissions in Beijing's building sector from 2011 to 2020 and estimates NEV-related indirect emissions from 2015 to 2020. Findings show that electricity consumption is the primary energy source in Beijing's building sector, increasing electricity-related carbon emissions from 63.36 % to 67.18 % of the total. Additionally, the indirect carbon emissions from NEVs have exhibited a steady increase from 208,800 tons in 2015 to 1.18 million tons in 2020, with their contribution to the overall carbon emissions from buildings escalating from 0.27 % to 1.44 %. Intriguingly, the study uncovers that private new energy cars do not significantly differ from conventional private fuel passenger cars in terms of their indirect carbon emissions. The findings of this study are expected to inform the development of accurate carbon emission estimation strategies in Beijing's building sector and facilitate the formulation of effective policies in the future. • Energy consumption of charging NEVs deducted from the building sector. • Carbon emission factors of electricity and heat in Beijing were reported. • Urban residential building has the greatest carbon emission reduction potential. • Energy use intensity is crucial for carbon reduction in residential buildings. [ABSTRACT FROM AUTHOR]

• Performance evaluation of bifacial PV systems incorporating dynamic albedo. • Study of the optimal installation angle of bifacial PV systems in the Chinese grid. • Prediction of carbon reduction potential for bifacial PV systems on life cycle. • Comparison between optimal fixed tilt and biannual tilt angle adjustment. Bifacial PV modules, capable of generating electricity from both sides, are highly efficient but vulnerable to environmental factors. This study investigated the photovoltaic performance characteristics and carbon emission reduction potential of bifacial PV systems, considering China's regional power grid independence, environmental diversity, variations in carbon emission factors, and daily fluctuations in albedo. When the installed capacities of bifacial and monofacial PV systems are 253.80 Wp/m2 and 235.00 Wp/m2 respectively, the initial annual electricity generation of the bifacial PV system installed in Beijing is 461.11 kWh/m2, which is only 83.95 % of that in Lhasa, but the corresponding carbon reduction in Beijing exceeds that of Lhasa by 11.13 %, amounting to 407.75 kgCO 2. These indicate significant regional disparities in both the electricity generation capacity and carbon reduction potential of PV systems. Furthermore, compared to fixed installations, adjusting the tilt angles twice a year can increase the annual electricity generation of bifacial PV systems by approximately 2.37 %-3.17 % and monofacial PV systems by approximately 2.23 %-3.83 %. The research findings offer valuable insights regarding the impact of regional climate and grid characteristics on bifacial PV systems, thereby providing a reliable reference for optimizing their design and enhancing performance. [ABSTRACT FROM AUTHOR]

In order to design an optimal carbon peak and carbon neutralization pathway for the high-density building sector, a dynamic prediction model is established using system-dynamics coupled building life cycle carbon emission model (SD-BLCA) with consideration of future evolutionary trajectory and time constraints. The model is applied in Beijing using the SD-BLCA combined with scenario analysis and Monte Carlo methods to explore optimal trajectory for its building sector under 30-year timeframe. The results indicate that by increasing the proportion of renewable energy generation by 7% and retrofitting 60 million m2 of existing buildings, these two mature measures can offset the growth of carbon emissions and achieve the peak target by 2025. However, achieving carbon neutrality necessitates a shift from isolated technologies to a comprehensive net-zero emissions strategy. The study proposes a time roadmap that integrates a zero-carbon energy supply system and the carbon reduction measures of the whole life cycle. This strategy primarily relies on renewable sources to provide heat, power, and hydrogen, resulting in estimated reductions of 29.8 Mt, 28.1 Mt, and 0.7 Mt, respectively. Zero energy buildings, green buildings, and renovated buildings can reduce carbon emissions through their own energy-saving measures by 8.4, 18.2, and 11.8 kg/m2, respectively. [Display omitted] • System-dynamics coupled life cycle dynamic prediction model were established. • The major CO 2 emission from building operation stage ranged 52%–73% in megacity. • CO 2 emission reduce 59 and 18 Mt from energy supply and consumption for building neutrality. • Renewable energy includes 51% Heat, 48% Power and 1% hydrogen in building neutrality. • Enhancement of energy efficiency and zero-carbon energy contribute building neutrality. [ABSTRACT FROM AUTHOR]

China's air pollution policies prioritize city heterogeneity, and launch the one-city-one-policy framework. Production fragmentation extends air pollution policies beyond the local scale. Therefore, air pollution needs to be controlled in coordination between cities rather than individually, considering the pollution embodied in supply chains. We illustrate the embodied NO x in supply chains and its transfer patterns in the highly polluted Beijing-Tianjin-Hebei (BTH) urban agglomeration in China, with a city-level multiregional input-output (MRIO) model in 2012. The results indicate that Tangshan and Beijing are BTH cities with the highest production- and consumption-based NO x emissions, respectively. The electricity and heat, metal, and nonmetal sectors are the main suppliers in the NO x supply chains. The critical supply chain paths largely terminate at the final demand of the construction sector in Beijing, Tianjin, Baoding and Shijiazhuang and the equipment manufacturing sector in southeastern Chinese provinces. Despite industry heterogeneity, the NO x transfer pattern between BTH cities is generally efficient, extending from low-to high-emission intensity cities, while the pattern between BTH cities and other provinces is the opposite. The results reveal the city-level emission reduction potential. The emission intensities of BTH production-oriented cities should be reduced because the transfer of polluting enterprises to southeastern coastal areas is unrealistic. Financial incentives can be offered to enterprises purchasing products from low-emission intensity enterprises. It is an effective measure to establish a capital and technical cooperation system between key supply chains node cities, such as Tangshan and its major steel product consumption regions. [Display omitted] [ABSTRACT FROM AUTHOR]

Beijing benefits from the promotion of electric vehicles (EVs) in the improvement of road tailpipe emissions; these emissions are caused by internal combustion engine vehicles (ICEVs) and reduce the surrounding environmental quality. When analyzing the electricity grid, upstream emissions of EVs in Beijing can be tracked back to Shanxi and Inner Mongolia. This study investigates the inharmonious mechanism of emission reduction to promote EVs in Beijing and Northern China based on 6 scenarios and 42 real EVs. Because there is a neighbor effect, Beijing only accounts for 34%, 34%, 41%, and 35% of the total CO 2 , NO x , SO 2 and PM 2.5 emissions, respectively. Although the local CO 2 , NO x , and PM 2.5 emissions can be easily reduced (as long as the conversion of "coal to gas" plan is realized), it is difficult to achieve emission reductions of NO x and SO 2 without increasing the clean electricity generation mix in Shanxi and Inner Mongolia at the total emission level. However, there is still a large reduction potential of EVs themselves due to an increasingly clean electricity mix in Beijing, Shanxi and Inner Mongolia. Beijing local CO 2 , NO x , SO 2 and PM 2.5 emissions can be reduced by 86.92%, 98.79%, 99.98% and 99.94%, respectively, and a total reduction of 78.43% of CO 2 , 93.83% of NO x , 97.85% of SO 2 and 99.26% of PM 2.5 emissions is possible. Compared with the corresponding ICEV, an EV of 18 kWh/100 km starts to reduce Beijing local CO 2 , NO x and PM 2.5 emissions in scenario 1, 3 and 1, respectively, while the SO 2 emissions cannot be reduced. However, the total CO 2 , NO x , SO 2 and PM 2.5 emissions can be reduced in scenario 2, 5, 5, and 1, respectively. A sensitivity analysis shows that the promotion of EVs can reduce Beijing local CO 2 , NO x , SO 2 and PM 2.5 emissions by 125.568–238.960 g/km, 0.059–0.113 g/km, −0.00003 - - 0.00007 g/km and 0.034–0.065 g/km, respectively. In addition, the total CO 2 , NO x , SO 2 and PM 2.5 reduction in emissions can be 132.883–253.757 g/km, 0.189–0.361 g/km, 0.299–0.569 g/km and 0.053–0.101 g/km, respectively. Image 1 • The inharmonious mechanism of the upstream emissions of EVs has been studied. • Just 34%, 34%, 41%, and 35% of the total CO 2 , NO x , SO 2 and PM 2.5 emit in Beijing. • The CO 2 , NO x , and PM 2.5 emissions are reduced in scenario 1, 3 and 1 for Beijing. • The total CO 2 , NO x , SO 2 and PM 2.5 emissions are reduced in scenario 2, 5, 5, and 1. • The SO 2 and NO x emissions are reduced when the proportion of coal-based electricity drops to 0.54. [ABSTRACT FROM AUTHOR]

The advent of the energy Internet (EI) has dramatically changed the energy model of today's world. Despite scholars have done a lot of research on energy Internet, few articles have been written to evaluate its CO 2 emission reduction. In order to fill the vacancy, system dynamics (SD) is used to set up the dynamic assessment model of CO 2 emission reduction of regional energy Internet. To illustrate the effectiveness of the model, we take the energy Internet in Yanqing district of Beijing as an example for simulation. The results show that the total CO 2 emission reduction of this energy Internet will reach 5056.82 tons in 2019, and the emission reduction will continue to increase in the following years, the total amount of CO 2 emission reduction peaked at 13384.80 tons in 2030. We conclude: (1) The CO 2 emission reduction dynamic assessment model established in this paper has a strong versatility and can be applied to any built or planned energy Internet. (2) Energy Internet has a good long term effect in emission reduction. (3) The emission reduction of the supply side is the most obvious; the user side has the greatest potential for emission reduction, while the contribution of the transmission side to emissions reduction is the most stable. The innovation points of this paper mainly include: (1) we put forward and solve the dynamic assessment of carbon emission reduction on the energy Internet for the first time. (2) We establish a dynamic assessment model of CO 2 emission reduction in the energy Internet based on system dynamics. (3) We quantitatively analyze the emission reduction contribution of the supply side, transmission side and user side of the energy Internet. [ABSTRACT FROM AUTHOR]

Using 2025 as the target year, we quantitatively assessed the reduction potentials of emissions of primary pollutants (including CO, HC, NO x , PM 2.5 and PM 10) under different vehicle control policies and the impacts of vehicle emission control policies in the BTH region on the regional PM 2.5 concentration in winter and the surface ozone (O 3) concentration in summer. Comparing the different scenarios, we found that (1) vehicle control policies will bring significant reductions in the emissions of primary pollutants. Among the individual policies, upgrading new vehicle emission standards and fuel quality in Beijing, Tianjin, and Hebei will be the most effective policy, with emission reductions of primary pollutants of 26.3%–54.7%, 38.0%–70.3% and 46.0%–81.6% in 2025, respectively; (2) for PM 2.5 in winter, the Combined Scenario (CS) will lead to a reduction of 0.5–3.9 μg m−3 (3.5%–11.6%) for the monthly average PM 2.5 concentrations in most areas. The monthly nitrate and ammonium concentrations would reduce by 5.8% and 5.3%, respectively, in the whole BTH region, indicating that vehicle emission control policies may play an important role in the reduction of PM 2.5 concentrations in winter, especially for nitrate aerosols; and (3) for O 3 concentrations in summer, vehicle emission control policies will lead to significant decreases. Under the CS scenario, the maximum reduction of monthly average O 3 concentrations in the summer is approximately 3.6 ppb (5.9%). Most areas in the BTH region have a decrease of 15 ppb (7.5%) in peak values compared to the base scenario. However, in some VOC-sensitive areas in the BTH region, such as the southern urban areas, significant reductions in NO x may lead to increases in ozone concentrations. Our results highlight that season- and location-specific vehicle emission control measures are needed to alleviate ambient PM 2.5 and O 3 pollution effectively in this region due to the complex meteorological conditions and atmospheric chemical reactions. • Emission reduction potentials under different vehicle control measures are estimated. • WRF-Chem model is used to simulate the emission control scenarios on PM 2.5 and O 3. • Upgrading new vehicle emission standards and fuel quality in the BTH region are the most effective. • Season- and location-specific vehicle control policies are needed. [ABSTRACT FROM AUTHOR]

With rapid economic growth and massive urbanization, China faces the problem of municipal solid waste (MSW) disposal and the pressing need for development of alternative energy. MSW incineration for power generation is playing an increasingly important role in MSW management in China. In order to study the reduction of GHG emissions caused by MSW incineration for power generation, the GHG emissions under the baseline level is calculated by using Clean Development Mechanism (CDM) methodology. Then, the GHG emission reduction is estimated based on the improved upstream-operation-downstream (UOD) framework. Finally, the GHG emission reduction in Beijing is studied and forecasted through grey prediction model and scenario analysis, and the main factors affecting the reduction potential are identified. The results show that the GHG emission reduction target can be achieved through MSW incineration for power generation. Direct and alternative GHG emissions from MSW incineration are the main sources of emissions, while indirect emissions account for a small proportion. The MSW disposal volume, the moisture content of MSW, the installed capacity of biomass energy, the average line loss of power generation and the quantity of fossil fuels consumed by power generation are five important factors that affecting GHG emission reduction potential. It is recommended that the dominant form of waste disposal in China should be replaced by MSW incineration for power generation, and the full classification of MSW needs to be promoted. Furthermore, the installed capacity of biomass energy should be increased and the average line loss of power generation should be reduced. Image 101195 • The improved Upstream-operation-downstream framework is employed to measure the emission reduction. • It is feasible to achieve GHG emission reduction by municipal solid waste incineration for power generation. • Direct and alternative emissions are the main sources of emissions. • Main factors affecting emission reductions are identified. [ABSTRACT FROM AUTHOR]