Search Results (851)

The main advantage of using biomass for energy generation is the reduction in carbon dioxide emissions. For a fast reduction effect, it is important to use biomass characterised by an annual growth cycle. These may be fallen leaves. The fuel properties of the leaves can change during the growth period. These changes can result from both the natural growth process and environmental factors—particulate matter adsorption. The main objective was to determine changes in the characteristics of leaves and needles during the growth period (from May to October). Furthermore, to determine the effect of adsorbed particulate matter, the washing process was carried out. Studies were carried out for three tree species: Norway maple, horse chestnut and European larch. Proximate and ultimate analysis was performed and mercury content was determined. During the growth period, beneficial changes were observed: an increase in carbon content and a decrease in hydrogen and sulphur content. The unfavourable change was a significant increase in ash content, which caused a decrease in calorific value. The increase in ash content was caused by adsorbed particulate matter. They were mostly absorbed by the tissues of the needle and leaves and could not be removed by washing the surface. Full article

Minimizing carbon dioxide emissions is crucial due to the generation of energy from fossil fuels. The significance of carbon capture and storage (CCS) technology, which is highly successful in mitigating carbon emissions, has increased. On the other hand, hydrogen is an important energy carrier for storing and transporting energy, and technologies that rely on hydrogen have become increasingly promising as the world moves toward a more environmentally friendly approach. Nevertheless, the integration of CCS technologies into power production processes is a significant challenge, requiring the enhancement of the combined power generation–CCS process. In recent years, there has been a growing interest in process intensification (PI), which aims to create smaller, cleaner, and more energy efficient processes. The goal of this research is to demonstrate the process intensification potential and to model and simulate a hybrid integrated–intensified adsorptive-membrane reactor process for simultaneous carbon capture and hydrogen production. A comprehensive, multi-scale, multi-phase, dynamic, computational fluid dynamics (CFD)-based process model is constructed, which quantifies the various underlying complex physicochemical phenomena occurring at the pellet and reactor levels. Model simulations are then performed to investigate the impact of dimensionless variables on overall system performance and gain a better understanding of this cyclic reaction/separation process. The results indicate that the hybrid system shows a steady-state cyclic behavior to ensure flexible operating time. A sustainability evaluation was conducted to illustrate the sustainability improvement in the proposed process compared to the traditional design. The results indicate that the integrated–intensified adsorptive-membrane reactor technology enhances sustainability by 35% to 138% for the chosen 21 indicators. The average enhancement in sustainability is almost 57%, signifying that the sustainability evaluation reveals significant benefits of the integrated–intensified adsorptive-membrane reactor process compared to HTSR + LTSR. Full article

Geological storage is an integral element of the green energy transition. Geological formations, such as aquifers, depleted reservoirs, and hard rock caverns, are used mainly for the storage of hydrocarbons, carbon dioxide and increasingly hydrogen. However, potential adverse effects such as ground movements, leakage, seismic activity, and environmental pollution are observed. Existing research focuses on monitoring subsurface elements of the storage, while on the surface it is limited to ground movement observations. The review was carried out based on 191 research contributions related to geological storage. It emphasizes the importance of monitoring underground gas storage (UGS) sites and their surroundings to ensure sustainable and safe operation. It details surface monitoring methods, distinguishing geodetic surveys and remote sensing techniques. Remote sensing, including active methods such as InSAR and LiDAR, and passive methods of multispectral and hyperspectral imaging, provide valuable spatiotemporal information on UGS sites on a large scale. The review covers modelling and prediction methods used to analyze the environmental impacts of UGS, with data-driven models employing geostatistical tools and machine learning algorithms. The limited number of contributions treating geological storage sites holistically opens perspectives for the development of complex approaches capable of monitoring and modelling its environmental impacts. Full article

Against the backdrop of global energy transition and strict environmental regulations, supercritical carbon dioxide (scCO₂) fracturing and oil displacement technologies have emerged as pivotal green approaches in shale gas exploitation, offering the dual advantages of zero water consumption and carbon sequestration. However, the inherent low viscosity of scCO₂ severely restricts its sand-carrying capacity, fracture propagation efficiency, and oil recovery rate, necessitating the urgent development of high-performance thickeners. The current research on scCO₂ thickeners faces a critical trade-off: traditional fluorinated polymers exhibit excellent philicity CO₂, but suffer from high costs and environmental hazards, while non-fluorinated systems often struggle to balance solubility and thickening performance. The development of new thickeners primarily involves two directions. On one hand, efforts focus on modifying non-fluorinated polymers, driven by environmental protection needs—traditional fluorinated thickeners may cause environmental pollution, and improving non-fluorinated polymers can maintain good thickening performance while reducing environmental impacts. On the other hand, there is a commitment to developing non-noble metal-catalyzed siloxane modification and synthesis processes, aiming to enhance the technical and economic feasibility of scCO₂ thickeners. Compared with noble metal catalysts like platinum, non-noble metal catalysts can reduce production costs, making the synthesis process more economically viable for large-scale industrial applications. These studies are crucial for promoting the practical application of scCO₂ technology in unconventional oil and gas development, including improving fracturing efficiency and oil displacement efficiency, and providing new technical support for the sustainable development of the energy industry. This study innovatively designed an amphiphilic modified amino silicone oil polymer (MA-co-MPEGA-AS) by combining maleic anhydride (MA), methoxy polyethylene glycol acrylate (MPEGA), and amino silicone oil (AS) through a molecular bridge strategy. The synthesis process involved three key steps: radical polymerization of MA and MPEGA, amidation with AS, and in situ network formation. Fourier transform infrared spectroscopy (FT-IR) confirmed the successful introduction of ether-based CO₂-philic groups. Rheological tests conducted under scCO₂ conditions demonstrated a 114-fold increase in viscosity for MA-co-MPEGA-AS. Mechanistic studies revealed that the ether oxygen atoms (Lewis base) in MPEGA formed dipole–quadrupole interactions with CO₂ (Lewis acid), enhancing solubility by 47%. Simultaneously, the self-assembly of siloxane chains into a three-dimensional network suppressed interlayer sliding in scCO₂ and maintained over 90% viscosity retention at 80 °C. This fluorine-free design eliminates the need for platinum-based catalysts and reduces production costs compared to fluorinated polymers. The hierarchical interactions (coordination bonds and hydrogen bonds) within the system provide a novel synthetic paradigm for scCO₂ thickeners. This research lays the foundation for green CO₂-based energy extraction technologies. Full article

There are many advantages of the smelting of vanadium–titanium magnetite pellets by hydrogen-based shaft furnace pre-reduction and electric arc furnace process, including high reduction efficiency, low carbon dioxide emission and high recovery of titanium and so on. However, vanadium–titanium magnetite pellets are highly susceptible to severe reduction disintegration when reduced in the gas-based shaft furnaces. H₂ and CO are the primary reducing gas components in the gas-based shaft furnace process, which significantly influences the reduction behavior of vanadium–titanium magnetite pellets. In this study, the reduction disintegration behavior and reduction kinetics of vanadium–titanium magnetite under mixed H₂–CO atmospheres at low temperatures (450–600 °C) were investigated. The differences in the reduction capacities and rates of H₂ and CO on iron oxides and titanium–iron oxides were revealed, along with their impact on the reduction disintegration behavior of the pellets at low temperatures. At lower temperatures, CO exhibited a greater reducing capability for vanadium–titanium magnetite. As the reduction temperature increased, the reduction capacities of both H₂ and CO improved; however, the reduction capacity of H₂ was more significantly influenced by the temperature. The disparity in the reduction capacities of H₂ and CO for vanadium–titanium magnetite pellets caused an inconsistent expansion rate in different regions of the pellet, increasing internal stress, contributing to a more severe reduction disintegration of vanadium–titanium magnetite pellets in the mixed H₂–CO atmospheres. Full article

Ferrocene (Fc) is a redox-active organometallic scaffold whose unique electronic properties, stability, and modularity have enabled a broad range of catalytic and sensing applications. This review critically examines recent advances in Fc-based systems for hydrogen evolution and carbon dioxide (CO₂) conversion, encompassing electrochemical, photochemical, and thermochemical strategies. Fc serves diverse functions: it operates as a reversible redox mediator, an electron reservoir, a ligand framework, and a structural modulator. Each role contributes differently to enhancing catalytic performance, improving selectivity, or increasing operational stability. We highlight how Fc integration facilitates proton-coupled electron transfer in hydrogen evolution, supports selective CO₂ reduction in molecular and hybrid catalysts, and promotes efficient CO₂ fixation and capture within functionalised frameworks. Emerging applications in electrosynthetic organic transformations are also discussed. Together, these findings position Fc as a foundational motif for designing future electrocatalytic and carbon management platforms. Full article

The aim of this work was to obtain biochar materials from plant biomass and to determine the changes occurring under the conditions of the pyrolysis process and physical activation, as well as to characterize the physicochemical characteristics of the produced products in terms of their practical use. The pyrolysis process was carried out at a temperature of 700 °C, under the flow of a protective gas, i.e., carbon dioxide, at a rate of 5.0 L/min. The pyrolysis processes were carried out in the absence and presence of an activating agent. For ecological safety, physical activation using water vapor was chosen. In the next stage of the work, biochars were produced and subjected to detailed physicochemical analysis. A scanning electron microscope with energy-dispersive SEM/EDS was used to determine the microstructure and changes in the chemical composition of the biochars. FTIR spectrophotometry was used to identify the functional groups present in the structures of biochars and to indicate changes occurring in the biomass during pyrolysis. Meanwhile, Raman spectroscopy was used to assess the ordering of the biochar structures based on the identification of spectral signals. The description of the specific surface areas of the biochars was made possible by studies conducted using a physical and chemical adsorption analyzer. Based on the obtained research results, the elementary structure, surface development, presence of functional groups on the surfaces of biochars and changes in the structure before and after activation with water vapor were determined. It was found that the biochars had functional groups, a well-developed specific surface area that increased after activation with water vapor, micropores and mesopores, as well as changes in structure under the influence of physical activation. It has been shown that the presence of functional groups influences the hydrogen sulfide sorption capacity. Full article

Acid gas injection (AGI), which primarily involves injecting hydrogen sulfide (H₂S) and carbon dioxide (CO₂), is recognized as a cost-efficient and environmentally sustainable method for controlling sour gas emissions in oil and gas operations. This review examines case studies of twelve AGI projects conducted in Canada, Oman, and Kazakhstan, focusing on reservoir selection, leakage potential assessment, and geological suitability evaluation. Globally, several million tonnes of acid gases have already been sequestered, with Canada being a key contributor. The study provides a critical analysis of geochemical modeling data, monitoring activities, and injection performance to assess long-term gas containment potential. It also explores AGI’s role in Enhanced Oil Recovery (EOR), noting that oil production can increase by up to 20% in carbonate rock formations. By integrating technical and regulatory insights, this review offers valuable guidance for implementing AGI in geologically similar regions worldwide. The findings presented here support global efforts to reduce CO₂ emissions, and provide practical direction for scaling-up acid gas storage in deep subsurface environments. Full article

The establishment of carbon capture, utilization, and storage supply chains at the national level is crucial for meeting global decarbonization targets: they have been suggested as a solution to maintain the global temperature rise below 2 °C relative to preindustrial levels. Optimizing these systems requires a balance of economic viability with environmental impact, but this is a challenge due to diverse operational limitations. This paper introduces an optimization framework that integrates life cycle assessment with a source-sink model while combining the geographical storage and conversion pathways of carbon dioxide into high-value chemicals. This study explores the economic and environmental outcomes of national carbon capture, utilization, and storage networks, considering several constraints, such as carbon dioxide reduction goals, product market demand, and renewable hydrogen availability. The framework is utilized in Germany as a case study, presenting three case studies to maximize overall annual profit and life cycle greenhouse gas reduction. In all analyzed scenarios, the results indicate a clear trade-off between profitability and emission reductions: profit-driven strategies are characterized by increased emissions, while environmental strategies have higher costs despite the environmental benefit. In addition, cost-optimal cases prefer high-profit utilization routes (e.g., gasoline through methane reforming) and cost-effective capture technologies, leading to significant profitability. On the other hand, climate-optimal approaches require diversification, integrating carbon dioxide storage with conversion pathways that exhibit lower emissions (e.g., gasoline, acetic acid, methanol through carbon dioxide hydrogenation). The proposed method significantly contributes to developing and constructing more sustainable, large-scale carbon projects. Full article

Poisoning and suffocation accidents occurred frequently in the pre-treatment pool workshops of biogas plants, so this paper provided a multi-dimensional risk analysis model: Bow-Tie-Qualitative Comparative Analysis (QCA)-Bayesian Neural Network-Consequence Simulation. First, the reasons for biogas poisoning and suffocation accidents were clarified through Bow-Tie. Then, the QCA method explored the accident cause combination paths in management. Next, the frequency distribution of biogas poisoning and suffocation accidents in the pre-treatment pool workshop was predicted to be 0.61–0.66 using the Bayesian neural network model, and the uncertainty of the forecast outcome was given. Finally, the ANSYS Fluent 16.0 simulation of biogas diffusion in three different ventilation types and a grid-independent solution of the simulation were conducted. The simulation results showed the distribution of methane, carbon dioxide and hydrogen sulfide gases and the hazards of the three gases to workers were analyzed. In addition, according to the results, this paper discussed the importance and necessity of ventilation in pre-treatment pool workshops and specified the hazard factors in biogas poisoning and suffocation accidents in the pre-treatment pool workshops. Some suggestions on gas alarms were also proposed. Full article

The reduction of environmental pollutant emissions—including greenhouse gases, particulate matter, and other harmful substances—represents one of the foremost challenges in climate policy, economics, and industrial management today. Excessive emissions of CO₂, NO_X, and suspended particulates exert significant impacts on climate change as well as human health and welfare. Consequently, numerous studies and regulatory and technological initiatives are underway to mitigate these emissions. One critical area is intra-plant transport within manufacturing facilities, which, despite its localized scope, can substantially contribute to a company’s total emissions. This paper aims to assess the potential of computer simulation using FlexSim software as a decision-support tool for planning inter-operational transport, with a particular focus on environmental aspects. The study analyzes real operational data from a selected production plant (case study), concentrating on the optimization of the number of transport units, their routing, and the layout of workstations. It is hypothesized that reducing the number of trips, shortening transport routes, and efficiently utilizing transport resources can lead to lower emissions of carbon dioxide (CO₂) and nitrogen oxides (NO_X). The findings provide a basis for a broader adoption of digital tools in sustainable production planning, emphasizing the integration of environmental criteria into decision-making processes. Furthermore, the results offer a foundation for future analyses that consider the development of green transport technologies—such as electric and hydrogen-powered vehicles—in the context of their implementation in the internal logistics of manufacturing enterprises. Full article

Catalytic methane decomposition offers an attractive and sustainable pathway for producing CO_x-free hydrogen and valuable carbon nanotubes. This work investigates the innovative use of liquid metals, particularly gallium and indium, as promoters for iron catalysts based on a titanium dioxide and alumina composite to improve this process even more. In a fixed-bed reactor operating at 800 °C and atmospheric pressure, all catalyst activities for methane decomposition were thoroughly assessed while keeping the gas hourly space velocity at 6 L/g h. Surface area and porosity, H₂-temperature programmed reduction/oxidation, X-ray diffraction, Raman spectroscopy, scanning transmission electron microscopy, and thermogravimetry analysis were utilized to investigate the physicochemical properties of the catalyst. The result showed that iron supported on a titanium-alumina catalyst exhibited higher activity, stability, and reproducibility with a methane conversion of 90% and hydrogen production of 81% after three cycles, with 240 min for each cycle and stability for 480 min. In contrast, the liquid metal-promoted catalysts improved the metal-support interaction and textural properties, such as surface area, pore volume, and particle dispersion of the catalysts. Still, the catalytic efficiency significantly improved. However, the gallium-promoted catalyst displayed excellent reusability. The characterization of the spent catalyst proved that both the iron supported on a titanium-alumina and its gallium-promoted derivative produced graphitic carbon; on the contrary, the indium-promoted catalyst produced amorphous carbon. These results demonstrate how liquid metal promoters can be used to adjust the characteristics of catalysts, providing opportunities for improved reusability and regulated production of carbon byproducts during methane decomposition. Full article

Supercritical combustion is a promising technique for improving the efficiency and reducing the emissions of next-generation gas turbines. However, accurately modeling combustion under these conditions remains a challenge, particularly due to the complexity of chemical kinetics. This study aims to evaluate the applicability of a reduced global reaction mechanism compared to the detailed Foundational Fuel Chemistry Model 1.0 (FFCM-1) when performing hydrogen combustion with supercritical carbon dioxide and argon as diluents. Computational fluid dynamics simulations were conducted in two geometries: a simplified tube for isolating chemical effects and a combustor with cooling channels for practical evaluation. The analysis focuses on the evaluation of velocity, temperature, and the water vapor mass fraction distributions inside the combustion chamber. The results indicate good agreement between the global and detailed mechanisms, with average relative errors below 2% for supercritical argon and 4% for supercritical carbon dioxide. Both models captured key combustion behaviors, including buoyancy-driven flame asymmetry caused by the high density of supercritical fluids. The findings suggest that global chemistry models can serve as efficient tools for simulating supercritical combustion processes, making them valuable for the design and optimization of future supercritical gas turbine systems. Full article

Carbon dioxide (CO₂) and hydrogen sulfide (H₂S) as harmful gases are always associated with methane (CH₄) in natural gas, biogas, and landfill gas. Given that chemisorption and physisorption are the key gas separation technologies in industry, selecting appropriate adsorbents is crucial to eliminate these harmful gases. The adsorption of CH₄, CO₂, and H₂S has been studied based on the density functional theory (DFT) in this work to evaluate the feasibility of transition metal (M = Mn, Fe, Co, Ni, Cu, Mo) porphyrin-like moieties embedded in graphene sheets (MN₄-GPs) as adsorbents. It was found that the interactions between gas molecules and MN₄-GPs (M = Mn, Fe, Co, Ni, Cu, Mo) are different. The weaker interactions between CH₄ and MN₄-GPs (M = Co, Ni, Cu, Mo) than those between CO₂ and MN₄-GPs or between H₂S and MN₄-GPs are beneficial to the separation of CH₄ from CO₂ and H₂S. The maximum difference in the interactions between gas molecules and MoN₄-GPs means that MoN₄-GPs have the greatest potential to become adsorbents. The different interfacial interactions are related to the amount of charge transfer, which could promote the formation of bonds between gas molecules and MN₄-GPs to effectively enhance the interfacial interactions. Full article

The iron and steel industry is a major emitter of carbon. In the context of China’s dual-carbon goals, hydrogen-based reduction ironmaking technology has garnered unprecedented attention. It is considered a crucial approach to reducing carbon dioxide emissions in the steel sector and facilitating the realization of carbon neutrality. This work conducted isothermal thermogravimetric analysis on limonite ore in a N₂/H₂ atmosphere. The influences of reduction temperature, particle size, and hydrogen partial pressure on the hydrogen reduction reaction process of limonite were investigated. Based on the principles of isothermal thermal analysis kinetics and the unreacted core model for flat-plate particles, the mechanism function and kinetic parameters for the reduction of limonite particles were determined. The research results show that the hydrogen reduction process of limonite ore is influenced by multiple factors, including temperature, hydrogen partial pressure, and particle size. Increasing the reduction temperature and hydrogen partial pressure can significantly speed up the reduction reaction rate and enhance the degree of reduction. The kinetic parameters for the hydrogen reduction of limonite particles were obtained as follows: the reaction activation energy was 44.738 kJ·mol⁻¹, the pre-exponential factor was 31.438 m·s⁻¹, and the rate constant for the hydrogen reduction of limonite was $k=31.438\times e^{-{\displaystyle \frac{44.738\times 1000}{RT}}}\mathrm{m}\cdot {\mathrm{s}}^{-1}$. In addition, contour maps were plotted to predict the reaction time and reaction temperature required for a complete reduction of limonite particles of different sizes to iron (Fe) particles under varying hydrogen partial pressures. The research findings can serve as a scientific basis for optimizing hydrogen-based reduction ironmaking technology in the iron and steel industry and achieving carbon neutrality goals. Full article