Search Results (469)

The expansion of ruminant production has increased methane (CH₄) emissions, highlighting the need for nutritional strategies that improve productivity while mitigating environmental impacts. Yaks, generally considered low CH₄ producers, are increasingly raised under intensive winter-housed systems on the Qinghai–Xizang Plateau, highlighting the need to assess how dietary concentrate-to-forage (C:F) ratios affect both CH₄ emissions and growth performance. This study investigated the effects of three dietary C:F ratios [L-C (48:52), M-C (60:40), H-C (72:28)] on growth performance, ruminal fermentation, microbial diversity (n = 6 per group) and CH₄ emission (n = 3 per group) in winter-housed yaks. The results indicated that average daily gain (ADG) was significantly higher in M-C and H-C, while the feed-to-gain ratio (F/G) was significantly lower in M-C and H-C than in L-C (p < 0.05). Total CH₄ production (g/day) did not differ among treatments (p > 0.05), while CH₄ yield per unit body weight gain (CH₄/BWG) was significantly reduced in M-C and H-C (p < 0.05). The protozoal count was significantly lower in H-C, and the proportions of isobutyrate and isovalerate were significantly higher in H-C and M-C compared with L-C (p < 0.05). 16S rRNA gene sequencing revealed that increasing the C:F ratio reduced the relative abundance of the archaeal genus Methanobrevibacter, while Thermogymnomonas exhibited a significant increase (p < 0.05). Collectively, these findings indicate that increasing the C:F ratio in winter-housed yaks improves growth efficiency and lowers CH₄/kg BWG, with the M-C group showing the most favorable balance between productivity and environmental sustainability. Full article

Goaf gas drainage and residual-coal spontaneous-combustion prevention are often designed independently, even though both are controlled by the same leakage-flow, oxygen-transport and heat-release fields in a longwall goaf. This decoupled design may reduce methane accumulation while unintentionally enlarging the oxidation zone. Taking the No. 1217 fully mechanized working face of Zhongxing Coal Mine, Shanxi Province, China, as an engineering prototype, this study develops an integrated laboratory-field numerical framework to quantify the drainage-induced evolution of the three zones of spontaneous combustion. Programmed temperature-rise experiments on the No. 2 coal seam were used to determine the oxygen-consumption rate, heat-release intensity and apparent activation energy under oxygen concentrations of 3–21%, yielding a critical oxygen concentration of 5.9%. Bundle-tube monitoring and distributed optical-fiber temperature sensing delineated the in situ three-zone boundaries, and a three-dimensional CFD model coupling porous-media seepage, species transport and Arrhenius-type heat generation was validated against the field data, with most relative errors below 5%. Parametric simulations for buried-pipe depths of 20, 30 and 50 m and negative pressures of 15 and 20 kPa reveal a pronounced asymmetric response: drainage compresses and advances the return-side oxidation zone toward the working face, but drives the inlet-side oxidation zone deeper into the goaf by enhancing oxygen-bearing leakage. Within the investigated parameter space, a buried depth of 30 m and a negative pressure of 20 kPa provide the best compromise, reducing the return-side oxidation-zone width from 32 to 21 m and the upper-corner methane concentration from 6.80% to 0.58%. The results demonstrate that drainage design should be constrained simultaneously by methane dilution and oxidation-zone control, and provide a quantitative basis for coordinating gas extraction with fire prevention in gas-rich, oxidation-prone longwall panels. Full article

CO₂-enhanced coalbed methane recovery and storage (CO₂-ECBM) is a promising approach for improving methane recovery and increasing CO₂ storage in low-permeability coal seams. However, limited injectivity and insufficient criteria for injection parameter optimization remain major constraints. Taking the No. 11-2 coal seam of the Zhangji Coal Mine in the Huainan mining area as the study object, this study established a thermo–hydro–mechanical coupled model that considers CO₂/CH₄ competitive adsorption, matrix diffusion, fracture seepage, gas–water two-phase flow, coal deformation, and porosity–permeability evolution. A 10-year numerical simulation was conducted to evaluate the effects of initial porosity, initial permeability, elastic modulus, CO₂ injection pressure, and injection scheme on CO₂-ECBM performance. The comprehensive sensitivity results show that initial porosity, CO₂ injection pressure, and initial permeability are the dominant controlling factors, whereas elastic modulus has a relatively weak influence. Initial porosity mainly determines reservoir storage space and CO₂ sequestration potential; permeability controls pressure propagation and gas migration; and injection pressure directly affects CH₄ displacement intensity, CO₂ storage capacity, and reservoir safety margin. Multi-objective evaluation indicates that the injection pressure should be controlled within 8.0–9.0 MPa, with 8.0–8.5 MPa recommended for long-term stable operation. When the engineering objective prioritizes CO₂ storage or CH₄ recovery and sufficient safety margin is confirmed, the injection pressure may be increased to approximately 9.0 MPa. Continuous constant-pressure injection favors cumulative CH₄ production and CO₂ storage, whereas stepwise pressurization reduces early pressure disturbance and improves later-stage injectivity. Therefore, an injection strategy combining early-stage stepwise pressurization with middle- and late-stage constant-pressure injection is recommended. These results provide a reference for injection parameter optimization in similar low-permeability coal reservoirs. Full article

Utilizing seawater samples collected during the summer of 2025 in the Dingzi Bay region, South Yellow Sea, this study conducted a comprehensive analysis of the contents and concentrations of dissolved gases (N₂, O₂, Ar, CO₂) and hydrocarbon gases (such as methane, ethane, and propane). The findings reveal that the dissolved gases in the study area are predominantly composed of N₂ and O₂, with average proportions of 77.8% and 21.6%, respectively. Notably, significant CO₂ anomalies were detected at certain stations, which may indicate intense organic matter degradation or the introduction of external fluids. Furthermore, wet gas constituents, including propane, butane, and isobutane, were identified in several samples, suggesting potential submarine oil and gas seepage or subsurface thermogenic gas input. Spatial analysis revealed that anomalous points were primarily concentrated at stations CJ01, CJ08, CJ10, and CQ01, with no significant correlation to water depth, suggesting that their distribution may be influenced by local geological structures or bottom currents. This study elucidates the complexity and heterogeneity of dissolved gas composition in the waters of Dingzi Bay, thereby providing a novel scientific foundation for regional carbon cycle research, seabed resource exploration, and marine environmental monitoring. Full article

Feed intake and diet quality are key factors influencing enteric methane (CH₄) emissions in ruminants. Low-quality C₄ grasses typically limit intake and are associated with high CH₄ yield. Nitrogen supplementation may improve rumen function and reduce CH₄ emissions per unit of feed intake, although responses under low-quality forage conditions remain insufficiently characterized. The goal of the study was to evaluate the effects of nitrogen supplementation (urea- or nitrate-containing supplements) on the utilization of low-quality weeping lovegrass hay (Eragrostis curvula) and CH₄ yield in beef steers. Twenty-four Aberdeen Angus steers (326 ± 27 kg body weight) were assigned to three treatments: (1) weeping lovegrass hay alone; (2) weeping lovegrass hay + sunflower expeller + urea; and (3) weeping lovegrass hay + sunflower expeller + potassium nitrate (KNO₃). The proportion of non-protein nitrogen (NPN; urea and KNO₃) included in the supplements was set according to the maximum tolerated threshold. Methane emissions were measured using the SF₆ tracer technique. Compared with the hay-only treatment, supplemented animals increased dry matter intake (DMI) by 35% and 38% in the urea and nitrate treatments, respectively (p < 0.01). Total CH₄ emissions (g/d) were not affected by treatment (p = 0.16). However, CH₄ yield (g CH₄/kg DMI) decreased by 27% and 38% in the urea and nitrate treatments, respectively (p < 0.01). The methane conversion factor (Ym) was also reduced in supplemented animals. Under the conditions of this study, supplementation of low-quality weeping lovegrass hay with nitrogen-containing supplements increased feed intake and reduced CH₄ yield without affecting total CH₄ emissions. These findings highlight the importance of considering CH₄ emission intensity, in addition to absolute emissions, when evaluating mitigation opportunities in forage-based beef production systems. Full article

With intensifying measures related to investor and policy requirements, corporate governance and sectoral environmental performance became a focal point for sustainability disclosure, especially in energy-intensive industries with high environmental externalities. This study evaluates whether corporate environmental governance practices in key sectors correspond to their pollution intensity and economic output, analysing a panel dataset across EU member states, for the 2000–2021 period. The empirical methodology includes ordinary least squares (OLS), fixed- and random-effects models, and dynamic system generalised method of moments (GMM) panel estimation to account for sectoral heterogeneity. Results prove that sectoral value added is an influential factor of greenhouse gas emissions, with carbon dioxide exhibiting the highest elasticity to economic activity, followed by methane emissions, and nitrous oxide displaying cross-country variations due to structural and regulatory differences. While services and manufacturing sectors partially decouple via cleaner technologies, overall growth positively correlates with emissions, and renewable energy offers limited mitigation due to scale and integration challenges. Conclusions emphasise robust governance frameworks in high-value energy sectors to meet EU climate-neutrality goals, as stronger environmental accountability attracts capital and supports sustainable development, underscoring the needs for targeted decarbonisation, regulatory coordination, and accelerated technological innovation within persistent industry disparities. Full article

Polyethylene microplastics (PE-MPs) are ubiquitous constituents of waste activated sludge (WAS), acting as a major land-based source threatening coastal environmental integrity. However, how particle size and dose govern the methanogenic outcome during WAS digestion remains poorly defined. This study evaluated two particle sizes (50 vs. 300 µm) and doses (100 vs. 200 particles/gTS) to elucidate the differential effects of PE-MPs on methane yield and the underlying biological mechanisms. The results show that, while low-dose treatments either slightly inhibited methane yield (RS1) or had no significant effect (RL1), high-dose treatments (RS2 and RL2) achieved a net positive effect, with significant increases of 10.2% (p < 0.05) and 9.0% (p < 0.05) relative to the control, respectively. Nevertheless, RS2 and RL2 achieved methanogenic enhancement via distinctly different biological pathways. RS2 harnessed the stress of reactive oxygen species (ROS) (110.5% of the control) to drive community restructuring and biomass accrual (positive correlation between ROS intensity and total VS, Pearson’s r = 0.99). Key syntrophic and electrogenic taxa (e.g., Syntrophales, Bacteroidetes vadinHA17) exhibited a fully interconnected, decentralized network, thereby achieving tight coupling between hydrolysis and methanogenesis. RL2 leveraged the physical carrier effect to promote granulation and biomass growth, enriching Syntrophobacter to enhance propionate degradation. This culminated in a highly modular, sparse network characterized by localized competitive interactions. Together, dosage governs the net methanogenic effect of PE MPs, whereas particle size dictates the mechanistic routes of action. This work offers a mechanistic framework to optimize energy recovery from PE-MP-contaminated sludge while mitigating secondary environmental risks, providing a science-based strategy for the sustainable management of plastic-laden sludge that reconciles renewable energy recovery with pollution control. Full article

Amid growing pressure to reduce carbon emissions, carbon capture, utilization, and storage (CCUS) has become an important pathway toward deep decarbonization. However, the conventional separated “capture–release–conversion” process suffers from high energy consumption and system complexity, which severely limits its large-scale application. Integrated CO₂ Capture and Utilization (ICCU), which enables the capture, activation, and conversion of CO₂ within a single system, has attracted widespread attention because it can effectively reduce intermediate energy-intensive steps and improve carbon utilization efficiency. This review systematically summarizes recent progress in ICCU technology, with particular emphasis on reaction mechanisms and interfacial coupling characteristics. The performance features of solvent-based chemical absorption and solid-sorbent adsorption, two widely studied capture routes, are summarized, and typical integrated conversion pathways, including reverse water–gas shift, methanation, and dry reforming of methane, are discussed. On this basis, the roles of non-conventional energy-assisted strategies, such as photocatalysis, electrocatalysis, non-thermal plasma, and microwave irradiation, in expanding ICCU systems are further examined, together with their system-level coupling potential in carbon-intensive industries such as steel, cement, and power generation. Finally, the key scientific issues and engineering challenges currently facing ICCU are analyzed from the perspectives of fundamental mechanisms, material design, and system engineering, and future development directions are proposed. This review highlights that elucidating multiscale synergistic mechanisms, developing high-performance dual-function materials, and optimizing system integration are crucial to promoting the industrial application of ICCU technology. Full article

Rice production in flooded paddy systems must increasingly balance grain productivity with greenhouse gas (GHG) efficiency. This study evaluated two GroMore^® crop-protection program variants under two nitrogen input levels in a temperate Korean paddy field to determine whether these treatments could improve yield-scaled climate performance without compromising grain yield. Heading date was identical across all treatments, indicating that treatment effects were not attributable to phenological shifts. Grain yield ranged from 6.87 Mg ha⁻¹ in the conventional treatment to 9.88 Mg ha⁻¹ in GroMore-Duo N90. GroMore-Star N90 maintained high yield (9.05 Mg ha⁻¹) with the lowest greenhouse gas intensity (GHGI; 0.69 kg CO₂-eq kg⁻¹ grain) and reduced cumulative methane emission by 10.6% relative to the conventional treatment. Logistic analysis showed that the GroMore treatments reached the methane-accumulation inflection point earlier than the control and conventional treatments. GroMore-Duo N90 and GroMore-Star N90 reached this point at approximately 69 days after transplanting, whereas the control and conventional treatments reached it at 86 and 89 DAT, respectively. Overall, the GroMore programs were associated with differences in yield components and yield-scaled climate performance under flooded paddy conditions without changing crop phenology. Full article

The efficient conversion of methane into hydrogen-rich syngas is essential for sustainable energy; however, integrating methane partial oxidation (POM) with the water–gas shift (WGS) reaction remains a significant challenge due to thermal and kinetic mismatches. This research presents a spatially decoupled dual-bed reactor configuration, utilizing Ni/GDC and Cu/GDC catalysts, to achieve synergistic hydrogen production. Unlike conventional physically mixed systems, which suffer from thermal hotspots and the unintended promotion of the endothermic Reverse Water–Gas Shift (RWGS) reaction, the dual-bed architecture effectively segregates the reaction zones. Advanced characterization, including O₂-TPO and Raman spectroscopy, reveals that the GDC support acts as a critical oxygen buffer via the Mars-van Krevelen mechanism, modulating the dynamic redox state of the active metal sites to prevent deep oxidation and carbonaceous deactivation. Furthermore, macroscopic performance and carbon–oxygen mass balance analyses confirm that this rational architectural design facilitates a seamless integration of POM and WGS pathways, resulting in significantly maximized H₂ yield. From a broader engineering perspective, this dual-bed strategy offers a practical, low-complexity alternative to intensive integrated technologies such as sorption-enhanced reforming (SER) or chemical looping, providing a robust and scalable framework for durable, high-efficiency hydrogen production. Full article

Rice husk is an abundant agricultural by-product with limited use in ruminant feeding due to its high lignocellulosic content and low digestibility. This study compared biological, enzymatic, and chemical additive strategies for improving the ensiling characteristics, chemical composition, and in vitro rumen fermentation of rehydrated rice husk. The experiment was conducted using a completely randomized design with seven treatments: Control (no additive); molasses + Lacticaseibacillus casei TH14 (MB); Acremonium cellulase (AC); laccase (LC); AC + LC; AC + LC + MB; and chemical treatment (CM). After 30 days of ensiling, CM reduced fiber contents and increased in vitro dry matter digestibility (IVDMD) and total volatile fatty acid concentrations (p < 0.05). Among the biological additives, MB and AC + LC + MB significantly reduced NDF and improved ensiling quality and IVDMD (p < 0.05). Notably, AC + LC + MB resulted in the lowest methane emission intensity (44.07 mg/g IVDMD). Although CM, which was included as a chemical-disruption benchmark, was the most effective approach for substrate solubilization, AC + LC + MB improved fermentation characteristics, in vitro digestibility, and methane emission intensity per unit of digested dry matter under the present in vitro conditions. Full article

Cement clinker production is a thermal- and emissions-intensive process requiring high-temperature heat for drying, calcination, and sintering. This review provides a process-based assessment of refuse-derived fuel (RDF), solid recovered fuel (SRF), tire-derived fuel (TDF), and biomass as partial substitutes for coal and petcoke in modern dry-process cement kilns. The study synthesized the evidence from plant-scale trials, pilot and laboratory experiments, process modeling, computational fluid dynamics, emissions studies, life-cycle assessment (LCA), techno-economic analysis (TEA), and regional case studies to evaluate alternative fuels across fuel properties, kiln-zone suitability, process stability, clinker quality, emissions performance, and environmental outcomes. The review shows that stable co-processing generally requires fuels with net calorific values above 14 MJ kg⁻¹ and moisture contents below 15%, although TDF can provide 26–33 MJ kg⁻¹ and sustain high-energy kiln duty when sulfur, zinc, and steel residues are controlled. RDF, SRF, and biomass require pre-processing, homogenization, calibrated dosing, and continuous fuel-quality monitoring to limit incomplete burnout, deposit formation, volatile circulation, and clinker-quality variation. LCA studies show that 20% RDF thermal substitution can reduce global warming potential by about 3.3–4.2%, increasing to approximately 6.7% when avoided landfill methane credits are included. Modern abatement systems can maintain particulate matter at about 10–30 mg Nm⁻³ and PCDD/F below 0.1 ng TEQ Nm⁻³ under stable operation. The review concludes that alternative fuels are quality-dependent co-processing options whose mitigation role is complementary to clinker-factor reduction, energy-efficiency improvement, low-clinker binders, electrified heating, oxy-fuel calcination, and carbon capture. Full article

To address the limitations in the accuracy of existing methods for calculating greenhouse gas emission intensity from underground coal mining, this study develops a more precise model for estimating methane emissions. The model is grounded in the methane release mechanism of coal, and incorporates field-measured original gas content, residual gas content after extraction, and retained gas content following ventilation. The model defines the computational scope based on different mining methods (with and without coal pillars) and incorporates potential direct emission reduction measures applicable at various stages of the mining process. Case studies of both a high-gas mine and a low-gas mine reveal that, while the pillarless mining method increases total methane emissions, emission intensity is reduced. Furthermore, the study demonstrates that preventing the direct release of low-concentration methane from ventilation systems is critical for further emission reductions. Compared to existing methods, the proposed framework adopts a computational approach that reduces operational complexity while maintaining accuracy through the use of readily available field-measured data. These findings offer a scientific basis for formulating tailored emission reduction strategies in the coal mining sector. Full article

Livestock production is a major source of agricultural methane (CH₄) and nitrous oxide (N₂O), making the synergistic mitigation of these two gases essential for meeting climate targets. Based on the EDGAR emission database from 2000 to 2024, this study employs international comparisons, spatial analysis, and STIRPAT-based scenario projections to characterize emissions from China’s animal husbandry and explore pathways for synergistic mitigation. The results reveal that China’s livestock CH₄ emissions exhibited a trend of early-stage fluctuation followed by a late-stage rebound, while N₂O emissions fluctuated sharply. The two gases are strongly synergistic yet driven by distinct mechanisms. China accounts for the largest share of global emissions and exhibits a distinctive emission structure—with comparable contributions from enteric fermentation and rice paddies—setting it apart from both pasture-based and intensive developed countries. High-emission areas are becoming increasingly concentrated in northern production regions. Under the baseline scenario, CH₄ and N₂O emissions are projected to peak in 2032 and 2030, respectively; under an ultra-low-carbon scenario, both gases peak around 2029, at substantially lower levels. Achieving synergistic mitigation calls for a regionally differentiated framework that combines top-down governance with bottom-up participation from farmers, integrating enteric fermentation control with optimized manure management to support a low-carbon transition. Full article

This article presents an environmental assessment of emissions from a solid waste landfill in the Karaganda Region of the Republic of Kazakhstan in order to study the dynamics of methane release and determine its energy potential. The study is based on an analysis of a 13-hectare facility that has been operating since 2015 in a reclaimed quarry with an average annual accumulation volume of up to 4000 tons. The methodology includes a detailed analysis of the morphological composition of waste (57% of the organic fraction) and consideration of regional climatic parameters for modeling the phase-specific formation of biogas, according to the approved national methodology. It has been established that, by 2030, the volume of methane will be 81.7–92.6 tons/year. Based on the data obtained, a set of environmental protection measures is proposed, including the installation of special pipes for degassing and the introduction of automated monitoring based on stationary sensors. The results confirm the technical feasibility of using landfill gas as an alternative energy resource and can serve as a scientific and methodological basis for designing environmentally safe landfills in a sharply continental climate and intensive industrial infrastructure. Full article