CO2 Emission Efficiency Research Articles

Perspective on pathways towards responsible surface engineering

In this perspective sustainability-relevant aspects of modern surface engineering technologies, which enable improved structural and functional surface properties, are critically evaluated. Although plasma-assisted physical vapour deposition (PVD) is increasingly employed to address global challenges, such as energy efficiency and reduction of CO2 emissions, their inherently resource-intensive nature is often not considered.Surface engineering research should thus embrace sustainability-relevant aspects from a processes and materials design point of view. While we are convinced that sustainability-relevant surface engineering has to be based on synchronised process and materials solutions, we will discuss processes and materials separately.In terms of processes, we are going to describe the challenges of state-of-the-art technology, including energy and mass balances as well as product cycles. With respect to materials, the coating and process purity as well as chemical and microstructural complexity are discussed.Such approaches are fully in line with the United Nations Sustainable Development Goal 12 Responsible Consumption and Production. We expect that the here discussed urgently needed pathways towards responsible surface engineering will become important for the surface engineering community and adopted within the near future. Responsible surface engineering includes the human behaviour and necessitates a change in mindset of materials scientists and process engineers. Hence, two main questions are critically evaluated in this perspective:1)What are sustainability-relevant aspects of PVD processes and materials?2)Which pathways are available to move towards responsible surface engineering?

Does a more compact urban center layout matter in reducing household carbon emissions? Evidence from Chinese cities

In recent years, compact urban development and carbon emissions reduction have been considered essential approaches for achieving sustainable development goals worldwide. Existing research has focused on the correlation between urban spatial structure and carbon emissions with inconsistent results. This study explores the correlation between urban compactness and household CO₂ emissions. Two indices of urban compactness and four categories of household CO₂ emissions are constructed. We utilize Spatial Durbin Models (SDM) and Spatial Autoregressive Models (SAC) on panel data from over 284 cities at the prefecture level and above in China, spanning 2008–2018. The results indicate that, except for heating consumption, household CO₂ emissions exhibit positive associations with two urban compactness indices. These findings suggest that a city with evenly developed urban cores within a relatively smaller urban area may have better household CO₂ emissions efficiency both locally and regionally. Our study contributes to the existing literature on the sustainability of compact city development with new evidence emphasizing a condensed but balanced urban structure.

The impact of internet development on carbon emission efficiency: Evidence from China

Modern information and communication technology presented by the Internet has become the significant driving force to promote the realization of “carbon peak and carbon neutrality” target in China. Taking China’s 30 provinces over the period 2006–2019 as research object, this paper investigates the effect of Internet development on carbon emission efficiency (CEE) and its impact mechanism by using the dynamic spatial Durbin model (DSDM) and mediation effect model. The regression results indicate that: (1) Internet development can significantly improve the carbon emission efficiency in the region and its neighboring areas. (2) The positive effect of the Internet development on CEE in long-term is greater than that in short-term. (3) Internet development can directly improve CEE, as well as indirectly increase CO2 emission efficiency by promoting technological innovation and industrial structure upgrading, as well as reducing the level of labor and capital resource mismatch. The conclusions of this paper are reliable after multiple robustness checks. Finally, we have put forward several policy implications to be conducive to achieving carbon neutrality.

Sustainable process design and multi-objective optimization of efficient and energy-saving separation of xylene isomers via extractive distillation based on double extractants

The focus of the chemical industry on environmental protection and energy conservation has driven the development of green distillation technology. Xylene isomers are extensively utilized industrial raw materials, whose separation is challenging and energy-intensive due to their closely similar boiling points. Therefore, it is urgent to develop energy-saving and environmental protection technology. In this paper, an energy-saving and environmental protection process for separating the xylene isomers by extractive distillation was designed combing the vapor recompression process with feed preheating (VRAPFP). The parameters of extractive distillation processes were synthetically optimized by multi-objective genetic algorithm (MOGA) with total annual cost (TAC), CO2 emission (ECO2) and separation efficiency (Eext) as the objective evaluation indexes. The economical optimal process was used further for VRAPFP design through heat integration to reduce energy consumption, and all the designed candidate processes were synthetically analyzed, compared and evaluated with performance indexes. Results show that the VRAPFP process has superior economic efficiency and ecological sustainability compared with the existing distillation process, wherein the TAC and ECO2 are reduced by 14.2 % and 30.2 %, respectively. This work provides a new reference and idea for separating xylene isomers with the economy and developing new processes for energy conservation and environmental protection.

Carbon productivity growth in China's thermal power industry: Empirical evidence using a bootstrapped Malmquist-Luenberger productivity index approach with fixed-sum undesirable outputs

The total amount of carbon emissions is limited by a fixed-sum constraint in the context of China's dual carbon target, a factor ignored in previous studies on carbon productivity. To address this gap, this study proposes a bootstrapped Malmquist-Luenberger productivity index approach with fixed-sum undesirable outputs. The proposed method not only considers the fixed-sum feature of undesirable outputs; it also reduces the calculation error caused by small samples and improves the accuracy of the measurement. We then apply the proposed approach to measure the carbon productivity growth of the thermal power industry in 30 provincial regions in China from 2011 to 2020 and analyze the driving forces of carbon productivity growth. The empirical results show that during the study period, China's overall carbon productivity increased with an annual average growth rate of 0.61 % due to CO2 emission efficiency improvement and technological progress. Additionally, 18 provincial thermal power industries had average carbon productivity growth rates between 0.06 % and 4.86 %, while the remaining 12 provinces showed carbon productivity declines at rates ranging from 0.03 % to 2.90 %. The driving forces of such growth differ among the 30 provinces. Policy suggestions are given for improving the carbon productivity of China's thermal power industry.

CROSS-BARGAIN-EEF EVALUATION APPROACH FOR CO2 EMISSION EFFICIENCY IN CHINA’S CONSTRUCTION INDUSTRY WITH FIXED-SUM UNDESIRABLE OUTPUT

The rapid urbanization in China has led to a substantial expansion of construction activities, causing notable energy consumption and a consequent rise in CO2 emissions. This study proposes an approach to assess CO2 emission efficiency in China’s construction industry by integrating data envelopment analysis cross-efficiency and the Nash bargaining game, considering CO2 as a fixed-sum undesirable output. The study identifies Jiangsu and Beijing as top performers, establishing benchmarks for other provinces. In contrast, Inner Mongolia displays the lowest efficiency. Generally, most provinces exhibit room to improve environmental efficiency in the construction sector. The study provides policy implications and tailored suggestions for specific provinces.

The Implementation of “WE R GREEN” Program in ADHI Construction Projects for CO2 Emission Efficiency

As the leading state-owned construction company in Indonesia, PT Adhi Karya (Persero) Tbk (ADHI) has taken certain steps to address sustainability issues, especially when it comes to improving the environmental quality of infrastructure projects. "WE R GREEN" is an environmental program that emphasizes water conservation (W), energy efficiency (E), waste management (R, which stands for remove, reduce, reuse, and recycle), and tree planting activity (GREEN). This study used a construction project in Depok as the sample, where every action has a close relationship with the environment. The purpose of this study is to determine the CO2 efficiency of some project activities following the implementation of the "WE R GREEN" initiatives. The data consists of water consumption, project office building usage, electricity consumption, solid waste production, and planted tree specification. According to the data, total CO2 emissions were 110,62 tons CO2e year prior to program implementation, and the emission has dropped to 73,59 tons CO2e annually following the initiatives. This concludes that the total of 37,03 tons CO2e per year, or 33%, are reduced. Assuming the same number of people and project activities throughout all 109 ADHI projects to put the program into practice. The estimated annual CO2 output would thus decrease 4.036,06 tons CO2e.

Upcycling of hazardous plastic waste by CO2 transformation-enhanced steam reforming over MgO-promoted Ni/C bifunctional catalyst

Disposing hazardous plastic waste (e.g., used masks) poses a challenging issue, as these waste plastics often carry the risk of virus infection. CO2 transformation-enhanced steam reforming (CTESR) route was developed and newly synthesized dual-support Ni bifunctional catalysts were explored for the upcycling of disposed mask. Among the single-support Ni catalysts, Ni/CaO presented a high H2 yield (52.18 mmol/g), but it was inferior to Ni/MgO and Ni/C in terms of CO2 transformation capacity. Importantly, Ni/MgO demonstrated the lowest carbon deposition (∼2.67 wt%) due to the interaction between MgO and NiO, forming a NiO-MgO solid solution. In this sense, dual-support Ni catalysts were prepared to achieve extensive H2 production and CO2 reduction. Dual-support Ni/MgO-C was superior to other dual-support catalysts in terms of H2 selectivity (57.77 vol%), H2 yield (51.58 mmol/g), CO2 emission (1.72 mmol/g), and H2 production efficiency (ƞ: 0.74 g CO2/g H2). Moreover, it presented a remarkable synergistic effect on H2 yield and production efficiency, with an enhancement of 117.27 % and 32.58 %, respectively. The super catalytic performance was attributed to the unique properties of Ni/MgO-C, high dispersion of Ni/NiO active core, and proper interaction of Ni/NiO with the dual supports. In addition, MgO-promoted Ni/C catalysts with multiple MgO proportions were examined. Ni/MgO5-C5 was identified as the optimal bifunctional catalyst for H2-rich syngas production and CO2 elimination. Overall, this study established a highly effective and promising route by using dual-support Ni catalysts for upcycling hazardous plastic waste into H2-rich syngas while suppressing CO2 emission.

Calculations of CO2 emission and combustion efficiency for various fuels

The specific CO2 production of fuels has commonly been expressed empirically in terms of kgCO2 (kWh)−1. No specifications regarding combustion conditions, transformation technology used, and efficiency are usually presented in detail. In this paper, however, we propose replacing this approach by the use of rigorous chemical engineering calculations based on the composition and the combustion conditions of the fuels. The MS EXCEL program, which is provided as supplementary material to this paper, calculates the specific CO2 production considering energy losses, adiabatic flame temperature, calorific value and heat of fuel combustion, flue gas temperature, energy losses through flue gas, slag, and the overall energy efficiency of the whole energy conversion process. Results are presented for three fuel groups: coal, hydrocarbons, and renewable fuels. The calculated results are compared with the literature data. A benefit of our approach is that the procedure can be generalized for any fuel of known composition and for different types of combustion-based energy transformation.

Response of soil CO2 emissions and water-carbon use efficiency of winter wheat to different straw returning methods and irrigation scenarios.

The shortage of water resources and the increase of greenhouse gas emissions from soil seriously restrict the sustainable development of agriculture. Under the premise of ensuring a stable yield of winter wheat through a reasonable irrigation scenario, identifying a suitable straw returning method will have a positive effect on agricultural carbon sequestration and emission reduction in North China Plain. Straw burying (SR) and straw mulching (SM) were adopted based on traditional tillage under in the winter wheat growing season of 2020-2021 and 2021-2022. Three irrigation scenarios were used for each straw returning method: no irrigation (I0), irrigation 60 mm at jointing stage (I1), and irrigation of 60 mm each at the jointing and heading stages (I2). Soil moisture, soil respiration rate, cumulative soil CO2 emissions, yield, water use efficiency (WUE) and soil CO2 emission efficiency (CEE) were mainly studied. The results showed that, compared to SM, SR improved the utilization of soil water and enhanced soil carbon sequestration. SR reduced soil respiration rate and cumulative soil CO2 emissions in two winter wheat growing seasons, and increased yield by increasing spike numbers. In addition, with an increase in the amount of irrigation, soil CO2 emissions and yield increased. Under SR-I1 treatment, WUE and CEE were the highest. SR-I1 increases crop yields at the same time as reducing soil CO2 emissions. The combination of SR and irrigation 60 mm at jointing stage is a suitable straw returning irrigation scenario, which can improve water use and reduce soil CO2 emission in NCP. © 2023 Society of Chemical Industry.

Analysis of transportation CO2 emission efficiency in the Yangtze River Economic Belt in China

ABSTRACT The transportation industry’s CO2 emissions and its main drivers are important for achieving sustainable development. With data from the Yangtze River Economic Belt (YEB) between 2004 and 2020, the efficiency of CO2 emissions is investigated by the super efficiency epsilon-based measurement method (super-EBM) and the Global Malmquist Luenberger Productivity Index (GML). The influencing factors on the different efficiency levels are explored by the panel quantile regression. This study shows that the overall CO2 emissions efficiency is not high, and the efficiency in different regions is largely consistent with the regional economy level. COVID-19 may reduce urban transport carbon emissions in the Yangtze River Economic Belt in 2020, as reflected by the reductions in average emissions and emissions efficiency. Findings also suggest that the influence of the number of private vehicles per 10,000 people on efficiency is positive at low and middle quantiles, and negative at high quantiles. Besides, the per-capita GDP, energy intensity, and transportation service structure negatively influence the efficiency at all quantiles, whereas urbanization and transportation intensity are positively related to the emissions efficiency.

The efficiency evaluation and the spatiotemporal differences of CO2 emissions in China's construction industry

Under the promotion of China's double carbon policy, China's construction industry (CI) is facing the pressure for CO2 emissions (CE) reduction. In order to promote China's high-quality green development, CO2 emissions efficiency (CEE) evaluation in China's CI was crucial. Based on the super-efficiency slacks-based measure–data envelopment analysis (SBM-DEA) model, the Global Malmquist-Luenberger (GML) index, the global and local Moran index in spatial autocorrelation, 11 indicators of CI were selected to evaluate CEE and the spatiotemporal differences of CEE in China's CI 31 provinces from 2000 to 2020 were analyzed. The results indicated the CEE was on the rise on the whole. The average annual CEE of Hainan, Heilongjiang, Tianjin, Shanghai and Xizang was bigger than 1. The CEE of Sichuan, Gansu and Guizhou was around 0.5. The order of CE of CI in China from high to low Was South China, North China, Northeast China, Central China, East China, Northwest China and Southwest China. The GML index increased by 6.25% annually, the average annual TC increased by 11.68%, and the average annual EC increased by 5.21%. The overall CEE of China's CI showed a positive correlation between 2010 and 2015, but the spatial agglomeration was weak.

Measurement of CO2 Emissions Efficiency and Analysis of Influencing Factors of the Logistics Industry in Nine Coastal Provinces of China

The surge in CO2 emissions affects global climate change and the development of society. The logistics industry, being a swiftly advancing industry, demonstrates an escalating trend in CO2 emissions. Therefore, this paper selects the more developed coastal provinces (districts) in China’s logistics industry and takes 2011–2020 as the research period. Using the Super-SBM model and the Malmquist index model, the article analyzes the changes in the carbon emission efficiency of the logistics industry from the static and dynamic perspectives and then explores the factors affecting it using the panel model and the mediating effect model. Findings from research indicate that: (1) The CO2 emission efficiency of the logistics industry is generally moderate when viewed from a static perspective. (2) Taking a dynamic viewpoint, there is a slight declining trend in the overall CO2 emission efficiency. (3) As environmental regulations become more stringent, the CO2 emission efficiency follows the “U”-shaped pattern, initially declining and then rising. Environmental regulations can influence CO2 emission efficiency by affecting technological innovation. Additionally, energy efficiency plays a positive role in promoting CO2 emission efficiency. Recommendations: Implement differentiated environmental regulations tailored to local conditions. Emphasize technological innovations. Enhance the energy efficiency.

SOME ISSUES OF VESSELS ENERGY EFFICIENCY ASSESSMENT IN THE INLAND SHIPPING ENERGY TRANSITION CONDITIONS

The problem of evaluating the energy efficiency in inland navigation is being investigated. The research focuses on analyzing the current state and achieving the goals of transitioning to eco-navigation. Emphasis is placed on the importance of developing new strategies and solutions to enhance the efficiency of navigation in the context of the energy transition. Existing methodologies and approaches for measuring fuel consumption and CO2 emissions efficiency, as well as the impact of energy-efficient technologies on navigation systems, are being examined. Attention is given to the use of alternative fuels and speed optimization as means of reducing fuel consumption and emissions. Special attention is devoted to Danube navigation, where large-tonnage convoys are used for cargo transportation. The technological peculiarities of this type of transport and navigation conditions that can affect vessel energy efficiency are analyzed. Measures are proposed to improve the efficiency of navigation. The authors suggest a new approach to forming an energy efficiency index that takes into account the specifics of inland navigation, specifically large-tonnage convoys and navigation conditions. This approach allows determining the level of vessel energy efficiency in the context of the energy transition, beyond the conversion to CO2 emissions alone. It is noted that inadequate navigation conditions can impact vessel energy efficiency, particularly by increasing water resistance and the need for higher power for propulsion. The authors explore the possibility of applying new technologies and solutions that can help reduce fuel consumption and enhance vessel energy efficiency under such conditions, and they propose new approaches to measuring and assessing the energy efficiency of navigation. As a result of the conducted research, an approach to transforming the form of the energy efficiency index for inland navigation vessels is proposed, which avoids limitations associated with measuring only CO2 emissions and allows for a comprehensive assessment of vessel energy efficiency. The proposed approach will contribute to a more accurate evaluation and comparison of different vessels in the context of the energy transition, considering their performance and fuel costs under real navigation conditions. The research findings can be valuable for scientists and experts in the field of inland navigation in developing effective strategies and policies for reducing greenhouse gas emissions and improving vessel energy efficiency.

Land urbanization and urban CO2 emissions: Empirical evidence from Chinese prefecture-level cities

Changes in land use and the resulting human practices in the land urbanization process would lead to variations in the function, intensity, and efficiency of CO2 emissions and greatly influence urban CO2 emissions. Therefore, using Chinese prefecture-level data for a time period ranging from 2003 to 2017, we systematically examine the mechanism of how land urbanization influences CO2 emissions based on land-use intensity regulation, land-use structure optimization, and land-use efficiency improvements. First, the benchmark results show that land urbanization's influence on urban CO2 emissions is significantly positive. This indicates that the consumption effect caused by land urbanization exceeds the agglomeration effect. Furthermore, the results of the nonlinear analysis using the spatial adaptive semi-parametric and semi-parametric spatial dynamic panel models show that the association between land urbanization and carbon emissions demonstrates an inverted U-shaped curve. Simultaneously, land urbanization represents a dynamic cumulative and spatial spillover effect on urban CO2 emissions. Second, a mechanism analysis reveals that effective land urbanization can promote CO2 emission reductions through efficiency improvement, structure optimization and proper control of the land-use intensity. Additionally, we analyze heterogeneity in regional differences. In the line with study findings, the central government in China should promote the optimization of territorial spatial governance, optimize energy consumption structures, make comprehensive use of its funds, tax policies, industrial development support, and market-oriented mechanisms, and further optimize the layout of urban space.

Mixed Land Use and Its Relationship with CO2 Emissions: A Comparative Analysis Based on Several Typical Development Zones in Shanghai

While development zones are the main locations of the urban industrial economy and sources of energy consumption, studies on the interactive relationship between mixed land use and CO2 emissions in these zones have not attracted much attention. In this paper, the development zone is selected as the research object, and a honeycomb grid with a side length of 50 meters is used as the unit to measure multiple dimensions of mixed land use. The efficiency and intensity of CO2 emissions are estimated for these units, and the coupling model is used to analyse the interactive relationship between these two factors. The results show that (1) the mixed land use degree of different types of development zones differs; the bonded zone has the highest degree, while the economic and technological development zone and the high-tech development zone have higher degrees than the industrial development zones. (2) The CO2 emissions capacities of economic and technological development zones and high-tech development zones are better than those of industrial development zones and bonded areas. (3) There is a strong interaction between the mixing degree of land use and the intensity of CO2 emissions; the relationship between the two may be diverse and complex in different development zones. (4) The coordinated development level between mixed land use and CO2 emissions in economic and technological development zones and bonded areas is better than that in high-tech development zones, which in turn is better than that in industrial development zones. Based on existing measurements of mixed land use, the index of land use intensity is introduced in this paper and the land use classification in development zones is refined to supplement the land use compatibility matrix. The results of this study have implications for the development zone to enhance mixed land use and low-carbon development.

CO2 emissions embodied in bilateral trade in China: An input-output analysis

The effects of export goods on CO2 emissions in China were calculated using input-output analysis via the hypothetical extraction method (HEM). The seven largest export partners of China were taken into account for the analysis: the US, Japan, South Korea, Germany, India, the UK and the Netherlands. First, using input-output analysis, the effects of CO2 emissions were allocated between the non-tradable goods, total export goods, exported final goods and exported intermediate goods sectors. Then, using a weighted multipliers approach, efficiency in CO2 emissions was allocated among the sectors. It was found that although non-tradable goods caused the highest CO2 emissions, export goods, especially intermediate goods showed the largest growth in emissions. In addition, export goods contributed more to emissions efficiency. Second, the HEM was implemented to explore which countries had significant effects on both emissions and emissions efficiency. The US was the largest source of CO2 emissions in China in terms of final goods. Nevertheless, the US also increased the role of exported intermediate goods on emissions. It was also an important country in stimulating efficiency in CO2 emissions. Hence, China does not have a chance to decrease its export performance against the countries such as the US, as their demand is the source of efficiency in CO2 emissions. However, it can focus on exported intermediate goods to mitigate emissions, and take the US into account for new policies.

Sustainable design and multi-objective optimization of heat pump assisted extractive distillation process for separating a ternary mixture of methyl acetate, tetrahydrofuran and methanol

The separation of a ternary mixture of methyl acetate (MeAc), tetrahydrofuran (THF), and methanol (MeOH) produced from chemical or pharmaceutical plants can not only recover the valuable chemicals but also reduce the environmental pollution caused by the emission of waste organics. In this study, a two-step extractive distillation process with four columns (FCED) with dimethyl sulfoxide and p-xylene serving as the entrainers was firstly proposed to separate the ternary mixture by using Aspen Plus simulation. The vapor recompression heat pump (VRHP) technology was introduced to improve the thermodynamic efficiency of the proposed FCED process. Subsequently, a multi-objective optimization using the non-dominated sorting genetic algorithm-II was employed to optimize the designed processes to accomplish a Pareto front trade-off in three crucial indicators, i.e., total annual cost (TAC), CO2 emission, and exergy efficiency. A Pareto ranking method, i.e., the technique for order of preference by similarity to ideal solutions combined with entropy weighting approach, was used to choose the best solution from the Pareto front. The results indicate that, compared to the FCED process, TAC (8-year payback period) and CO2 emissions of the VRHP-assisted FCED are reduced by 8.75% and 33.26%, respectively, while the exergy efficiency is increased by 8.06% from 3.67% to 3.96%, demonstrating that the introduction of VRHP can significantly improve the performance of the FCED process.

Techno-economic and energetic assessment of an innovative energy-saving separation process for electronic-grade acetone purification

With the impact of covid-19 and geopolitical instability, the price of energy and medical-related chemicals are increased. Acetone is used as the main material for the synthesis of important disinfectant isopropanol, which the price is influenced by covid-19 impact. The research on acetone purification, especially on the acetone refining section in the cumene hydroperoxide process is of great importance, which is high in energy cost but the most popular method for acetone production. This paper provided novel energy-saving acetone purification processes with heat integration, heat recovery, and molecular sieve adsorption, and made comprehensive research of different schemes applications with optimization. A modified TAC calculation model for adsorption units is first proposed in this paper, which includes the calculation of adsorption unit cost, molecular sieve loss, and molecular sieve regeneration cost. CO2 emission and thermodynamic efficiency of all the processes are compared. A semi-quantitative analysis is used to compare the relative industrial versatility and process controllability. The results show that the combination of adsorption and heat integration achieves a decrease of 27.75% in energy consumption, 15.30% in TAC, 7.09% in CO2 emission, and a 22.62% relative increase in thermodynamic efficiency.

Does carbon emission trading scheme really improve the CO2 emission efficiency? Evidence from China's iron and steel industry

The carbon trading market is an effective way to mitigate the threat of climate warming. In the context of carbon neutrality, what is the carbon emission trading scheme's carbon reduction effect? This paper answers the question by examining the carbon efficiency of China's iron and steel industry. This study first constructs CO2 emission efficiency by employing the data envelopment approach. It then uses the synthetic control method to identify the impact of the carbon emission trading scheme on the CO2 efficiency of the iron and steel industry. The results show that CO2 emission efficiency in pilot provinces increased at a 5% significance level compared with the counterfactual scenario. The carbon trading market plays a vital role in industrial CO2 emission efficiency improvement in Guangdong, Shanghai, Tianjin, Hubei, and Chongqing. From a dynamic perspective, the policy effect of enhancing CO2 efficiency becomes more prominent over time. Moreover, the effectiveness degree of the carbon emission trading scheme varies across pilot provinces, caused of regional policy differences. Based on the findings, we put forward targeted suggestions for improving the newly-established national carbon trading market.