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CO 2 sequestration is an effective technology for reducing greenhouse gas effect. To ensure the safety, assessment of well applicability should be conducted before CO 2 sequestration. However, current studies mainly focus on identifying which barrier has the highest risk of leakage rather than selecting a target well for injection in specific geological formation. To further investigate, this paper proposes well applicability assessment method combining reservoir and wellbore properties together for CO 2 sequestration. A novel assessment system combing Fuzzy comprehensive evaluation and Analytic hierarchy process has been established. Twenty-nine indexes subjected to seven categories (i.e., formation, well, cement sheath, cementing quality, casing, tubing, and wellhead properties) are taken into consideration. The weighting factors of these seven categories are 0.0673, 0.0552, 0.096, 0.1537, 0.2283, 0.2637 and 0.1369, respectively. Tubing and casing properties have the greatest influence on safety injection. Furthermore, the proposed system has been applied to S gas reservoir, China. Results show that Wells #P1 and #P2 are suitable for injection. Since more comprehensive indicators are considered comparing with previous studies, the results are more accuracy and objective. The findings of this paper could help efficiently and effectively evaluating well applicability for CO 2 sequestration and reducing the risk of CO 2 leakage. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) emissions and climate change risk have become constraints on global economic sustainable development. Environmental regulation (ER) is a key method for achieving synergy in CO 2 and pollution reduction in China. This paper is the first study to explore the effects of ER on CO 2 emissions by exploiting the National Environmental Protection 11th Five-Year Plan (NEP11-FYP). The implementation of the NEP11-FYP significantly decreases CO 2 emissions by 19.73% in key environmental cities relative to other cities. Heterogeneity analyses suggest that this negative impact is larger in western cities and cities with more pressure to reduce CO 2 emissions. Scale effects, structural effects, and technical effects might be three potential influencing channels through which ER contributes to the CO 2 reduction effect. In addition, the results of the spatial externality of the NEP11-FYP demonstrate a positive spillover effect in neighboring cities within a distance of 300 km and a negative spillover effect in cities more than 500 km away. Our empirical findings provide policy implications for implementing low-carbon transition strategies and reducing CO 2 emissions. [ABSTRACT FROM AUTHOR]

Greenhouse gas (GHG) emissions from wetlands have exacerbated global warming, attracting worldwide attention. However, the research process and development trends in this field remain unknown. Herein, 1865 papers related to wetlands GHG emissions published from January 2000 to December 2023 were selected, and CiteSpace and VOSviewer were used for bibliometric analysis to visually analyze the publications distribution, research authors, organizations and countries, core journal and keywords, and discussed the research progress, trends and hotspots in the fields. Over the past 24 years, the research has gone through three phases: the "embryonic" stage (2000–2006), the accumulation stage (2007–2014), and the acceleration stage (2015–2023). China has played a pivotal role in this domain, publishing the most papers and working closely with the United States, United Kingdom, Canada, Germany, and Australia. In addition, this study synthesized 311 field observations from 123 publications to analyze the variability in GHG emissions and their driving factors in four different types of natural wetlands. The results suggested that the average carbon dioxide (CO 2), methane (CH 4), and nitrous oxide (N 2 O) fluxes in different wetlands were significantly different. River wetlands exhibited the highest GHG fluxes, while marsh wetlands demonstrated greater global warming potential (GWP). The average CO 2 , CH 4 and N 2 O fluxes were 60.41 mg m−2·h−1, 2.52 mg m−2·h−1 and 0.05 mg m−2·h−1, respectively. The GWP of Chinese natural wetlands was estimated as 648.72 Tg·CO 2 -eq·yr−1, and CH 4 contributed the largest warming effect, accounting for 57.43%. Correlation analysis showed that geographical location, climate factors, and soil conditions collectively regulated GHG emissions from wetlands. The findings provide a new perspective on sustainable wetland management and reducing GHG emissions. [Display omitted] • A 24-year bibliometric analysis of GHG emissions from wetlands was conducted. • The historical evolution and future trends in the field were summarized. • River wetlands exhibited the highest GHG fluxes. • GWP of China's wetlands was estimated to be 648.72 Tg·CO 2 -eq·yr−1. • CH 4 emissions contribute 57.43% to the GWP value in China's wetlands. [ABSTRACT FROM AUTHOR]

Freshwater resources are scarce globally, and the increase in carbon dioxide (CO 2) concentration leads to both a decrease in soil moisture and arid climate, further limiting agricultural production. Therefore, it is critical to achieve water efficiency in agriculture under elevated CO 2 concentration. A comprehensive analysis was conducted on the research topic of efficient agricultural water under elevated CO 2 concentration using bibliometric methods. The results show that the number of papers on this research has changed from an accumulation phase (1992–2005, 395) to a growth phase (2006–2023, 963). "Carbon dioxide", "water-stress", "growth", "photosynthesis", "yield", and other keywords have been the focus of past research in this area. Kimball BA and Ainsworth EA are the most influential authors in this area. Leakey's (2009) paper in "Experimental Botany" was the most contributing study, summarizing six lessons about the effects of CO 2 enrichment on the relationship among carbon, nitrogen, and water in plants. The United States and China were the most influential countries. Over time, research has shifted from an early focus on atmospheric CO 2 change itself to the response of crops to elevated CO 2 in agricultural production. The efficient crop production strategy under the interaction of environmental factors is becoming a hot spot for future research, and the emission and use of greenhouse gases, the improvement of crop quality, and the efficient guidance of models are also worth exploring. Overall, this study presents a quantitative analysis and comprehensive review of past research conducted on the effect of water and fertilizer on agricultural production under CO 2 enrichment. It also offers suggestions and expectations for future research on the hot spot direction of efficient crop production under climate change. • The continuous research attention is closely related to climate change caused by CO 2 enrichment. • The main research fields included CO 2 enrichment, water stress, crop growth and photosynthesis. • The co-citation analysis reveals broad research clusters in the literature. • The new research focus will be interactive climatic factors, greenhouse gas recycling, and modeling. [ABSTRACT FROM AUTHOR]

By purchasing emission reduction equipment or reducing production scale, it is possible to effectively decrease CO 2. Therefore, understanding the marginal abatement cost (MAC) associated with these methods is crucial for making decisions. However, previous studies using the directional distance function (DDF) approach often mis-specified production functions and neglected data noise. They also assumed decision-making units (DMUs) to be on the production frontier and used proportional changes in inputs and outputs as abatement paths. This paper addresses these limitations by developing the convex quantile non-radial directional distance function (CQR-NDDF) method, which estimates the MAC of CO 2 and determines optimal abatement paths for DMUs without assuming a specific production function, employing linear programming techniques. Applying this method to 30 provinces in mainland China from 2011 to 2019, the study finds that China's CO 2 MAC increased from 182 to 247 yuan/ton. The lowest-cost abatement path varies by province and time. The club convergence and ordered probit model are employed to conclude that the second industry and urbanization increase the MAC of CO 2 , while factors such as foreign direct investment, openness level, and human capital decrease the MAC. Moreover, the CQR-NDDF method yields significantly lower MAC estimates than the NDDF method. In conclusion, this paper provides new insights into China's CO 2 MAC, emphasizing the importance of considering inefficiency and data noise in MAC estimation. We anticipate that utilizing CO 2 MAC as a benchmark for carbon trading market prices could lead to an increase in prices within China's carbon trading market. • A novel method for estimating CO 2 MAC has been developed. • Ignoring inefficiency will result in an overestimation of CO 2 MAC. • Three different emission reduction pathways are considered in the estimation. • The heterogeneity of the lowest cost abatement pathways has been identified. [ABSTRACT FROM AUTHOR]

This paper, based on the panel data of 284 Chinese prefecture level and above cities span 2010 to 2019, systematically investigated the relationship between digital economy and air pollution, with introducing difference-in-differences model, mediating effect model, and spatial difference-in-differences model, as well as treating the "National Big Data Comprehensive Pilot Area" policy as a quasi natural experiment. Finally, results show that:(1) Digital economy does negatively affect air pollution, in particular the industrial dust, followed by industrial sulfur dioxide and carbon dioxide. All these benchmark results have withstood the robustness test. (2) Almost all the mediating roles of industry structure upgrading, industry intensive development, and online life in the relationship between digital economy and air pollution have been confirmed, except it is partly absent in the digital economy-industrial dust nexus and the digital economy-industrial sulfur dioxide linkage. (3) Negative spatial spillover effect is evident between digital economy and air pollution, regardless of involving the neighboring pilot cities or the non pilot cities. (4) The passive air pollution effect of digital economy varies with the regional distribution, administrative scale, marketization level, and government competitiveness. All these findings shed new lights on government intervention. [ABSTRACT FROM AUTHOR]

It is proposed to develop a novel thermochemical cycle using nuclear energy to decompose H 2 S and CO 2 , thus producing H 2 and CO from acidic gas in petrochemical or coal chemical industries, reducing CO 2 emissions and promoting sustainable energy development. The upper limits and significant energy-consuming steps were determined based on two chemical routes of the thermochemical cycle systems 1 and 2. When the enthalpy of the H 2 S oxidation reaction served as part of the circulating energy input, the values for system 1 and system 2 were 38.7% and 34.3%, respectively. However, if only external energy is considered to satisfy the heat and work required to run the reaction and pump, the thermal efficiency rises to 58.4% and 61.2%, respectively. The life cycle assessment (LCA) was used to investigate the environmental effect of the hydrogen generation process base on the upper thermal efficiency in this study, and the results of the LCA are stated in terms of global warming potential (GWP) and acidification potential (AP). The GWP of systems 1 and 2 was calculated as 2.59 kg CO 2 -eq/kg H 2 , 2.54 kg CO 2 -eq/kg H 2 , The AP of systems 1 and 2 was calculated as 7.48 g SO 2 -eq/kg H 2 and 9.08 g SO 2 -eq/kg H 2 , respectively. This paper assesses the environmental effect of two different hydrogen systems used in manufacturing various subsystems in GWP and AP, and compares them to the life cycle of other hydrogen production pathways. • A novel thermochemical cycle using nuclear energy to split H 2 S-CO 2 is proposed. • Energy-consuming steps and the upper thermal efficiency were determined. • The upper thermal efficiency has been developed to assess environmental impacts. • The LCA integrated China's HTR-PM with the innovative H 2 S-CO 2 process. • GWP and AP in the H 2 S-CO 2 system are compared to other hydrogen methods. [ABSTRACT FROM AUTHOR]

Negative emission technologies driven by nature with less energy input, lower costs, and long carbon storage capacities are essential for meeting ambitious global carbon mitigation goals. This paper evaluates the carbon sequestration potential of bivalve shellfish farming because its sequestration process is driven by nature, and it is cost-effective and energy efficient. The carbon in shells and the carbon that enters sediments via bio-deposition are long-lived forms of carbon. Using China as a case study, a preliminary estimation suggests that the carbon sequestration efficiency and intensity of cultivated shellfishes are much higher than those of artificial forests. In China, approximately 6.23 Mt CO 2 -eq a−1 was fixed via net carbon sequestration during shellfish growth from 2015 to 2019. In addition, the farmed shellfishes provided 0.37 Mt of harvested protein, and approximately 37.39 Mt CO2-eq a-1 were reduced compared to the same amount of protein provided by beef, and thus, shellfish farming has the win-win benefits of carbon sequestration and high-quality food provision. More importantly, a total of 5.64 Gt CO 2 -eq, accounting for 17.63% of the total emissions in 2020, can be potentially sequestrated at the global scale under the world's largest farming area scenario. • A Negative Emission Technology via shellfish farming was introduced. • Carbon sequestration function and efficiency of shellfish farming were investigated. • Carbon sequestration potential for bivalve shellfish farming was evaluated globally. • Life cycle GHG emissions of shellfish farming in China was assessed. [ABSTRACT FROM AUTHOR]

Synergistic governance of emission reduction between pollutants and CO2 (hereinafter referred to as synergistic governance) reflects China's proactive response to climate change and will become a central task in China's environmental governance over the next decade and beyond. Given this, this paper aims to systematically understand why synergistic governance is possible and what China has achieved in synergistic governance. In order to achieve these aims, this paper constructs a scientific indicator system based on synergistic governance theory and applies the composite system synergy model to assess the level of synergistic governance in China. The results show that China has made great progress in synergistic governance in the past decade, achieving a leaping development from mild non-synergy to moderate synergy. The achievement mainly comes from the efforts of nearly 1/3 of Chinese provinces in advancing synergistic governance, and the improvement direction of synergistic governance in these provinces is consistent with the national level, jumping from mild non-synergy to moderate synergy. However, the level of synergistic governance in some provinces has decreased rather than increased. It is worth noting that the widening gap in the level of synergistic governance within China's regions may become a vital factor that hinders the sustainable promotion of synergistic governance. This paper clarifies the operational logic of synergistic governance and provides a comprehensive evaluation method, which is beneficial to provide some references for other countries that intend to work on synergistic governance. • Theoretical explanation on synergistic governance from resource flow and energy flow. • A composite system synergy model for the synergistic governance is developed. • Spatial-temporal evolution of synergistic governance in Chinese regions is analyzed. • Widening differences will constrain the sustainability of synergistic governance. [ABSTRACT FROM AUTHOR]

The conventional air conditioning system used in high-speed railways has limitations in heating performance and environmental impact, necessitating the exploration of alternative refrigerants. The transcritical CO 2 system has gained popularity due to its exceptional heating efficiency and environmental benefits. This study aims to evaluate the energy and environmental potentials for transcritical CO 2 systems in high-speed trains based on four-vertical-and-four-horizontal railway lines within different climatic regions of China. A high-fidelity transcritical CO 2 system model was first developed and validated through experiments. Then, a comprehensive energy and environmental evaluation method was proposed and applied to the four-vertical-and-four-horizontal railway lines. The results indicated that the transcritical CO 2 system had a superior heating performance and competitive cooling performance based on daily and annual operations. Furthermore, the transcritical CO 2 system exhibited significant environmental advantages with lower total life cycle climate performance for all lines, with an average emissions reduction ratio of 17.6% and a maximum emissions reduction ratio of 26.98%. These findings highlight the competitive energy performance and outstanding environmental benefits offered by transcritical CO 2 systems as promising alternatives to air conditioning systems in railway transportation. • This paper evaluates the potential of theCO 2 system in high-speed trains from an energy performance and environmental benefits perspective. • A high-fidelity model of the transcritical CO 2 system is developed and validated for effectiveness through experiments. • The energy and environmental evaluations are conducted based on China's four-vertical-and- four-horizontal railway lines. • The results indicate that the CO 2 system presents a competitive alternative for air conditioning systems in high-speed trains. [ABSTRACT FROM AUTHOR]

This paper examines the long-term effects and related short-term movements of energy security (ENS), economic policy uncertainty (EPU), and government ecological expenditure (GEE) on China's carbon dioxide (CO 2) emissions by applying the quantile autoregressive distributed lag approach. The empirical findings demonstrate that ENS and EPU have prominent negative and positive impacts, respectively, on CO 2 emissions in the long term for the majority of quantiles, while their short-term influences are less obvious. In addition, the effect of GEE is short-term and concentrated in high quantiles. The following are the article's main contributions. This study builds special energy security indicators based on the actual situation in China, providing a basis for better understanding the interaction mechanism between ENS and CO 2. Considering that China is the largest oil importer and greenhouse gas emitter, this study explores for the first time the linkages between ENS and CO 2. Both short- and long-term impacts are observed, and long-run effects are dominant in the linkages among variables, suggesting that the level of CO 2 emissions is mainly driven by long-term shocks. In addition, to clarify the nexus between ENS and CO 2 , time- and quantile-varying analyses are used, which take into account not only varied CO 2 emission levels but also distinct time periods for events. The findings emphasize the importance of market participants to form a better understanding of how ENS, EPU, and GEE affect CO 2 under different emission levels. Some detailed policies, including optimizing the energy consumption structure, making prudent economic policy adjustments, and strengthening ecological protection expenditures, are provided to curb pollution. • Energy security and carbon neutralization are main targets for China. • Energy security negatively affects carbon dioxide in the long-term. • Time-varying and quantile-varying features are captured for Energy security. • The quantile autoregressive distributed lag model is utilized in this paper. [ABSTRACT FROM AUTHOR]

• This paper conducts the assessment of CO2 storage capacity of offshore saline aquifers including Bohai Bay Basin in northern China, also Beibu Gulf Basin and Yinggehai Basin in southern China. • Different assessment methodologies are applied, and the mechanism and results are compared to analyze the applicability. • Results show that the CSLF and CO2BLOCK methods take into the account the storage mechanisms such as geological structure storage, residual gas storage and dissolution storage, the results seem more reasonable. Also different storage time interval could results in various capacity potential under safe injection in CO2BLOCK method. • In summary, the CO2 storage potential of Bohai Bay Basin, Beibu Gulf Basin, and Yinggehai Basin are 39.98, 53.22, and 13.37 Gt, respectively. Saline Aquifer CO 2 Storage (SACS) has become a vitally important technology for mitigating climate change brought on by anthropogenic and fossil fuel emissions. Application of SACS projects in offshore saline aquifers in China is quite promising, and the CO 2 storage technical and economic potential are considerable. However, the storage capacities achieved from different analytical and numerical methods varies a lot from each other since the main factors taken into account are variable. In this paper, different methodologies are applied to conduct the assessment of CO 2 storage capacity of offshore saline aquifers including Bohai Bay Basin in northern China, also Beibu Gulf Basin and Yinggehai Basin in southern China. Results show that the storage capacity obtained from European Commission's method is much less than that determined by the other three methods (i.e., USDOE, CSLF and CO2BLOCK method) since it mainly effected by the area of the saline aquifers. Since both of the CSLF and CO2BLOCK methods take into the account the storage mechanisms such as geological structure storage, residual gas storage and dissolution storage, the results seem more reasonable. In addition, the CO2BLOCK method considers the formation stability during injection as well, which is more in accordance with the reality. In summary, the CO 2 storage potential of Bohai Bay Basin, Beibu Gulf Basin, and Yinggehai Basin are 39.98, 53.22, and 13.37 Gt, respectively. This further verifies the great potential of industrial-scale pilot and demonstration CO 2 storage projects in offshore deep saline aquifers in China. [ABSTRACT FROM AUTHOR]

Both environmental regulation (ER) and different pollutants emission are characterized by differentiation, but the nonlinear relationship between different intensities of ER and different levels of pollutants emission has not yet been elaborated. This paper examines the nonlinear effects of ER at different intensities on PM 2.5 and CO 2 at different states with the help of cutting-edge Quantile on Quantile Approach (QQA), comprehensively reveals the inner law of ER to promote pollutants synergistic reduction. This study found that, both PM 2.5 and CO 2 show obvious regional differences but are not polarized. ER can effectively help reduce PM 2.5 and CO 2 in average, and this reduction effect is more obvious for central-western cities. The effects of different intensities of ER on different states of PM 2.5 and CO 2 have obvious nonlinear spillover characteristics. The impact of ER on PM 2.5 shows wave-like changes. Increasing ER intensity has a stronger inhibitory effect on PM 2.5 of high scale, but when PM 2.5 is relatively low, moderate ER is needed to match it, and excessive intensity of ER will be detrimental to reduce PM 2.5. The negative impact of ER on CO 2 fluctuates relatively stable. ER at high quantiles have more obvious reduction effect on CO 2 of high levels, but excessive intensity of ER is not conducive to reduce CO 2. Achieve the synergistic reduction of PM 2.5 and CO 2 should not only consider the differences in ER between regions, but also to combine the scale differences of pollution and carbon emission. Our study suggests that the improvement of synergistic emission reduction system needs to consider the strength of ER and the level of pollutants emission according to local conditions, which will help to realize green development more efficiently. • Assessing the impacts of different intensities of ER on different levels of PM 2.5 and CO 2. • The use of QQ approach can obtain richer nonlinear information. • The effects of ER on PM 2.5 and CO 2 are asymmetric and heterogeneous. • Increasing ER intensity has a stronger inhibitory effect on PM 2.5 of high scale. • Nonlinear changes in the negative impact of ER on CO2 fluctuates relatively stable. [ABSTRACT FROM AUTHOR]

Carbon Capture, Utilization, and Storage (CCUS) is an indispensable technology to achieve carbon neutrality in China, but confined by technology and economy, the offshore CCUS in China is still in the planning stage and has not yet reached the desired scale. Offshore source-sink matching and cost analysis of CCUS is the premise and basis of offshore CCUS deployment. Thus, based on the CO 2 storage potential of offshore sedimentary basins in China, this paper conducts the offshore source-sink matching and cost analysis of CCUS in China under different constraints. The result showed that: ⅰ) the CO 2 storage capacity of China's offshore sedimentary basins is estimated to be 767.3 Gt, which is enough to meet approximately 200 years of coal power CO 2 emissions in China. ⅱ) the CO 2 storage potential could reach 721.9 Mt/a by source-sink matching under different constraints. ⅲ) early opportunities for offshore CCUS would be in the Bohai Bay and Pearl River Mouth Basin, considering the compensation effect of CO 2 -EOR. ⅳ) combined with the CCUS cost and emission reduction in China under different time nodes, it is inferred that deploying offshore CCUS in China between 2030 and 2040 commercially will be advantageous. • The CO 2 storage potential in China's offshore sedimentary basin was evaluated. • The cost of offshore CCUS was analyzed under different technology combinations. • Bohai Bay and Pearl River Mouth Basin would be early opportunities for offshore CCUS. • 2030–2040 would be the favorable time to deploy the large-scale offshore CCUS. [ABSTRACT FROM AUTHOR]

Mitigating greenhouse gas emissions is a significant global challenge, and precise prediction of carbon emissions holds the utmost importance for China to attain its dual carbon goal. To overcome the limitations of existing studies using a single forecasting method, based on quadratic exponential smoothing, multiple linear regression, and Gaussian process regression models, this paper constructs a carbon emission combination forecasting model with the generalized induced ordered weighted average (GIOWA) operator and analyzes carbon emission reduction performance. Empirical testing utilizing China's carbon emission data from 1980 to 2020 reveals the following findings: (1) The GIOWA combination forecasting model significantly enhances the accuracy of carbon emission forecasts, with an average accuracy exceeding 99.5% over the sample period, surpassing various single forecasting methods. (2) The carbon emission reduction target can be achieved under three different scenarios of low, average, and high GDP growth rates. Specifically, under the low growth rate scenario, China can achieve a 60% reduction in carbon intensity by 2025 and a 65% reduction by 2030. This study offers valuable decision support for the development of effective carbon reduction policies. [ABSTRACT FROM AUTHOR]

China has set an ambitious national determined contributions target to peak CO 2 emissions by 2030 and aims to be carbon neutral by 2060. One of China's top energy consumers and CO 2 contributors, the steel industry accounts for 13% of the country's total consumption and 15% of CO 2 emissions. In response to the present global warming trend, there is an urgent need to cut energy consumption and CO 2 emissions to promote low-carbon growth. This paper attempts to provide a detailed analysis of the steel industry's CO 2 emission reduction path to carbon neutrality. Further efforts in terms of industrial structure, material efficiency, energy efficiency, and low- or zero-carbon technologies are required to achieve a low-carbon transition. Given that decarbonization is a significant priority in the steel industry in many countries, this study focuses on the goals and technological paths of low-carbon emissions projects to optimize existing technology priorities and propose development directions. Deep decarbonization is also projected to be achieved by combining CCUS and hydrogen metallurgy technologies. The steel industry requires collaborative efforts to standardize CO 2 emission accounting methodologies and establish a carbon trading system to strengthen carbon emission management. • The steel industry is one of the key contributors to carbon neutrality which needs to accelerate decarbonization. • Reducing energy consumption and CO 2 emissions to keep up with the current global warming trend are reviewed. • This paper selects low-carbon emission projects to optimize current technology priorities and provide development directions. • Policy recommendations and next steps for low-carbon transition are given. [ABSTRACT FROM AUTHOR]

This paper investigates the decoupling of carbon dioxide (CO 2 ) emissions from agricultural economic growth in 30 Chinese provinces from 1997 to 2014. First, CO 2 emissions from agricultural production activities, farming, and livestock husbandry are computed. Then, this paper explores the spatial and temporal heterogeneity of CO 2 emissions and their intensity in China’s agricultural sector. Finally, this paper compares decoupling of China’s agricultural CO 2 emissions from agricultural output value across different regions and years. The results indicate that fertilizer, in-season rice cultivation, and cattle generated the most CO 2 emissions in the categories of agricultural production activities, farming, and livestock husbandry, respectively. The results also show that East China covered more periods of the strong decoupling of CO 2 emissions from agricultural output value between 1997 and 2014. To decrease CO 2 emissions, this paper suggests imposing a higher value-added tax on fertilizer producers, while waiving value-added tax for organic fertilizer and substituting animal manure for conventional fertilizers where possible. [ABSTRACT FROM AUTHOR]

[Display omitted] To achieve carbon neutrality, it is urgent to quantify carbon emissions to support policy deployment. Based on life cycle assessment, this paper proposed calculation method for carbon emissions from road infrastructure in a Demonstration Zone, China. Based on scenario analysis, this paper quantified the carbon emissions currently and analyzed the trend and characteristics of carbon emissions of road infrastructure from 2020 to 2060 through 4 scenarios. The results show the carbon emissions fluctuate between 20 kt and 540 kt CO 2 from 2013 to 2019 and increase significantly in 2014 due to the surge in road mileage. In the first three scenarios, the carbon emissions show an increasing trend after 2030, with annual growth rates of 1.12%, 0.57%, and 0.27% respectively. However, in the optimal scenario, the peak year of carbon emissions is 2024, with the peak emissions of 649.333 kt CO 2 and an increase of 245% over the base year. [ABSTRACT FROM AUTHOR]

• Four time-delay weights structural types are designed by the grey incidence model. • The novel multivariable grey prediction model considering the time-delay periods and time-delay weights is proposed. • The accumulating impact of influencing factors on CO 2 emissions of China's transport sector is measured. CO 2 emissions from the transportation sector occupy an increasingly important proportion in China's carbon dioxide emissions. Measuring the accumulative impact of factors on carbon emissions over time is of great significance for formulating corresponding policies. This paper aims to propose a novel time-delay multivariate grey model to measure the CO 2 emissions' accumulating impact of China's transportation sector. Firstly, the grey incidence model is used to identify time lags between the input and output variables, and also analyze the structure type of time-delay weights. Then, an accumulative time-delay multivariate grey prediction model is developed. In this model, a Gaussian formula is used to discretize the convolution integral of the time response function, and the particle swarm optimization algorithm is employed to determine the optimal weight coefficients. Finally, a case for CO 2 emissions prediction is adopted to test the effectiveness and practicality of this model compared with the alternative models. The results show that the proposed model outperforms other six competing models in accordance with two measuring indices, and suggestions on emissions mitigation are proposed based on the prediction results. [ABSTRACT FROM AUTHOR]

• Solar-assisted PCM- based co-electrolysis of H 2 O and CO 2 for methanol production. • Energy, exergy and economic analysis of proposed high temperature innovative system. • Solar-to-fuel efficiency, methanol production and levelised fuel cost have competitive index. The co-electrolysis of H 2 O and CO 2 in a solid oxide electrolyzer cell (SOEC) integrated with solar energy leads to the development of renewable or near-zero emission technology for methanol production. Renewable methanol synthesis utilizing H 2 O and CO 2 captured from different industrial processes has received much attention. In this paper, a high-temperature electrolyzer integrated with solar dish collectors and photovoltaic arrays is proposed and investigated for syngas production and methanol synthesis. Phase change material is used for long-duration thermal energy storage to make an uninterrupted operation. Thermo-economic and technical feasibility analysis of the proposed system is performed and the most influential operating parameters (direct normal irradiance, current density, SOEC operating temperature and pressure) are varied to evaluate the system's performance by parametric study. The hourly data for the year 2021 of the direct normal irradiance (W/m2), wind speed (m/s) and ambient temperature (°C) for the studied location in China is accessed and presented. The results of the study show that solar-to-fuel efficiency and methanol production rate are 29.27 %, and 41.85 kg/h, respectively, while the levelised cost of fuel (LCoF) is calculated at approximately 0.399 Euros/kg. The sensitivity analysis for the economic and thermodynamic structure is conducted and discussed. [ABSTRACT FROM AUTHOR]

Hydrogen produced from renewables-fuelled electrolysis has the potential to provide deep decarbonisation for sectors that are the most difficult to decarbonise, but the intermittency of renewable sources may result in low electrolyser utilisation and, consequently, high costs. This study determines the greenhouse gas (GHG) emissions and levelised cost of hydrogen (LCOH) associated with blending wind electricity with the grid to increase electrolyser utilisation. A novel cost model was developed to determine the production performance, costs and embodied CO 2 emissions of an electrolyser with hybrid fuel supply (wind and grid) considering dynamic load constraints of alkaline (ALK) and Proton exchange membrane (PEM) electrolysers and using high-resolution historical weather data to determine wind production profiles in two case study regions: northern (Bayannur) and southern (Pingtan) China. The results show that using 52% of grid electricity in an ALK electrolyser in Bayannur reduces LCOH by 11%, increasing hydrogen production by 74% but with 17.4 kg CO 2 / kg H 2 generated in CO 2 emissions. When a carbon price is accounted for, the optimal electrolyser utilisation is reduced to 40%, with the LCE 44% reduced. Emissions of 9.8 kg CO 2 /kg H 2 are lower than for stream methane reforming with carbon capture. In Southern China (Pingtan), LCOH is higher than Bayanur because of the high electricity cost. The economic benefits of increasing grid power depend primarily on the total CAPEX cost, grid power cost, and carbon tax. By altering the carbon tax, the optimal blend of wind/ grid differs. The grid contribution to the optimal blend diminishes as a carbon tax approaches 35 USD/ t CO 2. • This paper analyses the value of adding grid electricity to a pure wind-powered H 2 production plant. • The LCOH and CO 2 life-cycle emissions are obtained for Alkaline and PEM electrolysers. • We are introducing the novel ICOH metric to optimise the trade-off of LCOH and CO 2 emission on H 2 production. • Using only 52% of grid electricity in an ALK electrolyser, H 2 production can increase by 75%. [ABSTRACT FROM AUTHOR]

• It maps the CO 2 storage potentials in shale basins in China comprehensively. • Both shale oil and gas basins are quantitatively estimated via different equations. • Basins are classified into three tiers for carbon storage with varied time scales. • The equations for the estimations of CO 2 storage potentials are optimised. • The density variation of CO 2 at different conditions was considered. China is the second largest shale gas and oil producing country possessing large and significant shale basins, and it is also one of the top carbon emitting countries. Therefore, there is significant potential to store CO 2 in shales in China to remove the carbon emission and enhance and gas recovery simultaneously. This research provides a comprehensive prediction of potentials of CO 2 storage in major shale gas/oil basins in China based on most recent publications where density variation of CO 2 at different subsurface conditions is considered and the different stages of development are classified. We optimise the calculation equations for shale gas and oil respectively, and further classified the three tiers (i.e. commercial, potential and possible reservoirs) in the calculation to prioritise the sequestration site selection. A total of around 6194 Gt, CO 2 sequestration in shales, including 172 Gt for commercial, 849 Gt for potential and 5147 Gt for possible storage, equivalent to a total of 620 years' carbon emissions in China is expected. These can be realised in around 20 years, 20–50 years and 50–100 years respectively. For future applications, more concerns should be on the evaluation criteria of sequestration sites in shales, CO 2 fracturing mechanisms and potential leakage, multi-phase seepage and reactions, and environmental monitoring systems. As a comprehensive assessment of potentials of CO 2 storage in shale basins in China, this paper will provide an important guide for future academic studies, industrial operations and government policy making. [ABSTRACT FROM AUTHOR]

Evaluating and improving the environmental efficiency of the power system is the key to achieving sustainable development. However, the classic DEA approach is susceptible to producing biased results due to its inability to address spatial dependence across factors. Considering the spatial dependence of inputs and outputs, this paper proposes a dynamic spatial network DEA model with slacks-based measure (SNSBM) to examine the environmental efficiency of China's power systems, with a focus on the undesirable outputs of CO 2 , NO x , and SO 2. The investigation incorporates the Moran's I test to account for the spatial interactions of patent counts, coal consumption, CO 2 emissions, and renewable power generation. Compared to the classic network DEA, the SNSBM results reveal distinct spatial characteristics and a heightened level of differentiation, which highlights the importance of eliminating spatial dependence. From a dynamic perspective, environmental efficiency shows a visible surge in transmission and distribution divisions after 2015, confirming the success of China's market-oriented reform. In addition, CO 2 is the largest contributor to the environmental inefficiency of the power systems, followed by NO x and SO 2. This study highlights the importance of spatial dependence and provides many insightful policy recommendations for improving the environmental efficiency of China's power systems. • A dynamic spatial network DEA model with slack measures is proposed. • A spatial weight matrix is used to introduce the spatial inputs and outputs into the spatial DEA. • Environmental efficiency of China's power systems is studied with SNSBM model. • Environmental efficiency seems to be overestimated if ignoring the factor's spatial dependence. • CO 2 contributes most to the inefficiency of China's power system compared to SO 2 and NO x. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) is the primary greenhouse gas, with annual emissions reaching up to 54 billion tons globally, leading to an unprecedented acceleration of global warming. In conjunction with carbon capture, utilization, and storage (CCUS), which represents the most advanced and efficient technology for energy conservation and emission reduction, as well as the innovative concept of CO 2 storage in salt caverns, this paper investigates the industrial application potential of supercritical CO 2. Herein the feasibility of large-scale storage of supercritical CO 2 in salt caverns was investigated, focusing on the stability aspect associated with such storage. Specifically concentrating on the impact of upper and lower injection/production pressures and frequencies on the stability of carbon storage in salt caverns, this study utilizes numerical simulation methods to simulate the creep process that occurs in China's bedded salt formations. Numerical simulation results showed that: 1) From the perspective of salt cavern stability, the volume shrinkage, creep and damage degree of surrounding rock during operation all fall within an acceptable range. Consequently, it is feasible to implement carbon storage in these salt caverns for a during of 100 years. 2) Shortening the range of internal pressure will enhance the stability of salt cavern for carbon storage. Furthermore, different pressure intervals have an impact on the creep concentration position within the cavern, primarily resulting in a transformation between internal contraction of surrounding rock and sediment accumulation caused by floor creep by altering the lower pressure limit. 3) The injection and production frequency of salt cavern carbon storage (SCCS) is characterized by a low occurrence rate (<10 cycles). The stability of the cavern can be enhanced by increasing the injection and production frequency, nevertheless, it is important to note that internal pressure remains the primary factor influencing cavern stability compared to the injection and production frequency. • A digital model for supercritical CO2 storage in salt caverns is developed. • The operational parameters for SCCS are designed from the perspective of pressure intervals, injection and production frequencies. • The numerical simulation method is employed to simulate the dynamic change process of SCCS during 100 years of long-term operation, followed by a corresponding stability evaluation. • The alterations in cavity morphology and damage severity of salt caverns utilized for carbon storage are examined. [ABSTRACT FROM AUTHOR]

The cement manufacturing industry, a resource- and energy-intensive sector, took up more than 15% of total greenhouse gas emissions in China, thus finding a clean technology option for sustainable development is essential. CO 2 curing has emerged as a promising novel method for large-scale carbon sequestration and mechanical properties improvement of cement-based composites. Currently, a body of related works is mainly investigated in the laboratory, and understandings of the behaviors of CO 2 -cured cement-based composites are still less than complete, including, 1) the CO 2 storage potential has plenty of room for improvement due to the influence mechanism of variables factors remains unclear; 2) previous evaluations were mostly based on the subsets of individual result rather than an integrated dataset; 3) whether CO 2 curing is suitable for the manufacturing process of reinforced concrete. Therefore, this paper presents a comprehensive overview covering a wide range of parameters as well as fabrication, mechanical (compressive strength), and environmental (CO 2 uptake value) performances on the basis of a correct understanding of the differences between active and passive carbonation reactions. Notably, the influences of critical factors, including those less understood, e.g., types of curing setup (flow-able, enclosed, and others), components of binder, and aggregate/binder ratio, are also analyzed and the corresponding mechanisms discussed to achieve satisfied curing efficiency. Besides, corrosion-related challenges are also be pointed out to convince the widespread acceptance of this technology. Finally, based on this paper, limitations of existing research are identified and future scope on CO 2 curing regime is proposed. • 170 studies related to CO 2 /carbonation-cured cement-based composites are analyzed. • The differences between active/passive-carbonation together with reaction mechanisms are expounded. • Fabrication and influence factors on engineering and environmental properties are systematically reviewed. • CO 2 -cured cement-based composites exhibit excellent resistance to aggressive conditions. • The challenges and opportunities in the CO 2 curing method are innovatively discussed. [ABSTRACT FROM AUTHOR]

A fair regional CO 2 allocation scheme is an important guarantee to achieve carbon peak and carbon neutrality. Most existing studies on CO 2 allocation focus on carbon sources while ignore the role of carbon sinks. By combining the carbon sinks estimated by remote sensing technology with the carbon sources identified from multiple dimensions, this paper first analyzes the characteristics of China's net CO 2 emissions in 2015. Then a centralized DEA model is developed to construct a net CO 2 allocation scheme in 2020 and 2030 using historical data in 2015 with the help of the Python programming. On this basis, the allocation schemes considering carbon sinks or not are further compared to verify the rationality of the proposed allocation results. It concludes that a net CO 2 allocation scheme considering carbon sinks delivers significantly better results as it eases the dispersion of inter-provincial carbon quota and balances the development among regions. Geographically, Southwest China, rich in carbon sinks but less developed, will be given more quotas if carbon sinks are included than if they are not, while North China, poor in carbon sinks but more developed, will assume more responsibility for reducing emissions. Our paper sheds light on the importance of incorporating carbon sinks into the CO 2 allocation issue. • A fairness-oriented regional CO 2 allocation scheme considering carbon sinks is proposed. • A new centralized DEA model is developed to balance the allocation over the past and in the future. • The inclusion of carbon sinks breaks and restructures the layout of China's CO 2 allocation. • The allocation scheme is beneficial to Southwest China while unfavorable to North China. [ABSTRACT FROM AUTHOR]

• The entrance of new countries into EU increased the trade among these countries and the EU's old members. This scenario of changes in trade patterns influenced the distribution of environmental pressures among countries, in particular, CO 2 emissions. • The changes in economic structure in the New European Union countries, given their insertion in a globally integrated supply chain, are important to explain the evolution in their CO 2 emissions. • Sourcing pattern changes contributed to the increase of CO 2 emissions in the New European Union countries. • The emissions' reductions associated with technology advances were not large to fully compensate for increases due to the change in sourcing patterns in the New European Union countries. This paper's interest lies in the environmental pressures of the European Union (EU). EU membership requires a series of economic and political changes that should impact a country's production and consumption structures and its trade relationships. These changes, in turn, will affect CO 2 emissions sources and levels. This is especially true for the new Member States that joined during the 2004–2007 enlargement of the European Union, given the difference in their levels of development and production structure. As these countries increase participation in a globally integrated production chain their emission's structure and level should change. Using a Structural Decomposition Analysis we are able to quantify the main drivers of changes in emissions differentiating six components, namely: emissions intensity, industrial structure and sourcing, consumer preferences, final demand sourcing and consumption levels. Grouping the countries into five groups, New European Union countries, Old European Union countries, the United States of America, China, and the Rest of the World, we measure trading pattern changes and their impact on CO 2 emission levels. The main results show that, although New European Union countries countries' emissions generally declined, the changes were not large enough to offset their increased emissions from access to more and wider ranging export demand. Increased CO 2 emissions embodied in final goods exports were especially notable. [ABSTRACT FROM AUTHOR]

With rapid urbanization and industrialization, the number of light-duty gasoline vehicles (LDGVs) in China has continued to grow rapidly, leading to a significant increase in traffic pollution. Therefore, it is essential to accurately calculate the emission of LDGVs for air quality monitoring and management. Fortunately, Motor Vehicle Emission Simulator (MOVES) is a sophisticated model for estimating mobile source emissions with good prediction accuracy. However, the parameters of MOVES are based on the field tests in the US, which is worth exploring whether MOVES can be applied to other countries. Hence, in this paper, we used the portable emission measurement system (PEMS) to conduct real driving emission (RDE) tests of LDGVs, aiming to explore the possibility of the MOVES application in China. Based on the field tests, we modified basic parameters in the MOVES model, but unsatisfactory prediction performance was obtained. Existing research on improving MOVES performance mainly involved new binning of operating modes, but these methods had limited improvements. Though studies have also used machine learning methods for predicting LDGV emissions, they lacked comparison and integration with the MOVES model. To further improve the prediction accuracy, we proposed a novel road vehicle emission model that integrated the machine learning method and the MOVES to predict the road-level emission rates of NO and CO 2 emissions of LDGVs. In addition, we employed the Boruta algorithm to capture the key influencing factors and promote prediction performance. The enhanced model outperformed MOVES and achieved higher R2 values. On average, the improvement for CO 2 was 0.132, and for NO, it was 0.261. This work will provide references for MOVES improvements in practical scenarios and better predict pollutant emissions for LDGVs using limited resources of field tests in cities outside the US. • Integrating engine characteristics with the MOVES model can improve model performance. • Integrating machine learning with MOVES performs well in prediction of vehicle CO 2 and NO emission. • The proposed emission model provides a possibility for calculation rather than costly an experiment in countries outside the USA. [ABSTRACT FROM AUTHOR]

In the past decades, resources such as iron ore were transported to the upper-middle reaches of the Yangtze River by river-sea combined mode in order to support the rapid economic development of Yangtze River Economic Zone. However, emissions from vessels have caused serious negative effect on the environment along the Yangtze River. Therefore, the Chinese government took a series of measures so as to control the emissions in this area. This paper draws comparisons among river-sea combined mode, river-sea mode and mixed mode (combination of the river-sea combined mode and river-sea mode) based on the ship emissions inventory of SO x , PM 10 , PM 2.5 , NO x , CO, HC, CO 2 , N 2 O and CH 4 for 13 common cases in the existing network by bottom-up method. In addition, the paper carries out in-depth analyses, providing evidence for future ship operation directions. The results indicate river-sea mode and mixed mode which implement river-sea vessels record less unit emissions compared to the traditional river-sea combined mode. Moreover, shorter transshipment (lightning) times, proper ports of transshipping and cleaner fuels are able to reduce ship emissions significantly. Hence, we conclude that first, river-sea vessels should be encouraged; second, the initiative of a deep-water channel of the Yangtze River should be continued; and last, stricter regulations of fuels have played a significant role in reducing ship emissions. • Vessel operation is closely related to ocean environmental protection. • Emissions of bulk Carriers in China's East Coast-Yangtze River network are assessed. • Vessel operation modes are compared based on the ship emissions inventory. • Case study and future ship operation directions are developed. [ABSTRACT FROM AUTHOR]

Investing in energy efficiency is considered to be an effective way to reduce the carbon emissions. However, the resulting CO 2 savings may be partially or totally offset by the rebound effect (RE). This paper goes beyond the traditional energy RE to investigate the rebound effect as related to CO 2 emissions, aims to explore the direct CO 2 rebound effect (CRE) in urban households at the provincial level. To achieve the objective, this study uses IPCC carbon emissions accounting method, then proposes an elasticity approach and constructs an individual fixed-effect variable coefficient panel data model. The results show that the total CO 2 emissions from household energy consumption were rising in most provinces during 2002–2017. The purchased electricity and heat CO 2 emissions are growing faster than combustion CO 2 emissions. Regarding the magnitude of the CRE, there are three types of direct CRE among urban households in China: the backfire effect, partial rebound effect and super conservation effect. Overall, the average direct CRE in urban households is 59.90%; specifically, the western region has the highest direct CRE (90.92%), compared with the eastern region (52.84%) and central region (24.88%). The government should take into account the CRE of households, in order to avoid overestimating the carbon reduction. Attention should also be paid to the differences between provinces when formulating energy policies. The analysis above helps local governments to formulate effective energy policies to promote households' carbon emission reduction. • This paper proposes an elasticity method for estimating CO 2 rebound effect. • The carbon emissions from household energy consumption are calculated. • There are three types of direct CO 2 rebound effect among urban households in China. • The average direct CO 2 rebound effect in urban households is 59.9%. [ABSTRACT FROM AUTHOR]

Carbon emissions from the electricity industry (CEEI) account for more than 40% of China's total emissions. This paper examines the influential factors of China's CEEI at both national and provincial level and explores targeted provincial strategies, which are critical for China to control its CEEI effectively and to achieve its carbon peaking aim. First, this study quantifies the contributions of nine factors influencing China's CEEI increase using Logistic Mean Divided Index (LMDI) decomposition. The results show that economic growth is the dominant driver, while power consumption intensity, energy intensity of thermal power generation (TPG) and power mix are the main inhibitors. After stepping into the new era in 2012, in general, the evolutions of all the 4 main factors aided CEEI control. Second, according to the recent status of the main factors, we classify 30 provinces into 4 groups with K-means clustering. And then, based on the characteristics of each group, the paper puts forward provincial targeted recommendations to address the rebound of CEEI since 2017 and to promote the low-carbon transformation of China's electricity industry. This study confirms that it is a promising direction for LMDI model to combine with cluster analysis and proposes a basic flow for this combination: LMDI → main influencing factors → clustering variables → cluster analysis → targeted strategies, which will conduce to deepen LMDI applications. [Display omitted] • Confirms it is a promising direction for LMDI to combine with cluster analysis and provides a flow. • Influencing factors' values as clustering variables aid more in targeted strategies. • Entering the new era, the evolutions of four main factors' roles aided CO 2 peaking. • Proposes targeted policies to address the rebound of CEEI in Stage 2–2. • Covers all energy types of thermal power generation including heat in carbon accounting. [ABSTRACT FROM AUTHOR]

• This paper analyzes China's challenges toward carbon neutrality (CN) by 2060. • Currently, up to 85% of China's energy consumption relies on fossil fuels. • China's zero-carbon technologies and economy are not yet sufficient for CN. • Thus, we propose a three-stage/four-step strategy for China to achieve CN. • This paper also presents seven suggestions to foster China's green transition. In response to climate change, the Chinese government has set a clear goal to reach its carbon peak by 2030 and achieve carbon neutrality by 2060, endeavoring to gradually realize net-zero carbon dioxide (CO 2) emissions. This paper explores the concept of carbon neutrality and makes a comparative analysis of the gap between China, the European Union, and the United States vis-à-vis carbon neutrality based on international data. The main challenges China faces in its progress toward carbon neutrality are the following: first, China's energy consumption and CO 2 emissions continue to increase, while its carbon peak has not yet been reached; second, carbon emission reduction in China is an arduous process, as the transition period allowed for the country to transition from its carbon peak to carbon neutrality is shorter than that of developed countries; third, China remains reliant on high-carbon fossil energy, with high energy consumption and low energy utilization efficiency; fourth, China's low level of economic development, compared with those of the EU, the US, or other developed countries, makes it relatively weak to withstand economic risks; and fifth, China's low-carbon and zero-carbon technologies are not mature. Therefore, this paper posits a three-stage/four-step strategy as well as seven specific suggestions that could benefit China's progress toward carbon neutrality. [ABSTRACT FROM AUTHOR]

• The principles of hydro-wind compensating operation are explored. • Hydropower compensation for wind power in a power grid is quantitatively analyzed. • The principles of hydro-wind compensation are used for the complementary operation of a power grid. • Carbon dioxide emissions can be reduced while satisfying the load demand of the power grid. The high randomness, intermittency and uncontrollability of wind power make large-scale wind power generation present large challenges for integration into a power grid. In this paper, the principles of hydro-wind compensating operation are explored, aiming at improving the power quality of wind power and promoting the integration of wind power into the power grid. Based on the principles of hydro-wind compensating operation, the calculation method of the hydropower compensation capacity for wind power is derived. Then, an optimizing operation model of a hydro-thermal-wind hybrid power system based on the hydro-wind power compensating principle is proposed to minimize the carbon dioxide emissions and obtain optimal operation scheduling of the hybrid power system by taking advantage of hydro-wind compensation and the peak regulation capacity of hydropower. In this model, the baseload and nonbaseload output emission rates are adopted to estimate the carbon dioxide emissions of different power output processes and the emission reduction benefits. Moreover, three scenarios of the operation mode are proposed to demonstrate the applicability of the hydro-wind power compensating principle in practice. The Northwest Power Grid in China is selected as a case study to verify the effectiveness of the proposed model compared to historical operating data. The results indicate that the hydro-wind power compensating principle plays a crucial role in hydro-thermal-wind combined optimal operation. Additionally, the proposed model can improve the wind power generation and reduce the carbon dioxide emissions of the power grid. In particular, the carbon dioxide emissions can be reduced by approximately 1696*104 t each year in the Northwest Power Grid. This study provides an approach to schedule optimal operation plans for power grids with large-scale wind power and provides a valuable reference for the large-scale utilization of other kinds of renewable energy worldwide. [ABSTRACT FROM AUTHOR]

Research has shown, that the replacement of conventional vehicles (CVs) by electric vehicles (EVs) can reduce urban heat island intensity (UHII). This leads not only to a more comfortable climate during summer but also to a reduction of carbon dioxide emissions from the vehicles themselves and to a reduction in the need for air conditioning (AC) and associated emissions. The current study examines to what extent a range of different mobility concepts, can lead to a reduction in urban heat island intensity and carbon dioxide emissions in the city of Beijing, China. For this purpose, the impact that electric vehicles fuelled with the average energy mix, hydrogen vehicles (HyVs) fuelled with hydrogen from electrolysis from the regular energy mix, HyVs fuelled with hydrogen produced through wind power, energy efficient CVs, EVs fuelled with wind power and energy efficient metro light railway (metro) travel have on summer heat island intensity (SHII) and CO 2 -emissions is analysed. The lowest SHII mitigation effect was found for a replacement of CVs with fuel efficient diesel cars while hydrogen cars that are fuelled with hydrogen generated from the average electricity mix even leads to higher SHII and higher CO 2 emissions. The largest SHII mitigation effect was found for a scenario where conventional vehicles are replaced with energy efficient metro travel. The CO 2 saving potential is highest for EVs which are powered with electricity generated from wind turbines, closely followed by HyVs that are fuelled with hydrogen generated from electrolysis of water using wind electricity. The paper helps policymakers and consumers to make the right choices when it comes to environmentally friendly mobility options. • Summer heat island intensity (SHII) is mitigated through different mobility choices. • CO 2 reduction by over 12,000 tons/day is possible through reduced usage of air conditioning. • Energy efficient public transportation leads to the highest mitigation of SHII and CO 2 levels. • Electric and hydrogen cars fuelled with renewable energies mitigate SHII and CO 2 levels. • Hydrogen cars fuelled with non-renewable energies lead to higher SHII and CO 2 levels. [ABSTRACT FROM AUTHOR]

As the basic sector providing basic service and promoting economy development, the increment demand of transport sector has brought much more pressure on the environment. Beijing-Tianjin-Hebei region is the representative region of the advanced region of China and it is significant to analyze how to achieve the low-carbon transport development in Beijing-Tianjin-Hebei region, meanwhile provide reference of green development for other regions. Using the panel data from 1995 to 2016, the paper analyses the driving factor of carbon dioxide emissions from transport sector with two different analytical methods. The results of LMDI show that transportation energy intensity and economic effect is the main factor increasing the carbon dioxide emissions and the contributing factors to the carbon dioxide emissions reduction in the transport sector are the energy structure effect, the freight turnover of unit industrial output effect and the industrialization effect. In different subclasses divided by different threshold variables, industrialization has the positive impact while the coefficients vary, which indicates that appropriate development policies should be formulated in light of the development characteristics of different regions. [ABSTRACT FROM AUTHOR]

• The decoupling status of China's manufacturing industry as a whole and its sub-sectors is recognized. • An improved PDA-IDA method is proposed to study the factors influencing the decoupling status. • Further decomposition of the energy intensity effect is conducted using the improved method. • The impacts of production technology related factors and potential factors are quantified. Manufacturing industry occupies an important position in China's national economy, and its decoupling from carbon dioxide emissions largely determines the realization of China's transition to a green economy. This paper uses the Tapio decoupling indicator to explore the decoupling status between manufacturing value added and carbon dioxide emissions in China from 1995 to 2015. Then, the improved production-theoretical decomposition analysis-index decomposition analysis (PDA-IDA) method is proposed to analyze the factors influencing changes in decoupling status, with the technology heterogeneity of manufacturing sub-sectors considered. The results show that China's manufacturing industry experiences a decoupling development trend from 1995 to 2015. The potential energy intensity is the dominant factor in promoting the decoupling development of manufacturing industry, while the output scale effect is the main inhibitory factor. In addition, industrial restructuring and adjustment in carbon density are far from achieving the expected emission reduction effects, while the effects of technological progress and technical efficiency on the decoupling are relatively small. [ABSTRACT FROM AUTHOR]

• Decoupling analysis combined with LMDI is conducted for China's industrial sectors. • The decoupling relationship between industrial economic growth and CO 2 emissions is investigated. • The decomposition of influential factors and the mechanisms of impact are investigated. • The CO 2 emissions coefficient has a great reducing effect on CO 2 emissions. • High energy-consumption sectors play a dominant role in influencing the decoupling in China. In China, industry produces the largest amount of CO 2 emissions and, thus, is the area with the greatest potential for emissions reductions. In this paper, we calculate the CO 2 emissions of 18 different energy sources for China's industry and subsectors from 1991 to 2015 (including indirect emissions from production processes). The LMDI (Logarithmic Mean Divisia Index) method and the Tapio decoupling model are combined to study the dynamic evolution of the characteristics and factors influencing the CO 2 emissions. The changes in CO 2 emissions were further decomposed into emissions coefficients, energy structure, energy intensity, CO 2 emissions intensity in production processes, industrial structure, per capita output, and population size. The high energy-consumption industrial sectors were analyzed in particular. The results show that: 1) in most years, the relationship between industrial economic growth and CO 2 emissions shows a weak decoupling. Only from 1996 to 1999 and 2014 to 2015 was a strong decoupling shown. 2) For the industry as a whole, the impact of per capita output on CO 2 emissions was positive from 1991 to 2015. The second factor is population size, and its effect was more obvious for 2006–2015. The CO 2 emissions coefficient is the most significant factor in suppressing CO 2 emissions, followed by the energy intensity and the CO 2 emissions intensity in production processes. In terms of CO 2 emissions reduction, the effect of industrial structure and energy structure are not as obvious. 3) The proportion of high energy-consumption sectors' emissions to total industrial emissions shows a steadily increasing trend, from 71.60% in 1991 to 90.59% in 2015; the total emissions for the Manufacture of Non-Metallic Mineral Products subsector was the highest, followed by the Smelting and Pressing of Ferrous Metals subsector. [ABSTRACT FROM AUTHOR]

• A high spatial resolution CO 2 emissions inventory of 280 Chinese cities was compiled. • Three methods were compared to evaluate the carbon efficiency of Chinese cities. • The best and worst-performing cities were consistent regardless of different methods. • Top-ranking cities were located in the coastal regions of China. • Lagging-behind cities were located in the central and western regions of China. Comprehensive and accurate city-level carbon dioxide emissions inventory is key to success in China's pursuit of low-carbon development. Based on a high-resolution gridded data, this paper evaluates and benchmarks the carbon emissions efficiency of 280 Chinese cities using three different methods, i.e., composite index, data envelopment analysis and stochastic frontier analysis. The comparative analysis reveals that the average carbon emissions efficiency of Chinese cities is about 70–90%, with only 9 efficient cities (3%). Although the ranking of intermediate cities varies greatly according to the method employed, the most and least carbon-efficient cities remain consistent. While the best-performing cities are found in the coastal regions, the worst-performing cities are located in the central and western regions, which suggests an imbalanced low-carbon development in China. Guided by the results, local governments are encouraged to compete and learn from similar ranking benchmarks in a new regime of "Top Runner City". Finally, the scores of carbon emissions efficiency can provide a scientific basis for the bottom-up allocation of carbon emissions rights to boost the development of the nationwide carbon market in China. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • We incorporate a variety of principles and indicators into an improved ZSG-DEA model. • We conduct a multi-criteria allocation of China's CEA by 2030 to provincial shares. • We measure the total and per capita space for carbon emissions by province. • All provinces reach the DEA frontier with different CEA ranging from 4.21 to 16.77 Gt. • Differentiated provincial reduction policies are the key to achieving China's INDCs. Abstract Accelerating global warming has suggested the importance of controlling greenhouse gas emissions associated with human activities. In striving to fulfill the Paris Agreement, China has announced its Intended Nationally Determined Contributions (INDCs) aimed at reducing its carbon dioxide (CO 2) emission intensity by 60–65% in 2030 against the level of 2005. However, China's INDCs cannot be fulfilled without formulating appropriate schemes for the allocation of carbon emission allowance (CEA) at sub-national scales. To help close the gap in our knowledge, this paper starts with measuring the overall CEA of China by 2030, and then proposes a science-based scheme for CEA allocation by developing an improved zero sum gains-data envelopment analysis (ZSG-DEA) model. It demonstrates that the final CEA of some northern provinces can be cut down as compared to their initial shares and, conversely, most southern provinces experience an increase in their CEA. Comparing the final share of CEA by province with current carbon emissions, we observe that provinces with abundant energy reserves, such as Shanxi, Inner Mongolia and Shaanxi, tend to be operating in a state of overshoot in terms of space for carbon emissions (SCE). In contrast, there remains SCE when it comes to Guangdong, Hunan, Fujian, etc. The remaining provinces, such as Heilongjiang, Hebei and Ningxia, are close to the break-even point. In view of the differing SCE of individual provinces, common but differentiated policies for CO 2 emission control would be the key to achieving China's INDCs. The research findings lay a scientific basis for the Chinese government to make its INDCs come true through inter-provincial collaboration on emission reduction, but also serve as a reference for fueling further scientific discussions and development of schemes for the allocation of responsibility for carbon emissions at multiple scales within and beyond China. [ABSTRACT FROM AUTHOR]

Abstract Industrial sector is responsible for the majority of China's carbon dioxide (CO 2) emissions and contributed most to the rapid increment in the first decade of this century. However, CO 2 emissions in the industrial sector stagnated due to China's economic slowdown since 2012. This paper aims to estimate the CO 2 emissions in China's industrial sector during 2010–2016 to deliver sectoral and regional details and uncover the reasons for the emissions stagnancy. We find that the emission stagnancy is a result of decreasing energy intensity and economic slowdown. Industrial restructuring within the entire industrial sector and emission intensity (emissions per unit of energy consumption) had limited effect on the emissions reduction. From the sectoral perspective, iron & steel and nonmetal sectors accounted for most reduced emissions in China's industrial sectors during 2014–2016. From the regional perspective, the emissions decrease mainly occurred in western and northeastern provinces, rather than more developed coastal provinces. Mitigation policies are raised, including the industrial structure shift from energy-intensive sectors to other sectors and addressing the emissions mitigation in rapid industrializing provinces, such as Xinjiang, Inner Mongolia and Ningxia, so that an earlier and lower emission peak of China's industrial sectors can be achieved. Highlights • Iron & steel and nonmetal sectors accounted for most emissions reduction. • Decreasing energy intensity and economic slowdown are the main reasons. • Emissions in most energy-intensive sectors have peaked or approach the peak. • Emissions decrease occurred mainly in the western and northeastern provinces. [ABSTRACT FROM AUTHOR]

Highlights • The increases of commuting CO 2 emissions are several times larger than the urban size, population, and economics' developments. • Metro services reducing commuting CO 2 emissions near the metro stations is not statistically significant, possibly because the proportions of car users near the metro stations are similar to the two cities' average levels, which is caused by their higher household income and the longer travel time using the metro. • In Beijing, there are the smallest commuting CO 2 emissions in the outer suburbs due to job-housing balances, short distance and large percentage of non-motorized mode uses while the largest commuting CO 2 emissions in the inner sprawl suburbs due to car trips with long distance. Abstract To understand the changing relationships between commuting CO 2 emissions (CCE), travel behavior and urban forms, this paper provides a comparative study between the typical Chinese cities of Beijing (more developed) and Xi'an (rapidly developing). Further, the effects of metro services on reducing CCE were explored, and comparative analysis on CCE between the inner sprawling suburbs and outer suburbs was conducted. It was found that: (i) the increases in CCE are several times larger than the increases in urban size, population, and economic developments; (ii) metro services reducing CCE near metro stations is not statistically significant, maybe because the proportions of car users near the metro stations are similar to the two cities' average levels, which is caused by their higher household income and the longer travel time using the metro; (iii) in Beijing, there are smallest CCE in the outer suburbs due to job-housing balances, short distance and large percentage of non-motorized mode uses while largest CCE in the inner sprawl suburbs due to car trips with long distance. These findings indicate that to cope with the rapidly increasing CCE, more attention should be paid to developing strong industry and real-estate simultaneously; the improvement in the feeder bus and public bicycle systems should also be reinforced to reduce the total travel time of metro users; and satellite cities with job-housing balance are greatly needed. The implications will benefit efforts to reduce CCE and mitigate global climate change, and they also provide empirical evidence and reference values for other global cities. [ABSTRACT FROM AUTHOR]

Abstract: This paper discusses the current status of CCS in China, providing an update of current projects and past activities in research and development, and a brief overview of prospects for CCS deployment in China. CCS related research in China has been building from a focus on research and development and exploration of the technical considerations o f CCS potential in China in coordination with international partners. While large scale demonstration of integrated CCS projects is still at an early stage, there is significant knowledge and technical expertise that can be derived from ongoing pilot projects. These projects employ various mature technologies that may be integrated and scaled to facilitate demonstration and deployment of CCS in the future. In addition, China is increasingly exploring opportunities in CO2 utilization to drive and support deployment of CCS–this is also known as CO2 capture, utilization and storage (CCUS). This paper provides information on some of these key activities, including details of specific projects and a background of the regulatory and policy frameworks and international cooperation on CCS and CCUS in China. [Copyright &y& Elsevier]

Highlights • The empirical analysis was conducted from regional and provincial perspectives. • Industrial output growth contributed the most to China’s industrial CO 2 emissions. • Energy intensity was the decisive factor in controlling industrial CO 2 emissions. • Most provinces exhibited weak decoupling effect. • The factors effects and decoupling progress show distinct spatial characteristics. Abstract This paper utilizes the Logarithmic Mean Divisia Index (LMDI) to quantify the contributions of various factors on industrial CO 2 emissions (ICE) at both the regional and provincial levels, and then analyzes the decoupling index and its components. The main results include: (1) Industrial activity was the leading promoting factor in ICE, while energy intensity was the decisive factor for controlling ICE in most provinces. (2) Energy structure change only had a marginal impact on ICE and varied considerably across provinces. (3) The effects of various factors are distinctly diverse in different provinces; generally, the inhibiting effects only partly offset the promoting effects. (4) Most provinces exhibited weak decoupling effect, energy intensity decline was the crucial factor in their decoupling progress, while energy structure switch only played a negligible role in decoupling progress, even exerted an opposite effect in emission mitigation in some provinces, and therefore dragged down their decoupling progress. [ABSTRACT FROM AUTHOR]

Abstract: This paper applies portfolio theory to evaluate China''s 2020-medium-term plans for generating technologies and its generating portfolio. With reference to the risk of relevant generating-cost streams, the paper discusses China''s future development of efficient (Pareto optimal) generating portfolios that enhance energy security in different scenarios, including CO2-emission-constrained scenarios. This research has found that the future adjustment of China''s planned 2020 generating portfolio can reduce the portfolio''s cost risk through appropriate diversification of generating technologies, but a price will be paid in the form of increased generating cost. In the CO2-emission-constrained scenarios, the generating-cost risk of China''s planned 2020 portfolio is even greater than that of the 2005 portfolio, but increasing the proportion of nuclear power in the generating portfolio can reduce the cost risk effectively. For renewable-power generation, because of relatively high generating costs, it will be necessary to obtain stronger policy support to promote renewable-power development. [Copyright &y& Elsevier]

Initiatives to mitigate climate change have recently aroused great interest in the role of natural carbon sinks in coastal ecosystems. Seaweeds are widely distributed in the world and represent a large biomass. Since they are part of the global carbon reserves, they remove carbon dioxide and influence climate change. Using the recent 20 years of seaweed mariculture in China's coastal areas as a case, this paper quantifies the carbon storage in cultivated seaweed biomass, and evaluates the carbon sink potential, the remediation ability of nitrogen and phosphorus and other environmental benefits. The carbon sink potential of cultivated seaweeds exhibits a rising trend from 2000 to 2019. The total carbon, nitrogen, and phosphorus removal amount of seaweed were 3,551,754.9 ± 177,587.75, 297,772.25 ± 14,888.61, 39,967.15 ± 1998.36 tons according to the seaweed cultivation yield in China coast. The total benefit of carbon sequestration was 22,405.67 ± 259.59 million CNY, and the average benefit was 1120.28 ± 263.27 million CNY, with the average annual growth rate of 4.00%. The total environmental benefit was 1,962,020.88 ± 22,747.42 million CNY, and the average benefit was 98,103.04 ± 23,073.08 million CNY, with the average annual growth rate of 4.00%. The present study illustrates distinctly the ecological value of large-scale cultivated seaweeds in increasing marine carbon sequestration and resolving offshore environmental issues, which is an efficient approach and comparable to other key marine ecosystems. Based on the carbon sink role of seaweed mariculture, and with the goal of global carbon neutrality, more attention should be paid to the carbon sink capacity of large-scale seaweed cultivation industry and be vigorously developed worldwide. • Seaweed has an active effect in N, P remediation and quantities of CO 2 accumulation. • Seaweed has a strong carbon sequestration capacity and is a key part of carbon sink. • Carbon sequestration benefit of seaweed cultivation is 22,405.67 ± 259.59 millions CNY. • Suggesting to pay more attention to the seaweed carbon sink on a global scale. • Suggesting to vigorously develop and promote seaweed cultivation industry worldwide. [ABSTRACT FROM AUTHOR]

Based on the extended environmental input-output model and complex network theory, this paper reviews and evaluates the global energy transition based on the principle of shared responsibility, and identifies the key countries affecting the energy transition from the perspective of embodied energy. The results show that although the proportion of clean energy and renewable energy use remains low (only 34.6% and 8.8%), the global energy transition process has progressed rapidly in the past 20 years. From 2000 to 2016, global energy consumption decreased global warming potential (GWP) by 18.7%, acidification potential (AP) decreased by 33.37%, but eutrophication potential (EP) increased by 28.42%. The United States is the largest contributor to the global energy transition, with a total reduction of 1.52 × 10^5 Mt CO 2 -eq, 148.32 Mt SO 2 -eq and 12.4 Mt P O 4 3 − -eq through the energy transition. The energy-consumption emissions from China and other developing countries show an increasing trend (From 2000 to 2016, China increased its emissions by 1.49 × 10^5 Mt CO 2 -eq, 65.09 Mt SO 2 -eq and 76.64 Mt P O 4 3 − -eq). With the slowdown of economic growth and the promotion of energy transition, the growth rate of energy-consumption emissions gradually decreases. Considering embodied energy plays an important role in the scientific evaluation of global energy transition. Under the principle of shared responsibility, ignoring embodied energy is expected to overestimate China's GWP by 4.5%, AP by 3.7%, and EP by 7.4%, and underestimate America's GWP by 10.5%, AP by 7.48%, and EP by 12.5%. We, therefore, focus on the transfer of pollution due to embodied energy and find that China, Russia, India, and South Africa are important agents for the embodied pollution transfer between communities. • Consider the impact of embodied energy on energy transition assessments. • Identifying key countries affecting energy transition from embodied energy. • Calculated the energy transition process of each country. • Measure the energy transition process from multiple perspectives. [ABSTRACT FROM AUTHOR]

As a major carbon-emitting sector, transportation promotes regional linkages and triggers embodied CO 2 flows that accompany trade. This paper first constructs a 'provincial-national-global' multi-scale input–output (MSIO) model based on IO-nested technology. Then it evaluates the embodied CO 2 in transportation-related trade (TTEC) flows between Chinese provinces and Belt and Road Initiative (BRI) countries, and assesses their driving factors from multi-scale regional and cross-sectoral. Empirical findings show that regions with large TTEC flows are mainly concentrated in the northeastern, eastern and southern areas of China. The construction sector is the largest contributor to exported TTEC, while the energy sector has the largest imported TTEC. Singapore and India are the main exporting countries of TTEC from China, and India and Russia occupy a dominant position in importing TTEC. Finally, policy implications are put forward, that should provide quantitative and theoretical support for decision-making on reducing carbon in transportation between China and BRI regions. [ABSTRACT FROM AUTHOR]

• Two new indicators are proposed to assess the impact of sector CO 2 reduction on other sectors. • These indicators consider the cascading effect between sectors in the industrial chain. • Compared with existing indicators, new indicators can provide more information for policy. • Electricity and hot water production and supply sector has a major impact on China's CO 2 emissions. To mitigate environmental pressure, many studies have calculated the CO 2 emissions of a sector from the perspectives of production and consumption. However, determining a sector's CO 2 reduction tasks based on these two indicators may underestimate the contribution of that sector to CO 2 reductions in the entire economic system. The total CO 2 emission reduction in the entire economic system cannot be regarded as a simple sum of CO 2 emission reductions in various sectors. The situation that the reduction of CO 2 emissions in one sector can promote the reduction of CO 2 emissions in other sectors through a series of chain reactions in the industrial chain needs to be considered. Therefore, the purpose of this paper is to develop new indicators to assess the impact of sectoral CO 2 reduction in the industrial chain, that is, when CO 2 emissions are reduced in one sector, how much it promotes to the reductions in other sectors. We take China as a case and gain additional insights that are not available from existing indicators. The results reveal when the CO 2 emissions of the Electricity and hot water production and supply sector change by 10%, its PCIC-CE and CCIC-CE are 4.13% and 3.83%, respectively. This indicate that the direct reduction of CO 2 emissions in the sector has an additional impact on the CO 2 emissions of the entire economic system. Hence, the new environmental indicators proposed in this paper can complement the existing indicators and guide sector-level environmental pressure mitigation strategies from a holistic perspective. [ABSTRACT FROM AUTHOR]

• The paper analyze the drivers of the per-capita CO 2 emissions inequality in building sector across China. • Economic growth helps to narrow regional disparities for residential buildings. • Energy intensity is the primary contributor to emissions inequality. • This paper highlights the importance of per-capita CO 2 emissions in formulating carbon peak planning. There are significant regional differences in CO 2 emissions in China's building sector. Analyzing and understanding this geographic inequality and its drivers is crucial for balanced regional development and greenhouse gas (GHG) emissions reduction. In this paper, we estimated the CO 2 emissions of China's building sector at the provincial level and then calculated the Theil Index of per-capita CO 2 emissions generated from different building types. Based on these results, a Kaya identity was applied to analyze the drivers of the inequality in CO 2 emissions across China. We found that the inequality index of the different types of buildings makes a significant difference. In general, the Theil Index for public buildings and urban buildings is higher than that for rural buildings. Income, energy intensity and energy mix are the principal drivers of regional disparity of per-capita emissions. Economic growth helps to narrow regional disparities for residential buildings, but its contribution is not significant for public buildings. For all building types, energy intensity is the primary contributor to emissions inequality, and the imbalanced implementation of energy efficiency policies is a leading factor. Energy mix plays an increasing role in the regional disparities of per-capita CO 2 emissions, especially for rural buildings. Reducing these regional disparities is crucial to China's goal of achieving peak GHG emissions and reaching carbon neutrality. This paper highlights the importance of per-capita CO 2 emissions in formulating carbon peak planning, allocating regional emissions reduction targets, formulating building energy policies and allocating low-carbon resources. [ABSTRACT FROM AUTHOR]

• An improved method to evaluate the marginal abatement cost of CO 2 in China. • The economic proximity is introduced to deal with the heterogeneity. • A smaller inefficiency, 2.551%, is estimated by the improved method. • China's average marginal CO 2 abatement cost is 797.79 CNY/ton with a growing trend. • The optimal quota allocation can save approximately 797.793 billion CNY. Marginal emission abatement costs play an important role in the emission trading market and in the allocation of emission reduction allowances. The traditional methods for estimating marginal emission abatement costs do not account for technological heterogeneity, which leads to biased results. To solve this problem, an improved method that combines the clustering method with a parametric output directional distance function is proposed in this paper. This method integrates the economic proximity of each examined province into its assessment of the environmental production technology of the province and takes multiple pollutants (CO 2 , SO 2 and NO X) into consideration. Based on this method, in this paper, the environmental performance of 30 provinces in China from 2006 to 2017 is measured, the marginal emission abatement cost of CO 2 is estimated, and a nonlinear programming method is used to study the optimal allocation of emission reduction in China. The results indicate the following: First, categorizing the provinces according to their economic proximity results in groups that differ greatly from geographically based groups. Second, the average inefficiency of these 30 Chinese provinces is 2.551%, which is less than that estimated by the methods that do not consider heterogeneity. Third, China's average marginal CO 2 abatement cost is 797.79 CNY/ton, and it exhibits a growing trend. Finally, compared to the grandfathering rule, the optimal quota allocation proposed by this paper can save approximately 797.793 billion CNY. [ABSTRACT FROM AUTHOR]