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Copyright of Ecosistemas y Recursos Agropecuarios is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• The CLC and cyclic CO2 were integrated to form a high-efficient syngas production and generating system. • The CLC CCR system achieved exergy efficiency of 55.02%, an improvement of 2.55 percentage points over the CCR system. • The cost of liquid fuel production was reduced by 9.21% compared to CCR system. • The extremely improvement potential in terms of energy savings and carbon emissions owned to CLC CCR. The utilization of greenhouse gases, such as CO 2 and CH 4 , as feedstocks for the production of synthetic fuels and chemicals has gained noteworthy traction. Converting syngas produced by carbon dioxide and methane into liquid fuel through Fischer-Tropsch synthesis is important method to address domestic oil shortage. However, the significant difference between the reforming and the combustion drive temperature can result in an energy level mismatch. Chemical looping combustion technology utilizes oxygen carriers to achieve graded utilization of energy, thereby reducing the irreversible losses in the conventional combustion process. This study conducted comprehensive thermodynamic and economic analysis of the chemical looping combustion coupled with methane carbon dioxide reforming (CLC CCR) process compared to the conventional process (CCR). The results demonstrate that the CLC CCR system has higher efficiency of 53.10% compared to 50.69% in the CCR system, leading to 9.21% decrease in production costs for liquid fuel. Additionally, the CLC CCR system increased liquid fuel output by approximately 5%, achieving impressive energy saving rate of 7.74% and significant reduction in carbon dioxide emissions by 21.51%. Furthermore, the efficiencies and economic performance were introduced to the study, and optimization measures were proposed to improve the efficiency and economic outcomes benefits of the main components. [Display omitted] [ABSTRACT FROM AUTHOR]

Copyright of Canadian Foreign Policy Journal (CFPJ) is the property of Routledge and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dual-throat Nozzle (DTN) is known as one of the most effective approaches of fluidic thrust-vectoring. It is gradually flourishing into a promising technology to implement supersonic and hypersonic thrust-vector control in aircrafts. The main objective of the present study is numerical investigation of the effects of secondary injection geometry on the performance of a fuel-injected planar dual throat thrust-vectoring nozzle. The main contributions of the study is to consider slot and circular geometries as injector cross-sections for injecting four different fuels; moreover, the impact of center-to-center distance of injection holes for circular injector is examined. Three-dimensional compressible reacting simulations have been conducted in order to resolve the flowfield in a dual throat nozzle with pressure ratio of 4.0. Favre-averaged momentum, energy and species equations are solved along with the standard k - ε model for the turbulence closure, and the eddy dissipation model (EDM) for the combustion modelling. Second-order upwind numerical scheme is employed to discretize and solve governing equations. Different assessment parameters such as discharge coefficient, thrust ratio, thrust-vector angle and thrust-vectoring efficiency are invoked to analyze the nozzle performance. Computationally predicted data are agreed well with experimental measurements of previous studies. Results reveal that a maximum vector angle of 17.1 degrees is achieved via slot injection of methane fuel at a secondary injection rate equal to 9% of primary flow rate. Slot injection is performing better in terms of discharge coefficient, thrust-vector angle and thrust-vectoring efficiency, whereas circular injection provides higher thrust ratio. At 2% secondary injection for methane fuel, vector angle and vectoring efficiency obtained by slot injector is 8% and 34% higher than the circular injector, respectively. Findings suggest that light fuels offer higher thrust ratio, vector angle and vectoring efficiency, while heavy fuels have better discharge coefficient. Increasing center-to-center distance of injector holes improves thrust ratio, while having a negative effect on discharge coefficient, vector angle and vectoring efficiency. A comparison between fuel injectant of current study and inert injectant in the previous studies indicates that fuel reaction could exhibit substantial positive effects on vectoring performance. Secondary-to-primary momentum flux ratio is found to play a crucial role in nozzle performance. [ABSTRACT FROM AUTHOR]

This study aimed at evaluating the feasibility of CH 4 production in a mesophilic (30 °C) single-stage anaerobic co-digestion of cassava wastewater (CW) and glycerol in an anaerobic fluidized bed reactor (AFBR) with mixing ratio of 50 % / 50 % CW/Gly on a (chemical oxygen demand)COD basis. Thus, the following strategy was used: increasing the organic loading rate (OLR) (1–20 g COD.L−1.d−1) by increasing the substrate concentration (1–20 g COD.L−1) and applying a hydraulic detention time (HRT) of 24 h. The AFBR presented a maximum methane (CH 4) content of 88.38±1.94 % and a CH 4 yield (MY) of 293.48±18.37 mL of CH 4.mL−1COD rem in the OLR of 1 g COD.L−1.d−1 and the maximum methane production rate (MPR) of 62.09±2.75 mL of CH 4.L−1.h−1 in the OLR of 20 g COD.L−1.d−1. The conversion of glycerol and carbohydrates remained above 91±0.54 % and 82±2.79 %, respectively, and the COD conversion was above 80±0.65 %. The main metabolites were HAc, HPr, HBu, EtOH and HVa. The most abundant genera identified in the AFBR were Izemoplasmatales and Enterobacteriaceae for the bacteria domain, and Methanosaeta , Methanobacterium for the archaea domain. The single-stage system is robust and can operate with higher OLR without reducing the efficiency of wastewater treatment and CH 4 production. [Display omitted] • Co-digestion of cassava wastewater and glycerol on CH4 production was evaluated. • The maximum CH4 production rate was 62.09 mL CH4. L−1. h−1 at 20 g COD.L-1.d-1. • A higher CH4 yield of 293.48 mL CH4.gCOD−1 rem was observed at 1 g COD.L-1.d-1. • The acetoclastic archaea Methanosaeta was the most abundant genus in all samples. • Genes encoding enzymes related to acetoclastic path were the most inferred ones. [ABSTRACT FROM AUTHOR]

As a prevailing hydrometallurgical extraction system for bismuth sulfide concentrate, the acidic chloride solution has superior applicability to raw materials and high recovery ratio of metallic bismuth. Nevertheless, it has disadvantages of being easily volatile and strongly corrosive, as well as large energy consumption and poor deposition morphology during chloride electrolysis. Methane-sulfonic acid (MSA) solution is widely considered as the next generation of green hydrometallurgical system, due to its excellent physicochemical properties such as high metal salts solubility, low volatility, and biodegradability. In this study, membrane electrolysis technique was adopted based on the acidic bismuth methane-sulfonate leaching solution, and the influence of electrolyte composition, cathode current density (CCD), and temperature parameters on the bismuth conversion ratio (BCR) and deposition rate (BDR), techno-economic indicators and cathodic bismuth morphology were studied. The results show that the CCD affects the deposits morphology significantly, and the bismuth metal is partially dark and composed of loose ellipsoidal particles at high current density. Under the optimal conditions (70 g/L Bi3+ ions, 5 g/L Fe2+ ions, 110 g/L MSA, 35 °C, 180 A/m2), high-purity metallic bismuth (Bi 99.97 %) with silver-white luster is obtained. The BCR and BDR are 9.43 % and 0.46 kg/(h·m2), respectively. The cathodic current efficiency (CCE) reaches over 98 %, and specific energy consumption (SEC) is less than 715 kWh/t Bi. Compared with the traditional chloride system, the MSA-based membrane electrolysis medium has advantages of environmental friendliness, low occupational risks, low carbon and energy consumption, and can thus provide a sustainable green solution for bismuth hydrometallurgy. [Display omitted] • Bismuth metal is produced from MSA-based electrolyte by membrane electrolysis. • Acidic iron methane-sulfonate leaching agent can be regenerated in the anode chamber. • Adjusting electrolyte composition can greatly reduce specific energy consumption. • Excessive cathode current density deteriorates the morphology of bismuth metal. [ABSTRACT FROM AUTHOR]

The production of short-chain carboxylates (SCCs) from readily degradable food waste exhibits superior product value compared to biogas production, but SCCs' high solubility poses challenges in their production and recovery. In this study, we applied two novel modules to in-situ extract SCCs from the continuously produced fermentative broth, namely direct coupling of bipolar membrane electrodialysis (BPED) and the integration of upstream membrane permeation (MP) and BPED. The remarkable extraction efficiency of BPED effectively mitigated the inhibitory effects from the accumulation of SCCs products, yielding 475.2 mg gVS−1, which was 20.26% higher than the control phase. The OH− generated by the bipolar membrane was cycled back to regulate the pH of bioreactor, thereby completely eliminating the need for external alkaline additives. The upstream MP effectively prevented ion exchange membrane fouling, and the OH− generated by BPED achieved the in-situ regeneration of MP's alkali extract, reducing the OH− demand by 40% in MP+BPED stage. It was also observed that BPED exhibited higher selectivity towards small-molecule acetic acid, while MP tended to recover larger-molecule caproic acid. Selective extraction of specific SCC drove the product spectrum of the bioreactor to produce more SCC that was selectively extracted. [Display omitted] • In situ BPED extraction increased SCCs yield by 20.26%. • Upstream MP helped to prevent the ion exchange membrane fouling. • The generated OH− by BPED reduced the external base input. • BPED exhibited higher selectivity towards C2 acid while MP towards C6 acid. • Extraction selectivity drove to form a different product spectrum. [ABSTRACT FROM AUTHOR]

This study investigates the potential of foam flooding for enhanced oil recovery in oil-wet fractured systems under reservoir conditions. Two surfactants with distinct ionic properties were employed in combination with methane to generate foam via simultaneous injection into propped fractures, aiming to optimize the diversion of gas from fractures to the matrix for improved oil recovery. Core flooding experiments demonstrated the critical roles of total injection rate and foam quality in controlling foam performance. Increasing the total injection rate from 1 to 3 cm³/min enhanced foam generation rates and foam lamella stability, facilitating better interactions between fractures and the matrix. However, beyond an injection rate of 4 cm³/min, there was a decline in apparent viscosity and mobility reduction factor. Foam strength was directly proportional to higher foam quality within the 50 to 80% range, but beyond 85% foam quality, fluctuations in pressure drop signaled the formation of weaker, less stable foams. Micro-scale experiments validated these macroscopic findings, revealing that smaller bubbles were associated with higher flow rates and lower foam qualities. This research contributes valuable insights into both micro and macro-scale in-situ foam generation, which can inform the design and application of foam-based enhanced oil recovery methods in fractured reservoirs. • We investigate the performance of hydrocarbon foam in propped fractured oil-wet carbonate at reservoir conditions. • We present an efficient experimental methodology to test surfactants and determine their suitability for field applications. • Spontaneous imbibition, static adsorption, and emulsion tendency tests were conducted to probe the solid-fluid interactions. • Results from macro- and micro-scale experiments provide key insights into the dynamics of foam generation and propagation. • We examined the effects of key parameters, such as surfactant type, total flow rate, and foam quality, on foam performance. [ABSTRACT FROM AUTHOR]

Coal slime can significantly enhance anaerobic digestion (AD) of chicken manure (CM) for methane production; However, the underlying mechanism is still unclear. This study has mainly discussed variation characteristics of key metabolic pathways in the AD process of CM by coal slime. Dry CM and coal slime (CS) were selected and coal seam mine water was applied as bacteria source. CS effects on the metabolic pathway of CM fermentation system were studied by biogas production simulation experiments and metagenomic analyses. The results indicated that variations in pH and CS amount exerted significant effects on the biogas generation in the contest of CM fermentation. Optimal conditions for enhanced biogas production were observed when the pH approached neutrality, and the CS quantity was 0.2 g, highlighting substantial potential of CM for biogas generation. The addition of CS resulted in a 13.1%, 1.9%, and 1.8% increase in the relative abundance of Bacteroides , Aminobacterium , and Methanothrix. This, in turn, elevated gene abundance of essential enzymes in the glycolytic pathway (glycolysis and pyruvate metabolism), promoting acetic acid production and providing a foundational basis for methanogen metabolic gas production. Furthermore, the addition of CS lead to a notable increase in the abundance of the pilA gene in Methanocorpusculuma (111.5%) and Methanothrix (66.1%). This suggested the involvement of CS in DIEF, thereby augmenting the anaerobic methane production potential of CM. These outcomes offer valuable theoretical insights for optimizing the biogas production potential of CM and maximizing the resource utilization of CS. [Display omitted] • Coal slime increased methane yield from chicken manure. • Biogas yield of chicken manure was analyzed by response surface methodology. • Key metabolic functions of substrate metabolism were efficiently expressed. • Coal slime enrichment led to an increased abundance of key genes related to DIET. [ABSTRACT FROM AUTHOR]

• CH 4 carbonylation to olefins and alcohols over carbon-based Fe and Co-oxide catalysts. • Fe– and Co–catalysts were designed through the construction of co-assembly strategy. • An excellent CH 4 conversion of 40% over the iron oxide catalyst. • High selectivity toward C 2 –C 4 olefins (42%) and C 1 –C 4 alcohols (38%) over Fe catalyst. • The alcohols selectivity of >75% over the non-doped cobalt oxide catalyst. Herein, iron– [Fe] and cobalt–oxide [Co] nanoparticles supported on carbon were synthesized through the construction of the co-assembly strategy via the mixture of carbon source resol, diglyme, triblock copolymer, and M(acac) x (M = Fe3+ and Co2+) complexes. The prepared nanocomposites possess large pore sizes, high surface areas, large pore volumes, and highly dispersed nanoparticles. The exceptional catalytic performance together with high selectivity toward alcohol and light olefin products over the [Fe] and [Co] catalysts were observed in the CH 4 carbonylation reaction. The [Fe] catalyst displayed an acceptable CH 4 conversion of 40% and high selectivity toward C 2 –C 4 light olefins (>42%) and C 1 –C 4 alcohols (>38%) while exhibiting a low CO 2 production at moderate CO conversion of >52%. The CH 4 conversion was lower over the [Co] catalyst, although the selectivity of alcohols stretched beyond the [Fe] catalyst (~76%), with CH 4 and CO conversion of 15.40 and 31.83%, respectively. Besides alcohol, low acetic acid and ethanal (acetaldehyde) formed over the [Co] catalyst. The catalysts were also employed in the Fischer–Tropsch synthesis (FTS). The [Fe] catalyst demonstrated high FTS catalytic performance with 85% CO conversion, the high C 2 –C 4 selectivity, and low selectivity of methane. In comparison, the [Co] catalyst exhibited high conversion of CO (>81%) and suitable selectivity toward C 2 –C 4 and C 5+ hydrocarbons. [Display omitted] [ABSTRACT FROM AUTHOR]

This research aimed to develop a new method for clean utilization and treatment of landfill leachate and solid waste weathered coal. Landfill leachate and weathered coal were adopted for combined anaerobic fermentation for methane production. The characteristics of microbial community, mechanism of biological methane production, and utilization characteristics of fermentation broth and solid residue for co-fermentation were analyzed through metagenomics, soluble organic matter detection and thermogravimetric (TG) analysis. The obtained results revealed that combined anaerobic fermentation increased methane production by 80.1%. Syntrophomonas , Salipiger , Methanosaeta and Methanothrix were highly correlated. Gene abundances of 2-oxoacid ferredoxin oxidoreductase and enolase were increased in methane conversion pathway mainly by acetic acid. Pyruvate-ferroredoxin oxidoreductase, 2-oxoglutarate synthase and succinate dehydrogenase acetate synthase intensified electron transfer pathways among microorganisms. Fulvic acid, tyrosine and tryptophan contents were high in fermentation broth. Volatile decomposition temperature, ignition point and residual char combustion temperature of residual coal were decreased and combustion was more stable. The obtained results showed that the co-fermentation of landfill leachate and weathered coal improved biological methane gas production, degraded weathered coal and improved combustion performance, which provided a new idea for weathered coal clean utilization. [Display omitted] • Combined anaerobic fermentation promotes biomethane conversion. • Key metabolic functions of acetic acid are effectively expressed. • Abundance of enzyme genes related to electron transfer between microorganisms increased. • Combustion performance of solid residue after anaerobic fermentation was improved. [ABSTRACT FROM AUTHOR]

The oil and gas sector produces a considerable volume of greenhouse gas emissions, mainly generated from flaring and venting natural gas. Herein, a techno-economic analysis has been performed of a switchable catalytic process to convert the CH 4 and CO 2 in flared/vented natural gas into syngas or methanol. Specifically, it was shown that depending on greenhouse gas composition, dry methane reforming (DRM), reverse water-gas shift (RWGS), and CO 2 methanation could be chosen to valorise emissions in an overall profitable and flexible operation scenario. The switchable process produced methanol and synthetic natural gas as its products, resulting in an annual income of €687m and annual operating expenses of €452m. The pre-tax profit was calculated at €234m, and at the end of the project, the net present value was calculated as €1.9b with a profitability index of 4.7€/€. The expected payback time of this process was ca. 4 years, and with a 35% internal rate of return (IRR). Most importantly, this process consumed 42.8m tonnes of CO 2 annually. The sensitivity analysis revealed that variations in operation time, green hydrogen price, and products' prices significantly impacted the profitability of the process. Overall, this techno-economic analysis demonstrated that switchable catalysis in greenhouse gas utilisation processes is profitable, and thus it could play an important role in achieving net zero emissions. • A switchable CO 2 catalytic process that used flared/vented gas was investigated. • Methanol was produced via RWGS and DRM and natural gas via CO 2 methanation. • CO 2 consumption and profitability analyses were carried out. • The designed switchable catalytic plant was carbon negative. • The process was profitable, mainly due to the production of synthetic natural gas. [ABSTRACT FROM AUTHOR]

Photocatalytic dry methane reforming uses light energy and a nanostructured photocatalyst to convert both carbon dioxide and methane gas to syngas for production of fuels and value-added chemicals. The conversion of these two greenhouse gases (GHG) makes photocatalytic dry methane reforming a potentially environmentally attractive process; however, little research has been done to assess its life cycle environmental impacts in comparison to conventional commodity chemical production methods. Further, practical research has been limited to lab scale studies, which do not fully reflect the technical and environmental performance of commercial scale systems. In this work, a simulation describing the production of methanol from a photocatalytic dry reforming process is used to inform a life cycle assessment to estimate its potential environmental impacts at scale. Results indicate that for methanol produced via photocatalytic dry methane reforming to have the same life cycle GHG intensity as methanol produced through conventional steam methane reforming, a combination of improved technological performance and process intensification is required. This includes increased chemical conversion, electricity grid decarbonization, and the use of low greenhouse gas intensive feedstocks. Promisingly, results indicate that methanol produced using a photocatalytic dry methane reforming process that employs landfill gas as a feedstock and 100% renewable electricity, could potentially produce methanol with a negative global warming potential. Opportunities to improve the environmental impact of a photocatalytic dry reforming process so as to widen its scenario applicability are also discussed. • Solar Photocatalytic Dry Methane Reforming had low feedstock conversion efficiency. • Low conversion efficiency represented the major driver of environmental impacts. • Use of renewable energy and biogenic feedstocks improved environmental performance. • Technical advancements with process intensification are required for competitiveness. [ABSTRACT FROM AUTHOR]

Many studies have been conducted for the two-stage solid oxide fuel cell (SOFC) module. Since there are presently no studies for the fuel regenerator's effect on the electrical efficiency of the module to the best of the authors' knowledge, the effect of removing H2O and/or CO2 was investigated. To estimate the electrical efficiency, models of the two-stage SOFC stacks with a fuel regenerator that use hydrocarbon or hydrogen fuel were used. The electrical efficiency was estimated by calculating the maximum fuel utilization rate and the cell voltage. The risk of carbon deposition from the regenerated anode off-gas was estimated by calculating the chemical equilibrium region of the anode gas. The maximum electrical efficiency had a net alternating current (AC) of 71.8% (lower heating value (LHV)) from methane fuel. This was obtained when 100% of the H2O and CO2 were removed by the fuel regenerator. In addition, the net AC efficiency of 60.8% (LHV) was obtained from the 10% humidified hydrogen fuel when 98.0% of H2O was removed by the fuel regenerator. These results suggest a high potential to generate a highly efficient power by the two-stage SOFC stacks with a fuel regenerator. [ABSTRACT FROM AUTHOR]

In this work, a numerical study has been carried out in order to investigate the effects of a micro combustor size on the exergy and energy efficiencies of a premixed hydrogen/air for a micro thermophotovoltaic system. For this purpose, six combustors in different sizes are designed, in which geometry dimensional size gradually reduced. The effects of the combustor size on the entropy, exergy, radiation power, and energy conversion efficiency are investigated. Also, mean and uniform wall temperature are discussed. In order to compare the entropy generation of each micro combustor, a dimensionless entropy generation rate is defined. The hydrogen/air combustion with 9 species and 19 reversible elementary reactions were simulated by using the Eddy Dissipation Concept (EDC) model. Results indicate the micro-combustor geometry size has important effects. A reduction of the combustor geometry size dimensionality causes an increase in average wall temperature and makes it uniform. Moreover, by decreasing micro combustor size, the radiation power efficiency increases from 41.96 to 45.62% and total energy conversion efficiency from 6.46 to 7.02%. The highest exergy efficiency, 38.63%, is achieved in the smallest micro combustor while the minimum exergy efficiency 33.22%, is obtained in the largest micro combustor. [ABSTRACT FROM AUTHOR]

Metal supported solid oxide fuel cell (MSC) technology has a significant potential for mobile applications, due to high electrical efficiencies, fuel flexibility, cheap materials, and mechanical robustness. The MSC concept in the current study relies on scalable, ceramic processing methodology. Two MSC generations with different anodes, one with a FeCr-ScYSZ-based anode backbone and one with a FeCr-titanate based anode backbone, both infiltrated with GDC and Ni electro catalysts, were tested using methane containing fuel. It was found that the internal reforming activity of the anodes is reduced as compared to state-of-the-art Ni-cermet anodes, due to the lower Ni content in the anodes of the MSCs. Still, power densities of ca. 0.22 W cm-2 were obtained at 650 °C in a methane/steam fuel and long-term tests at medium to high fuel utilization were successfully demonstrated on the titanate based MSC. [ABSTRACT FROM AUTHOR]

In this work, a numerical study has been carried out in order to investigate the effects of a micro combustor size on the exergy and energy efficiencies of a premixed hydrogen/air for a micro thermophotovoltaic system. For this purpose, six combustors in different sizes are designed, in which geometry dimensional size gradually reduced. The effects of the combustor size on the entropy, exergy, radiation power, and energy conversion efficiency are investigated. Also, mean and uniform wall temperature are discussed. In order to compare the entropy generation of each micro combustor, a dimensionless entropy generation rate is defined. The hydrogen/air combustion with 9 species and 19 reversible elementary reactions were simulated by using the Eddy Dissipation Concept (EDC) model. Results indicate the micro-combustor geometry size has important effects. A reduction of the combustor geometry size dimensionality causes an increase in average wall temperature and makes it uniform. Moreover, by decreasing micro combustor size, the radiation power efficiency increases from 41.96 to 45.62% and total energy conversion efficiency from 6.46 to 7.02%. The highest exergy efficiency, 38.63%, is achieved in the smallest micro combustor while the minimum exergy efficiency 33.22%, is obtained in the largest micro combustor. [ABSTRACT FROM AUTHOR]

• 3D MAX Ti 3 AlC 2 /TiO 2 synthesized for photocatalytic CO 2 reduction with CH 4 and H 2 O. • Photo-activity of Ti 3 AlC 2 /TiO 2 was 6.8 folds higher than using TiO 2 for DRM process. • DRM promoted CO evolution, while BRM found efficient for both CO and H 2 production. • Activity of Ti 3 AlC 2 /TiO 2 in monolith was 3.5 folds higher than fixed-bed photoreactor. • 3D Ti 3 AlC 2 MAX with monolithic support promoted activity and reusability in cycles. Design and fabrication of three dimensional Ti 3 AlC 2 MAX/TiO 2 composite immobilized over monolithic support was obtained through sol-gel approach. With partial oxidation and incorporation of Ti 3 AlC 2 essentially promotes light absorption, charge transfer and extends photo-induced charge carrier lifetime. The highest CO yield of 1566 μmol g-cat−1 was obtained over Ti 3 AlC 2 MAX/TiO 2 , being 6.8 folds higher than pure TiO 2 NPs. Performance of structured composite tested in methane steam reforming (MSR), methane dry reforming (MDR) and methane bi-reforming (MBR) reveals 1.2 and 1.6 folds higher activity in MBR than using MDR and MSR, respectively. Similarly, quantum yield in a monolith photoreactor was 3.5 folds higher than using a fixed-bed system. This divulges that MBR gave proficient oxidation and reduction reactions in electron-rich 3D MAX structure, whereas, monolith photoreactor provides larger photon-energy consumption with improved sorption process to boost production of CO and H 2 with enhanced stability. Thus, this work demonstrated 3D Ti 3 AlC 2 MAX/TiO 2 a promising catalyst and monolith photoreactor an efficient photon flux harvesting system for boosting hydrogen rich syngas production. [ABSTRACT FROM AUTHOR]

The focus of this research is the potential of biomethane in Britain's gas grid. It examines its relative ability to address Britain's sustainability and energy security challenges from an economic perspective. Such research is important because UK is wedded to gas for heat production and power generation and is increasingly dependent on imported gas, in line with shrinking domestic production, and uncertain future trading relationships. Also, dependency on natural gas, threatens Britain achieving its legally-binding carbon budgets. The study included a thorough literature review, primary research to finally uncover the views of key UK market participants plus analytical modelling. The findings reveal that the market is cautiously optimistic, despite reservations regarding feedstock availability and the impending cessation of subsidy approvals. Investors are in greater need of long-term certainty, however, and the challenge of decarbonising heat and heavy-duty transport warrants this. Retail price premiums are polarised but, in line with wholesale costs, relatively high compared to electricity. The key recommendation is for the policymakers to follow precedents in renewable electricity and liquid biofuels, by mandating that energy suppliers, owners of heavy-duty road fleets and occupiers of new buildings purchase biomethane. In tandem, feedstock and grid-entry restrictions must be tackled creatively. • Dependency on natural gas threatens Britain achieving its carbon budgets. • Biomethane is a solution for sustainable and clean gas supply for the UK. • Cautiously optimistic market in the UK on the future of biomethane in the energy mix • Polarised retail price premiums for green gas relatively high compared to electricity • Recommendation: UK policymakers to follow renewable electricity precedents [ABSTRACT FROM AUTHOR]

Automobile numbers are increasing day by day that demand more fuel and produce more emission. In addition, petroleum sources are limited in nature and emission norms are tightening day by day. Those scenarios are motivating the researcher to find non-petroleum clean energy source. Gaseous fuel supplementation is helpful in obtaining the above stated objective. In this study, methane gas supplementation has done to diesel engine. The investigation was carried out to analyze the performance and emission of CI engine using 0–75% substitution of diesel indicated power by methane energy in dual fuel mode at varying load (25%, 50% and 75%). The result shows that brake thermal efficiency (BTE) and relative air fuel ratio decreases with methane energy share (MES), while unaccounted heat loss increases. Here, a comparison of NO and NO 2 emissions have been presented to investigate the non-thermal effect of CH 4 on NO x emission. Combined reduction in nitrogen oxide and soot emission makes the outcomes of this study more suitable to implement for achieving the strict emission norms. Hence, CH 4 augmentation is beneficial at mid and higher load conditions with lower emissions and energy consumption. [ABSTRACT FROM AUTHOR]

• The reduction of CO 2 to produce the renewable fuels or valuable chemicals. • The main reduction products are discussed and a more superior catalyst is selected from the viewpoint of the product. • A common strategy for converting CO 2 to the desired target product. The emissions of carbon dioxide (CO 2) from the combustion of hydrocarbon fuels have brought increasingly serious global warming. Photocatalytic conversion of CO 2 to the renewable fuels or valuable chemicals is proposed as an effective solution to simultaneously achieve the reduction of CO 2 emission, the use of sustainable solar energy and the harvest of products with high added-value. Various products such as methane (CH 4), methanol (CH 3 OH), carbon monoxide (CO) have been gained through the photocatalytic conversion of CO 2. This review systematically summarized the research progress of photocatalytic conversion of CO 2 from the product selectivity point of view. Particularly, the common strategies to covert CO 2 into the desired target products, including the surface modification of catalyst, the control of reaction conditions, the selection of incident light source, are completely discusses. Finally, the challenges and prospects in achieving efficient, stable and selective CO 2 photoconversion are pointed out. [ABSTRACT FROM AUTHOR]

In this work, the novel N-damo (Nitrite dependent anaerobic methane oxidation) process was investigated at high biomass activities for its potential to remove simultaneously nitrite and methane, as well as selected antibiotics commonly found in sewage in trace amounts. For this purpose, two MBRs were operated at three high nitrite loading rates (NLRs), namely 76 ± 9.9, 161.5 ± 11.4 and 215.2 ± 24.2 mg N–NO⁻ 2 L−1 d−1, at long-term operation. The MBRs performance achieved a significantly high nitrite removal activity for an N-damo process (specific denitrifying activity of up to 540 mg N–NO⁻ 2 g−1 VSS d−1), even comparable to heterotrophic denitrification values. In this study, we have implemented a novel operational strategy that sets our work apart from previous studies with similar bioreactors. Specifically, we have introduced Cerium as a trace element in the feeding medium, which serves as a key differentiating factor. It allowed maintaining a stable reactor operation at high NLRs. Microbial community composition evidenced that both MBRs were dominated with N-damo bacteria (67–87% relative abundance in period III and I, respectively). However, a decrease in functional N-damo bacteria (Candidatus Methylomirabilis) abundance was observed during the increase in biomass activity and concentration, concomitantly with an increase of the other minor families (Hypomicrobiaceae and Xanthobacteraceae). Most of the selected antibiotics showed high biotransformation such as sulfamethoxazole, trimethoprim, cefalexin and azithromycin, whereas others such as roxithromycin and clarithromycin were only partially degraded (20–35%). On the contrary, ciprofloxacin showed almost no removal. Despite the metabolic enhancement, no apparent increase on the antibiotic removal was observed throughout the operation, suggesting that microbiological composition was of greater influence than its primary metabolic activity on the removal of antibiotics. [Display omitted] • High N-damo activity was achieved, with a maximum of 540 mg N g⁻1 VSS d⁻1. • Most antibiotics were biotransformed except for CIP that showed persistent behavior. • High NLRs increased the microbial diversity by decreasing N-damo as dominant taxon. • Changes in N-damo abundance appear to have influenced the OMPs removal. [ABSTRACT FROM AUTHOR]

The inefficient conversion of carbon dioxide (CO 2) to methane often restricts the advancement of CO 2 biomethanation technologies. This study explored the degrading performance, microbial community compositions, and functional gene abundance to examine the impact of zirconium metal-organic frameworks (Zr-MOFs) on the CO 2 biomethanation process. The results showed that the maximum utilization rates of CO 2 and H 2 increased by 2.77 times and 2.36 times after the addition of Zr-MOFs, respectively, and the corresponding conversion rate of CO 2 to methane also increased by 57.53%. Additionally, Zr-MOFs enhanced the COD removal efficiency and hydrolysis of tryptophan-like proteins and humic acid-like substances, resulting in more volatile organic compounds, such as tetradecane, 2-pentanone, and hexadecanoic acid. The analysis of microbial community structure revealed that the relative abundance of Methanothrix and Metanobacterium increased by 24.40% and 36.02% after the addition of Zr-MOFs, respectively. The methane metabolism revealed that Metanobacterium was a member of the same aceticlastic methanogenic pathway as Metanothrix , which encodes acetyl-CoA synthetase to catalyze the synthesis of acetyl-CoA from acetate, and Zr-MOFs also increased the relative abundance of genes that encode the enzyme responsible for converting intermediates to methane. Finally, Zr-MOFs improved the biogenesis and utilization of acetate and hydrogen (H 2) by enhancing the activity of enzymes, thereby providing more nutrients for methanogenesis. This study provided thorough explanations for the application and improvement of Zr-MOFs in CO 2 biomethanation technology. [Display omitted] • Zr-MOFs improve the utilization rates of CO 2 for biomethane production. • Zr-MOFs enhance the hydrolysis of extracellular polymers. • Zr-MOFs promote the generation of volatile organic compounds. • The activity of methanogens is enhanced by Zr-MOFs. • Zr-MOFs increase the abundance of enzymes involved in CO 2 biomethanation. [ABSTRACT FROM AUTHOR]

It has been a common way to recycle digestate after biogas production as a biofertilizer. However, the huge generation of digestate especially its liquid part surpasses the market consumption quantity, which in turn hinders the sustainable operation of a biogas plant. Biotreatment of liquid digestate (LD) with microorganisms is one way to reduce chemical oxygen demand (COD) and nitrogen content. This study enriched three microflorae from environmental water, liquid and solid digestate. After community structure analysis, the microflora from LD itself exhibits superior nitrogen removal function to the other two microflorae, and its predominant microbial strains are from Aliidiomarina , followed by Parapedobacter. The microflorae can grow at pH range from 7 to 10. pH and ammonium concentration show synergistic effect on the growth of microflorae. The microflora from LD can completely realize nitrogen removal in man-made medium within 48 h, and remove 93.7 % ammonia nitrogen (NH 3 -N) and 88.1 % COD from LD at optimum C/N ratio of 9. Sodium acetate and the fermented mash from grain ethanol production process are the preferable carbon sources to improve the removal of nitrogen and COD. The re-inoculation of indigenous microflora into LD can realize 2.9∼10.9 % increase of NH 3 -N removal with or without addition of carbon sources, and 0.1∼11.7 % improvement on COD removal with addition of carbon sources except glycerol. It means that the enrichment of the indigenous microflora combined with the addition of proper carbon source is a potential way to enhance the nitrogen and COD removal from LD. [Display omitted] • NH 3 -N removal from liquid digestate can be improved by its indigenous microflora. • pH and NH 4 + concentration can synergistically impact the growth of microflorae. • Better growth of microflora doesn't mean superior denitrification ability. • Fermented mash from grain ethanol production process is an ideal carbon source. [ABSTRACT FROM AUTHOR]

The direct conversion of methane (CH 4) to methanol (CH 3 OH) is a significant but challenging reaction. We present a photocatalytic system composed of brookite mesoporous titanium dioxide and methanotrophs (Methylosinus trichosporium OB3b) for the conversion of CH 4 to CH 3 OH with high activity, selectivity and stability at ambient temperature and pressure. This system obtains the highest CH 3 OH production rate (15,761 ± 142 μmol g−1 h−1), which is dozens of times higher than most researches and 5 times of the optimal value of photcatalytic CH 4 conversion under the same condition. The process achieved nearly 100% selectivity and excellent stability under simulated sunlight irradiation and without any cocatalysts, sacrificial agent or inhibitors. The biocompatibility of semiconductor materials and the contact mode with OB3b have significant impact on the process. Titanium dioxide is used as an exogenous electron donor to greatly promote the conversion activity of CH 4 by OB3b under light irradiation. The work has significant pioneering implications for efficient CH 4 selective conversion using natural gifts combined with artificial materials. [Display omitted] • The idea of constructing biohybrid system was first proposed in the field of CH 4 activation. • This system obtains the highest CH 3 OH production rate (15,761 ± 142 μmol g−1 h−1), which is dozens of times higher than most researches. The process achieved nearly 100% selectivity and excellent stability under simulated sunlight irradiation. • The reaction is achieved at ambient temperature and pressure without any cocatalysts, sacrificial agent or inhibitors. [ABSTRACT FROM AUTHOR]

A multi-anode, proton exchange membrane electrolysis cell has been used to evaluate commercial and developmental catalysts for the oxidation of methanol, ethanol, ethylene glycol, and glycerol at 80°C. By operating the cell in crossover mode, with the fuel supplied to the cathode, steady-state mass transport limited currents can be achieved. This provides a measure of the stoichiometry of the reaction, which is controlled by the product distribution. The method has been benchmarked by using commercial PtRu black and carbon supported catalysts with 20% and 70% Pt. In all cases, the PtRu alloy decreased onset and half-wave potentials relative to Pt. However, stoichiometries for ethanol, ethylene glycol, and glycerol oxidation were greatly decreased by the presence of Ru. This effect was mitigated by employing Ru as the core in Ru@Pt nanoparticles or in a mixed Ru + Sn oxide support material. Although not as effective as the PtRu alloy for promoting low potential activity, these catalysts exhibited selectivity similar to Pt. Use of alloyed Rh and a Rh core was also evaluated, but did not show any benefits over Pt alone. [ABSTRACT FROM AUTHOR]

Highlights • The detailed process and power system of methanol co-production with coal and methane are proposed. • The technology of calcium looping for CO 2 capturing is involved. • Realizing two levels of adjustment about the ratio of H 2 /CO in the methanol synthesis gas. Abstract This work presents a detailed investigation on coal/methane-based co-production of methanol and power with a two-level adjustment system, and the potential feasibility of the system were verified through thermodynamic perspective. The whole process was modeled and simulated with Aspen Plus (v8.6). The purity of methanol product in the proposed system reaches 99.3%. And almost 100% of the captured CO 2 concentration can be achieved. Meanwhile the system energy performance was presented. The net power efficiency is 4.75% while the methanol efficiency is 51.08%. Three key factors, gasification temperature, methane/coal, and steam/syngas, were analyzed. With the increase of gasification temperature, the methanol production would grow up. However, the influence of gasification temperature on the methanol concentration and whole plant efficiency were not obvious. When the methane/coal is 0.3, the methanol concentration reaches the peak value. With the increase of methane/coal, the whole plant efficiency was rose up. The methanol concentration was declined with the increase of steam/syngas, while the methanol production shown an opposite trend. And the effect of steam/syngas on the system efficiencies was not obvious. Graphical abstract Image, graphical abstract The two-level adjustment system includes five parts, namely methane reforming, coal gasification, WGS-CaL, methanol synthesis, and HRSG. The syngas of coal gasification has a H 2 /CO ratio of near 1:2, while the syngas of methane reforming has a 3:1. Through regulating the amount to the two feedstocks, the H 2 /CO in the mixed syngas would roughly be 2:1, which is benefit for methanol synthesis. The use of WGS-CaL has two functions include capturing CO 2 and adjusting the H 2 /CO ratio in the methanol synthesis gas subtly. As a result, two levels of adjustment system for methanol synthesis is build. At the same time, the heat requirement of methane reforming is provided by combusting partial of the coal gasification syngas. The whole process has many temperature different streams. A heat recovery steam generation unit is employed to generate HP/MP-steam by exchanging heat between hot flue gas and HP-water. These pressured steam will be used to produce electricity through turbine. [ABSTRACT FROM AUTHOR]

The methane hazard is one of the most dangerous phenomena in hard coal mining. In a certain range of concentrations, methane is flammable and explosive. Therefore, in order to maintain the continuity of the production process and the safety of work for the crew, various measures are taken to prevent these concentration levels from being exceeded. A significant role in this process is played by the forecasting of methane concentrations in mine headings. This very problem has been the focus of the present article. Based on discrete measurements of methane concentration in mine headings and ventilation parameters, the distribution of methane concentration levels in these headings was forecasted. This process was performed on the basis of model-based tests using the Computational Fluid Dynamics (CFD). The methodology adopted was used to develop a structural model of the region under analysis, for which boundary conditions were adopted on the basis of the measurements results in real-world conditions. The analyses conducted helped to specify the distributions of methane concentrations in the region at hand and determine the anticipated future values of these concentrations. The results obtained from model-based tests were compared with the results of the measurements in realworld conditions. The methodology using the CFD and the results of the tests offer extensive possibilities of their application for effective diagnosis and forecasting of the methane hazard in mine headings. [ABSTRACT FROM AUTHOR]

Increasement of demand for gayo arabica coffee has influenced the coffee industry, either in increasing the coffee production and also in increasing the usage of coffee machinery and equipment significantly. However, combustion of oil fuels result the emissions of carbon dioxide (CO2), methane (CH₄) and nitrous oxide (N2O) which increase the effect of greenhouse gases from the coffee production process. This study aimed to analyze the direct impact of gayo coffee production towards environment using the Life Cycle Assessment (LCA) method, including several stages such as (1) the goal and scope definition, (2) the inventory analysis, (3) the impact assessment, and (4) the interpretation. Results of this study showed that the energy needed to process 1000 kg of coffee was 7.67 MJ, while the produced liquid waste was 5 953.2 kg. The value of the global warming impact on the coffee life cycle was 56 807 165.63 CO2eq. [ABSTRACT FROM AUTHOR]

• The hype cycle in the Austrian anaerobic digestion (AD) niche is reconstructed. • The associated shift in understanding from a 'biogas' to a 'biomethane' frame is described. • The slow 'uptake' of the biomethane frame is explained by outlining competing technological narratives. • The normative character of technological frames is demonstrated. • A conceptual framework that relates the emergence of technological frames to hype cycle and transition dynamics is presented. Socio-technical niches are often presented as key drivers for transitioning established production and consumption systems to more sustainable configurations. In previous research, the important roles of collectively shared expectations in shaping the development and nurturing of such niches has been emphasised. At the same time, this research has shown that niches are often associated with fluctuating expectations, typically showing patterns of hype and disappointment. In this study, we analyse how such hype and disappointment patterns interact with framing dynamics by combining the concept of technological frames with the sociology of expectations and the multi-level perspective. By using the shift in understanding that has occurred from a 'biogas' to a 'biomethane' frame in the Austrian anaerobic digestion (AD) niche as an example, we shed light on niche-internal framing struggles, illustrate the normative character of technological frames, and relate the emergence of dominant frames to hype cycle and transition dynamics. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrocatalytic conversion of methane (CH 4) into high-valued liquid products have been studied extensively, yet still limited by their low product yields. Herein, we report the electrocatalytic conversion of CH 4 into CH 3 COOH in HCO 3 --contained electrolyte. By optimizing the surface-active sites via defects engineering, a high CH 3 COOH yield of 347.31 mmol g cat −1 h−1, accompanied with a CH 3 COOH selectivity of 85.4 %, was obtained at 1.3 V vs RHE over the optimal catalyst. This CH 3 COOH yield is 2–5 orders of magnitude to previous reports so far as we know. Combinations of DFT theoretical simulation, defect sites characterization and control experiments of CH 4 electrochemical conversion confirmed the important roles of ample surface Zn/O defects. Our work provides a new insight into the design of highly active and selective catalysts toward CH 4 electrocatalytic conversion into CH 3 COOH. • ZnO nanosheets with plenty of atomic defects were synthesized. • They were used for highly efficient CH 4 conversion to acetic acid. • High yield rate and selectivity of 3473115 μmol (g cat h)−1 and 85.4 % are achieved. • The electrocatalytic performance outperforms the previous reports as we know. • Roles of Zn/O atom defects were studied in detail. [ABSTRACT FROM AUTHOR]

The formation of methane (CH 4) via a biomethanation process using hydrogen (H 2) and carbon dioxide (CO 2) as feedstock is impeded by H 2 gas-liquid mass transfer limitations. To address these limitations and improve the CH 4 production rate in H 2 /CO 2 biomethanation, perfluorocarbon (PFC) nanoemulsions exhibiting a high solubility for gases were proposed as H 2 transfer carriers to promote the H 2 utilization rate and methanogenesis kinetics. The presence of PFC nanoemulsions in a volume fraction of 1.5% increased the peak rate of CH 4 production by 30.6% and decreased the lag time by 84.5%. These nanoemulsions, composed of PFC and surfactants, efficiently transported H 2 molecules to alleviate gas-liquid transport limitations in biological solutions. Furthermore, lipophilic PFC, which is nonspecifically bound to cell membranes of Methanosarcina barkeri (M. barkeri) cells, also provided the transport of H 2 molecules from PFC nanoemulsions to the cells. The PFC nanoemulsions separated from these cell membranes primarily through physical oscillations. However, physical separation was difficult when using 2 vol% PFC nanoemulsions due to their strong combination with M. barkeri cells, which hindered H 2 transmission and utilization. [Display omitted] • PFC nanoemulsions exhibit a high solubility as H 2 transfer carriers. • CH 4 production rate increased by 30.6% with PFC nanoemulsions addtition. • CH 4 production lag time decreased by 84.5% with PFC nanoemulsions addtition. • Nonspecifically bound exists between PFC and cell membranes of Methanosarcina barkeri. [ABSTRACT FROM AUTHOR]

In the article is researched the cycle by cycle variation of SI engine working with methane. On investigation is made analysis what is the effect of the fuel on the value of the maximum pressure into the cylinder from cycle to cycle under different engine operating modes when changing the air-fuel equivalence ratio and the angle of supply of the electric spark. From the collected experimental data on the graphs is shown how is chance the cycle by cycle variation depending from the air-fuel equivalence ratio at three different angles of electric spark delivery. [ABSTRACT FROM AUTHOR]

Methane from anaerobic fermentation in the rumen of cattle is a major contributor to greenhouse gases (50–60%). Methanogenesis is an important process in the ruminants as it scavenges hydrogen produced during the anaerobic fermentation of sugars in the rumen and, thereby, balances the fermentation process. This work focuses on mitigation of methane production in rumen by bioaugmentation with hydrogenotrophic acetogenic strains thus, channelizing hydrogen towards acetate instead of methane. For this two acetogenic cultures: Acetobacterium woodii and a stable consortium from a baby kangaroo feces sample were used as potential competitors for hydrogen-carbon dioxide against rumen methanogens. Addition of Acetobacterium woodii or an acetogenic kangaroo consortium had only limited effect on methane production from continuously grown rumen cultures. However, one-time treatment with an inhibitor of methanogenesis (2-bromoethanesulfonic acid), along with addition of either of the two acetogenic cultures resulted in well-functioning fermentation process with acetogenesis with no methane production. Monod's growth kinetics studies were done to test the ability of selected homoacetogens to compete against methanogens for hydrogen. The results show a lower K s value for the methanogenic culture (0.737 mM hydrogen) compared to the K s values for Acetobacterium woodii and the kangaroo consortia of 6.844 mM and 3.788 mM hydrogen, respectively. The V max was found to be similar for the methanogenic and kangaroo culture (0.381 mM/h and 0.331 mM/h, respectively) but lower for Acetobacterium woodii (0.217 mM/h). [Display omitted] • Successful bioaugmentation with two homoacetogenic cultures as a methane mitigation strategy. • Methanogens had lower K s value for H 2 than both the selected homoacetogens. • The homoacetogenic kangaroo consortia had V max values similar to rumen methanogens. • Homoacetogenic cultures completely metabolized H 2 in the absence of methanogens. • BES treatment with acetogenic bioaugmentation would be an effective methane mitigation strategy. [ABSTRACT FROM AUTHOR]

Continuous flaring of natural gas remains a great environmental threatening practice going on in most upstream hydrocarbon production industry across the globe. About 150 billion m3 of natural gas are flared annually, producing approximately 400 million tons of carbon dioxide alone among other greenhouse gases. A search into a viable method for natural gas conversion to methanol becomes imperative not only to save the soul of the ever-changing climate but also to bring an end to wastage of valuable resources by converting hitherto wasted natural gas to wealth. Currently the technologies of conversion of natural gas to methanol could be categorized into the conventional and the innovative technologies. The conventional technology is sub-divided into the indirect method also called the Fischer-Tropsch Synthesis (FTS) method and the direct method. The major commercial technology currently in use for production of methanol from methane is the FTS method which involves basically two steps which are the steam reforming and the syngas hydrogenation steps. The FTS method is highly energy intensive and this is a factor responsible for its low energetic efficiency. The direct conversion of methane to methanol is a one-step partial oxidation and lower temperature method having higher energetic efficiency advantage over the FTS method. The direct method occurs at temperature range of 380–470 °C and pressure range of 1–5 MPa while the FTS occurs at temperature range of 700–1100 °C and atmospheric pressure. Both methods are carried out under effect of metallic oxide catalysts such as Mo, V, Cr, Bi, Cu, Zn, etc. The innovative methods which include electrochemical, solar and plasma irradiation methods can be described as an approach to either of the two conventional methods in an innovative way while the biological method is a natural process driven by methane monooxygenase (MMO) enzyme released by methanotrophic bacteria. The aim of this study is to review the current state of the technology for conversion of methane to methanol so as to make abreast the recent advances and challenges in the area. • Appraisal of technologies for conversion of natural gas to methanol as viable solutions against gas flaring was presented. • Merits and demerits of the conventional indirect method were elucidated and compared with unconventional methods. • Contribution of catalyst choice, and reaction conditions were analysed in determination of a more viable method. • Direct method was identified as a more viable alternative at appropriate catalyst and operating conditions. [ABSTRACT FROM AUTHOR]

The methane isothermal adsorption experiment was conducted on the Lower Silurian marine shale of the Longmaxi Formation from the Upper Yangtze Platform, China, at pressures up to 10.94 MPa and temperatures of 30 °C and 39 °C to investigate the key factors affecting its methane adsorption capacity. Basic shale reservoir characteristics were obtained using total organic carbon measurements, thermal maturity assessment, X-ray diffraction, and nitrogen adsorption. An abundance of organic matter in the reservoir with total organic carbon (TOC) ranging between 0.49 and 4.8 wt% was overmature. The matrix minerals mainly consisted of clay (16%–33%) and quartz (37%–53.9%). The Brunauer–Emmett–Teller (BET) surface areas of the shale samples varied from 6.34 to 21.3 m 2 /g. The Langmuir-based absolute adsorption model was used to correct the measured adsorption isotherms into absolute adsorption isotherms, which represented the actual adsorption. Furthermore, the Langmuir volume was in the range of 1.04–5.36 m 3 /t. Shale gas adsorption capacity presented a significantly positive correlation with an abundance of organic matter that provided a larger BET surface area. The absence of apparent correlation with the clay indicated that the clay did not significantly contribute to the gas adsorption capacity in the shale samples. Variations in temperature and pressure were also key factors affecting shale gas adsorption capacity. Therefore, TOC, temperature, and pressure were optimized to establish the forecast model, combined with multiple regression methods and a set of cited data. The results of the isothermal adsorption experiment in this study were used to verify the model's feasibility for predicting the shale gas adsorption capacity of the Longmaxi Formation. The predicted results were highly correlated with the actual measured results, with a correlation coefficient as high as 0.9887. The function of shale gas adsorption capacity derived and analyses employed in this study can be used to illustrate the impact of pressure and temperature regimes on shale gas adsorption capacity, given varying abundance of organic matter and compositions of matrix minerals. [ABSTRACT FROM AUTHOR]

In this research, first, hydrate with high saturation in porous media (sand sediments) was formed in fully filled high pressure cell by using a mixture of the following gases at 4 °C: methane (CH 4 ), propane (C 3 H 8 ) and carbon dioxide (CO 2 ). The feed mole percent of the gases used was selected as follows: CH 4 (95%), C 3 H 8 (3%), CO 2 (2%). This selection was made in order to form natural gas hydrate of thermogenic origin (sII type hydrate). Thereafter, CO 2 injection into the high saturation hydrate media was performed in order to elucidate possible CH 4 recovery. However, it was observed that injected CO 2 was not able to flow through sediments, because of the impermeable barrier created by hydrate, and because of the fact that no free space was left in the cell as it was completely filled with porous media resulting in mass transfer limitations. Therefore, it was proposed that methane recovery occurred only near the hydrate interface. Taking into consideration obtained results, in the next step we decreased the volume of the sand, to create a space for the free gas evolution above the high saturation hydrate, and further completely replaced free gas composition by CO 2 . We observed that this time not only CH 4 , but C 3 H 8 was recovered from hydrate phase implying further reconsideration of the injection of CO 2 into sII hydrate. The results of this study imply that it is possible to recover hydrocarbon gases from hydrates more stable than CO 2 hydrate by creating a CO 2 rich environment. [ABSTRACT FROM AUTHOR]

Natural gas (NG) is a naturally gaseous hydrocarbon mixture that is formed under the earth’s surface. NG is considered to be the cleanest fossil fuel and is a safe source of energy when transported, stored and used. The primary constituent of NG is methane, it may also contain (C 2 + hydrocarbons, N 2 , CO 2 , He, H 2 S, and noble gases) according to its origin. Different gas processing technologies can be employed to remove constituents other than methane. Due to importance of NG as a fuel and the increasing global demand of it, this article reviews the fundamentals of NG origin, composition, and processing. [ABSTRACT FROM AUTHOR]

Production and transportation of natural gas through pipeline is often hampered by formation of gas hydrates, which can be mitigated by using efficient inhibitors. In this work, the effect of L-tyrosine and NaCl on Polyvinylpyrrolidone (PVP) as kinetic inhibitor on formation of hydrate from methane/ethane/propane (89.93/7.04/3.03 mol %) gas mixture was studied. The effect of L-tyrosine, NaCl and PVP on the nucleation and growth of hydrates was investigated by measuring the hydrate nucleation time and gas consumption profile. The addition of inhibitors was found to prolong the hydrate nucleation time and decrease the amount of gas consumption. The results showed that the presence of both NaCl and L-tyrosine enhanced the inhibition strength of PVP. Addition of 1.0% (wt) PVP increased the induction time to 45 min compared to pure water system where induction time was only 27 min. Again addition of 0.25% (wt) NaCl, 0.25% (wt) L-tyrosine and 0.5% (wt) PVP to the system increased the hydrate nucleation time further to 65 min and decreased the gas consumption 27% compared to pure water system. [ABSTRACT FROM AUTHOR]

Numerical modeling studies have been performed for a methane dry reforming using a shell and tube type packed-bed reactor and a membrane reactor both with a heating tube as heat source in the center of a reactor. Mathematical models for a reformer bed, a heating tube, and an insulating jacket coupled with reaction kinetics were proposed to investigate axial and radial temperature and concentration profiles within both reactors with a reformer temperature of 923 K and heating tube temperatures from 1023 to 1223 K. 3-D visualizations of temperature, CH 4 conversion, CH 4 concentration, and H 2 concentration profiles were possible by COMSOL Multiphysics modeling software and significant variations within both reactors were observed providing a critical guideline for an efficient reactor design. Further studies for the effect of hydrogen mass flux on a hydrogen yield enhancement revealed that a threshold hydrogen mass flux in a membrane reactor to outperform a packed-bed reactor exists with a trend of a lower threshold hydrogen mass flux for a higher heating tube temperature. [ABSTRACT FROM AUTHOR]

A large amount of experimental data for methane adsorption capacity in shale are available and the Langmuir model is capable to describe most of these adsorption isotherms. Two parameters used in the Langmuir model are the Langmuir pressure constant P L and the Langmuir volume constant V L . However, experimental data also demonstrate that the gas adsorption capacity of shale is greatly affected by temperature and the classic Langmuir model, with temperature independent V L and temperature dependent P L , could not well interpret the experimental data. This is partly attributed to the isosteric heat of adsorption, which makes V L vary with temperature. The change of V L with temperature for gas adsorption in shale and its dependency on shale properties are still not well understood. In this study, the variation characteristics of V L with temperature for gas shale are investigated through a modeling analysis on the published gas sorption data on the shales from the US, China, Canada, and etc. The classic Langmuir model is improved by considering the temperature dependent V L . The results show that the improved Langmuir model can reasonably describe the shale gas sorption data with less fitting parameters required and it allows a better understanding of gas sorption capacity under the combined effect of temperature and pressure. In addition, the model parameter analysis indicates that the adsorption capacity of shale samples with lower TOC is more likely to be affected by temperature change on the basis of the limited data available. More experiments are required to investigate how the shale properties affect the thermal impact on the gas adsorption capacity on gas shale. [ABSTRACT FROM AUTHOR]

Molecular dynamic simulations have been served to investigate various properties of methane/water system at two extreme conditions: away from hydrate formation and threshold it. The results that compare the two conditions have been discussed in the terms of surface tension, mean square displacement (MSD), diffusion coefficient, radial distribution function and thermodynamic functions. Investigation over a timescale of 500 ps demonstrated that the thermodynamic functions at 275 K and high pressures (corresponding to the hydrate formation threshold) are smaller than that of at 298 K, implying that the hydrate formation threshold is more stable. An increase in the system pressure and temperature leads to a decrease in the surface tension because of decreasing the intermolecular attractive forces. Besides, the comparison of oxygen–oxygen, carbon–carbon and carbon-oxygen radial distribution functions at temperatures of 275 and 298 K has been indicated that the height of peaks decreases due to increasing the temperature, demonstrating that the system become more stable at the threshold of hydrate formation. [ABSTRACT FROM AUTHOR]

Natural gas vehicles (NGVs) with the ability to accept a broader range of fuel specifications can play a significant role in increasing Renewable Natural Gas (RNG) utilization in the transportation sector. The Wobbe Index is a critical factor in evaluating the interchangeability between different high methane fuels. This study details the development and testing of a compact, reliable Wobbe Index sensor for use in NGVs. The concept uses a combination of a thermal conductivity and an infrared sensor together with temperature and pressure measurement. The signals from these sensors are indexed in an algorithm that estimates the Wobbe Index in real time. The sensor was confirmed to operate over a temperature range of −20 °C to 70 °C under pressures of up to ∼3600 psi. A multivariate algorithm was developed to estimate the fuel Wobbe Index from the measured temperature, pressure and thermal conductivity data. The accuracy was improved to ±1% using the CH 4 concentration data from the IR sensor additionally. Compared to the existing methods, this sensor provides a cost-effective, ruggedized solution that can be used to develop a “Variable-blend Natural Gas Vehicle”(VNGV), allowing refueling from a broad range of natural gas sources. This technology has the potential to significantly increase RNG usage for transportation purposes. [ABSTRACT FROM AUTHOR]

This paper presents a detailed analysis of the influence of sulfur formation on performance and efficiency of Solid Oxide Fuel Cells (SOFC) operating on methane containing fuels. Our previously developed multi-step reaction mechanism of sulfur formation and oxidation is coupled with a complex heterogeneous mechanism of methane reforming, channel gas-flow, porous-media transport and elementary kinetic charge transfer and is used to describe sulfur-induced degradation and performance drops of Ni/YSZ anodes. Experimental literature data is used to validate the model and to interpret important aspects of cell performance degradation. Comparisons of the model predictions to the experiments illustrate that the developed model, without any modifications, reproduces the observed voltage decrease well and is able to capture the changes in fuel conversion and selectivity for different gas mixtures. It is shown that atomically adsorbed sulfur significantly influences heterogeneous reforming chemistry, causing substantial voltage degradation. At constant current densities, cell voltage decreases in a non-linear way with faster recovery than in H2/H2O mixtures. [ABSTRACT FROM AUTHOR]

• Waste activated sludge is a renewable and sustainable source of biomolecules. • Proteins, lipids, fatty acids, enzymes and humic acids can be recovered from sludge. • High protein recovery by precipitation using ultrasound and alkali treatments. • Polymeric membranes of 30–50 kDa were the most suitable to recover humic acids. • Two integrated methods for the complete recycling of activated sludge were proposed. The need of developing a new growth model based on circular economy has led to an increasing interest in the revalorization of urban and industrial wastewaters in order to use the resources efficiently. The most stablished way of valorising these residues implies the energy production in the form of biomethane. However, urban and industrial wastewaters can also be considered promising raw sources for the recovery of valuable chemical compounds. Especially, waste activated sludge from water treatment plants is a fantastic source of biomolecules such as lipids (triglycerides or fatty acids), proteins and enzymes, carbohydrates, and humic and fulvic acids. However, prior to the recovery of these biocompounds, sludge solubilization processes (thermal hydrolysis, sonication and acidification, among others) must be conducted, in order to break the cell walls and release the protoplasmic content into the liquid media, thus obtaining a matrix of high complexity, which condition the possible strategies to be applied. This review gathered and discussed in-depth the studies that deal with the recovery of valuable biocompounds from secondary waste activated sludge. Furthermore, other types of sludge comparable to the activated one, such as cell cultures and food-related sources, have been also discussed here, in order to be used as a starting point for further research on the valorisation of waste activated sludge. [Display omitted] [ABSTRACT FROM AUTHOR]

The article discusses economic aspects of global energy developments as of June 2015. Topics include the gap between the infrastructure requirements for transporting natural gas and the time lag between local development and its impact on global markets, the cost effectiveness of transporting methane as a gas , which is reflected in the price differential between U.S. gas as compared to the landed price of liquefied natural gas in Belgium, and the association between the economic return from newfound energy resources and oligopolistic behavior and corruption.

The effect of methane–CO 2 blends with varying CO 2 concentrations (corresponding to various biogas compositions) on combustion and emission characteristics were investigated numerically for a gas engine generator. CO 2 variation in a methane-based biogas fuel produced effects similar to the CO 2 effects of exhaust gas recirculation (EGR), decreasing the cylinder temperature, pressure, heat release rate, and flame speed. By design of experiment (DOE) analysis, the maximum brake torque (MBT) timing was calculated for various values of the spark timing and excess air ratio (EAR). As the EAR increased from 1.2 to 1.8 and the CO 2 content decreased, the MBT timing was far advanced from top dead center (TDC). At 50% CO 2 content, incomplete combustion phenomena were detected in the leaner region at EAR values above 1.6. In spite of the performance degradation of the engine itself, the addition of CO 2 up to 50% in volumetric content improved the electrical generating efficiency by an average of 6.4%, with lower NO X formation. [ABSTRACT FROM AUTHOR]

In this study, the effect of sodium tungstate on anaerobic digestion of waste sewage sludge (WSS) was investigated. Methane production was enhanced by sodium tungstate in a dose-dependent manner. Sodium tungstate did not affect the hydrolysis stage as the same level of protease activity was detected in the WSS sample with or without sodium tungstate. At the acidogenesis stage, the concentration of acetate decreased during the anaerobic digestion of WSS supplemented with sodium tungstate whereas that of isobutyrate increased. The pH of WSS increased in the presence of sodium tungstate, correlating with the result of acetate consumption with time during the anaerobic digestion of WSS. The analyses of methanogenesis via acetoclastic and hydrogenotrophic methanogens indicate that methane production from acetate was high in the WSS with sodium tungstate. In addition, the addition of sodium tungstate to the initial fresh WSS did not enhance methane production from acetate; therefore, sodium tungstate may increase the number of acetoclastic methanogens rather than promote the catalytic reaction related to the methane production. The analyses of archaeal population supported that acetoclastic methanogens (mostly Methanosaeta) increased with time in the WSS with sodium tungstate. In detail, when compared to the control WSS, the percentage of Methanosaeta significantly increased from 3.02% to 31.20% in the presence of sodium tungstate. Furthermore, the addition of sodium tungstate enhanced the growth of Methanosarcina acetivorans C2A. Taken together, sodium tungstate increases methane production via the anaerobic digestion of WSS by increasing the activity of acetoclastic methanogenesis. [Display omitted] • Sodium tungstate enhanced methane production (2.17-times higher) through the anaerobic digestion using waste sewage sludge. • The pH of WSS in the presence of sodium tungstate increased at pH 7.2. • The consumption of acetic acid was promoted by sodium tungstate, by which methane production was improved. • Acetoclastic methagenesis was activated by sodium tungstate through increased growth of methanogens. [ABSTRACT FROM AUTHOR]