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A very important method of reducing carbon emissions is to make sure industrial plants are operated at optimal energy efficiency. The oil and petrochemical industries spend large amounts of energy in the transportation of petroleum and its various products that have high viscosities. A critical component in these plants is abrupt pipe contraction. Large amounts of energy are lost in pipe contractions. In this paper we investigate the energy losses in pipe contraction using the local entropy generation method after solving the detailed flow field around an abrupt pipe contraction. We have applied the method at various Reynolds numbers covering laminar and turbulent flow regimes. Furthermore, we have used an integral entropy analysis and found excellent agreement between the differential and integral entropy methods when the computational grid is well refined. The differential analysis was able to predict the local entropy generation and find where the large losses are located and therefore be able to minimize these losses effectively. Based on the detailed entropy generation field, it is recommended to use rounded contraction in order to reduce the losses. By introducing rounded contractions in laminar flow, the losses have been reduced by 22%. In the case of the turbulent flow regime, the losses were reduced by 96% by introducing a rounding radius to diameter ratio r/D₂ of 10%. The turbulent flow results for the case of pipe entrance, which is a special case of abrupt contraction (D₂/D₁ goes to zero) agree very well with the present results. This work addresses a large range of D₂/D₁ for laminar and turbulent flows. It is recommended that companies involved in designing petrochemical plants and installations take these findings into consideration to reduce carbon emissions. These recommendations also extend to the design of equipment and piping systems for the food industry and micro-device flows. Full article

The strategic goal of the transition to a low-carbon economy in Russia requires the active integration of forest-climatic projects into regional sustainable development strategies, especially for areas with high agricultural pressure such as the central forest-steppe of the European part of the Russian Federation. The region contains over 18 million hectares of forest land, which is approximately 2.1% of the area of Russian forests, and intensive agricultural development increases the need for innovative approaches to restoring forest ecosystems. The work uses indicators of the state forest register, data on 18 reforestation projects and 22 afforestation projects, and the results of forecasting the dynamics of greenhouse gas absorption until 2030. It is estimated that by 2030, the sequestration potential of the forests of the central forest-steppe can be increased by 28–30%, which will neutralize up to 12% of emissions from industrial enterprises in the region. In the paper, to unify the assessment, it is proposed to use the carbon intensity factor of investment costs, which, in a number of implemented projects, ranged from 1.2 to 2.7 RUB/1 kg CO₂ eq., reflecting the cost of achieving one ton of absorbed CO₂ equivalent. At ratios above 1, the economic value of the carbon units created exceeds investment costs by at least 20%. Environmental–economic modeling showed that with an increase in the forest cover of the region by 1% (180 thousand hectares), the annual absorption of CO₂ increases by approximately 0.9–1.1 million tons, and the increase in potential income from the sale of carbon units could amount to 1.6–2.2 billion RUB per year at the current price of 1.8–2 RUB/kg CO₂-eq. The use of an integral criterion of environmental and economic efficiency helps increase the transparency and investment-attractiveness of forest-climatic projects, as well as the effective integration of natural and climatic solutions into long-term strategies for the sustainable development of the Central Forest-Steppe of Russia. Full article

The circular economy (CE) aims to reduce environmental degradation by ensuring the continuous use of materials and energy resources, aligning with the decarbonization agenda. However, despite the rising acceptance of CE concepts, the economic and managerial aspects remain underexplored in policy and practice. Therefore, this study seeks to bridge the knowledge–practice gap by studying how technology-driven innovation, renewable energy, and energy efficiency interact with CE principles to advance sustainable environmental connections in a detailed manner. The economic analysis of this study was conducted using two base and moderation models, utilizing global data from 78 developing and developed countries, and applying Fixed Effect, Random Effect, and Generalized Method of Moments estimates. The samples were selected based on data availability from internationally recognized databases from 2010 to 2021. The key findings suggest that technology-driven innovation and renewable energy reduce carbon emissions, whereas gross domestic product (GDP) growth and energy efficiency show no standalone positive effects. Notably, moderation effects reveal that the integration of technology with GDP promotes sustainability outcomes, but energy efficiency and renewable energy interact negatively with emissions, a contradictory result warranting further policy investigation. CE-driven innovation promotes decarbonization by striking a balance between environmental preservation, economic expansion, and technology uptake. This study emphasizes region-specific techniques and offers policy insights for combining the CE with natural capital and green GDP. It increases the knowledge of how circular business models powered by technology support sustainable growth and the shift to a circular economy. Full article

Electrochemical glycerol oxidation presents a sustainable and environmentally friendly pathway for formic acid production, addressing the significant carbon emissions and resource dependency associated with conventional industrial processes. However, the development of advanced electrocatalysts with high formic acid selectivity and durability remains challenging due to the polyhydroxy structure and carbon chain complexity of glycerol, which lead to intricate oxidation pathways and a wide variety of products. To tackle this issue, we report a AuCu-Ag/AgBr catalyst with a multiphase interface, referring to the integrated boundaries among AuCu, Ag, and AgBr phases that interact with the liquid electrolyte, for high-rate and high-efficiency glycerol oxidation. Comprehensive characterizations reveal that the multiphase interface may effectively modulate the adsorption configurations of glycerol molecules and enhance charge transfer efficiency. Under ambient conditions, glycerol electro-oxidation at 1.43 V for 8 h yielded a conversion of 38% and a formic acid selectivity of 81%, and recycling tests confirmed its high stability under prolonged electrolysis. This synergistic catalytic effect provides a kinetically favorable pathway for formic acid production, demonstrating the potential of AuCu-Ag/AgBr catalysts in advancing sustainable glycerol valorization. Full article

To further improve the economic benefits of operators and the low-carbon performance within the system, this paper proposes a hierarchical distributed low-carbon economic dispatch strategy for regional integrated energy systems (RIESs) based on the Alternating Direction Method of Multipliers (ADMM). First, the energy coupling relationships among conversion devices in RIESs are analyzed, and a structural model of RIES incorporating an energy generation operator (EGO) and multiple load aggregators (LAs) is established. Second, considering the stepwise carbon trading mechanism (SCTM) and the average thermal comfort of residents, economic optimization models for operators are developed. To ensure optimal energy trading strategies between conflicting stakeholders, the EGO and LAs are embedded into a master–slave game trading framework, and the existence of the game equilibrium solution is rigorously proven. Furthermore, considering the processing speed of the optimization problem by the operators and the operators’ data privacy requirement, the optimization problem is solved in a hierarchical distributed manner using ADMM. To ensure the convergence of the algorithm, the non-convex feasible domain of the subproblem bilinear term is transformed into a convex polyhedron defined by its convex envelope so that the problem can be solved by a convex optimization algorithm. Finally, an example analysis shows that the scheduling strategy proposed in this paper improves the economic efficiency of energy trading participants by 3% and 3.26%, respectively, and reduces the system carbon emissions by 10.5%. Full article

This study focuses on the power systems of inland waterway vessels in Chinese Yangtze River, systematically outlining the low-carbon technology pathways for different power system types. A comparative analysis is conducted on the technical feasibility, emission reduction potential, and economic viability of LNG, methanol, ammonia, pure electric and hybrid power systems, revealing the bottlenecks hindering the large-scale application of each system. Key findings indicate that: (1) LNG and methanol fuels offer significant short-term emission reductions in internal combustion engine power systems, yet face constraints from methane slip and insufficient green methanol production capacity, respectively; (2) ammonia enables zero-carbon operations but requires breakthroughs in combustion stability and synergistic control of NO_X; (3) electric vessels show high decarbonization potential, but battery energy density limits their range, while PEMFC lifespan constraints and SOFC thermal management deficiencies impede commercialization; (4) hybrid/range-extended power systems, with superior energy efficiency and lower retrofitting costs, serve as transitional solutions for existing vessels, though challenged by inadequate energy management strategies and multi-equipment communication protocol interoperability. A phased transition pathway is proposed: LNG/methanol engines and hybrid systems dominate during 2025–2030; ammonia-powered systems and solid-state batteries scale during 2030–2035; post-2035 operations achieve zero-carbon shipping via green hydrogen/ammonia. Full article

To analyze the effects of remanufacturing subsidies and emission reduction investments on pricing and quality decisions under cap-and-trade regulation, four profit-maximization Stackelberg game models for a remanufacturing supply chain (RSC), i.e., without remanufacturing subsidies and emission reduction investments, with remanufacturing subsidies only, with emission reduction investments only, and with both remanufacturing subsidies and emission reduction investments, are constructed, derived, compared, and analyzed. Results show that government subsidies and emission reduction investments can improve profits for the RSC members, while possibly leading to more total carbon emissions. Furthermore, it is worth noting that profit growth and emission reduction can be achieved even though reducing remanufacturing subsidies in some scenarios. Moreover, increasing emission reduction targets will reduce profits of the RSC members but does not necessarily contribute to emission reduction. Therefore, to help the RSC improve profits and reduce emission, the policymaker should formulate differentiated policies based on the types of manufacturers. For the non-abating manufacturer, the government should set higher emission reduction targets and cut down subsidies; for the low-efficiency abating manufacturer, higher emission reduction targets and subsidies are more suitable. However, for the high-efficiency abating manufacturer, lower emission reduction targets and subsidies are more effective. Full article

Porous media gas bearings utilize gas as a lubricating medium to achieve non-contact support technology. Compared with traditional liquid-lubricated bearings or rolling bearings, they are more efficient and environmentally friendly. With the uniform gas film pressure of gas bearings, the rotating shaft can achieve mechanical motion with low friction, high rotational speed, and long service life. They have significant potential in improving energy efficiency and reducing carbon emissions, enabling oil-free lubrication. By eliminating the friction losses of traditional oil-lubricated bearings, porous media gas bearings can reduce the energy consumption of industrial rotating machinery by 15–25%, directly reducing fossil energy consumption, which is of great significance for promoting carbon neutrality goals. They have excellent prospects for future applications in the civil and military aviation fields. Based on the three-dimensional flow characteristics of the bearing’s fluid domain, this paper considers the influences of the transient flow field in the variable fluid domain of the gas film and the radial pressure gradient of the gas film, establishes a theoretical model and a three-dimensional simulation model for porous media gas bearings, and studies the static–dynamic pressure coupling mechanism of porous media gas bearings. Furthermore, through the trial production of bearings and performance tests, the static characteristics are verified, and the steady-state characteristics are studied through simulation, providing a basis for the application of gas bearings made from porous media materials in the civil and military aviation fields. Full article

As internal combustion engines (ICEs) remain dominant in maritime transport, reducing their greenhouse gas (GHG) emissions is critical to meeting IMO’s decarbonization targets. Ammonia (NH₃) has gained attention as a carbon-free fuel due to its zero CO₂ emissions and high hydrogen density. However, its low flame speed and high ignition temperature pose combustion challenges. This study investigates the combustion and emission performance of NH₃-diesel dual-fuel engines, applying Response Surface Methodology (RSM) for multi-objective optimization of key operating parameters: ammonia fraction (AF: 0–30%), engine speed (1200–1600 rpm), and altitude (0–2000 m). Experimental results reveal that increasing AF led to a reduction in Brake Thermal Efficiency (BTE) from 39.2% to 37.4%, while significantly decreasing NOₓ emissions by 82%, Total hydrocarbon emissions (THC) by 61%, and CO₂ emissions by 36%. However, the ignition delay increased from 8.2 to 10.8 crank angle degrees (CAD) and unburned NH₃ exceeded 6500 ppm, indicating higher incomplete combustion risks at high AF. Analysis of variance (ANOVA) confirmed AF as the most influential factor, contributing up to 82.3% of the variability in unburned NH₃ and 53.6% in NOₓ. The optimal operating point, identified via desirability analysis, was 20% AF at 1200 rpm and sea level altitude, achieving a BTE of 37.4%, NOₓ of 457 ppm, and unburned NH₃ of 6386 ppm with a desirability index of 0.614. These findings suggest that controlled NH₃ addition, combined with proper speed tuning, can significantly reduce emissions while maintaining engine efficiency in dual-fuel configurations. Full article

Blast furnace (BF) ironmaking remains one of the most efficient countercurrent processes; however, achieving further CO₂ emission reductions through conventional methods is increasingly challenging. Currently, BF ironmaking emits approximately 2.33 tonnes of fossil-derived CO₂ per tonne of crude steel cast. Integrating briquettes composed of biochar and in-plant fines into the BF process offers a promising short- to medium-term strategy for lowering emissions. This approach enables efficient recycling of fine residues and the substitution of fossil reductants with bio-based alternatives, thereby improving productivity while reducing energy and carbon intensity. This study investigates the reduction behavior of (i) biochar mixed with pellet fines, (ii) various in-plant residues individually, and (iii) briquettes composed of biochar and in-plant fines. The reduction rate of biochar–pellet fine mixtures was found to depend on biochar type, with pyrolyzed pine sawdust exhibiting the highest reactivity, and pyrolyzed contorta wood chips the lowest. A correlation between reduction rate and the alkali index of each char was established, although other factors such as char origin and physical properties also influenced reactivity. The effect of biochar addition (0, 5, and 10 wt.%) on the reduction of steelmaking residues was also studied. In general, biochar enhanced the reduction degree and shifted the reaction onset to lower temperatures. The produced briquettes maintained high mechanical integrity during and after reduction, regardless of biochar origin. Thermogravimetric and XRD analyses revealed that mass loss initiates with the dehydroxylation of cement phases and release of volatiles, followed by carbonate decomposition and reduction of higher oxides above 500 °C. At temperatures ≥ 850 °C, the remaining iron oxides were further reduced to metallic iron. Full article

Grounded in the core principle of green transportation, this paper proposes a metro train service planning approach aimed at enhancing efficiency and reducing carbon emissions. The approach integrates environmental, passenger, and operator benefits, employing multiple train formations under full-length and short-turning route operations. Considering the high dimensionality of model variables and the complexity of the solution process, improvements are made to the neighborhood search strategy in the Adaptive Large-scale Neighborhood Search (ALNS) algorithm, and the improved algorithm is applied to the model solving process. Comprehensive data experiments are conducted to calibrate the algorithm parameters. Using Jinan Metro as a case study, the approach is empirically validated. The results demonstrate that, compared to the single-route and single-formation train service plans, the multi-route and multi-formation plan delivers superior performance in terms of carbon emissions, enterprise operating costs, and passenger travel time costs. Additionally, the Improved Adaptive Large-scale Neighborhood Search (IALNS) algorithm significantly outperforms the ALNS algorithm in both computational efficiency and solution quality. The main contribution of this paper is to balance the interests of both enterprises and passengers while effectively reducing carbon emissions. It also contributes to providing decision support for the green operation and sustainable development of metro systems. Full article

Hydrogen is emerging as a crucial energy carrier, yet effective insulation for liquid hydrogen (LH2) storage remains a significant challenge. This study focuses on evaluating the thermal properties of mineral fiber insulation at cryogenic temperatures, utilizing the guarded hot plate method to determine thermal conductivity values between 223 K (−150 °C) and 573 K (300 °C). The measured effective thermal conductivities ranged from 0.0147 to 0.2113 W/mK, varying with temperature. Notably, while high-density materials can be accurately modeled using linear approximations, low-density materials exhibit significant nonlinearity, with discrepancies in thermal conductivity estimates reaching up to 30%. The implications of this research highlight the necessity for precise thermal property assessments in the design of cryogenic systems, emphasizing their potential impact on energy efficiency and reduced carbon emissions. Ultimately, these findings provide essential insights for advancing cryogenic insulation technologies, supporting the broader transition to sustainable hydrogen energy solutions. Full article

This study investigates the impact of key economic variables on carbon dioxide (CO₂) emissions in Ecuador within the broader context of sustainable development. Annual data from 1990 to 2022 are analyzed using an Autoregressive Distributed Lag (ARDL) model in first logarithmic differences, estimated via Ordinary Least Squares (OLS). The model examines both short- and long-term relationships between CO₂ emissions and three core macroeconomic indicators: gross fixed capital formation (GFCF), GDP per capita, and oil consumption. Descriptive analysis reveals substantial variation in investment and fossil fuel use across the study period. Empirical findings indicate that oil consumption has a positive and statistically significant effect on emissions, while GFCF exhibits a significant negative association in the current period, suggesting the role of cleaner or more efficient investment. Lagged GDP per capita shows a negative effect on emissions, partially supporting the Environmental Kuznets Curve hypothesis. Although renewable energy is discussed in the conceptual framework, it is not included in the current empirical specification—a limitation that will be addressed in future model extensions. The results provide empirical support for directing investments toward low-carbon sectors and accelerating the energy transition, particularly in transport and industry. Full article

In order to explore the increase in the environmental benefits of solar ground source heat pump (SGSHP) systems, this study assesses the environmental benefits of SGSHPs through a comprehensive sustainability evaluation, integrating life cycle assessment, carbon emission analysis, and emergy analysis based on a real project in Tianjin (39.13° N, 117.2° E). By comparing an SGSHP with the conventional GSHP system, improvements in sustainability performance are quantified. The analysis reveals that the SGSHP system has a full-cycle EI16 of 1.88 × 10³, which is 15% higher than the GSHP value of 1.63 × 10³. The SGSHP demonstrates a significant advantage in terms of carbon emissions at all stages, with an overall carbon emission of 31,671 kgCO₂-eq, which is a reduction of about 9.4% compared to the 34,955 kgCO₂-eq of the conventional GSHP system. The emergy conversion rate of SGSHP is 3.58 × 10³, which is 16.23% higher than that of GSHP. This shows that the system with the addition of solar energy is able to convert raw energy into useful heat or cooling energy more efficiently, reducing emergy wastage and making it operate more efficiently, with emergy saving and environmental advantages. The SGSHP system has an ESI value of 1.12, indicating that it is in a developmental or intermediate stage, with significant potential for sustainable economic contributions. In contrast, the GSHP system, with an ESI value of 0.98, demonstrates that it is not sustainable over the long term. By using a comprehensive environmental assessment framework and comparative data analysis, this study aims to better understand the SGSHP system’s performance in energy use, carbon emissions, and ecological impact, providing a scientific foundation for its wider adoption. Full article

To explore fertilization strategies that achieve both high yield and emission reduction in greenhouse tomato production, a two-season experiment was conducted in autumn 2023 and spring 2024 under equal nitrogen input. Seven treatments were established: conventional fertilization (CK1), biogas slurry alone (CK2), 0.5% biochar + biogas slurry (T1), 2% biochar + biogas slurry (T2), dicyandiamide + biogas slurry (T3), 0.5% biochar + biogas slurry + dicyandiamide (T4), and 2% biochar + biogas slurry + dicyandiamide (T5). The effects of each treatment on tomato root traits, yield, irrigation water use efficiency (IWUE), partial factor productivity of nitrogen (PFPN), and soil N₂O emissions were systematically evaluated. An analytic hierarchy process (AHP) was applied for comprehensive assessment. The results showed that fertilization treatments significantly affected tomato root traits (p < 0.05), with T5 exhibiting the best performance in root length, average diameter, total surface area, total volume, and root activity, all significantly higher than CK1. T5 also achieved the highest yield in both seasons, with increases of 8.13% (autumn 2023) and 10.19% (spring 2024) over CK1. Moreover, T5 showed superior IWUE (475.38 kg ha⁻¹ mm⁻¹) and PFPN (405.92 kg kg⁻¹). In terms of environmental performance, T5 significantly reduced soil N₂O flux, with the largest reduction reaching 16.16%, particularly during the peak emission stages in the flowering and fruit-setting periods. The AHP-based comprehensive evaluation confirmed that T5 had the highest overall weight with satisfactory matrix consistency. In conclusion, compared with conventional fertilization, the integrated T5 treatment increased tomato yield by up to 10.19% and reduced cumulative N₂O emissions by up to 16.16%, highlighting its potential as a feasible fertilization pathway and technical reference for low-carbon and sustainable agriculture. Full article