Search Results (1,939)

Hydrogen enrichment of compression ignition (CI) engines has emerged as a promising strategy to simultaneously enhance thermal efficiency and reduce carbon-based emissions. This study numerically investigates how hydrogen enrichment affects engine performance and emissions in methanol–diesel dual-fuel CI engines, a combustion mode gaining increasing attention for replacing fossil diesel with sustainable fuels, particularly in hard-to-abate sectors such as maritime transport. The simulations are based on the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations, incorporating the RNG k–ε turbulence model, the Eddy Dissipation Concept (EDC) for turbulence–chemistry interaction, and the G-equation for turbulent premixed flame propagation. The numerical model is validated against experimental data for in-cylinder pressure and heat release rate at 45% methanol substitution ratio (by energy). The results indicate that increasing the hydrogen enrichment ratio (HER, defined on an energy basis) from 5% to 20% raises the Sauter mean diameter (SMD) of the diesel fuel from 20.2 µm to 28.0 µm (+38%), driven by reduced aerodynamic breakup intensity associated with modified gas-phase properties under hydrogen enrichment. Furthermore, hydrogen’s elevated adiabatic flame temperature and superior mass diffusivity intensify combustion, raising peak in-cylinder pressure from 75.2 to 79.1 bar (+5.2%), amplifying the peak heat release rate from 129 to 211 J/°CA (+63.6%), and elevating maximum in-cylinder temperature from 1542 to 1735 K (+193 K). Under the investigated CFD operating conditions, these thermodynamic gains translate into an engine-level 6% improvement in indicated thermal efficiency and a 14% reduction in indicated specific fuel consumption (accounting for hydrogen, methanol, and diesel) at HER 20%. On the emissions front, CO₂ declines by 24% in direct proportion to the carbon-containing fuel mass displaced by hydrogen substitution, while NOₓ increases approximately twofold from 0.10 g/kWh at HER 0 to 0.21 g/kWh at HER 20, driven by peak temperature elevation. These findings establish hydrogen-enriched methanol–diesel dual-fuel combustion as a viable pathway toward high-efficiency, low-carbon CI engine operation for heavy-duty transport applications. Full article

Reducing agricultural carbon emissions is an important component of China’s efforts to achieve its carbon peaking and carbon neutrality goals. As an important policy oriented financial instrument, green credit can facilitate lower agricultural carbon intensity by directing resources more efficiently across regions and encouraging low carbon transformation in agriculture. Using panel data for 30 Chinese provinces from 2005 to 2022, this study measures agricultural carbon emission intensity (ACEI) from six sources. It then examines the spatial spillover effects, transmission channels, and nonlinear characteristics associated with green credit by using a spatial Durbin framework, mediation analysis, and panel threshold model. The results indicate that: (1) green credit development is significantly associated with lower ACEI; (2) green credit exhibits significant spatial spillover effect, being associated with lower ACEI both within a province and in neighboring provinces; (3) green credit exhibits marked regional heterogeneity in its impact on ACEI: it shows both direct and spillover effects in the eastern region, only spillover effects in the central region, and only direct effects without effective diffusion in the western region; (4) green credit is associated with lower ACEI through industrial structure upgrading and lowering agricultural energy consumption intensity; (5) green credit has a single threshold effect on ACEI based on its own development level. After crossing the threshold, the emission intensity reduction effect weakens but remains significant. These results offer empirical evidence for refining green credit arrangements and advancing coordinated agricultural emission reduction across regions. Full article

Environmental implications of resource dependence remain a central concern for hydrocarbon-based economies undergoing energy transition. Using panel data for GCC countries over 1990–2024 and second-generation econometric techniques that account for cross-sectional dependence and heterogeneity, this study identifies a stable long-run relationship between natural resource rents, renewable energy, and CO₂ emissions. The results show that a 1% increase in natural resource rents is linked to a 0.21% rise in CO₂ emissions, highlighting the persistence of carbon-intensive economic structures. By contrast, renewable energy is associated with a 0.15% reduction in emissions, although its environmental contribution remains modest. The interaction effect is negative (−0.048) but only partially robust, indicating that renewable energy weakens, but does not fully offset, the environmental pressure associated with resource dependence. These findings suggest that energy transition in GCC economies remains gradual and structurally constrained, requiring not only renewable expansion but also deeper transformation of hydrocarbon-based growth models. Full article

Peatlands cover approximately 3% of the global land area but store about 44% of the world’s soil carbon, making them a major carbon sink. Indonesia alone accounts for about 37% of global tropical peat carbon stocks. However, large-scale carbon emissions caused by fires and drainage during past economic development have transformed peatlands from carbon sinks into carbon sources. In response, restoration efforts have been implemented at both international and national levels. Tropical peatland restoration typically includes rewetting, revegetation, and community-based approaches, highlighting the need for quantitative assessments of carbon storage under different restoration strategies. This study focuses on the Perigi peatland in South Sumatra, Indonesia. We conducted field surveys of vegetation and soils to estimate carbon stocks per unit area and developed time-series land cover maps using satellite imagery. Based on these data, we assessed potential carbon storage under different restoration intensity scenarios. The results show that carbon stocks in the Perigi peatland are lower than the Indonesian average. However, under a full restoration scenario, up to 950,259 tC of additional carbon storage is possible, indicating high restoration potential. In contrast, without restoration, further carbon emissions are likely, underscoring the necessity of restoration efforts. Effective restoration requires a phased strategy from vegetation recovery to peat layer recovery, combined with socioeconomic approaches that consider local livelihoods, enabling degraded tropical peatlands to function as effective carbon mitigation systems. Full article

The challenge of attaining energy–efficient nitrogen removal at low carbon–to–nitrogen (C/N) ratios is a fundamental issue in the sustainable management of municipal wastewater treatment plants (WWTPs). This study investigates a pilot–scale Anaerobic–Swing–Anoxic–Oxic (ASAO) system coupled with an AvN (Ammonia versus NOx⁻–N)–based aeration control strategy. A systematic evaluation of the system’s performance, nitrogen removal mechanisms, and microbial communities under a 350–day long–term pilot–scale operation using real municipal sewage is presented. The results reveal that the AvN control strategy can optimize aeration intensity and enhance nitrogen removal efficiency. Even under low influent C/N conditions, the ASAO system maintained stable operation with low dissolved oxygen levels (0.5–1.5 mg L⁻¹), and the AvN control strategy effectively optimized aeration intensity and stabilized nitrogen conversion, achieving a total nitrogen (TN) removal rate of 83% and an average effluent TN concentration of 4.9 ± 2.6 mg L⁻¹. Mechanistic analysis indicated that AvN regulation could alleviate over–nitrification and enhance intracellular carbon storage, thereby creating conditions that support the coordinated operation of multiple nitrogen removal routes, such as simultaneous nitrification–denitrification (SND), endogenous denitrification (EnD), and potentially anaerobic ammonium oxidation (anammox). These findings suggest that the AvN–controlled ASAO process offers a robust and scalable strategy for achieving high–efficiency nitrogen removal with reduced aeration demand, providing a promising technological pathway toward energy–neutral and sustainable municipal wastewater treatment. Full article

Sustainable power-system operation requires carbon-reduction strategies that are emission-effective, physically deliverable, economically feasible, and compatible with user-side decarbonization claims. As Scope 2 carbon accounting increasingly emphasizes temporal, spatial, and physical consistency, dispatch models need to link user-level carbon claims with network-constrained power delivery. This paper proposes a User-Centric Carbon Cost-Constrained Low-Carbon Dispatch (CCC-LCD) framework that integrates carbon emission flow (CEF), nodal carbon intensity (NCI), network-constrained optimal dispatch, and endogenous demand response. A PTDF-based DC-OPF model represents active-power deliverability, while dual virtual flow variables determine carbon-flow directions endogenously. The model minimizes the target user’s physically traced Scope 2 emissions under a cost-tolerance budget and flexible-load constraints. Case studies on a modified IEEE 14-bus system show that nodal decarbonization is topology-dependent: high-load and high-NCI nodes obtain larger reductions from source-side generation substitution, whereas renewable-adjacent nodes exhibit limited marginal gains. The CEF-DR strategy outperforms single-mechanism cases, indicating the value of coordinating physical carbon-flow constraints with flexible demand. From a sustainability perspective, the proposed framework supports verifiable low-carbon electricity consumption, improves the economic feasibility of user-side decarbonization, and provides a practical dispatch tool for sustainable energy transition and corporate Scope 2 emission reduction. Full article

The pantograph–catenary system is a crucial component of rail transit vehicles, performing the vital function of electric energy transmission. During train operation, the current-carrying components continuously emit particulate matter into the surrounding environment due to friction, and these particulate emissions have a significant impact on human health. However, research on the correlation between the current-carrying friction of carbon contact strips and particulate matter emission characteristics is rarely reported. Based on a semi-enclosed pin-on-disc current-carrying friction and wear test rig, this paper investigates the effects of varying current intensity under different contact load conditions on the friction and wear performance of carbon/copper pairs, as well as the associated particulate matter emission behavior. It reveals the damage characteristics of carbon contact strips, the particulate matter emission characteristics, and the relationship between them under different service conditions. The results indicate that the wear mechanism and particulate matter emission behavior of carbon contact strips are jointly influenced by current magnitude and contact load. In the absence of current, increasing the load exacerbates the mechanical wear on the carbon friction pair surface, while elevating the emission concentration of particles of various sizes and stabilizing the particle size distribution. Under current-carrying conditions, a higher contact load effectively reduces the frequency of arc discharges between the friction pair. Meanwhile, the degree of arc erosion on the contact surface worsens with increasing current intensity. Arc discharges instantaneously lead to a sharp increase in particulate emissions, and the higher the discharge intensity or the greater the number of discharges, the higher the particulate concentration around the contact pair. Full article

Climate finance has become a major means of fostering sustainability in the construction industry, which encounters higher pressures to mitigate its environmental footprint without sacrificing economic viability. In line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, this study employs a hybrid approach, integrating a systematic literature review (SLR) and bibliometric analysis, to provide a comprehensive overview of the role and mechanisms of climate finance for sustainable practices in the construction industry. From 2019 to 2025, 176 papers were identified in the Scopus (73) and Web of Science (103) databases. The SLR enables both systematic collection and qualitative analysis of financial instruments, policy frameworks, and sustainability performance metrics, and bibliometric analysis provides a report of publication behavior, geographic distribution, and thematic network. Findings suggest intense clustering of research in countries, with India, China, and the United States as key focus areas, and that construction firms predominantly accessed climate finance on instruments including green bonds, sustainability-linked loans, public–private partnerships, and multilateral climate funds. Sustainability performance is commonly assessed using indicators such as carbon emissions, energy efficiency, lifecycle costs, and environmental, social, and governance (ESG) metrics. The findings also highlight the critical role of public policies, such as green procurement, carbon pricing, and fiscal incentives, in enabling sustainable construction practices. From a theoretical perspective, this study contributes to the understanding of how financial mechanisms, policy frameworks, and sustainability metrics interact to drive sectoral transformation. Future research should focus on standardizing sustainability metrics, evaluating financing impacts, and expanding studies in emerging economies. Full article

As climate conditions become increasingly extreme, greater emphasis should be placed on environmental considerations in outward investment to achieve sustainable green development for Chinese enterprises. Therefore, based on panel data of Chinese listed enterprises from 2008 to 2023, this study examines the impact of Outward Foreign Direct Investment (OFDI) and climate policy uncertainty (CPU) on corporate green total factor productivity (GTFP). The findings indicate that OFDI significantly enhances GTFP, but CPU weakens this positive effect. Mechanism analysis reveals that OFDI improves corporate GTFP through promoting green management innovation, deepening digital transformation, and increasing green investment, while CPU exerts negative effects by undermining these mechanisms. Heterogeneity analysis shows that the effect of OFDI is more pronounced for enterprises in eastern regions, non-heavy-pollution enterprises, and low-carbon-intensity enterprises. Furthermore, spillover effect analysis demonstrates that OFDI’s impact on corporate GTFP exhibits significant spatial boundary characteristics and time-varying evolutionary patterns. Finally, external incentives (government environmental subsidies) and internal drivers (climate risk) can hedge against the negative effects of the interaction between CPU and OFDI. Full article

With the global emphasis on sustainable development, supply chain management is facing new challenges and opportunities. Enterprises often face a large number of suppliers when selecting suppliers, which makes the selection process complex. Considering the crucial role of supplier selection in sustainable supply chains, a sustainable supplier selection model based on multi-attribute utility analysis and a fuzzy approximation ideal solution ranking method is proposed to reduce carbon emissions and environmental pollution. This model helps companies scientifically evaluate and select suppliers by comprehensively considering three aspects: environment, economy, and society. Meanwhile, the study utilizes an optimized genetic algorithm-based order allocation model to raise the efficacy and fairness of order allocation. Reducing procurement costs often relies on improving resource utilization and reducing production waste, which directly lowers the energy consumption and carbon emission intensity per unit of product. At the same time, reducing product damage and delivery delay rates can avoid additional greenhouse gas emissions caused by rework, abandonment, and emergency transportation. By improving supplier productivity and optimizing order allocation, the developed model can not only reduce economic costs but also control environmental pollution and carbon footprints from the source of the supply chain. The outcomes indicate that technological level is a crucial factor influencing supplier selection, with a significant positive impact on supplier willingness to choose, and its standard path coefficient is 0.199, with a significance level of 0.001. Meanwhile, the optimized genetic algorithm exhibits strong stability and convergence in order allocation. This optimization model has high efficiency in handling large-scale orders. This provides strong support for the decision-making of enterprises in sustainable supply chain management and a valuable reference for China’s exploration and practice in the field of sustainable development. Full article

Recycled aggregates (RAs) from construction and demolition waste (CDW) provide substantial circular-economy benefits, yet their elevated porosity, adhered mortar, and heterogeneity typically impair the mechanical performance and durability of recycled aggregate concrete (RAC). This PRISMA 2020-compliant systematic review synthesises 2180 records (2015–2026) to evaluate advanced strategies for enhancing RA quality prior to structural use. This paper critically compares removal-based treatments (mechanical, thermal, acid cleaning) with strengthening and densification approaches, including accelerated carbonation, pozzolanic and nano-silica coatings, polymer impregnation, microbial-induced calcium carbonate precipitation (MICP), and modified mixing methods such as triple-stage mixing (TSMA). Evidence shows that while all RA types (including recycled fine aggregate (RFA), recycled coarse aggregate (RCA), and their combination (RFCA)) can slightly reduce compressive strength and 30% replacement serves as a critical threshold, beyond this, strength loss accelerates, particularly in RCA and RFCA mixes. However, accelerated carbonation and TSMA consistently refine the interfacial transition zone, reduce water absorption by 17–30%, and recover 85–94% of natural aggregate concrete strength. Bio-deposition reduces water absorption by 13–21%, while acid/silica fume treatments improve late-age strength but carry environmental trade-offs. This review formulates a practice-oriented implementation framework for structural-grade RAC. Sustainability analyses indicate that carbonated RA can achieve net-positive CO₂ abatement when under low-carbon energy supply. A mechanistic schematic is presented to synthesise treatment-to-pore-structure/durability pathways across the four principal treatment routes, and a quantitative synthesis plot compares water absorption reductions across all treatment types using 13 data points drawn from included studies. A structured treatment comparison evaluates the energy intensity, industrial scalability, CO₂ footprint, and technology readiness level for each strategy. The remaining challenges include a lack of hybrid treatment studies, limited real-scale durability data, and insufficient mechanistic models linking treatment to pore structure evolution. This review recommends harmonised durability-based criteria and updates to standards (e.g., BS 8500, EN 12620) to support the scalable deployment of treated RA. Full article

This research paper examines the environmental impact of natural and synthetic fur coats, focusing exclusively on the processing and manufacturing stages. Using one coat weighing approximately 5 kg as the functional unit, a comparative Life Cycle Assessment (LCA) is conducted from raw material processing to final garment production, explicitly excluding animal farming. The analysis includes key processes such as cleaning, tanning, dyeing, and sewing for natural fur, and polymer production, fabric formation, dyeing, and finishing for synthetic fur. Data from international academic literature (Google Scholar and Scopus) are used to evaluate CO₂ emissions, energy and water consumption, chemical inputs, and waste generation. Results indicate that synthetic fur production is energy-intensive but requires relatively low water use, whereas natural fur processing involves high water consumption and chemical treatments, resulting in significantly higher emissions—often reaching hundreds to thousands of kg CO₂e per coat. The study further investigates the role of embedded IoT systems in improving efficiency within tanneries and textile manufacturing. Real-time monitoring and automated dosing systems can reduce emissions and chemical use by approximately 10–20%. Case studies of a smart tannery and an IoT-enabled synthetic fur production line illustrate potential implementation pathways. Although such optimizations can reduce environmental impacts, the findings clearly show that natural fur processing remains considerably more carbon-intensive than synthetic alternatives. This research highlights the importance of integrating digital technologies into industrial processes and suggests directions for future work based on real-world operational data. Full article

Mitigating trade-embodied carbon is essential for the sustainable, low-carbon transition of China’s manufacturing sector amid increasingly integrated domestic and global production networks. This study measures total trade-embodied carbon, embodied carbon outflows, and embodied carbon exports within a China-embedded global multi-regional input–output framework. Using a panel dataset covering 30 provinces, 15 manufacturing industries, and 7 benchmark years from 2002 to 2020, the study employs high-dimensional fixed-effects models to examine the effect of green finance—defined as finance directed toward environmentally sustainable and low-carbon activities—on trade-embodied carbon. The results show that green finance significantly reduces trade-embodied carbon, with a relatively stronger effect in the domestic trade dimension. Mechanistic analysis indicates that this effect operates through both technological and structural channels. Heterogeneity analysis further suggests that the carbon mitigation effect of green finance is more pronounced in the eastern and central regions and in energy-intensive industries. This study extends the analysis of the environmental effects of green finance from the value-chain trade perspective and provides empirical evidence to advance the low-carbon transition of manufacturing under intertwined domestic and global production networks. Full article

Green technology innovation is widely recognized as a crucial driver for combating environmental pollution and achieving carbon reduction goals. Based on panel data from 30 provinces in China spanning 2006 to 2021, this study aims to examine the impact of green technology innovation (GTI) on carbon emission performance (CEP). The results indicate that (1) a significant U-shaped relationship exists between green technology innovation and carbon emission performance. (2) Heterogeneity analyses reveal that the effect is more pronounced in regions with higher levels of human capital, stronger macro-control, and a smaller urban–rural income gap. (3) Mechanism tests reveal that green technology innovation significantly improves carbon emission performance by driving the decarbonization of energy consumption structure. Furthermore, energy intensity negatively moderates the U-shaped relationship, leading to an “energy rebound effect”. (4) Spatial spillover analysis indicates that green technology innovation has a U-shaped impact on the carbon emission performance of adjacent regions. The findings of this study provide empirical evidence of and new perspectives on the crucial role of green innovation in achieving low-carbon sustainable development. Full article

To investigate the effects of water-saving irrigation and different straw retention methods on soil CH₄ and N₂O emissions from paddy fields in cold regions and their potential underlying mechanisms, a field experiment was conducted in Qing’an City, Heilongjiang Province. Two water management regimes were set, combined with four straw retention treatments. The static chamber-gas chromatography method was used to monitor CH₄ and N₂O emission fluxes during the entire rice growth period. Meanwhile, soil pH, oxidation–reduction potential (Eh), dissolved oxygen (DO), and dynamic changes in carbon and nitrogen substrates were measured, and the global warming potential (GWP) and greenhouse gas emission intensity (GHGI) were comprehensively evaluated. The results showed that controlled irrigation significantly increased soil dissolved oxygen content and oxidation–reduction potential. Compared with conventional flooding irrigation, total CH₄ emission decreased by more than 50%, while N₂O emission increased by 1.5–2.5 times, exhibiting an obvious divergent correlation with the two gas emission fluxes. Among different straw retention methods, organic fertilizer returning and direct straw returning significantly promoted CH₄ emission by supplying easily decomposable organic carbon. In contrast, biochar, due to its stable carbon structure and favorable pore properties, inhibited CH₄ emission without significantly stimulating N₂O emission. The treatment of controlled irrigation combined with biochar returning (CB) achieved the lowest global warming potential and greenhouse gas emission intensity at 7230.82 kg CO₂-eq/hm² and 0.8054 kg CO₂-eq/kg, respectively, while maintaining high rice yield. Path analysis based on soil physicochemical properties and emission fluxes further revealed that Eh and DO were significantly negatively correlated with CH₄ emission but positively correlated with N₂O emission. Path inference from flux and substrate data indicated that carbon and nitrogen availability were the key factors limiting the denitrification process. In conclusion, the combined application of controlled irrigation and biochar returning can realize the synergistic effect of stable yield and emission reduction in cold-region paddy fields by improving soil aeration and regulating the transformation of carbon and nitrogen substrates, providing a scientific basis for establishing a green and low-carbon rice production technology system for black soil in cold regions. Full article