Search Results (4,888)

Freshwater contamination by phosphate and pathogenic bacteria requires low-cost multifunctional treatment materials. Unlike previous studies that use a single biogenic agent to synthesize a single nanoparticle type, this work uses one fixed Aloe vera extraction protocol to generate three chemically distinct nanoparticles (Ag, CuO, Fe₃O₄) on the same waste-derived carbon support, enabling a direct, extract-controlled comparison of nanoparticle identity on water-treatment performance. Activated carbon (AC) was prepared from waste wattle bark (Acacia mearnsii) by steam activation at 700 °C and functionalized with biogenically synthesized Ag, CuO, and Fe₃O₄ nanoparticles (NPs) using Aloe vera extract as a reducing and stabilizing agent. Average nanoparticle sizes were 43 nm for Ag, 59 nm for CuO, and 13 nm for Fe₃O₄. FTIR, PXRD, SEM-EDS, TEM, DLS, TGA, and BET analysis characterized the materials. Among the composites, Fe₃O₄NPs/AC showed the best phosphate removal performance, achieving 93% removal and a maximum adsorption capacity of 9.3 mg/g under acidic conditions, compared with 3.3 mg/g for pristine AC. Equilibrium data were better described by the Freundlich model (R² = 0.999), indicating adsorption on a heterogeneous surface. Ag NPs/AC exhibited complete inactivation of both Escherichia coli and Staphylococcus aureus within 2 h, while CuO NPs/AC (a more economical alternative) achieved near-complete inactivation of both bacteria within 6 h. AC from spent wattle bark and functionalized with green-synthesized nanoparticles is thus a promising platform for combined phosphate removal and antibacterial water treatment. Consistent with their respective roles, Fe₃O₄ NPs/AC was evaluated exclusively for phosphate adsorption, while Ag NPs/AC and CuO NPs/AC were evaluated exclusively for antibacterial activity; no single composite was tested for both functions. Full article

The increasing penetration of variable renewable energy sources (RESs) poses significant challenges to power system flexibility and reliability, particularly in systems with high solar generation. At the same time, existing Concentrating Solar Power (CSP) plants in Europe face declining economic viability due to high capital costs and the expiration of incentivized tariff schemes. This study proposes and evaluates a novel approach to repurpose CSP plants as flexible energy assets through the integration of cold thermal energy storage (CTES) within a Thermally Integrated Power-to-Heat-to-Power Energy Storage (TI-PTES) framework. The proposed system combines an ice/water-based cold storage with a CO₂-based refrigeration cycle to enhance the efficiency of the CSP steam cycle by reducing condenser temperatures, while also enabling temporal shifting of electricity consumption. A techno-economic optimization model based on PyPSA is developed to determine the optimal sizing and operation of the storage and refrigeration system under realistic load and electricity price conditions representative of the Spanish market. Results show that the integration of cold storage significantly alters system operation, shifting the chiller from a continuous demand-following mode to an intermittent, high-intensity regime. This leads to a reduction in annual operating expenditures by approximately 32% and an increase in annual profit and net present value (NPV), despite higher capital investment. While hourly net revenue becomes more volatile, with negative values during charging periods, cumulative annual performance improves due to effective temporal optimization. However, the absence of strong electricity price arbitrage and negative price signals limits the revenue potential of the storage system, which primarily acts as a cost-reduction mechanism. The findings demonstrate that cold thermal storage can successfully reposition CSP plants as flexible, value-generating assets in modern electricity systems. The proposed concept offers a promising pathway for extending the operational lifetime of existing CSP infrastructure while supporting higher integration of renewable energy sources. Full article

Micro gas turbines are small-scale systems based on the Brayton cycle and represent a viable solution for distributed generation. However, the main limitation to extending their application range is the cycle efficiency. Numerical and experimental analyses of power plants are important for evaluating the energy performance of different cycle configurations. Another issue is the formation of pollutants, including nitrogen oxide emissions. The humidified gas turbine cycle is one alternative to address these problems. Among wet cycles, the regenerative evaporative cycle offers a means to improve gas turbine efficiency. However, this configuration is less commonly discussed in the literature, which focuses more on steam injection cycles. Therefore, this paper presents an energy, exergetic, and nitrogen oxide formation analysis of an evaporative regenerative cycle for a 30 kW micro gas turbine across the gas turbine load range to define the most suitable operational system regime. The novelty of this study lies in an integrated assessment that simultaneously covers the operation of the micro gas turbine at full and part load under different conditions of water injection into the evaporator. The analyses conducted show that, for the micro turbine operating at full load, the benefits in terms of energy and pollutant formation are positive for all fractions of injected water. However, decreases in cycle performance are reported at power outputs below 19 kW compared with the dry cycle. Although nitrogen oxide formation decreases with increasing water injection, the reduction is less pronounced at lower microturbine power levels. Full article

The HEROn magazine was created as an innovation project by the S-TEAM team for the 2024/2025 SUBMERGED season of the FIRST^® LEGO^® League Challenge category. The primary aim of the HEROn project was to implement game-based learning methods to enhance environmental awareness, particularly concerning the protection of our water resources. This initiative is designed to engage individuals from ages 9 to 99 in a creative and enjoyable manner. At the core of the HEROn project is a well-known game that challenges players to find the differences between two photos. This activity not only provides entertainment but also educates participants about the importance of protecting and preserving the aquatic environment. By discovering subtle differences between images, players become more attuned to environmental issues, which promotes a deeper understanding and appreciation of water conservation. The chapters of the HEROn magazine are thoughtfully organised into themes, each focusing on various aspects of water’s importance, its protection, and sustainable usage. Additionally, a random sample of participants was surveyed to gather opinions and feedback on HEROn magazine as part of the project and this research. This feedback is invaluable for assessing the magazine’s impact and for improving future editions to better serve the goals of raising environmental consciousness. The online HEROn questionnaire consisted of 10 items and employed a 5-point Likert scale for responses. Data were collected over a three-month period (28 January–28 April 2025), with 630 Hungarian respondents participating in the survey. The HEROn magazine was generally well received, with mean scores ranging from 4.2 to 4.6. Age-group differences were examined using nonparametric Kruskal–Wallis tests, with Dunn–Bonferroni post hoc comparisons. These analyses show statistically significant differences between adults (30–89) and the younger cohorts for aggregated awareness, design/engagement, and branding measures, while teenagers (9–15) and young adults (16–29) did not differ significantly from each other. The Find-the-Difference game showed the greatest variability across groups, with young adults giving the lowest mean. Full article

To alleviate grid peak-shaving pressure from high-penetration renewable energy integration, coupling thermal energy storage (TES) with coal-fired power plants is an effective approach for enhancing operational flexibility. This paper systematically investigates the peak-shaving performance of a coal-fired unit integrated with molten salt storage and heat pump storage systems, focusing on load response characteristics, peak-shaving capability, and the influence of discharge strategies on thermodynamic performance under various rated turbine heat acceptance (THA) conditions. The results indicate that, under identical peak-shaving capacity, the molten salt system exhibits greater storage capacity, which increases with rising THA levels, whereas the heat pump storage capacity remains largely THA-independent. Regarding discharge strategies, replacing high-pressure extraction steam achieves the fastest ramp rate and largest incremental power output, introducing steam into the intermediate-pressure cylinder yields the slowest response but highest round-trip efficiency, and replacing low-pressure extraction steam delivers the smallest peak-shaving capacity and lowest round-trip efficiency. Although TES integration slightly reduces thermal efficiency due to heat exchange losses, this trade-off is justified by significant flexibility improvement, demonstrating clear engineering value for high-renewable grids. Full article

Adjustable steam ejectors exhibit significant adaptability to various operating conditions. However, the coupling regulation mechanism between ejector performance and the internal flow field remains insufficiently understood, thereby limiting further optimization. The novelty of this study lies in elucidating the ejector’s performance regulation mechanism by examining the influence of spindle position on non-equilibrium condensation in wet steam. This approach clarifies the flow–thermal–phase-change coupling mechanism and interprets the resulting condensation suppression and shock wave dynamics. In this study, the effects of operating conditions and spindle position on ejector performance were quantitatively characterized. The flow-field evolution was further analyzed through key flow-field variables (pressure, Mach number, temperature, and condensate mass fraction). Moreover, the relationship between ejector performance and flow characteristics was investigated. The flow–thermal–phase-change coupling analysis reveals that the spindle effectively regulates steam ejector performance, internal thermodynamic behavior, and phase-transition processes by adjusting the equivalent throat diameter. Under a representative operating condition, compared with the baseline position (d_t = 5.66 mm), moving the spindle in the positive x-axis direction (to d_t = 5 mm) decreased the equivalent throat diameter and the motive-fluid mass flow rate by 11.7% and 22.6%, respectively. Consequently, the distance between adjacent shock waves gradually decreased along the flow direction (by approximately 14.1%), and the global maximum Mach number decreased sharply from 2.0 to 1.6 (a 20% reduction). The jet core was significantly shortened, while both the intensity and number of shock waves in the diffuser were reduced. Additionally, the local backflow near the wall of the mixing chamber’s contraction section was suppressed, resulting in a weaker temperature rise in the backflow region. The fluid temperature approached the outlet temperature more gradually, while the average flow-field temperature increased. Meanwhile, the condensate mass fraction in the mixing chamber was significantly reduced (from 0.1 to 0), and the entrainment ratio was enhanced. This configuration is suitable for applications requiring low discharge pressure, high motive pressure, or high suction pressure. Conversely, moving the spindle in the negative x-axis direction enlarged the equivalent throat diameter, which generated higher Mach numbers and stronger shock waves. This enlarged throat configuration enhances the ejector’s resistance to elevated discharge pressure and increases the critical discharge pressure, making it more suitable for high discharge pressure, low motive pressure, or low suction pressure conditions. Full article

The endothermic nature of methanol steam reforming (MSR) for hydrogen production induces varying thermal effects along the flow direction, resulting in a non-uniform temperature distribution within the catalytic bed. Optimizing temperature uniformity has been demonstrated to enhance hydrogen production efficiency. In this study, a novel Fresnel lens-driven non-evacuated tapered cavity solar reactor was proposed for methanol steam reforming, which can provide a reference for optimizing hydrogen production using Fresnel lens solar concentrators. The thermal flux distribution on the reactor’s inner walls was determined by Monte Carlo ray-tracing simulations. A three-dimensional CFD model integrating fluid flow, heat and mass transfer, and methanol steam reforming reaction kinetics was developed to investigate the effects of key operational parameters on this novel reactor performance. Multi-objective optimization using response surface methodology revealed that high reactant inlet temperature (T_in > 550 K) and low flow velocity (u_in < 0.2 m/s) conditions significantly improve reactor methanol conversion (99.99%) and hydrogen yield (91.48%), but at the cost of increased CO selectivity (S_CO > 28%). Conversely, low temperature (T_in < 500 K) and high flow velocity (u_in > 0.4 m/s) conditions suppress CO formation (S_CO < 0.03%), although with reduced hydrogen production efficiency. Full article

This study aims to evaluate the cradle-to-gate environmental impacts of industrial-scale lyocell fiber production in Türkiye using site-specific foreground data. The assessment was conducted in accordance with ISO 14040 and ISO 14044 using SimaPro 9.4 software and the Ecoinvent v3.7.1 database, with a declared unit of 1 kg of lyocell fiber at the facility gate. The results indicate that climate change, fossil resource use, freshwater use, and land use are the most relevant impact categories within the evaluated system. The total Global Warming Potential was calculated as 4.13 kg CO₂ eq/kg fiber. Contribution analysis showed that the production stage was the dominant source of climate change impacts, followed by raw material supply, transportation, pulp production, and waste management. Electricity consumption, steam generation, dissolving pulp production, and transportation logistics were identified as the main environmental hotspots. A screening-level sensitivity assessment further indicated that electricity supply is a key improvement lever, with photovoltaic electricity substitution showing substantial potential for reducing GWP. The findings provide site-specific evidence for industrial lyocell production in Türkiye and demonstrate the value of primary LCA datasets for hotspot identification, product-level environmental reporting, sustainability benchmarking, and possible future EPD development. Full article

In response to the increasing needs for environmentally friendly products, lignocellulosic natural fibers have been of interest as potential replacements for synthetic reinforcement materials in textiles, composites, and related applications. Among these resources, bast fibers derived from plant stems (flax, hemp, nettle, jute, hop), which contain a high cellulose content, have good mechanical properties, low density, and are renewable, are highly promising. Steam explosion has emerged as a green fiber extraction, defibrillation, and surface modification pretreatment technology. Despite the growing number of studies on steam-exploded natural fibers, a comprehensive understanding of the relationships between processing conditions, fiber modifications, mechanisms, and end-use performance remains limited. This review investigates the structural, chemical, and morphological influences of steam explosion on bast fibers. Specifically, it focuses on the mechanism of steam explosion including the solubilization of hemicellulose, partial lignin redistribution or removal, fiber individualization, and cellulose enrichment. The literature indicates that steam explosion can improve fiber separation, fineness, surface morphology, and interfacial adhesion of the composite materials and reduce the use of hazardous chemicals compared with conventional extraction methods. Nonetheless, conflicting results have also been documented, where the same steam explosion conditions can yield distinct fiber characteristics according to biomass type, composition of biomass, moisture concentration, and the amount of processing involved. Excessive treatment severity may lead to fiber shortening, cellulose degradation, and deterioration of fiber quality, particularly for textile applications requiring long fibers. This review highlights current knowledge gaps regarding the optimization of processing conditions, the understanding of steam explosion mechanisms, and the scale-up of the technology for industrial applications. Full article

Steam-assisted gravity drainage (SAGD) remains one of the most energy-intensive technologies for heavy-oil recovery because production response is controlled not only by injected heat but also by spatial heat delivery, wellbore losses, viscosity reduction and steam chamber geometry. This paper develops a physics-guided digital twin for SAGD with distributed thermocable assistance and a bounded residual machine learning correction layer. The framework combines a heat-delivery model, temperature-dependent oil mobility, scenario analysis and decision-oriented visualization within a reproducible computational experiment. A reference operating envelope was formulated for heavy-oil reservoirs, including depth, horizontal well length, permeability, porosity, oil viscosity, steam temperature, injection rate, thermocable power and cable coverage. The analysis includes sensitivity testing, cumulative-production/SOR dynamics and Pareto-type operating-window mapping. In the reference computational scenario, which is treated as an illustrative screening case rather than as field-history validation, the thermocable-assisted hybrid configuration changed the model-calculated eight-year cumulative oil from 452.5 × 10³ m³ to 615.2 × 10³ m³ and the mean SOR from 3.17 to 2.72 t/t relative to the conventional SAGD physics-core case. The largest sensitivities were associated with steam rate, steam temperature, initial viscosity and permeability. Within the declared operating envelope, the results support the use of the framework as a pre-field screening tool and indicate that thermocable assistance should be interpreted primarily as spatial heat distribution control rather than as a field-validated production-improvement guarantee. Full article

Offshore high-temperature steam flooding suffers severe steam channeling, uneven steam intake and low thermal efficiency, while conventional profile control agents fail to adapt to coupled harsh environments of 200–350 °C high temperature, ultra-high salinity and continuous steam shear. Existing reviews mainly focus on onshore thermal reservoirs or single foam/gel materials, lacking a targeted, gel-oriented systematic review matching unique offshore platform constraints. Guided by the integrated framework of “flow control–diversion–enhanced sweep efficiency”, this work establishes a six-dimensional quantitative screening standard and unified performance comparison database to systematically review foam, gel, particle, thermo-responsive and composite profile control systems. Differing from petroleum engineering-oriented summaries, this paper subdivides high-temperature gels into six categories from a polymer material perspective, elaborating their crosslinking mechanisms, thermal rheology and cyclic steam degradation rules; the inherent advantages, limitations and offshore applicable boundaries of each medium are quantitatively compared, with special emphasis on the unique “deep migration followed by in situ thermal activation” mechanism of thermo-responsive materials. Composite systems relieve single-material defects via multi-mechanism synergy yet face complicated on-site deployment barriers. Three core bottlenecks restricting field application are identified: the irreconcilable trade-off between deep propagation and stable plugging, large deviation between static aging results and dynamic anti-scouring performance, and exclusive engineering limitations of offshore platforms. A dedicated standardized dynamic laboratory evaluation scheme for cyclic steam flooding is proposed to narrow lab-field performance gaps. Future research priorities include salt-resistant thermally responsive composite gel modification, low-cost multi-component compound formula optimization, unified dynamic evaluation criteria and staged material matching guidelines to realize balanced performance of high-temperature tolerance, deep delivery and offshore operability. Full article

High-temperature corrosion severely impairs the service life of boiler heating tubes and threatens the safe and economical operation of thermal power units. With diversified fuels (coal, biomass and refuse-derived fuels) and continuously elevated operating parameters (steam temperature exceeding 620 °C for ultra-supercritical units), boiler heating surfaces are exposed to increasingly complex corrosive environments. High-temperature oxidation, sulfidation, chlorination, molten salt hot corrosion and deposit-induced multi-factor coupled corrosion coexist and exacerbate each other. This paper adopts a four-dimensional analytical framework of “mechanisms–technologies–materials–evaluation” to systematically summarize relevant research progress. From the perspective of corrosion mechanisms, the evolution of understandings from single high-temperature oxidation to multi-factor coupled corrosion is reviewed. In terms of surface coating technologies, seven mainstream processes including HVOF/HVAF spraying, plasma spraying, cold spraying, laser cladding and weld overlay are compared in terms of preparation characteristics and engineering applicability. For coating materials, twelve material systems such as NiCr alloys, MCrAlY, cermets, Fe-based amorphous/nanocrystalline alloys and high-entropy alloys are evaluated for their corrosion resistance under diverse service conditions. As for monitoring and evaluation, this work introduces full-range corrosion management technologies covering electrochemical monitoring, non-destructive testing, numerical simulation and life assessment. Finally, the paper discusses the application prospects of gradient coating design, AI-assisted material screening and digital twin technology, and points out key research gaps including long-term service reliability verification of coatings and quantitative prediction models for multi-factor coupled corrosion. Full article

The increasing global demand for freshwater, together with the high energy consumption and environmental footprint of conventional desalination technologies, has stimulated growing interest in interfacial solar steam generation (ISSG). ISSG is a solar-driven water purification strategy that localizes heat at the air–water evaporation interface, thereby promoting surface evaporation without heating the entire bulk water body. The development of efficient, durable, and multifunctional ISSG systems depends strongly on substrate materials that can regulate water transport, heat localization, vapor release, and mechanical stability. This review focuses on cellulose-based substrates for ISSG and examines how their molecular structure, fibrillar assembly, and macroscopic porous architecture influence evaporation behavior and device function. The reviewed cellulose platforms are classified into three major groups: bottom–up assembled nanocellulose substrates, including cellulose nanocrystals, cellulose nanofibers, and bacterial cellulose; natural hierarchical substrates, including wood, cotton fabrics, and agricultural residues; and commercial planar substrates, including cellulose paper and membranes. Beyond evaporation performance, this review discusses multifunctional design strategies for salt regulation, antifouling and antibacterial operation, water–electricity cogeneration, and photocatalytic pollutant degradation, with emphasis on their mechanisms and functional trade-offs. Finally, we identify critical bottlenecks limiting practical deployment and propose a roadmap for future intelligent, adaptive, and multi-energy-coupled cellulose-based ISSG systems. These systems offer a promising platform for distributed and resource-efficient water treatment, but their practical and environmental benefits depend on fabrication energy, material safety, device lifetime, and end-of-life management. Full article

This study examined the removal of toxic heavy metals Pb²⁺ and As⁵⁺ from wastewaters by applying a waste nut biomass for adsorption. The waste material was steam-activated and further modified with zinc nitrate tetrahydrate to improve its affinity for arsenate. The adsorption performance was evaluated across a range of contact times, sorbent dosages, initial metal concentrations, and pH levels, for both single-metal and mixed-metal systems. When the raw material was modified by Zn, the maximum uptake of As⁵⁺ reached a value of 51 mg/g, at a sorbent dosage of 2 g/L. In binary metal solutions, the biochar exhibited maximum capacities of 25.5 mg/g for Pb²⁺ and 48.5 mg/g for As⁵⁺, indicating minimal competition between the two ions for adsorption sites on the biochar surface. Full article

Given the critical need for scalable technologies that decouple industrial production from fossil feedstocks, this study introduces a green hydrogen-driven and carbon-negative industrial complex that employs renewable energy to simultaneously produce methanol and Fischer–Tropsch hydrocarbon products via feedstocks of carbon dioxide (CO₂) and water. The proposed complex (FARMOW) integrates six major sections: (i) a Fischer–Tropsch synthesis process (FTSP), (ii) an alkaline water electrolysis process (AWEP), (iii) a reverse water–gas shift process (RWGSP), (iv) a methanol synthesis process (MSP), (v) an off-gas combustion process (OGCP), and (vi) a water treatment process (WTP). In this complex, the green hydrogen produced from AWEP is reacted with CO₂ from a carbon capture unit and sent to the MSP and FTSP sections, respectively, to generate methanol and Fischer–Tropsch hydrocarbon products. The byproduct (water) from the complex is utilized to generate steam through rigorous process simulation, and the technical efficacy of the complex has been modeled and validated, yielding high-value hydrocarbons, methanol, steam, and oxygen. Furthermore, a comprehensive techno-economic assessment with sensitivity analysis is performed to evaluate the commercial flexibility of the system under varying market conditions. Full article