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The direct conversion of methane to methanol has attracted increasing interest due to abundant and low-cost natural gas resources. Herein, by anchoring Cr-oxo/-oxyhydroxides on UiO-66 metal–organic frameworks, we demonstrate that reactive anionic oxyl radicals can be formed by controlling the coordination environment based on the results of density functional theory calculations. The anionic oxyl radicals produced at the completely oxidized CrVI site acted as the active species for facile methane activation. The thermodynamically stable CrVI-oxo/-oxyhydroxides with the anionic oxyl radicals catalyze the activation of the methane C–H bond through a homolytic mechanism. An analysis of the results showed that the catalytic performance of the active oxyl species correlates with the reaction energy of methane activation and H adsorption energies. Following methanol formation, N2O can regenerate the active sites on the most stable CrVI oxyhydroxides, i.e., the Cr(O)4Hf species. The present study demonstrated that the anionic oxyl radicals formed on the anchored CrVI oxyhydroxides by tuning the coordination environment enabled facile methane activation and facilitated methanol production. [ABSTRACT FROM AUTHOR]

In this study, we used a high-throughput computational screening approach to examine the potential of metal–organic frameworks (MOFs) for capturing propane (C3H8) from different gas mixtures. We focused on Quantum MOF (QMOF) database composed of both synthesized and hypothetical MOFs and performed Grand Canonical Monte Carlo (GCMC) simulations to compute C3H8/N2/O2/Ar and C3H8/C2H6/CH4 mixture adsorption properties of MOFs. The separation of C3H8 from air mixture and the simultaneous separation of C3H8 and C2H6 from CH4 were studied for six different adsorption-based processes at various temperatures and pressures, including vacuum-swing adsorption (VSA), pressure-swing adsorption (PSA), vacuum–temperature swing adsorption (VTSA), and pressure-temperature swing adsorption (PTSA). The results of molecular simulations were used to evaluate the MOF adsorbents and the type of separation processes based on selectivity, working capacity, adsorbent performance score, and regenerability. Our results showed that VTSA is the most effective process since many MOFs offer high regenerability (>90%) combined with high C3H8 selectivity (>7 × 103) and high C2H6 + C3H8 selectivity (>100) for C3H8 capture from air and natural gas mixtures, respectively. Analysis of the top MOFs revealed that materials with narrow pores (<10 Å) and low porosities (<0.7), having aromatic ring linkers, alumina or zinc metal nodes, typically exhibit a superior C3H8 separation performance. The top MOFs were shown to outperform commercial zeolite, MFI for C3H8 capture from air, and several well-known MOFs for C3H8 capture from natural gas stream. These results will direct the experimental efforts to the most efficient C3H8 capture processes by providing key molecular insights into selecting the most useful adsorbents. [ABSTRACT FROM AUTHOR]

Indoor sources of air pollution worsen indoor and outdoor air quality. Thus, identifying and reducing indoor pollutant sources would decrease both indoor and outdoor air pollution, benefit public health, and help address the climate crisis. As outdoor sources come under regulatory control, unregulated indoor sources become a rising percentage of the problem. This American Thoracic Society workshop was convened in 2022 to evaluate this increasing proportion of indoor contributions to outdoor air quality. The workshop was conducted by physicians and scientists, including atmospheric and aerosol scientists, environmental engineers, toxicologists, epidemiologists, regulatory policy experts, and pediatric and adult pulmonologists. Presentations and discussion sessions were centered on 1) the generation and migration of pollutants from indoors to outdoors, 2) the sources and circumstances representing the greatest threat, and 3) effective remedies to reduce the health burden of indoor sources of air pollution. The scope of the workshop was residential and commercial sources of indoor air pollution in the United States. Topics included wood burning, natural gas, cooking, evaporative volatile organic compounds, source apportionment, and regulatory policy. The workshop concluded that indoor sources of air pollution are significant contributors to outdoor air quality and that source control and filtration are the most effective measures to reduce indoor contributions to outdoor air. Interventions should prioritize environmental justice: Households of lower socioeconomic status have higher concentrations of indoor air pollutants from both indoor and outdoor sources. We identify research priorities, potential health benefits, and mitigation actions to consider (e.g., switching from natural gas to electric stoves and transitioning to scent-free consumer products). The workshop committee emphasizes the benefits of combustion-free homes and businesses and recommends economic, legislative, and education strategies aimed at achieving this goal.

The combustion technology of hydrogen enriched natural gas can directly apply hydrogen energy to household gas, playing an important role in promoting the development of hydrogen energy. This study designed a domestic burner with porous media for hydrogen enriched natural gas. The effect of hydrogen blending ratio on the primary mix process in the injector was analyzed numerically, and an experiment was conducted to investigate the flame morphology, thermal efficiency and pollutant emissions of the hydrogen-enriched natural gas. The results show that there is a risk of backfire inside the injector when the hydrogen blending ratio exceeds 45%, and the pre-mixing uniformity decreases as the hydrogen doping ratio increases. Corresponding to variable hydrogen doping ratios, two combustion modes appear in the porous medium region, immerged combustion and surface combustion. When a combustion mode transition occurs, CO emissions increase rapidly, while thermal efficiency and NOx emissions show a downward trend. Additionally, the critical hydrogen doping ratio of mode transition drops as the porous density increases. Overall, taking the environmental characteristic and efficiency into considerations, the maximum hydrogen blending ratio should be not exceed 35%. [Display omitted] • A domestic burner with porous media for hydrogen enriched natural gas was designed. • The effect of hydrogen blending ratio on the primary mix process was analyzed. • The combustion performance and emissions of the domestic burner was investigated. • The transition of combustion mode induced by hydrogen doping ratio was observed. [ABSTRACT FROM AUTHOR]

In Canadian remote oil sites, natural gas extracted with the bitumen is flared or vented, impacting on the environment. Providing a pipeline network to recover the gas is unaffordable in most cases. Here we propose the economic framework of an innovative process to recover the gas, based on pyrolysis at T = 1223 K and P = 0.1 MPa, performed in situ. Part of produced hydrogen combusts to sustain the process, while solid carbon is sold. We conceptualised and simulated in Aspen Plus two process alternatives. In configuration 1, the remaining part of hydrogen is sent to a gas turbine, where it burns to produce electricity. In configuration 2, the unburnt hydrogen is purified and sold. Both configurations reduce CO 2 emissions by more than 92 % compared to flaring. Both configurations produce a profit over 10 years, being their IRR above 20 % and payback time below 3.5 y. • Flaring and venting natural gas contribute to 1.7 % of Canada's global emissions. • Methane pyrolysis is a promising technology to abate oil sector's emissions. • We present techno-economics and sensitivity analysis of two process alternatives. • Turquoise H 2 sustains energetically the process that produces carbon, to be sold. • Emissions compared to the flaring scenario are reduced by over 90 %. [ABSTRACT FROM AUTHOR]

Hydrogen blending has proved to be a promising alternative to reduce CO 2 emissions in current applications such as the industrial sector in which natural gas is the fuel source since it can mitigate GHG emissions and help to reach nation's goal of decarbonization. This study explored the feasibility of different hydrogen blend compositions going from 1% to 30% hydrogen content (by volume) by computational simulations to determine the best performance of the system considering real operating conditions from Central Plant at UC Irvine. This work also performed an economic analysis as part of the implementation plan. It was determined that a blend of 19% H 2 content could be implemented without any major renovation of utility infrastructure based on the operating conditions and change in the properties of the mixture. An addition of 30% H 2 can reduce around 11% of the emissions produced by pure natural gas. This is equivalent to 1422 kg of CO 2 in 1 h. It is evident that the higher the H 2 content, the better the CO 2 benefits that would be produced, but for the actual application of higher hydrogen content, there is a need for a better understanding of the effects of hydrogen in the current natural gas pipeline. Based on the CO 2 savings, it was determined that a 30% blending of hydrogen may save about 22.2% of the economic cost compared to natural gas. • A hydrogen blending model is developed considering a hydrogen content between 1% and 30% by volume. • Real operating conditions such as temperature, pressure, pipeline dimensions, and power output requirements were considered based on UCI power plant for validation. • An economic analysis is considered as part of the implementation plan. • A blend of 19% H 2 content could be implemented without major renovation of infrastructure based on the operating conditions and change in the properties of the mixture. • 30% H 2 can reduce ∼11% of the emissions produced by pure natural gas. [ABSTRACT FROM AUTHOR]

The direct liquid‐phase oxidative carbonylation of methane, utilizing abundant natural gas, offers a mild and straightforward alternative. However, most catalysts proposed for this process suffer from low acetic acid yields due to few active sites and rapid C1 oxygenate generation, impeding their industrial feasibility. Herein, we report a highly efficient 0.1Cu/Fe‐HZSM‐5‐TF (TF denotes template‐free synthesis) catalyst featuring exclusively mononuclear Fe and Cu anchored in the ZSM‐5 channels. Under optimized conditions, the catalyst achieved an unprecedented acetic acid yield of 40.5 mmol gcat−1 h−1 at 50 °C, tripling the previous records of 12.0 mmol gcat−1 h−1. Comprehensive characterization, isotope‐labeled experiments and density functional theory (DFT) calculations reveal that the homogeneous mononuclear Fe sites are responsible for the activation and oxidation of methane, while the neighboring Cu sites play a key role in retarding the oxidation process, promoting C−C coupling for effective acetic acid synthesis. Furthermore, the methyl‐group carbon in acetic acid originates solely from methane, while its carbonyl‐group carbon is derived exclusively from CO, rather than the conversion of other C1 oxygenates. The proposed bimetallic catalyst design not only overcomes the limitations of current catalysts but also generalizes the oxidative carbonylation of other alkanes, demonstrating promising advancements in sustainable chemical synthesis. [ABSTRACT FROM AUTHOR]

Geopolitical tensions have put the use of strategic trade policy instruments back on the agenda of policy makers. In this paper we investigate the interaction of the threat and use of three unilateral trade policy instruments: embargoes, import price caps and tariffs. In a game-theoretic framework with different scenarios and game variants, we show that the strategic use of the right combination of the respective trade policy instruments can be used to achieve more desirable outcomes for the players. In our setup, a credible threat of a tariff supports the successful implementation of an import price cap. While the results can be generalised, we show the concrete functioning of the interplay of these strategic trade policy instruments in a hypothetical game of resumption of natural gas sales from Russia to the EU. Following the application to this example, we derive policy suggestions to improve the EU's position in the specific game. [ABSTRACT FROM AUTHOR]

The establishment of a natural gas production model under multi factor control provides support for the formulation of planning schemes and exploration deployment decisions, and is of great significance for the rapid development of natural gas. Especially the growth rate and decline rate of production can be regulated in the planning process to increase natural gas production. The exploration and development of conventional gas in the Sichuan Basin has a long history. Firstly, based on the development of conventional gas production, the influencing factors of production are determined and a production model under multi factor control is established. Then, single factor analysis and sensitivity analysis are conducted, and multi factor analysis is conducted based on Bayesian networks. Finally, combining the multivariate Gaussian mixture model and production sensitivity analysis, a production planning model is established to predict production uncertainty under the influence of multiple factors. The results show that: 1) the production is positively correlated with the five influencing factors, and the degree of influence is in descending order: recovery rate, proven rate, growth rate, decline rate, and recovery degree. After being influenced by multiple factors, the fluctuation range of production increases and the probability of realization decreases. 2) The growth rate controls the amplitude of the growth stage, the exploration rate and recovery rate control the amplitude of the stable production stage, the recovery degree controls the amplitude of the transition from the stable production stage to the decreasing stage, and the decreasing rate controls the amplitude of the decreasing stage. 3)The article innovatively combines multiple research methods to further obtain the probability of achieving production under the influence of multiple factors, providing a reference for the formulation of production planning goals. [ABSTRACT FROM AUTHOR]

The USA has committed to cutting its emissions of methane, an extremely potent greenhouse gas, by at least 30% by 2030 (‘30 × 30’). This is part of the Global Methane Pledge, signed by 155 countries, to keep global warming within 1.5 °C and thereby to forestall the disastrous effects of ‘runaway climate change’. It will be a major challenge for the USA to reach 30 × 30 and there is no consensus on how to do so. This paper provides a concrete, data‐driven roadmap to indicate how to reach 30 × 30 feasibly, focusing on two enormous sources of methane emissions: organic waste and oil and gas production. It calculates that building approximately 4700 anaerobic digesters (ADs) to process food waste and animal manure would cost about $74.2 billion in capital expenditure (capex) and cut 13.6% of total US methane emissions per year. On average, each project would take roughly 2–6 years to build. Of the various methane mitigation measures analyzed in the oil and gas sectors, the most impactful would be full compliance with the US Environmental Protection Agency's (EPA's) revised New Source Performance Standards (NSPS) for oil and gas production by 2029. This would cut 17.5% of total US methane emissions annually, at a cumulative capex of $20.7 billion from 2024 to 2029. Together, the 13.6% cut from food waste and manure ADs and the 17.5% cut from full NSPS compliance would amount to a 31.5% reduction, exceeding the 30 × 30 goal. Greater clarity from the federal government on funding eligibility and additional incentives would accelerate the buildout of ADs. [ABSTRACT FROM AUTHOR]

Geochemical investigation of hydrogen (H 2), brine, rock formations, and residual gases (nitrogen – N 2 , methane – CH 4 , and carbon dioxide – CO 2) is crucial for understanding H 2 storage processes in depleted gas reservoirs. This study examines the effects of injecting a gas mixture (60% H 2 + 30% N 2 + 5% CH 4 + 5% CO 2) into Bandera Grey sandstone with notable clay mineral content. The experiment lasted 50 days at 42 °C, 1350 psi, and 5 wt% NaCl brine, with detailed analytical characterization before and after aging. Results show minimal sample reactivity, causing slight alterations in petrophysical characteristics. Dissolution primarily affected dolomite and barite minerals, while illite and kaolinite caused pore blockage. Gas chromatography data indicate only 0.45% of injected H 2 is lost (via dissolution in brine and reaction with CO 2), CH 4 increased by 6.22%, N 2 remained stable, and CO 2 decreased by 1%. These results provide valuable insights into the feasibility and safety of utilizing depleted gas reservoirs for H 2 storage. • Effect of storing 60% H 2 and 40% cushion gas in clay-rich sandstone is investigated. • Geochemical reactions (dissolution/precipitation) induced by the mixture are very weak. • PH increased from 6.13 to 7.24 led to mineral dissolution and precipitation. • Only 0.45% of injected H 2 was lost based on gas chromatography. • Findings provide insights into the feasibility and safety of depleted gas reservoirs for H 2 storage. [ABSTRACT FROM AUTHOR]

We state the appropriate thermodynamic and transport properties to use for the delivery of hydrogen through pre-existing natural gas distribution networks. We show that the flow is not as fully-turbulent as past work has assumed, that hydrogen makes the flow even less turbulent, and that the pipe friction calculation requires more careful treatment in this partially-turbulent regime. We propose that the relevant final energy demand is the energy delivered as heated water. The different dew points of the flue gases from hydrogen versus natural gas combustion affect the boiler efficiency. This impacts the relative amount of hydrogen required to be delivered. We find that to deliver the same amount of useful energy as hot water, hydrogen requires a gas velocity of 3.076 × and a pressure gradient that is 1.29 × higher. The compression power increase required to deliver hydrogen through the low pressure network can be up to 7.85 × that for natural gas, depending on the flow regime. • Replacing natural gas with hydrogen reduces the Reynolds number. • Hydrogen flue gas changes the efficiency of a condensing boiler. • Replacing natural gas with hydrogen increases the pressure drop 1.29x. • The changing efficiency of condensing boilers affects how much hydrogen is needed. • The Blasius parameter ρ 3 / 4 ⋅ μ 1 / 4 has a very low temperature dependence. [ABSTRACT FROM AUTHOR]

Diisopropylamine (DIPA), aminomethyl propanol (AMP), amino ethoxy ethanol (AEE), diethanolamine (DEA), ethanolamine (EA), pyridine (PYR) and methyl diethanolamine (MDEA) are used for carbon capture and to sweeten sour gas, and are found in groundwater. They are also used in cosmetic products. Taurine is abundant in the body, with key biological functions linked to its charged SO groups. Interactions between SO and amines have not been studied, but can strongly affect the biological function of taurine. Fourier transform infrared spectroscopy indicates SO...HN hydrogen bonding between taurine and DIPA, AMP, AEE, DEA, EA and MDEA. These interactions induce the formation of hydrophobic amine-taurine clusters, thus decreasing amine miscibility in water, as revealed by light scattering. This effect is most marked for DIPA, leading to turbid mixtures indicative of micron-sized droplets. PYR and taurine likely interact via S...N bonding. This study offers insights regarding potential mechanisms of amine toxicity to humans. [ABSTRACT FROM AUTHOR]

Ultrasound technology has been recognized as the mainstream approach for the identification of gas-liquid two-phase flow patterns, which holds great value in engineering domain. However, commercial rigid probes are bulky, limiting their adaptability to curved surfaces. Here, we propose a strategy for autonomous identification of flow patterns based on flexible ultrasound array and machine learning. The array features high-performance 1–3 piezoelectric composite material, stretchable serpentine wires, soft Eco-flex layers and a polydimethylsiloxane (PDMS) adhesive layer. The resulting ultrasound array exhibits excellent electromechanical characteristics and offers a large stretchability for an intimate interfacial contact to curved surface without the need of ultrasound coupling agents. We demonstrated that the flexible ultrasound array combined with machine learning can accurately identify gas-liquid two-phase flow patterns, in a circular pipeline. This work presents an effective tool for recognizing gas-liquid two-phase flow patterns, offering engineering opportunities in petroleum extraction and natural gas transportation. [ABSTRACT FROM AUTHOR]

Detection of underground natural gas pipeline micro-leakage based on unmanned aerial vehicle (UAV) hyperspectral remote sensing and GIS. Hyperspectral images can indirectly detect underground natural gas pipeline micro-leakage through spectral and spatial variation characteristics of surface vegetation. However, most of existing studies were based on ground-mounted platforms, which could only perform small-range single-point detection and might occur misidentifications. UAV hyperspectral remote sensing can allow wide-range detection of surface vegetation. Moreover, underground pipeline distribution GIS data can provide prior knowledge about leakage points to exclude misidentifications. Therefore, a natural gas pipeline micro-leakage experiment was set up. UAV hyperspectral images of grasslands and pipeline distribution vector data were obtained, which led to a proposed new wide-range multi-points detection methodology of underground natural gas micro-leakage. Firstly, the vegetation identification index (WVI) $\left({{R_{470}} + {R_{674}}} \right)/\left({{R_{555}} + {R_{750}}} \right)$R470+R674/R555+R750 was designed based on WOA–VMD (whale optimization algorithm – variational modal decomposition) to segment and extract the vegetation stress zones. Then, UAV- and GIS-based natural gas micro-leakage vegetation stress identification model was constructed to obtain the leak points of natural gas micro-leakage. Finally, the recognition ability was evaluated by comparing with three stress vegetation identification indices proposed in previous studies. The result showed that there was no missing or false detection in identification results; the identification and positioning effect was better than other indices, which could meet the practical application requirements. [ABSTRACT FROM AUTHOR]

In response to growing reliance on electricity and gas systems, this paper introduces a stochastic bi‐level model for the optimized integration of these systems. This integration is achieved through sizing and allocating of power‐to‐gas (P2G) and gas‐to‐power (G2P) units. The first level of the model focuses on decisions related to P2G and G2P unit installations, while the second level addresses optimal system operation considering decisions made from first level and stochastic scenarios. The primary aim is to enhance energy‐sharing capabilities through coupling devices and mitigate wind generation curtailment. An economic evaluation assesses the model's effectiveness in reducing costs. N − 1 contingency analysis gauges the integrated system's ability to supply load under emergency conditions. Two new indices, performance of the electricity system and performance of the natural gas system, are proposed for N − 1 contingency analysis. These indices quantify the proportion of the supplied load to the total load, thereby illustrating the system's capacity to meet demand. For numerical investigation, the proposed model is applied to a modified IEEE 14‐bus power system and a 10‐node natural gas system. Numerical results demonstrate a 9.426% reduction in investment costs and a significant 10.6% reduction in wind curtailment costs through proposed planning model. [ABSTRACT FROM AUTHOR]

Due to the increasing demand for natural gas, solidified natural gas (SNG) technology provides an attractive option for natural gas storage and transportation. However, the use of sodium dodecyl sulfate (SDS) to promote hydrate formation will have a negative impact on the environment. To overcome this difficulty, the compounding system of environmentally friendly additives with SDS was intended to find the synergistic promotion effects aiming to reduce the usage of SDS in this study. Three kinds of cyclodextrins including αCD, βCD, hydroxypropyl-βCD (HPCD) with SDS were compounded to study the effect of their interaction on hydrate formation kinetics. The result showed that when used with SDS, the formation of hydrates was promoted by αCD and βCD but inhibited by HPCD. It is emphasized that the promoting effect depended on the water channel (completely hydrophilic zones) formed by H-bonds between cyclodextrin and SDS self-assembled channel-type complexes. Compared with 500 ppm SDS used along, it was possible to reduce the dosage of SDS by 40%. Finally, by observing the morphology of hydrate formation, it is found that the addition of cyclodextrins would affect the driving force for hydrate growth in the horizontal direction during hydrate formation. This study provides theoretical support for further understanding of cyclodextrin and surfactant compounding and shows an effective way for the application of SNG industry. [ABSTRACT FROM AUTHOR]

The combination of renewable energy and liquefied natural gas (LNG) cold energy can effectively improve energy utilization efficiency and achieve the goal of energy conservation and emission reduction, which is one of the important directions of future development. This work proposed a cascade organic Rankine cycle (ORC) driven by a geothermal heat source and an LNG heat sink. Seven organic fluids are chosen as candidates to form different working fluid pairs. The effects of the main design parameters on system performance are carried out through the thermodynamic analysis. Then, the optimal design conditions and fluid selection schemes are searched based on the singleobjective optimization results. Finally, the exergy destruction study is conducted under the optimal design conditions and working fluid pair. Results showed that the cascade ORC system using the working fluid pair of R601/R290 had the highest exergy efficiency, which could reach 20.02%. At the same time, under the optimal design conditions, the secondary cycle condenser and LNG direct expansion brought high exergy destruction, which was respectively 29.3% and 25.8%, and followed by the two turbines in the cascade ORC system, which were 16.1%, 11.2% and 7.7%. [ABSTRACT FROM AUTHOR]

Due to changes in urban residents' consumption habits and lifestyles, accurately predicting natural gas consumption has become increasingly important. To address this issue, this paper proposes a forecasting model that combines Ensemble Learning (EL), Variational Mode Decomposition (VMD), Transformer, and LSTM. First, XGBoost, CatBoost, and LightGBM are used as base learners in the ensemble learning framework, with the predictions generated by the ensemble model integrated into the original dataset. Next, the VMD method is employed to decompose the natural gas load sequence into several intrinsic mode functions (IMFs), effectively extracting the inherent features of the natural gas load sequence. Finally, the data is input into the Transformer-ResLSTM network for prediction. This network replaces the original Transformer decoder structure with an LSTM network and fully connected layers, creating a new decoder structure. Additionally, a residual connection mechanism is introduced in both the encoder of the Transformer network and the new decoder structure. Experimental results show that, compared to traditional models such as ARIMA, Transformer, GRU, and LSTM, the proposed hybrid model significantly improves prediction accuracy, reducing MSE by 92–98% and MAE by 74–83%. In summary, this method demonstrates significant potential and practical value in enhancing the accuracy of natural gas load forecasting. [ABSTRACT FROM AUTHOR]

The efficient utilization of methane, a vital component of natural gas, shale gas and methane hydrate, holds significant importance for global energy security and environmental sustainability. However, converting methane into value-added oxygenates presents a formidable challenge due to its inert nature. Direct selective oxidation of methane (DSOM) under mild conditions is essential for reducing energy consumption and carbon emissions compared with traditional indirect routes. Achieving total selectivity in methane hydroxylation remains elusive due to the competitive CO2 formation. This feature article highlights recent advancements in methane hydroxylation using thermo-, photo-, and electro-catalytic systems. Through strategically designing the structure of catalysts to control the reactive oxygen species and optimizing reaction parameters, significant progress has been made in enhancing oxygenate selectivity and minimizing overoxidation. A comprehensive understanding of the mechanisms underlying methane hydroxylation with total selectivity offers insights for improving catalyst design and reaction parameter optimization, promoting sustainable methane utilization. [ABSTRACT FROM AUTHOR]

A novel static mixer is designed specifically to blend hydrogen into natural gas pipelines, and its effectiveness is validated by numerical simulation method. Firstly, the structural model of the proposed static mixer model for hydrogen-methane blending is introduced, and the evaluation indicators are defined. Secondly, the computational fluid dynamic model for the mixing process is established based on the Large Eddy Simulation(LES) method, and the accuracy of the numerical results is validated against the experimental data of a benchmark gas mixing model. Subsequently, using LES, effects structural parameters (angle and height of trapezoidal baffle, number of mixing elements, and spacing and installation distance of mixing elements) and flow parameters (main flow velocity and hydrogen blending ratio) on the mixing homogeneity and pressure drop of the static mixer are investigated systematically to explore the optimal design and operational conditions. The numerical results showed that the static mixer can significantly improve the mixing efficiency of hydrogen and natural gas with acceptable pressure loss. In the range of flow conditions concerned, a best performance of mixing could be obtained by installing the mixer at a distance of 3 D (D is the diameter of the natural gas pipeline) downstream the blending point, setting the spacing between mixing elements as 1 D and employing four mixing elements. Finally, the underlying physics of mass transportation are analyzed based on the vortex structures generated by the mixer. • A novel static mixer is designed to blend hydrogen into natural gas pipelines. • A Large eddy simulation solution procedure is proposed to solve multi-component mixing. • Effects of key parameters of the static mixer and operating conditions are revealed. • The mixing mechanism of static mixer is revealed based on vortex dynamics analysis. [ABSTRACT FROM AUTHOR]

In this study, we developed a diagnosis method for combustion instability and validated its performance using experimental data obtained from a hydrogen/natural gas co-firing gas turbine combustor. Four criteria, namely temporal kurtosis, permutation entropy, energy entropy, and zero-crossing rate, were considered. First, the performance of each criterion was compared with that of the conventional method for determining combustion instability using the root mean square (RMS) of dynamic pressure. Temporal kurtosis the best performance in terms of detection speed (instability onset detected 0.71 s earlier than the RMS method). Permutation entropy yielded the best performance in terms of accuracy and precision with accuracy, recall, precision, and F1-score values of 96.6%, 100%, 92.6%, and 96.2%, respectively. The performances of combinations of these criteria were investigated using AND and OR gates. Twenty-two cases were considered and the combination of permutation entropy and zero-crossing rate (best case) achieved detection time, accuracy, precision, recall, and F1-score values of 8.49 s, 97.2%, 93.9%, 100%, and 96.8%, respectively. Other combinations exhibited competitive performance; however, the method combining two criteria was selected to simplify the computing process. The proposed method is expected to contribute to the safe and stable operation of hydrogen/natural gas co-firing gas turbines. • A Novel diagnostic method for detecting the onset of combustion instability is proposed. • The detection speeds and accuracies of TK, PE, EoE, and ZCR are assessed. • TK can detect instability onset 0.71 s earlier than the root mean square method. • PE achieved superior performance with 96.6% accuracy and 92.6% recall. • The PE∩STD ZCR combination improved accuracy (97%) and recall (100%). [ABSTRACT FROM AUTHOR]

In urban pipelines, blending hydrogen into natural gas has been considered as an effective way of hydrogen usage to reduce carbon emission on household appliances. However, few studies, especially experimental ones are dedicated to address the characteristics of a typical domestic cooker due to the transition from natural gas to 20%hydrogen-enriched natural gas. This study experimentally investigated the changes in terms of the gas flow rate, flame temperature, heat transfer and emission characteristics of a domestic cooker as a result of such transition. Using a self-developed gas blending system, the flow rates of the both the mixed fuel and its components are obtained. The data shows that after blending hydrogen, the mixed gas flow rate becomes higher. Compared to the original cooker burning natural gas, hydrogen blending results in a decreased natural gas flow rate, leading to lower carbon emission. In addition, the thermal input to the cooker is lowered and hydrogen blending leads both the inner and outer combustion zones of the flame to shorten while the flame temperature to increase. As an attempt to optimize the performance of the cooker, the effects of wok stand height on heat transfer efficiency and NO/NO x /CO emissions are examined. It is found that the cooker fueled by 20%hydrogen-enriched natural gas exhibits lower heat transfer efficiency, higher NO/NO x emissions and lower CO emission. According to the fact that the heat transfer efficiency increases at lower wok stand height, the wok stand height is lowered from its original 7 cm–6 cm and 5 cm. The finding indicates that when the wok stand height is moderately decreased to 6 cm, NO/NO x emissions decrease and CO emission is only marginally increased. This study proposes that when natural gas is replaced by 20%hydrogen-enriched natural gas on a swirl flame cooker, the wok stand height can be slightly lowered to exploit the advantages of blended hydrogen combustion. • A systematic experimental study of the flow/temperature/emission/heat transfer of a cooker. • The changed flow rates are measured by using a self-developed device. • The height of the swirling flame shortens after blending hydrogen to natural gas. • The flame temperature/NOx emission increase while CO emission decrease. • Lowering the wok leads to higher heat transfer efficiency, lower NO x while only marginally higher CO. [ABSTRACT FROM AUTHOR]

Background: Fossil fuels can be replaced with electricity and hydrogen. However, the implementation and use of these low-carbon energy carriers require a sociotechnical transition. This transition might not be completed in time. Main text: CO 2 -based methane is a substitute for natural gas that is less carbon-intensive. This methane is synthesized by capturing CO 2 from air and by performing water electrolysis to produce hydrogen. CO 2 -based methane is compatible with our current fossil-based society. An analysis of the substitution of natural gas with different energy carriers will be performed, and the results will be compared. The effects of CO 2 -based methane, hydrogen, and electricity will be evaluated for energy storage, high-temperature level heat production, and residential heating. The multi-level perspective will be applied to assess these energy carriers in the context of our society. Conclusions: CO 2 -based methane is the least energy efficient energy carrier among those analyzed. Nevertheless, this type of methane supports the acceleration of the energy transition. Highlights: CO2-based methane is a valuable, renewable, and carbon-neutral energy carrier that supports a timely energy transition. The implementation of hydrogen and electricity requires more modifications to our current sociotechnical society than the implementation of CO2-based methane. The urgency of reducing CO2 emissions is not being considered adequately in the current societal discussion, and a multi-level perspective analysis should provide valuable results that account for the temporal aspect. [ABSTRACT FROM AUTHOR]

Natural gas dehydration is a critical process in natural gas extraction and transportation, and the membrane separation method is the most suitable technology for gas dehydration. In this paper, based on molecular dynamics theory, we investigate the performance of a metal–organic composite membrane (ZIF-90 membrane) in natural gas dehydration. The paper elucidates the adsorption, diffusion, permeation, and separation mechanisms of water and methane with the ZIF-90 membrane, and clarifies the influence of temperature on gas separation. The results show that (1) the diffusion energy barrier and pore size are the primary factors in achieving the separation of water and methane. The diffusion energy barriers for the two molecules (CH4 and H2O) are ΔE(CH4) = 155.5 meV and ΔE(H2O) = 50.1 meV, respectively. (2) The ZIF-90 is more selective of H2O, which is mainly due to the strong interaction between the H2O molecule and the polar functional groups (such as aldehyde groups) within the ZIF-90. (3) A higher temperature accelerates the gas separation process. The higher the temperature is, the faster the separation process is. (4) The pore radius is identified as the intrinsic mechanism enabling the separation of water and methane in ZIF-90 membranes. [ABSTRACT FROM AUTHOR]

This study analyses data from natural gas combination boilers across a 6-year timeframe, exploring how demand for space heating and hot water have both changed over time, and highlights the impact of factors such as external temperature and the UK energy price cap. The results show that there has been a significant decrease in annual space heating and hot water demand since 2021. Space heating typically contributes 88% of the total annual gas demand of the boilers, with hot water contributing the other 12%. For the same mean temperature across the fourth quarter (8.5 °C), 2018 had a daily mean energy demand of 50.4 kWh, whereas the 2022 value was 41.4 kWh. This 9.0 kWh (18%) difference of the daily mean for Q4 suggests a shift in consumer demand influenced by other factors such as the energy price cap. This analysis provides additional understanding of how consumer energy demand for heating continues to evolve and invites further studies to be completed on future trends of energy demand for both space heating and hot water. Here, we also highlight the benefit of considering space heating and hot water as separate demands, as this provides additional insights and is something the paper helps to advocate for. [ABSTRACT FROM AUTHOR]

The ongoing transition to energy systems with high shares of variable renewables motivates the development of novel thermal power cycles that operate economically at low capacity factors to accommodate wind and solar intermittency. This study presents two recuperated power cycles with low capital costs for this market segment: (1) the near-isothermal hydrogen turbine (NIHT) concept, capable of achieving combined cycle efficiencies without a bottoming cycle through fuel combustion in the expansion path, and (2) the intercooled recuperated water-injected (IRWI) power cycle that employs conventional combustion technology at an efficiency cost of only 4% points. The economic assessment carried out in this work reveals that the proposed cycles increasingly outperform combined cycle benchmarks with and without CO2 capture as the plant capacity factor reduces below 50%. When the cost of fuel storage and delivery by pipelines is included in the evaluation, however, plants fired by hydrogen lose competitiveness relative to natural gas-fired plants due to the high fuel delivery costs caused by the low volumetric energy density of hydrogen. This important but uncertain cost component could erode the business case for future hydrogen-fired power plants, in which case the IRWI concept powered by natural gas emerges as a promising solution. [ABSTRACT FROM AUTHOR]

Radon is a natural radioactive gas, which has great radiation hazards. Mastering the radon exhalation law under complex conditions is of great significance to the safety and stability of uranium tailings pond. Based on the self-developed artificial microclimate chamber, the single factor influence of water content, temperature and crack rate of overburden soil on radon exhalation rate of uranium tailings pond was explored through simulation experiments, and the corresponding single factor mathematical model was obtained. The response surface model of radon exhalation rate was constructed by combining whale optimization algorithm to achieve accurate prediction of radon exhalation rate. The test results of simulated seismic station vibration test also confirm the scientificity of the model. The results of this study can be used not only to guide the prediction and prevention of radon, but also to guide the early warning of uranium tailings pond instability. [ABSTRACT FROM AUTHOR]

Purpose: In response to the challenges posed by the conventional manual flange docking method in the LNG (Liquefied Natural Gas) loading process, such as low positioning accuracy, constraints on production efficiency and safety hazards, this study analyzed the LNG five-axis loading arm's main functions and structural characteristics. Design/methodology/approach: An automated solution for the joints of the LNG loading arm was designed. The forward kinematic model of the LNG loading arm was established using the Denavit–Hartenberg (D-H) parameter method, and its workspace was analyzed. The Newton–Raphson iteration method was employed to solve the inverse kinematics of the LNG loading arm, facilitating trajectory planning. The relationship between the target position and the joint variables was established to verify the stability of the arm's motion. Flange center identification was achieved using the Hough transform function. Based on the ROS platform, combined with Gazebo and Rviz, an experimental simulation of automatic docking of the LNG loading arm was conducted. Findings: The docking errors in the XYZ directions were all less than 0.8 mm, meeting the required docking accuracy. Moreover, the motion performance of the loading arm during docking was smooth and free of abrupt changes, validating its capability to accomplish the automatic docking task. Originality/value: The proposed trajectory planning and automatic docking scheme can be used for the rapid filling of LNG filling arms and LNG tankers to improve the efficiency of LNG transportation. In guiding the docking, the proposed automatic docking scheme is an accurate and efficient way to improve safety. [ABSTRACT FROM AUTHOR]

The current study investigates the effects of an abundance of natural resources on the healthcare industry worldwide. Various natural resources proxies such as rents for coal, mineral, natural gas, and oil are used and analyzed by using a quarterly datasets for the period 2000:Q1–2020:Q4. Results from regional and income group datasets show that various forms of natural resources abundance around the globe exert statistically significant, but a mix of positive and adverse effects on the healthcare sector. Results also reveal that changes in and shocks given to natural resources precede significant changes in the healthcare sector in general. This study advises that countries need to achieve careful resource management, open governance, and economic diversification top priority in order to lessen reliance on a single resource and mitigate any negative effects. Further implications are provided at the end of this study. [ABSTRACT FROM AUTHOR]

Liquefied natural gas (LNG) exports from the United States have risen dramatically since the LNG‐export ban was lifted in 2016, and the United States is now the world's largest exporter. This LNG is produced largely from shale gas. Production of shale gas, as well as liquefaction to make LNG and LNG transport by tanker, is energy‐intensive, which contributes significantly to the LNG greenhouse gas footprint. The production and transport of shale gas emits a substantial amount of methane as well, and liquefaction and tanker transport of LNG can further increase methane emissions. Consequently, carbon dioxide (CO2) from end‐use combustion of LNG contributes only 34% of the total LNG greenhouse gas footprint, when CO2 and methane are compared over 20 years global warming potential (GWP20) following emission. Upstream and midstream methane emissions are the largest contributors to the LNG footprint (38% of total LNG emissions, based on GWP20). Adding CO2 emissions from the energy used to produce LNG, total upstream and midstream emissions make up on average 47% of the total greenhouse gas footprint of LNG. Other significant emissions are the liquefaction process (8.8% of the total, on average, using GWP20) and tanker transport (5.5% of the total, on average, using GWP20). Emissions from tankers vary from 3.9% to 8.1% depending upon the type of tanker. Surprisingly, the most modern tankers propelled by two‐ and four‐stroke engines have higher total greenhouse gas emissions than steam‐powered tankers, despite their greater fuel efficiency and lower CO2 emissions, due to methane slippage in their exhaust. Overall, the greenhouse gas footprint for LNG as a fuel source is 33% greater than that for coal when analyzed using GWP20 (160 g CO2‐equivalent/MJ vs. 120 g CO2‐equivalent/MJ). Even considered on the time frame of 100 years after emission (GWP100), which severely understates the climatic damage of methane, the LNG footprint equals or exceeds that of coal. [ABSTRACT FROM AUTHOR]

Trillions of cubic meters of gas reserve have been found in the Sinian Dengying carbonate reservoirs with normal pressure in the central Sichuan Basin, while no industrial gas reservoir have been detected in the Sinian Dengying reservoir with normal pressure in the eastern Sichuan Basin. The pore fluid pressure of gas reservoir is usually closely related to total gas content. To investigate the pore fluid pressure evolution and its implication for gas reserve preservation in the Sinian Dengying reservoir of the central and eastern Sichuan Basin, we conducted a comprehensive analysis including fluid inclusion petrography, microthermometry and Raman spectroscopy. The timings of gas inclusions captured in the central and eastern Sichuan Basin occurred from 175 to 92 Ma and 191 to 183 Ma, respectively. The presence of two‐phase vapour‐solid bitumen inclusions with similar phase proportions in a single fluid inclusion assemblage of fluorite provides direct evidence of in situ oil cracking to gas. The widespread solid bitumen from the Sinian Dengying reservoir in the central Sichuan Basin indicates the existence of massive oil cracking, which results in the formation of overpressure in the reservoir. Pore fluid pressure evolution of the Sinian Dengying reservoir of the central Sichuan Basin experiences normal pressure stage (200–155 Ma), overpressure development stage (155–90 Ma) and overpressure release stage (90–0 Ma). The maximum pore fluid pressure and its corresponding pressure coefficient of the Sinian Dengying reservoir of the central Sichuan Basin are approximately 141.4 MPa and 1.95, respectively. The overpressure development stage reflects the processes of oil cracking and gas accumulation, and the overpressure release stage reflects the dissipation of some natural gas in the Sinian Dengying reservoir of the central Sichuan Basin. The pore fluid pressure of the Sinian Dengying reservoir in the eastern Sichuan Basin has maintained at normal pressure since 200 Ma, indicating that the gas reservoir was small during the oil cracking stage and natural gas completely leaked due to tectonic uplift. [ABSTRACT FROM AUTHOR]

Methane dominated gas is one of the cleanest energy resources; however, there is no direct method to determine its source rock. Natural gases produced from the eastern Sichuan Basin together with seismic data were studied for their sources and secondary alteration by thermochemical sulfate reduction (TSR). Our results demonstrate that Upper Permian to Lower Triassic (P3ch-T1f) gases in the surrounding of the Kaijiang-Liangping area show volatile organic sulfur compounds (VOSCs) δ34S values close to those of the associated H2S, and may have been altered by methane-dominated TSR, resulting in positive shift in methane δ13C1 values with increasing TSR extents. Other (or group 2) gases produced from the P3ch-T1f reservoirs from the southern area and the Upper Carboniferous to Middle Permian (C2h-P2q) from the eastern Sichuan Basin are not significantly changed by TSR, show similar δ34S values between the kerogens and some VOSCs, and may have been derived from the Lower Silurian and Middle Permian source rocks. This study demonstrates a case for the first time showing the δ34S values of VOSCs can be used as a tool for direct correlation between non-TSR altered gas and source rocks. Methane-dominated gas pools can be found using gas and source rock geochemistry combined with seismic data. [ABSTRACT FROM AUTHOR]

Helium is an irreplaceable strategic mineral resource, and commercial helium-rich gas fields (He>0.1%) worldwide are typically discovered serendipitously during hydrocarbon exploration efforts. According to an analysis of 75 helium-rich gas fields and 1048 natural gas samples worldwide, helium in natural gas generally exhibits "scarce", "accompanying", and "complex" properties, and helium-rich gas fields often occur at depths <4500 m. Helium concentrations in He-CH4 and He-CO2 gas fields are notably lower than those in He-N2 gas fields (He>1%). However, geological reserves in the former two types of gas fields are mainly in the range of 107–1011 m3, whereas in the latter, they are only in the range of 105–107 m3. There are nevertheless notable disparities in the genesis and migration patterns between helium and gaseous hydrocarbons. Helium necessitates carriers (such as formation water, hydrocarbon fluids, N2, mantle-derived fluids, etc.) during both accumulation and long-distance migration processes, where migration conduits are not confined to sedimentary strata, and may extend to the basin's basement, lower crust, and even lithospheric mantle. However, the accumulation conditions of both helium and gaseous hydrocarbons are generally considered equivalent. The presence of gaseous hydrocarbons facilitates both the rapid exsolution of helium within helium-containing fluids and subsequent efficient aggregation in gaseous hydrocarbons, while both reduce helium diffusion and diminish escape flux. In terms of caprock, gypsum, salt, and thick shale as sealing layers contribute to the long-term preservation of helium over geological timescales. Large helium-rich gas fields, predominantly crust-derived gas fields, are primarily concentrated in uplifted zones of ancient cratonic basins and their peripheries. Based on a diagram of the He concentration versus He/N2 ratio, crust-derived helium fields can be categorized as basement, combined basement-sedimentary rock, and sedimentary rock helium supply types. Comprehensively given China's helium grade, helium resource endowment, natural gas industrialization process, and current helium purification processes, the foremost deployment zones for the commercial production of helium should be the helium-rich gas fields located in the Ordos, Tarim, Sichuan, and Qaidam Basins in western and central China. In addition, certain (extra) large helium-containing gas fields serve as important replacement zones. [ABSTRACT FROM AUTHOR]

The present study conceptualizes and simulates a methanol production process through the direct hydrogenation of captured CO2. CuO/ZnO/ZrO2 was employed as the catalyst and Aspen HYSYS was used for the process simulation. Configurational optimization of the process flowsheet was carried out using a step-by-step hierarchical approach. Many alternate flowsheets have resulted, and their capital investment, product cost, and profitability measures were calculated. The discrimination among the competing flowsheets was carried out based on net profit and percent return on investment. The retained flowsheet was further analyzed for optimizing the recycle ratio and evaluating the effect of the price of captured CO2, green H2, natural gas (fuel), and catalyst on the economic performance of the plant. The optimum value of the recycle ratio was computed to be 4.23. Additionally, it was found that the price of H2 is the most important parameter in defining the feasibility and profitability of the process. Mathematical correlations were also developed that relate the profitability and price of the above-mentioned feed materials. [ABSTRACT FROM AUTHOR]