Greenhouse Gases: Science and Technology最新文献

This work represents an extensive molecular dynamics (MDs) simulation study with the microstructural insight at the interface to simultaneously predict the phase equilibria, transport, and interfacial properties of the CO₂–H₂S–brine system within the range of temperatures 323.15–393.15 K, pressures up to 30 MPa, H₂S contents of 0–70 mol%, and salt molalities of 1–4 mol/kg, aiming to address the insufficiency of data under typical conditions of acid gas sequestration. The validation results demonstrate that the average absolute deviations (AAD%) for the predicted solubility of CO₂ and H₂S in water and in 2 mol/kg NaCl solution were found to be 5.45%, 6.34%, 5.78%, and 5.41%, respectively. Moreover, the AAD% for interfacial tension (IFT) and density were 6.74% and 3.70%, respectively, verifying the validity and performance of the applied force field parameters and computational methods. The simulation results indicated that H₂S solubility in brine is more sensitive to changes in the acid gas composition and temperature compared to CO₂ solubility. The presence of H₂S remarkably reduces the CO₂–H₂S–brine IFT, with the reduction degree depending on the H₂S content. Increasing the H₂S mole fraction in acid gas mixtures delays convective mixing by reducing the brine density. At about 64 mol% H₂S, the aqueous solution's density equals that of fresh brine, which is the highest H₂S content that can maintain the benefit of convective mixing in the dissolution trapping. The maximum acid gas column height that can be safely stored is most significant at lower temperature and H₂S content. On the basis of the results, pressure, temperature, and salt molality have a higher influence on the viscosity than density in the studied ranges. The new data generated by the current study can be utilized to develop predictive models of acid gas long-term behavior, which will reduce the uncertainty of real storage schemes.

This study aims to accurately predict the risk of coal and gas outbursts in coal seams located near small faults. Models of small-scale normal faults in the Changping mine field were constructed using the FLAC3D software, with fault dip angles of 65° and 70°, and drops of 1, 3, 5, 8, and 10 m. The objective was to analyze the effects of fault drop and dip angle on stress distribution near the faults and to predict the related outburst risks. The results indicate that in the hanging wall of the fault, the peak stress correlates with the fault drop through a linear function, whereas the range of influence is described by a quadratic function. As the fault drop increases, the impact range and stress peak also increase. The position of the stress peak gradually shifts away from the section, whereas the stress concentration area widens. Furthermore, the protruding danger zone expands and similarly moves farther from the section. When the fault drop is constant, the impact range of the 65° dip fault is smaller; however, the stress peak and the stress concentration zone in the nearby coal seam are larger and closer to the fault surface. Additionally, the highlighted danger zone is also larger and nearer to the fault surface. On the basis of the measured fundamental parameters of coal seam gas in the region, within a distance of 6 m from the fault surface (Zone I), there is a significant influence from the fault, resulting in a higher risk of outburst in this area. In the range of 6–15 m from the fault surface (Zone II), the gas content continues to increase, leading to an overall heightened risk of outburst.

Addressing the escalating threat of climate change requires a global response, with significant actions from every nation. Uzbekistan, a member of the Paris Agreement, is actively pursuing sustainable development by reducing greenhouse gas emissions and promoting renewable energy. However, the country's Green Economy strategies currently lack Carbon Capture, Storage, and Utilization (CCUS) technology. A feasibility assessment is crucial to evaluating CCSU's potential for achieving net-zero emissions, benefiting both the public and scientific communities by informing policy decisions, and providing valuable data. The primary aim of this study is to evaluate Uzbekistan's potential for carbon dioxide (CO₂) storage and utilization (CSU) in the near and mid-term. To achieve this, this work proposes a methodology for efficient CO₂ source-sink matching to facilitate the deployment of CCUS technologies in Uzbekistan. Resource evaluation and spatial analysis methods are used to estimate the total CSU capacity of the region and the geographical distribution of CO₂ sources in two large-scale emitting sectors, specifically from the power and cement plants. According to the results, Uzbekistan has an annual CSU capacity of 1171 million tons CO₂, which is several times higher than the annual CO₂ emission rate. Additionally, CSU resources are primarily located in the eastern, western, and southern regions of the country, whereas CO₂ sink locations near the capital city and its surrounding areas are limited compared to their abundance of CO₂ sources. Overall, although the country has ample CO₂ storage capacity for CCUS deployment, the prospects for its chemical utilization remain limited in scale. © 2025 Society of Chemical Industry and John Wiley & Sons, Ltd.

Carbon dioxide capture technology, while established, faces operational and economic challenges with current absorbents. Ionic liquids (ILs), though promising for their selectivity and low volatility, often have drawbacks like high toxicity and viscosity. This study explores nonionic low transition temperature mixtures (LTTMs) of menthol (MET) and polyethylene glycol 200 (PEG200) at various ratios for CO₂ uptake. The 1:2 molar ratio showed maximum CO₂ loading of 0.599 mol CO₂/mol solvent at 303.15 K and 1000 kPa, with water addition boosting CO₂ uptake by 25%. This rise in uptake with water could be due to altered hydrogen bonding within the mixture constituents. Molecular dynamics simulations support these findings, indicating experimental results, showing that water disrupts hydrogen bonds, exposing hydroxyl and ether sites for CO₂ interaction. This LTTM solvent system presents a promising, low-toxicity alternative for efficient CO₂ capture. © 2025 Society of Chemical Industry and John Wiley & Sons, Ltd.

In order to minimize greenhouse gas emissions, it is essential from an environmental point of view to employ CO₂ sequestration technology to store CO₂ in underground coal layers. To study this strategy, a triaxial testing apparatus is required. This study introduces a novel triaxial testing apparatus developed to explore enhanced coal bed methane (ECBM) and carbon dioxide (CO₂) sequestration techniques. Several laboratory tests were conducted to validate the apparatus and study the behavior of coal exposed to CO₂ using this machine. In fact, the implementation of this machine marks the initial step in an empirical feasibility analysis of CO₂ sequestration in Iranian coal seams. This analysis involves examining the impact of ash content, ambient temperature, and saturation direction on CO₂ adsorption and emission in various coal samples. Two different thermal coal samples from Chamestan and Tash mines were utilized. Some results, such as the trend of the coal sample's strain, show good correlation with previous work. Additionally, some results presented in this work are novel. On the basis of the results, the developed apparatus demonstrated satisfactory performance, and its innovative design fully meets the desired outcome. Higher ash content increases coal strength and reduces deformation. Lower ash content leads to more gas adsorption and deformation post-saturation. Gas adsorption is higher at 25°C than at 4°C. Moreover, coal samples at 25°C had 12.5 times more axial strain than those at 4°C. Lateral saturation causes 13.72% larger axial strain changes than top and end saturation due to increased gas-sample contact and penetration into the coal matrix.

Greenhouse gas (GHG) emissions have caused serious global climate change, and countries worldwide are taking steps to mitigate the greenhouse effect caused by carbon emissions. CO₂ geological storage (CGS) is emerging as a large-scale technology for reducing GHG emissions and is gradually becoming one of the most important means of mitigating the greenhouse effect. There are several problems in the implementation of this technology, among which the geomechanical problems caused by injection sequestration cannot be ignored. This article reviews the impacts and hazards of geomechanical problems caused by injection and sequestration in CGS, which can lead to risks, including changes in reservoir and caprock mechanical properties, reservoir stability, caprock closure, fault activation, and induced seismicity during CO₂ injection and sequestration. This article reviews the above studies and summarizes the research methods of CGS geomechanical problems and generation mechanisms, which can help to comprehensively understand the risks faced in the CGS process and provide references and guidance for the operation, monitoring, and research of CGS in the future.

HFC-134a (1,1,1,2-tetrafluoroethane) is one of the most common refrigerants with global warming potential (100 years) of 1300. It is regulated to be phased out gradually according to the Kigali Amendment to the Montreal Protocol. Treatment of this stable chemical poses significant challenge. Highly efficient nickel aluminum spinel catalysts were fabricated by sol–gel method for the catalytic dehydrofluorination of HFC-134a. The effect of Ni/Al ratio in the NiAl₂O₄ spinel precursors on the performance of NiAl catalysts was studied by x-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscope (SEM), transmission electron microscopy (TEM), NH₃-TPD, and XPS. Nickel–aluminum ratio in the nickel–aluminum spinel precursor plays a major role on the formation of strong acid and active species Ni-F-Al. With Ni/Al ratio of 4, the (3 1 1) crystal face of NiAl₂O₄ interfaced with the (1 1 1) crystal face of NiO and the (4 0 0) crystal face of NiAl₂O₄. This interaction facilitates the formation of Ni-F-Al active species following the dehydrofluorination reaction. Furthermore, the Ni-F-Al species altered the acid structure of NiAl catalysts. It was found that NiAl catalyst with a Ni/Al ratio of 4 has the best catalytic performance compared with other catalysts (with conversion of 35%), and no deactivation trend was observed after 50 h of time on stream. (Reaction conditions: N₂/CF₃CH₂F = 10, T = 450°C, GHSV = 660 h⁻¹).

As a potential carbon emission reduction measure, carbon capture, utilization and storage technology is of great significance to achieve the goals of “carbon peak” and “carbon neutrality.” The implementation of carbon capture, utilization, and storage-enhanced oil recovery (CCUS-EOR) in the oil and gas industry serves the dual purpose of utilizing greenhouse gases as resources and enhancing oil recovery. This approach is a key strategy for achieving carbon emission reductions. In this study, the key problems of source-sink matching, injection mode, oil displacement storage, and leakage were analyzed in conjunction with CCUS-EOR technology used in both domestic and foreign oil fields. Additionally, the carbon emission reduction accounting methods of different oil fields were compared. Carbon source, carbon dioxide concentration, capture, and transportation mode are important influencing factors of carbon source selection. The project should follow the principle of proximity and select high-concentration gas source as the development object in the early stage; the main methods of carbon dioxide injection are continuous carbon dioxide injection, alternating water and gas injection, and CO₂ huff and puff among which injection speed and injection pressure are the key parameters; the underground occurrence state and storage capacity of carbon dioxide gas are dynamic changes in the process of oil displacement and storage; the three parts of surface leakage, injection wellbore leakage, and production well production are the key points of CCUS-EOR project leakage. The corresponding monitoring methods are analyzed for different leakage modes; the CCUS-EOR carbon emission reduction accounting method is comprehensively analyzed, and the application of carbon emission reduction accounting methods in major oilfields is compared. The accounting method of “life cycle assessment (LCA) + emission factor method + actual measurement method” is proposed. The research holds significant importance for enhancing the entire CCUS-EOR technology chain and refining the CCUS-EOR emission reduction accounting methodology. It also facilitates the integration of CCUS-EOR projects into the carbon trading market, thereby enabling the efficient development of carbon assets in carbon dioxide flooding projects within oil and gas fields.

Direct measurements of greenhouse gas emissions from the increasingly intensified African livestock production are important to assess locally available mitigation strategies. As such, measurements were conducted from March to June using static flux chambers to quantify the emission rates of CH₄, N₂O, and CO₂ from manure in poultry and pig production systems in Cameroon. Emissions were measured from two layer barns, two pig facilities, six broiler farms, and one farm with Brahman birds. Mean emission factors inside two layer barns were 0.06–0.21 and 602–958 mg animal⁻¹ h⁻¹ for CH₄ and CO_2, respectively, and 21–112 µg animal⁻¹ h⁻¹ for N₂O. Mean emission factors inside four broiler barns with wood shavings as bedding material were 0.31–1.22 and 355–1884 mg animal⁻¹ h⁻¹ for CH₄ and CO₂, respectively, and 2.33–1052 µg animal⁻¹ h⁻¹ for N₂O. Broiler N₂O emissions were 971.38 ± 250.23 and 26.14 ± 30.27 µg animal⁻¹ h⁻¹ from manure underneath a meshed floor barn and a shelter with bare soil, respectively. Emissions from a storage tank with wastewater from a piggery were 8.30 ± 7.36 and 40.41 ± 5.54 mg m⁻² min⁻¹ for CH₄ and CO₂, respectively, and 2.80 ± 1.67 µg m⁻² min⁻¹ for N₂O. Mean emissions from two outdoor storages of a mixture of poultry and pig manure were 0.76–0.9 and 69–136 mg m⁻² min⁻¹ for CH₄ and CO₂, respectively, and 10–15 µg m⁻² min⁻¹ for N₂O. Emissions depended highly on manure production and management systems. CH₄ emissions were lower from poultry compared to pig manure. Younger layers emitted higher CH₄ compared to older layer hens. CH₄ emissions were higher from slurry compared to solid manure, whereas N₂O emissions were higher from solid compared to slurry manure storages. These findings indicate that mitigation strategies for greenhouse gas emissions should depend not only on the type of gases and manure management systems but also on the animal types and their ages.