Search Results (1,847)

Dark fermentative biohydrogen (bio-H₂) production is a promising renewable energy technology for converting organic waste and wastewater into clean fuel. However, practical application is limited by low H₂ yield, volatile fatty acid (VFA) accumulation, incomplete substrate utilization, electron diversion to competing pathways, prolonged lag phases, and inhibitory byproducts from lignocellulosic pretreatment. Magnetite nanoparticles (Fe₃O₄ NPs) have attracted attention as redox-active additives because of their electrical conductivity, reversible Fe²⁺/Fe³⁺ cycling, magnetic recoverability, biocompatibility, and microbial interaction potential. This review examines the physicochemical properties of Fe₃O₄ NPs and their proposed roles in dark fermentative bio-H₂ production. Particular emphasis is placed on Fe₃O₄-mediated extracellular electron transfer (EET) in fermentative communities, which differs from direct interspecies electron transfer (DIET) in methanogenic systems. Fe₃O₄ NPs may enhance bio-H₂ production by facilitating electron transfer, supporting hydrogenase activity, regulating redox balance, promoting acetate- and butyrate-type pathways, and enriching H₂-producing bacteria such as Clostridium spp. Hybrid systems combining Fe₃O₄ with biochar, activated carbon, reduced graphene oxide, bimetallic nanocomposites, or immobilization matrices may further improve microbial retention and process stability. Remaining challenges include aggregation, dosage-dependent toxicity, recovery, environmental fate, mechanistic uncertainty, and scale-up feasibility. Full article

Sub-Saharan Africa is rich in agricultural biomass, yet its biogas utilization is far below its potential. Most earlier studies failed to identify the nonlinear, multi-factor relationships that shape real national biogas yields and fully clarify this imbalance. This study constructs a 2007–2023 panel dataset for ten sub-Saharan African countries, merging agricultural output, socioeconomic, and infrastructure metrics. Gradient Boosting model and SHapley Additive exPlanations (SHAP) analysis are applied for empirical evaluation. SHAP analysis confirms that charcoal consumption yields the largest contribution to biogas production, with a mean absolute SHAP value of 1.018. The correlation between the two variables is negative under the threshold and becomes positive beyond this critical level. Urbanization has an inverted U-shaped correlation with biogas output, and the marginal contributions of predictors vary substantially across sampled countries. Instead, fragile supply chains, rural labor loss, and fierce competition in clean energy markets curb local biogas production. Forecasts show that regional biogas output will continue to fall until 2030. Targeted national policies matching each country’s core influencing factors are therefore urgently required. Full article

High ash andsss urea formaldehyde (UF) resin contents in particleboard sanding powder (SP) have restricted the effective resource utilization of SP and make it a hazardous biomass material for particleboard enterprises. To achieve high-value resource utilization of SP while addressing its hazardous disposal issues, different HCl concentration-oriented deashing pretreatments of SP coupled with fast pyrolysis was proposed for producing value-added pyrolytic sugar levoglucosan (LG) and high-quality pyrolytic char. The results show that H⁺ ions released from HCl solution could effectively remove structural ash, likely by disrupting the chemical linkages between the structural ash and lignocellulosic matrix. An amount of 2 mol/L HCl could achieve an over 95% removal rate of alkali and alkaline earth metals (AAEMs) in the ash while maintaining a low loss of polysaccharides. This considerably facilitated the glycosidic cleavage of cellulose into levoglucosan (LG), with the LG yield increasing from 2.18% of raw SP to 13.69% of 2 mol/L HCl deashed SP. Interestingly, it was found that HCl washing of SP facilitated the co-production of value-added platform chemical acetic acid via acid-catalyzed hydrolysis of acetyl groups in UF resin attached to the xylose unit, with the yield increasing from about 7% of raw SP to over 11% of HCl deashed one. Specifically, 2 mol/L HCl deashing pretreatment of SP significantly improved the quality of pyrolytic char with the ash content decreasing from 7.24% to 2.39% and fixed carbon content lifting from 54.08% to 76.04%, thus drastically improving the higher heating value (HHV) from 24.66% of raw SP-derived char to 30.05% of deashed SP-derived char. Moreover, the pyrolytic char CO₂ gasification reactivity increased from 0.027 min⁻¹ of raw SP-derived char to 0.034 min⁻¹ of that derived from 2 mol/L HCl deashed SP, approaching that of the widely used industrial charcoal fuel. Pyrolysis kinetic analysis indicates that deashing pretreatment of SP makes the formation of value-added platform chemicals and high-quality carbonaceous fuel proceed more easily at a lower activation energy (214.39 kJ·mol⁻¹) than that of raw SP (245.81 kJ·mol⁻¹). This study offers a novel approach for the synergistic production of value-added chemicals and high-quality carbonaceous fuel from biomass waste materials with high contents of ash and UF resin, providing a feasible strategy for the clean and high-value resource utilization of wood-based industrial residues. Full article

Electrochemical water splitting for hydrogen production is an important path for the preparation of green hydrogen. However, the sluggish kinetics and high energy consumption of the anode oxygen evolution reaction (OER) have restricted its development. The hydrazine oxidation reaction (HzOR), with its low theoretical potential, fast kinetics, clean products, and the ability to simultaneously treat hydrazine-containing wastewater, has emerged as an ideal anode reaction to replace OER. Transition metal phosphides (TMPs) have shown noble-metal-like activity in HzOR catalysis due to their tunable d-band electronic structure, abundant active sites, high conductivity, and structural stability, making them highly promising non-noble metal catalysts. However, most existing reviews focus on the catalytic performance of TMPs in general hydrogen evolution reaction (HER)/OER systems or merely briefly mention HzOR as one of many anode reactions. Therefore, this review aims to comprehensively and systematically elaborate on the design strategies of TMPs catalysts for hydrazine-assisted electrolytic water splitting for hydrogen production and their applications in HzOR, deeply discuss the current progress, challenges, and future directions, and provide references for the development and industrial application of low-cost, high-efficiency, and high-stability hydrazine-assisted hydrogen production catalysts. Full article

In this manuscript, we present the results of our studies on the exclusive photoproduction of quarkonium-photon pairs with large invariant mass. In our analysis, we focus on the production of the ${\eta }_c\gamma$ and ${\chi }_{cJ}\gamma$ pairs in high energy kinematics. We use the Color Glass Condensate (CGC) framework for analysis and demonstrate that at leading order in ${\alpha }_s$ the cross-sections of these processes are determined by the forward dipole scattering amplitude. The kinematic distributions of the produced particles allow us to study the dipole amplitude in detail, making this process a very clean probe for studies of saturation physics. Using phenomenological parametrizations of the dipole amplitudes, we estimate numerically the differential production cross-sections for ${\eta }_c\gamma$ and ${\chi }_c\gamma$ in the kinematics of ultraperipheral collisions at the LHC and the future Electron-Ion Collider (EIC). Furthermore, we assess the role of this process as a possible background to the exclusive photoproduction of C-even quarkonia, which is frequently considered as a tool for odderon searches. Full article

This study investigates how O₂ concentration affects the combustion performance and kinetic response of Changji and Fushun oil shales under CO₂-based oxy-fuel atmospheres. Coupled TGA–DSC–MS analysis was performed to characterize thermal decomposition, heat release and absorption, gaseous product evolution, and apparent kinetic parameters. The results show that raising the O₂ concentration facilitates oil shale combustion. The TG–DTG and heat flow profiles move to lower-temperature regions as O₂ concentration increases. At 20 °C·min⁻¹, increasing the O₂ concentration from 35% to 100% reduced T_p1 and T_p2 from 357.3 and 519.7 °C to 331.2 and 491.5 °C for CJ oil shale, and from 352.3 and 484.0 °C to 326.6 and 429.7 °C for FS oil shale, respectively. These shifts were accompanied by decreases in ignition and burnout temperatures and an increase in the comprehensive combustion index. Fushun oil shale shows a more concentrated main mass-loss and heat-release region than Changji oil shale. It also exhibits lower ignition and burnout temperatures, indicating stronger overall combustion reactivity. By contrast, Changji oil shale displays more evident mass loss and thermal responses at high temperatures, suggesting a greater contribution from carbonate mineral decomposition in the later reaction stage. MS results further show that CO₂, H₂O, SO₂, and NO₂ release mainly occurs within 300–600 °C. Their release peaks shift toward lower temperatures as the O₂ concentration increases, indicating that oxygen-enriched atmospheres promote the oxidative conversion of organic carbon, hydrogen-containing structures, and S- and N-containing functional groups. The Vyazovkin nonlinear iso-conversional analysis provides conversion-dependent apparent activation energies rather than a single global kinetic parameter. The substantial variation in E_α with conversion highlights the overlapping and multi-stage nature of oil shale combustion. When the O₂ concentration is raised from 21% to 75%, E_α generally follows an upward trend; under pure O₂, however, it drops sharply. This non-monotonic variation suggests that O₂ concentration changes not only the combustion rate but also the dominant reaction routes at different conversion stages. These findings provide experimental support for selecting suitable oxy-fuel combustion conditions and improving the clean and efficient utilization of oil shale. Full article

Against the background of the “dual carbon” goals and the integration of a high proportion of renewable energy, hydrogen energy storage, with its advantages of long duration and large scale storage as well as clean energy conversion, has become an important approach to improving the flexibility and security of energy systems. To address the accident risks associated with leakage from high pressure hydrogen storage in stationary hydrogen energy storage facilities, this study takes an integrated hydrogen energy storage station involving hydrogen production, storage, compression, and utilization as the research object. A numerical model for hydrogen leakage and dispersion from high-pressure storage cylinders in an open environment is established to investigate the effects of leakage aperture, natural ventilation, mechanical ventilation, and emergency shutdown on hydrogen cloud evolution and deflagration risk. The results show that an increase in leakage diameter significantly increases the flammable hydrogen volume and Q9 peak value. Large-scale leakage is prone to local accumulation under the influence of blast walls and obstacles, resulting in a 780 m³ combustible volume and 14.7 m³ Q9; medium-scale leakage has a longer duration, whereas small-scale leakage presents the lowest risk. Under natural wind conditions, crosswind provides better dilution, reducing Q9 by 53%. Mechanical ventilation can effectively reduce the value of Q9 by 36%, with ventilation layout exerting a more significant influence than wind speed. The combined use of mechanical ventilation and emergency shutdown can further reduce the 42% flammable volume and shorten the duration of high concentration hydrogen clouds. The findings can provide guidance for the safety layout, ventilation design, and emergency protection of hydrogen energy storage stations. Unlike conventional CFD-based leakage consequence analyses, this study couples hydrogen dispersion simulation with Q9-based deflagration risk assessment and a hierarchical safety strategy involving natural, mechanical ventilation, and emergency shutdown. Full article

Platinum group metals (PGM) are essential for clean-energy technologies, including proton exchange membrane (PEM) electrolyzers for hydrogen production and PEM fuel cells for hydrogen use, as well as catalytic, electronic, and advanced industrial applications. However, their supply is exposed to geological concentration, co-product dependence, and market volatility. This study evaluates the medium-term cost-based accessibility of known primary PGM resources using a cumulative availability curve. The analysis combines resource estimates and allocated production-cost data for 61 known PGM-bearing deposits and projects, with costs expressed in 2022 USD per metric ton of combined PGM output. Because PGM deposits differ in ore type, processing route, and co-product setting, the results are interpreted by deposit cluster rather than only by country or aggregate cost threshold. The low-cost portion of the curve is dominated by Ni–Cu sulphide by-product systems, but this cluster represents only 1.87% of the compiled resource base. In contrast, UG2/Merensky/Great Dyke reef-type systems account for 72.95%, and Platreef/Northern Limb and Platreef-type systems account for 19.82%. Thus, most known primary PGM resources occur outside the low-cost by-product segment. Cluster-weighted PGM basket-price benchmarks are used instead of individual metal-price comparisons. Several cluster-level cost ranges fall below or near indicative April 2025 basket-price benchmarks, but these comparisons are not project-level profitability tests. Overall, the cumulative availability curve provides a deposit-cluster-based framework for evaluating known primary PGM availability and informing critical-material policy, recycling strategy, supply-chain planning, hydrogen-technology deployment, and responsible resource development. Full article

Cobalt has emerged as a strategic critical metal due to its essential role in rechargeable batteries, high-performance alloys, catalysts, and clean energy technologies. However, its supply chain remains heavily dependent on cobalt produced as a by-product of copper and nickel mining and is geographically concentrated, particularly in the Democratic Republic of Congo. This review provides a comprehensive assessment of cobalt geology, mineralogy, global reserves, market trends, primary extraction routes, and emerging secondary recovery strategies. Unlike previous reviews that address these topics separately, this work integrates geological occurrence, mineralogical characteristics, extraction technologies, and resource circularity within a unified framework aimed at evaluating future cobalt supply resilience. The main cobalt-bearing deposit types of sediment-hosted Cu–Co deposits, Ni–Co laterites, and magmatic Ni–Cu–Co sulphide deposits are compared in terms of their mineralogical characteristics and processing requirements. Hydrometallurgy is identified as the dominant industrial route, typically combining high-pressure acid leaching (HPAL) with downstream purification and recovery processes such as solvent extraction and electrowinning (SX–EW). Emphasis is placed on the relationship between ore mineralogy and process selection, as well as on the growing integration of secondary resources, including tailings, slags, and spent batteries, into existing cobalt production chains. Despite promising recovery rates at laboratory scale, challenges remain in impurity control, economic scalability, and integration into established refining infrastructure. This review demonstrates that secondary resources are evolving from supplementary feedstocks to strategically important contributors to cobalt supply. Future supply security will depend on feedstock diversification, more flexible refining systems, improved impurity management, and the implementation of sustainable circular-economy strategies. Full article

Sustainable rural development requires households to move beyond defensive medical spending and emergency borrowing toward more productive, forward-looking resource allocation. This study uses panel data from the China Household Finance Survey (CHFS), covering the 2017, 2019, and 2021 waves plus a newly released 2023 green-channel wave. We examine whether improvements in safe drinking water, clean cooking energy, and sanitation are associated with lower rural household economic vulnerability. We employ a staggered difference-in-differences design with household and year fixed effects, complemented by event–study tests, mediation analysis, and robustness checks. Environmental infrastructure improvements are significantly associated with lower child hospitalization and out-of-pocket medical expenditure, reduced reliance on high-cost informal credit, and higher income-generating asset shares. Mechanism analysis supports a “health–credit–income” channel, in which environmental improvements reduce preventable health shocks, ease emergency borrowing, and relax liquidity constraints on productive asset allocation. Threshold results further show that these financial-resilience benefits are strongest among households with the lowest baseline resource endowments. The study focuses on rural China, yet the identified health–credit–income mechanism offers a broader, scalable framework. Environmental infrastructure first reduces preventable disease burden, then eases emergency informal borrowing, and finally frees liquidity for income-generating assets. This sequence helps explain how environmental investment can create the financial preconditions for sustainable consumption and investment across developing economies. These findings offer micro-level evidence for integrating environmental infrastructure, rural financial resilience, and ESG social-value assessment. Full article

Battery cell manufacturing is highly energy intensive, with clean and dry rooms being among the largest consumers of electricity and thermal energy. Due to the moisture sensitivity of most advanced cathode materials (e.g., NMC 811) and sulfide-based solid-state materials, production environments must operate at extremely low humidity, requiring energy-intensive HVAC systems to remove moisture introduced mainly by workers and infiltration. To reduce energy consumption, a detailed understanding of the airflow patterns in the room is essential. Because of complex flow patterns (exhaust air demands, energy dissipation), tracer gas techniques using CO₂ as a marker provide an operation-integrated method for determining local air age. The studies presented in this paper apply tracer gas techniques for the first time to a room in which air is almost completely recirculated at high air change rates of approximately 27 h⁻¹, with the supply air being conditioned by removing all process-relevant contaminants such as moisture and particles. Measurements in a separate flow box show successful air age calculations that agree with simplified CFD simulations. For the clean and dry room, the empirical variable relative exposure (REX) was introduced. The measurements indicate an inhomogeneous air distribution inside the room, accompanied with short-circuit flows, partial displacement flow, and mixing, and therefore have the potential to provide a cost-effective first-hand insight into the prevailing airflow patterns. Nevertheless, the presented measurement technique must be further optimized and validated for rooms with air recirculation and high air change rates. Full article

In the context of accelerated progress in clean energy development, an increasing number of regions are utilizing photovoltaic modules (PVMs) for the purpose of energy production. Numerous studies have demonstrated that the installation of these PVMs can exert both positive and negative effects on local ecosystems in different regions. However, there is a paucity of studies that have explored the ecological recovery mechanisms following PVM removal from another perspective, which may hinder a comprehensive understanding of PVM ecological impacts and impede the formulation and implementation of ecological management policies. The PVMs installed on Jiaogang Lake, which were to be removed due to policy adjustments, provided a valuable opportunity to address this issue. The taxonomic and functional diversity of waterbird communities in Jiaogang Lake was assessed and compared before and after the removal of PVMs. The results demonstrated that following the removal, there was a significant increase in both waterbird species richness and functional diversity, whilst the functional nestedness patterns between waterbird communities became more pronounced, implying the restoration of lake littoral areas. Subsequent analysis of individual waterbird functional traits revealed a significant trend towards larger body sizes in waterbirds following the removal of PVMs. Although temporal changes in certain traits did not attain statistical significance, the consistent trends observed in numerous traits led to this extrapolation with confidence. The present study thus aims to encourage decisive decision-making, particularly in short-term macroecological research in the local-scale region, avoiding delays in ecological management measures due to an obsession with perfect statistical data and analysis outcomes. Full article

The efficient removal of tenacious oxide scales from hot-rolled steel surfaces represents a persistent challenge in advanced manufacturing, as traditional manual grinding methods exhibit poor efficiency and environmental compatibility. This investigation develops an innovative methodology, i.e., a “coarse-to-fine” hierarchical cleaning paradigm consisting of dual-stepwise laser cleaning with variable parameters that successfully addresses the restrictive process window inherent to conventional single-parameter techniques. Through a strategically designed sequential treatment protocol—employing initial low-frequency (20 kHz), high-energy-density (200 mm/s) laser irradiation for primary oxide ablation, succeeded by high-frequency (60 kHz), low-energy-density (4000 mm/s) processing for residual scale elimination—we demonstrate an optimal synergy between ablative and thermomechanical vibration mechanisms. Rigorous multi-modal characterization incorporating SEM-EDS microscopy, oxygen content quantification, and metallographic analysis confirms exceptional performance metrics, including 98.7% oxide removal efficiency and 43.2% reduction in substrate surface roughness relative to standard methods. The developed protocol achieves a 2.8-fold expansion of the operational parameter space while establishing a novel “coarse-to-fine” hierarchical cleaning paradigm. These findings offer fundamental insights into laser–matter interactions while delivering a transferable technological framework for high-value manufacturing sectors, particularly in automotive and aerospace component production. Full article

Hydropower dams constitute key components of sustainable energy and water resource management, while their long-term operation increasingly depends on social acceptance and local community support. Within this context, the current study investigates residents’ perceptions of the environmental, social, and economic advantages and adverse impacts associated with the operation of the Nestos River dams. It explores the role of the NIMBY (Not In My Back Yard) phenomenon in shaping local attitudes. Data were collected during 2020–2021, and a stratified random sampling design was applied, involving 1101 residents living in mountainous, semi-mountainous, and lowland areas of the Nestos River basin. Reliability analysis and factor analysis were employed to assess the consistency of responses and identify the underlying factors shaping residents’ perceptions. The results indicate that respondents recognize significant benefits associated with the dams, particularly clean energy production and the creation of lacustrine ecosystems, while simultaneously expressing concerns regarding the disruption of the river’s natural flow, biodiversity degradation, and landscape alteration. The findings also reveal complex, spatially differentiated NIMBY dynamics, suggesting that although dams are perceived as socially beneficial infrastructures, their localized impacts influence community acceptance. Overall, the study highlights the importance of incorporating local perceptions into the planning and management of hydraulic infrastructures and provides evidence supporting socially acceptable and sustainable approaches to existing and future dam projects. Full article

With the growing energy demand and concerns about environmental impacts, green hydrogen has become one of the main alternatives for a clean and reliable energy future. Brazil presents itself as one of the main potential suppliers of this renewable fuel, considering its resource abundance, such as solar irradiation. Therefore, the present study aims to evaluate in detail the hydrogen production potential of one of Brazil’s main states when it comes to solar power potential, Minas Gerais. The potential for each of the 853 municipalities of the region was assessed individually using three different methodologies, indicating that the state could produce 2365.2 TWh of electricity or 47.3 Mt_H2/year (with a maximum variation of 3.4% between the methodologies), nearly five times the EU’s projected 2030 hydrogen import demand. This estimation, however, was significantly reduced when only areas with a slope lower than 8% were considered, decreasing land availability by 40% and cutting hydrogen potential by 18.8 Mt/year. On the other hand, increasing power density from 4 to 15 MWh/km² almost tripled hydrogen production potential, while electrolyzer efficiency also presented a positive effect on hydrogen output. Finally, the comparison of hydrogen potential with Human Development Index (HDI) data indicates that the most productive mesoregions often coincide with lower human development levels, particularly in the “Norte de Minas” and “Jequitinhonha” mesoregions, highlighting the opportunity to align energy transition with regional development goals. Therefore, targeted investments in these regions could generate jobs, boost income, and reduce inequalities, reinforcing green hydrogen as both an environmental and social driver. Full article