Greenhouse Gases: Science and Technology最新文献

In this paper, the mechanisms of long-term CO₂ sequestration and the effects of injection modes (including injection temperature, injection rate and injection cycle) in Zhujiang Formation characterized by high porosity and permeability were investigated using the numerical simulation method. Simulation results showed that more than 88% of the injected CO₂ would exist in a supercritical state during the injection period and more than 79% of CO₂ would be sequestrated in the reservoir by mineral trapping after 5,000 years. Eventually, the distribution shape of SC-CO₂ was a quarter funnel near the injection well, while the distribution shapes of dissolved and mineralized CO₂ were both one quarter rotunda. During the long-term CO₂ sequestration in Zhujiang Formation, the dissolved minerals were anorthite, chlorite and smectite in turn, while the top three main precipitated minerals were calcite, dawsonite and albite. Moreover, higher injection temperature leads to a higher mineral tapping and more dissolved/precipitated minerals. While higher injection rate reduces the mineral tapping and total amount of dissolved/precipitated mineral. Compared to injection temperature and injection rate, the injection cycle has little effect on the CO₂ phase evolution and mineral dissolution/precipitation process. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

The research on the mechanism of coal and gas outburst is still in the hypothesis stage, and exploration of the outburst mechanism fro m an energy perspective often focuses on the calculation of coal rock elastic energy and gas expansion energy. There are some studies on elastic energy and gas expansion energy of coal rock caused by added water during outburst, although hydr aulic measures not only improve the permeability of coal seam, but also increase the water content. For calculating the gas expansion energy, the atmospheric gas desorption characteristic is generally utilized, while the gas desorption is completed on the condition of dropping pressure in outburst, and the expansion energy research, based on that law, inevitably brings about errors, thus affecting the objectivity of the potential research. In this study, uniaxial cyclic loading experiments were carried out on briquette coal samples with water content of 0%, 1%, 2% and 4%, whose elastic energy density was analyzed, in addition to examining how the added water affected the mechanical properties and the elastic energy of coal. The pressure drop gradient of the experiment is set 2.5 –2 MPa, 1.5 –1 MPa, 0.5 MPa-0 Pa. By stepwise depressurization desorption of coal samples after water injection, the gas expansion energy in different moisture is measured in each pressure drop stage, and the influence of moisture on gas expansion energy is quantitatively explored. Research has shown that the higher the water content, the lower the elastic energy density, while the higher the stress, the greater the elastic energy of coal. The gas expansion energy grows linearly with the increase of adsorption equilibrium pressure and diminishes in negative exponential law with the increasing moisture. Under the experimental conditions, the expansion energy decreases by 7%–9% and the elastic energy by 9.7% on average for every 1% increase in added water, and the influence gradually weakens when the moisture exceeds the critical value. This study innovatively simulates the pressure swing desorption when a coal and gas outburst occurs in the laboratory, confirms the critical moisture that affects the outburst potential, and is a useful exploration in the coal and gas outburst mechanism. Significantly the research results can guide the engineering practice when using hydraulic measures to prevent and control outburst disasters. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Anthropogenic activites release greenhouse gas emissions into our atmosphere, especially carbon dioxide (CO₂). This abundant accumulation of CO₂ generates numerous problems like global warming and climate change. However, research has been conducted to capture CO₂ from significant single-point emitters like compression ignition (CI) engines, backup generators, and distributed power production plants. Moreover, research has also been done on post-combustion adsorption chamber to capture CO₂ emissions from small stationary engines. Biomass-based activated carbon as an adsorbent for capturing CO₂ from engine exhaust has recently been investigated. Three biomass-based adsorbents, (a) coconut shell adsorbent, (b) rice husk adsorbent and (c) eucalyptus wood adsorbent, are used in the capture unit to trap CO₂ from the CI engine exhaust. This study uses a single-cylinder, four-stroke, air-cooled, naturally-aspirated, direct-injection (DI) CI engine running at a constant speed of 1,500 rpm and producing power of 4.4 kW. The adsorption performance of adsorbent samples is investigated by coupling the adsorption chamber to the exhaust system of a test engine operated on diesel (D100) at various loads. Temperature swing adsorption (TSA) is used to regenerate the original adsorbent. The adsorbents’ adsorption capacities are evaluated by performing multiple adsorption–desorption test cycles using the same adsorbents. During TSA, CO₂ released from the capture unit is further captured and stored in a gas bag. The captured gas sample is characterized through gas chromatography-mass spectroscopy (GC-MS) characterization to examine and ensure the gas adsorption efficacy of adsorbent samples. The outcomes of this research study are discussed and presented in detail. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Pipelines transporting impure supercritical carbon dioxide in the carbon capture, utilization, and storage (CCUS) chain exhibit varying decompression characteristics due to engineered emissions or accidental leakage, resulting in diverse temperature drops and heat transfer mechanisms in the media and pipe walls. Therefore, studying heat transfer characteristics during slow and instantaneous decompression is crucial to investigating pipeline operational risks. In this work, supercritical CO₂ pipeline valve release and rupture disc release experiments were performed with a 1.5% molar ratio of N₂ content in an experimental pipeline (16 m long, 100 mm inner diameter). The evolution of the medium and pipe wall's physical properties was measured and discussed. Two methods of depressurization were employed to analyze the phase changes and heat transfer processes in the pipe. The instantaneous decompression process has a shorter decompression time and undergoes fluctuating and stable decompression stages. The slow decompression process has a slower temperature drop rate, but the wall during the process can reach a lower minimum temperature. Both release methods cause a larger temperature drop and Nusselt number at the bottom of the pipe wall due to evaporation heat transfer compared to the middle and top. The slow decompression process demonstrates a higher peak Nusselt number at the bottom, resulting in superior heat transfer efficiency compared to the instantaneous decompression process. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

The present work investigated the effects of some non-condensable impurities (i.e., N₂, O₂, CH₄, and Ar) on the phase behaviour of CO₂-rich systems at low temperature conditions (228.15–273.15 K). The study focused on bubble point measurements of CO₂-rich systems using the isothermal (pressure–volume) method at different mole fractions of CO₂ (99.5%–95%). The obtained experimental data were used to validate multi-fluid Helmholtz energy approximation (MFHEA) and Peng–Robinson (PR) equations of state (EoSs). For all data points, the measurements’ uncertainties for temperature and pressure were 0.14 K and 0.03 MPa, respectively. While the composition uncertainty of the CO₂ systems was a maximum of 0.024%. The findings reveal that as the mole fractions of the impurities increased, the bubble point pressures of the binary mixtures were elevated. Among all the investigated impurities, N₂ has the most significant effect on the bubble point pressures of CO₂ binary mixture at all the isotherms and compositions. Both MFHEA and PR models agreed well with the measured equilibrium points. For all systems, the average absolute deviations of the measured experimental data against the MFHEA and PR EoSs, were found to be less than 3.4% and 2.2%, respectively. Although the MFHEA EoS overpredicted most of the data points, the overall trend agreed with the experimental data and was consistent with the data available in the literature. The findings imply that the presence of these non-condensable impurities (even as low as 0.5% mole fraction) increases the risk of two-phase flow at higher pressures in a CO₂-rich system. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

Recently, CO₂ methanation has become a technique that aims to reduce anthropogenic CO₂ emissions by converting CO₂ captured from stationary and mobile sources and H₂ produced from renewable sources into CH₄. Due to their excellent performance-to-cost ratio, Ni-based catalysts were frequently used in such conversions. The main drawbacks, however, are that Ni has the propensity to aggregate and deposit carbon during the high-temperature reaction. These issues can be partially resolved by including a support (e.g., MOF, zeolite, activated carbon, etc.) and a second transition metal (e.g., Mo, Co, or Fe) in Ni-based catalysts. Therefore, the activity of Ni-based catalysts at low temperatures needs to be improved. In this study, a series of mesoporous activated carbon (AC) supported bimetallic Ni–Mo catalysts (Ni–xMo/AC, Ni = 13 wt.%, x = 5, 7, 9, 11 wt.%) were synthesized using the incipient wetness impregnation method. The effect of Mo content on the catalyst's activity was examined in a fixed-bed reactor. At 250–650°C, 1-atmosphere pressure, gas hourly space velocity (GHSV): 1200 mL h⁻¹ g⁻¹, and H₂/CO₂ ratio: 4:1, the catalytic efficiency of these catalysts was examined. The catalysts were analyzed using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), N₂-physisorption, and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM-EDX). Ni–7%Mo/AC catalyst showed the lowest carbon deposition rate, superior stability, and the best activity. The addition of Mo can improve the heat resistance of the Ni/AC catalyst and the interaction between the metal nickel and the support, which prevents the sintering of the catalyst. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Pore-fracture structure distribution heterogeneity (PFSH) affects dynamic variation of porosity-permeability of tight sandstone reservoirs, then restricting gas production performance. A fractal model by low-field nuclear magnetic resonance technology (LF-NMR) has been used in the quantitative characterization of PFSH. Among some literature, PFSH was studied by using a saturated T₂ spectrum. However, there are few studies on fractal characteristics of T₂ spectral morphology in a centrifugal state and its influence on porosity-permeability parameters. In this paper, 30 tight sandstone samples were collected from Taiyuan Formation in Qinshui Basin. Then LF-NMR technology was used to analyze PFSH, and sample types were divided by using T₂ spectra difference under saturated and centrifugal conditions. Meanwhile, single (model 1 and 2) and multi-fractal model are adopted to calculate fractal parameters of saturated and centrifugal T₂ spectra, and then a difference in fractal parameters under different water conditions was compared. Correlation between different fractal parameters, pore structure and T_{2 cut-off} value are studied, and a mathematical prediction model for T_{2 cut-off} value by using fractal and pore structure parameters are established. The results are as follows. (1) All the samples are divided into four types A/B/C/D. For example, the type A sample is characterized by a single peak of T₂ spectrum and T₂ value is less than 10 ms, which indicates that this type belongs a smaller-pore developed. Type B sample is characterized by a single peak of T₂ spectrum and T₂ value is10–100 ms, which indicates that this type belongs to mesopore developed. (2) In saturated state (D_S), PFSH of type A sample by using model 1 and 2 is stronger than that of type B, followed by type C and D. Then the multifractal model shows that PFSH of type B sample is stronger than that of other sample types. Correlation between fractal dimension calculated by using single fractal and pore structure parameters is stronger than that of multifractal dimension. (3) T₂ spectrum in centrifugal state has fractal characteristics (D_i), and there are certain correlation D_i with D_s. Therefore, a mathematical prediction model for T_{2 cut-off} value by using fractal and pore structure parameters is established. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

To-date, only two UIC Class VI permits have been issued by the US Environmental Protection Agency. We illustrate a four-phase workflow to first identify regional storage resources and then down-select sites to yield permit-ready locations that can accept and store large volumes of CO₂. Specific permit requirements should guide objectives and define deliverables of respective workflow phases. In the first phase we used available regional data and screened structure and injection zones to locate resources that match CO₂ volumes planned to be captured. Available data were also used to assess presence and depth of usable groundwater, the key resource being protected via permitting. We then used advanced, closed-form, analytical solutions (EASiTool) to estimate CO₂ injectivity into each hydrologically connected injection compartment. In the second phase we acquired and conditioned additional wireline logs and leased available seismic datasets. We interpreted the depositional systems from wireline well-log character and mapped sandbody geometry to interpolate injection and confining-zone distribution. Using available data, we mapped faults and locations of freshwater and overpressure (or other capacity-limiting geologic parameters) in more detail. In the third phase, we used the augmented geologic data to develop a static model for the selected area, extracted the areas of highest interest, and generated and ran dynamic (flow) models. In a fourth phase, we reduced major uncertainties identified in earlier phases. Our case study indicates that to complete preparation of a permit application requires (1) improved lithologic characterization information (thicknesses and horizontal and vertical connectivity) and (2) better definition of poorly defined local faults. © 2023 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley & Sons Ltd.

The chemical looping oxidative dehydrogenation (CL-ODH) of ethane represents a highly effective approach for converting ethane into the value-added product ethylene. This investigation focused on the synthesis of SrMnO₃ and its halide ions doped derivatives (SrMnO₃Cl and SrMnO₃Br) through the sol-gel method. The performance of these perovskites, employed as oxygen carriers in CL-ODH of ethane, was explored. The results unveiled several advantageous outcomes arising from the incorporation of halide ions (Cl⁻ and Br⁻) with larger radius into the oxygen sites of the SrMnO₃ perovskite. Halide ions doping notably induced cell volume expansion and enhanced lattice fringe spacing. Furthermore, it contributed to elevated oxygen vacancy concentration, increased Mn⁴⁺/Mn³⁺ molar ratio, and improved oxygen ions mobility within the bulk lattice. Fixed-bed experiments demonstrated that these redox catalysts, doped with halide ions, exhibited outstanding activity and stability during cycling tests, exhibiting enhanced both ethylene selectivity and yield in CL-ODH of ethane. In summary, the introduction of halide ions into SrMnO₃ emerges as a promising strategy for enhancing the performance of CL-ODH in ethane conversion for SrMnO₃ based oxygen carriers. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.

Ghana is determined to reduce greenhouse gas (GHG) emissions by at least 15% by 2030 and attain net-zero emissions by 2070. However, like many developing countries, Ghana must utilize its limited resources effectively to actualize its climate goals. Currently, climate policies in the country are not driven by emission data, which has important implications on effective utilization of resources and selection of efficient mitigation techniques. We analyzed energy consumption and GHG emission data between 1990 and 2016 from Ghana's energy sector which is responsible for about 36% of the country's total emissions. Predictive models were then developed using machine learning to forecast energy related emissions up to 2030. Based on the analysis and projections, attainable data-driven recommendations were proposed to direct climate policies in the country. We found that between 1990 and 2016, petroleum fuel consumption increased by about 64.5% and the corresponding GHG emissions increased by 303%. The projections suggests that by 2030, energy sector emissions could increase by 131% compared to 2016 levels. Transport sector emission is also projected to increase by a whopping 219% and fuel consumption could hit 6742 ktoe by 2030, which is about 106% increase from the 2016 benchmark. The findings from this work will direct policy for effective mitigation of GHG emissions in the country while ensuring effective utilization of climate resources to pursue its net-zero targets. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd.