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In the present study, we have investigated the impact of introducing different amounts of hydrogen peroxide into the air on the co-combustion behavior of propane and ammonia. Various combustion criteria including flame speed, ignition delay, heat release, NO emission, and reaction pathways have been explored within different compositions of propane/ammonia/air/hydrogen peroxide. This investigation has been performed through the kinetic study applying a detailed mechanism compromising 188 species and 1604 reactions. According to the findings, air replacement by hydrogen peroxide might improve the laminar burning velocity, heat release rate, flame temperature. The substantial reactivity of hydrogen peroxide leads to a significant increase in OH and H radicals, consequently accelerating the reaction rates as the hydrogen peroxide content in the oxidizer increases. The reaction H + O 2 ↔O + OH (R906) plays the most significant role in enhancing flame propagation in a fuel/air mixture. However, as the hydrogen peroxide content in the mixture increases, the influence of this reaction diminishes, and the reaction H 2 O 2 (+M)↔2OH(+M) (R929) becomes more dominant. Initially, NO levels increase with the addition of hydrogen peroxide, but they start to decline at higher proportions of hydrogen peroxide. The initial increase may be attributed to the higher flame temperature, while the subsequent decrease could be linked to a substantial reduction in atmospheric nitrogen levels in the oxidizer. In situations where, pure hydrogen peroxide is used as the oxidizer, there is no production of NO x in pure propane combustion due to the lack of nitrogen. When compared to pure ammonia combustion, cofiring results in approximately half the amount of NO x emissions. • A comprehensive kinetic study was performed to examine NH 3 /C 3 H 8 /Air/H 2 O 2 combustion. • The addition of C 3 H 8 to NH 3 shortens ignition delay time. • Adding H 2 O 2 to air enhances flame speed, temperature, and HRR. • Adding H 2 O 2 to air enhances reaction rates and radicals' concentrations. [ABSTRACT FROM AUTHOR]

The effect of H 2 O 2 addition to the air on ammonia combustion was investigated in the current research using a computational fluid dynamics approach. The numerical simulation was conducted in a 10-kW laboratory-scale furnace. The oxidizer and fuel were injected into the furnace in a non-premixed mode. Furthermore, a kinetic study was carried out to analyze the sensitivity of NO production during combustion and to determine reaction pathways under various conditions. The findings indicate that the addition of H 2 O 2 to the mixture increases flame temperature and NO levels, while decreasing N 2 O levels. Moreover, the study demonstrates that, with a maximum concentration of only 10 ppm, the amount of NO 2 is very low under various percentages of H 2 O 2 and different operating conditions. Furthermore, it is concluded that during ammonia/air combustion, lowering the oxidizer inlet temperature and increasing wall heat extraction may cause the combustion to become unstable. Under pure air oxidizer conditions, where T in = 973 K and T wall = 1273 K, the combustion is stable. However, instability occurs when T wall falls to 1173 K. In this instance, adding merely 5 % H 2 O 2 to the oxidizer is sufficient to provide self-sustaining and stable burning. More H 2 O 2 must be introduced into the furnace to maintain stable combustion as T in and T wall continue to decline. Interestingly, while adding H 2 O 2 raises NO levels, decreasing the inlet and wall temperatures at higher H 2 O 2 concentrations can help regulate NO emissions. These findings clearly indicate that introducing H 2 O 2 into the fuel mixture could be a promising strategy for reducing the inlet temperature and enhancing heat extraction, which will both reduce energy consumption and increase system efficiency. • A comprehensive CFD-kinetic model was developed to study NH 3 /H 2 O 2 /air combustion. • The addition of H 2 O 2 to the oxidizer enhances flame temperature. • Adding H 2 O 2 to the oxidizer raises NO levels, while reducing N 2 O. • The addition of H 2 O 2 makes higher wall heat extraction achievable in NH 3 combustion. [ABSTRACT FROM AUTHOR]

As environmental pollution worsens, many strategies are emerging to reduce CO 2 in various chemical processes. The practical strategy of byproduct hydrogen utilization in propane dehydrogenation is also being reviewed a lot. In this work, a comprehensive analysis was conducted for propane dehydrogenation process design integrated with membrane reactor and solid oxide fuel cell. Especially, membrane reactor and sequential reactor were used to increase the yield of the process. All assessments were investigated based on Aspen Plus®, which is commercial software for process simulation. Levelized cost of electricity was derived through itemized cost estimation. The 2.81 $ kWh-1 of levelized cost of electricity was revealed through itemized cost estimation; it is higher than industrial electricity in general. Therefore, various scenarios were conducted to reduce the levelized cost of electricity compared to industrial electricity price on sale, currently. The optimistic case (1.20 $ kWh-1) can be priced close to industrial electricity price through 100 % of propane recycling rate and − 20 % of reduction in the price of the influential factors. For life cycle assessment, the environmental impact of global warming potential was assessed as 4.93 kg CO 2 eq MJ-1 of CO 2 emissions. Various scenarios had been proposed to reduce CO 2 as with the economic assessment. Under pessimistic, realistic, and optimistic conditions, the results of global warming potential were 5.61, 4.93, and 4.25 kg CO 2 eq MJ-1, respectively. The comprehensive analysis will be presented as guidelines for the actual use of byproduct hydrogen. • Comprehensive analysis was conducted for the proposed process. • Levelized cost of electricity was derived as 2.81 $ kWh-1 for the process. • Economic and environmental assessment was conducted based on process modeling. • Global warming potential was estimated as 4.93 kg CO 2 eq MJ-1 for the process. [ABSTRACT FROM AUTHOR]

Nickel catalysts supported on the K 2 Ti x O y –Al 2 O 3 were prepared by the wet impregnation method for steam methane reforming to produce hydrogen. X-ray diffraction, N 2 physisorption, scanning electron microscopy with energy dispersive spectroscopy, the H 2 temperature-programed reduction technique, and X-ray photoelectron spectroscopy were employed for the characterization of catalyst samples. The results revealed that the performance of the Ni/K 2 Ti x O y –Al 2 O 3 catalysts was comparable to that of commercial FCR-4 for steam methane reforming under the mild condition. In particular, a catalytic stability test at 800 °C and in the reactant flow with the steam-to-carbon ( S / C ) feed ratio of 1.0 indicated that the Ni/K 2 Ti x O y –Al 2 O 3 catalysts were more active, thermally stable and resistant to deactivation than the non-promoted Ni/Al 2 O 3 . It is considered that the appropriate interaction strength between nickel and the modified support and proper K 2 Ti x O y phases with a surface monolayer coverage achieved at ca. 15 wt.% loading in the support play important roles in promoting the steam methane reforming activity as well as suppressing the sintering of the catalyst. [ABSTRACT FROM AUTHOR]

Abstract: Thin and defect-free Pd–Cu composite membranes with high hydrogen permeances and selectivities were prepared by electroless plating of palladium and copper on porous alumina supports with pore sizes of 5 and 100nm coated with intermediate layers. The intermediate layers on the 100nm supports were prepared by the deposition of boehmite sols of different particle sizes, and provided a graded, uniform substrate for the formation of defect-free, ultra-thin palladium composite layers. The dependence of hydrogen flux on pressure difference was studied to understand the dominant mechanism of hydrogen transport through a Pd–Cu composite membrane plated on an alumina support with a pore size of 5nm. The order in hydrogen pressure was 0.98, and indicated that bulk diffusion through the Pd–Cu layer was fast and the overall process was limited by external mass-transfer or a surface process. Scanning electron microscopy (SEM) images of the Pd–Cu composite membrane showed a uniform substrate created after depositing one intermediate layer on top of the alumina support and a dense Pd–Cu composite layer with no visible defects. Cross-sectional views of the membrane showed that the Pd–Cu composite layer had a top layer thickness of 160nm (0.16μm), which is much thinner than previously reported. [Copyright &y& Elsevier]

Alkaline water electrolysis has been in the spotlight for green H 2 production using electricity generated from renewable energy because of its high technology readiness level and low investment. However, commercialization of alkaline water electrolysis is challenging because of the low current density. Therefore, a techno-economic and environmental assessment was conducted for green H 2 production by alkaline water electrolysis with experimental data from the advanced alkaline water electrolysis system of the Korea Institute of Energy Research (KIER) to identify the potential of this technology. Based on techno-economic analysis results, the stack cost and unit electricity price must be below 0.035 $ kWh−1 and 406 $ kW−1, respectively, to make this technology cost-competitive compared to the conventional H 2 production method (< 2 $ kgH 2 −1). Furthermore, CO 2 emissions of 30.7, 17.4, 7.04, and 3.12 kgCO 2-eq kgH 2 −1 were obtained for the current, 2030, 2050, and renewable Korean electricity mix scenarios, respectively, indicating that both scenarios (Korean electricity mix in 2050 and renewable) have lower CO 2 emissions than the conventional H 2 production method (11.5 kgCO 2-eq kgH 2 −1). In addition, environmental impact reductions of 89.8%, 83.6%, 65.9%, and 91.0% for CO 2 emissions, stratospheric ozone depletion, fine particulate matter formation, and fossil resource scarcity, respectively, were obtained for the renewable scenario compared to the current Korean electricity mix. Therefore, the electricity source has significant effects on the economic feasibility and environmental impacts for green H 2 production. [Display omitted] • TEA was performed to calculate unit H2 production based on experimental data. • Life cycle assessment was conducted to evaluate environmental impacts for green H2 production. • Economic and environmental guidelines can be provided. [ABSTRACT FROM AUTHOR]

• A comprehensive CFD-economic model was developed to study NH 3 -CH 4 cofiring. • NH 3 addition into the fuel mixture results in a significant decrease in CO 2. • At high levels of NH 3 in the fuel mixture, NO decreases due to the DeNO X process. • As NH 3 content in the fuel mixture increases, there is a notable rise in N 2 O level. • Cofiring is cost-effective vs. CH 4 derived from landfill gas and H 2 methanation. In recent years, there has been a growing emphasis on the co-firing of conventional fossil fuels with carbon-free alternatives to mitigate CO 2 emissions. In the current study, a computational fluid dynamics (CFD) simulation was carried out to investigate the co-combustion of ammonia and methane in a combustion furnace located at the University of Lisbon. To examine the interaction between turbulence and chemistry, the Eddy Dissipation Concept (EDC) model was utilized. The fuel mixture consisted of methane and ammonia, ranging from 100 % methane combustion to 100 % ammonia combustion. The fuel proportions were determined based on their respective calorific values, ensuring an equivalent thermal input to the furnace. Subsequently, the CFD results were analyzed from an economic perspective. The research findings revealed that ammonia-methane cofiring led to a noteworthy reduction in CO 2 emissions compared to pure methane combustion. However, an increase in NO x emissions during ammonia combustion was observed. Interestingly, as the proportion of ammonia in the fuel mixture increased, the NO and NO 2 emissions decreased, while the amount of N 2 O increased. Based on the economic analysis results, the lowest annual cost (1922 USD y−1) was observed from the use of 100 % CH 4 fuel, primarily due to the relatively lower CH 4 cost compared to the NH 3 and NO x reduction system. However, as the NH 3 -contained fuel was considered, the annual cost increased with the NH 3 contained percentage, reaching the highest annual cost (5811 USD y−1) in the case of 100 % NH 3 -contained fuel. Among the economic parameters examined, the cost of NH 3 emerged as the most influential factor affecting the annual cost in the co-firing system. Furthermore, the co-firing system proved to be an economically viable option when considering CH 4 sourced from landfill gas and the renewable H 2 methanation process. [ABSTRACT FROM AUTHOR]

Ammonia emerges as a promising substitute for traditional fuels, offering a potential reduction in fossil fuel consumption and the associated emissions. Given its weak reactivity, an effective strategy to harness the potential of ammonia involves cofiring it with methane, to establish a self-sustaining combustion process. The understanding of heat release rate (HRR) in the cofiring process of ammonia and methane is crucial for burner design. This study introduces novel HRR indicators through a machine learning-based approach, focusing on species significantly contributing to HRR. Kinetic analysis is carried out utilizing a one-dimensional freely propagating flame model, applying a mechanism including 59 species and 356 reactions. Domain knowledge-based feature selection narrows down the search space, enhancing computational efficiency during HRR indicator identification. A random forest model is then employed to identify radical/radical combinations and their respective reaction orders, representing HRR optimally based on mean decrease impurity. The proposed HRR markers are [CH 4 ]0·76[OH]1.08, [HCO]0·65[NO]0.24, [CH 3 ]0.65[O]0.63, [NH 2 ][O]0.59, and [NH 3 ]0·93[OH]0.96. The root mean square error for each marker was extracted and compared with literature data, demonstrating higher reliability of the proposed indicators over those previously suggested. Additionally, the paper concludes with a discussion of the feasibility of measuring these markers from an experimental perspective. [Display omitted] • Thorough kinetic analysis of focusing on key HRR contributors. • Pioneering ML for crucial HRR indicator identification in ammonia-methane cofiring. • Domain-based feature selection streamlines HRR marker identification for efficiency. • Proposed 5 HRR markers that are superior in accuracy compared to existing markers. [ABSTRACT FROM AUTHOR]

H 2 has gained global attention owing to its clean energy characteristics. As an energy vector, long-term storage and transportation of H 2 in liquid form is essential which requires effective pretreatment. Standalone technologies, such as pressure swing adsorption, membrane, and cryogenic, cannot produce highly pure H 2 with high recovery in an energy-efficient manner. The integration of technologies is a promising alternative to overcome these limitations. In this regard, membrane and cryogenic (desublimation) techniques are integrated to separate H 2 with high purity and recovery. Purified H 2 is liquefied to produce 100% saturated liquid H 2 (LH 2). The proposed process is designed in Aspen Hysys v11 and evaluated with respect to energy, exergy, and economic considerations. The results have shown that the proposed process resulted in H 2 separation with 99.99% purity and 95.87% recovery. The total net energy consumption of the proposed integrated process was 11.53 kWh/kg. Exergy analysis revealed that the liquefaction section had the highest specific exergy destruction (∼92%). Moreover, the detailed economic calculations showed that the total annualized process cost was 671.6 m$/y. In this study, the potential of membrane–cryogenic integration with LH 2 production is evaluated and shown to be fundamental in the development of a sustainable H 2 economy. [Display omitted] • Membrane and desublimation technologies are integrated. • CO 2 desublimation is validated from CO 2 phase diagram. • H 2 is separated with 99.99% purity. • The proposed process consume 11.53 kWh/kg energy. • The total annualized cost of the process is 671.6 m$/y. [ABSTRACT FROM AUTHOR]

• S. japonica seaweed industrial-scale pyrolysis, heat and power. • Biocrude and upgraded biocrude modeling methodology for process simulation. • Detailed process design and Brayton cycle integration. • TEA, sensitivity analysis, market uncertainty analysis, selling price variation. • CO 2 emission comparison with platform-based crude oil process. Carbohydrate-rich and fast-growing seaweeds such as the S. japonica species are increasingly becoming the 3rd generation biomass of choice. Environmentally friendly as well as economically sound processes for biofuel production are essential if the benefits of these novel marine feedstocks are to be harnessed. This study features an experiment-based process design that combines a fluidized bed fast pyrolysis reactor system, non-intensive pretreatment, and a Bryton power cycle in an, energy-wise, nearly self-sustainable system, considerably reducing the utilization of fossil fuel-derived utilities. Complex liquid products of pyrolysis and catalytic upgrading were modeled using a specialized software ensuring strict adherence to experimental data, hence retaining a highly realistic simulation. Results of comprehensive techno-economic and market uncertainty assessments have shown a capital investment of 170 mil. USD, and a minimum selling price range of 1.534–1.852 USD/L. When compared to traditional oil and gas extraction and refining processes, the designed process yielded a 12.8-fold reduction of the total CO 2 emitted, indicating a superior process in terms of environmental sustainability. [ABSTRACT FROM AUTHOR]

Herein, a methane steam reforming (MSR) reaction was carried out using a Pd composite membrane reactor packed with a commercial Ru/Al 2 O 3 catalyst under mild operating conditions, to produce hydrogen with CO 2 capture. The Pd composite membrane was fabricated on a tubular stainless steel support by the electroless plating (ELP) method. The membrane exhibited a hydrogen permeance of 2.26 × 10 −3 mol m 2 s −1 Pa −0.5 , H 2 /N 2 selectivity of 145 at 773 K, and pressure difference of 20.3 kPa. The MSR reaction, which was carried out at steam to carbon ratio (S/C) = 3.0, gas hourly space velocity (GHSV) = 1700 h −1 , and 773 K, showed that methane conversion increased with the pressure difference and reached 79.5% at ΔP = 506 kPa. This value was ∼1.9 time higher than the equilibrium value at 773 K and 101 kPa. Comparing with the previous studies which introduced sweeping gas for low hydrogen partial pressure in the permeate stream, very high pressure difference (2500–2900 kPa) for increase of hydrogen recovery and very low GHSV (<150) for increase hydraulic retention time (HRT), our result was worthy of notice. The gas composition monitored during the long-term stability test showed that the permeate side was composed of 97.8 vol% H 2 , and the retentate side contained 67.8 vol% CO 2 with 22.2 vol% CH 4 . When energy was recovered by CH 4 combustion in the retentate streams, pre-combustion carbon capture was accomplished using the Pd-based composite membrane reactor. [ABSTRACT FROM AUTHOR]

Techno-economic analysis (TEA) for CO 2 reforming of methane in a membrane reactor (MR) was conducted by using process simulation and economic analysis. Parametric studies for key operating conditions like a H 2 permeance, a H 2 O sweep gas flow rate, operating temperature, and a CO 2 /CH 4 ratio were carried out for a conventional packed-bed reactor (PBR) and a MR using Aspen HYSYS ® , a commercial process simulator program and some critical design guidelines for a MR in terms of a H 2 O sweep gas flow rate and a CO 2 /CH 4 ratio were obtained. Further economic analysis based on process simulation results showed about 42% reduction in a unit H 2 production cost in a MR (6.48 $ kgH 2 −1 ) than a PBR (11.18 $ kgH 2 −1 ) mostly due to the elimination of a pressure swing adsorption (PSA) system in a MR. In addition, sensitivity analysis (SA) revealed that reactant price and labor were the most influential economic factors to determine a unit H 2 production cost for both a PBR and a MR. Lastly, profitability analysis (PA) from cumulative cash flow diagram (CCFD) in Korea provided positive net present value (NPV) of $443,760∼$240,980, discounted payback period (DPBP) of 3.03–3.18 y, and present value ratio (PVR) of 7.51–4.97 for discount rates from 2 to 10% showing economic feasibility of the use of a MR as simultaneous CO 2 utilization and ultra-pure H 2 production. [ABSTRACT FROM AUTHOR]

In this paper, we report techno-economic analysis for CO 2 reforming of a medium-grade landfill gas in a membrane reactor (MR) for a H 2 production capacity of 7 m 3 h −1 in Korea. Parametric studies for the effect of key operating conditions like a H 2 permeance, a H 2 O sweep gas flow rate, and temperature on the performance in a conventional packed-bed reactor (PBR) and a MR were conducted using Aspen HYSYS ® , a commercial process simulator. Based on process simulation studies, economic analysis was carried out to find a unit H 2 production cost for both a PBR and a MR. Respective unit H 2 production costs of 9.72 and 6.46 $ kgH 2 −1 were obtained for a PBR and a MR showing about 34% reduction in the MR. Sensitivity analysis was employed to identify key economic factors to determine a unit H 2 production cost with labor the most influential factor for both reactors. Probability analysis (PA) was performed with influential factors based on a Monte-Carlo simulation method as uncertainty analysis and a cumulative probability (CP) curve was created for a PBR and a MR under various discount rates from 2 to 10% and key factor ranges from ±10 to ±40%. PA using stochastic approach provided a wide range of a unit H 2 production cost coupled with its probability and a critical CP value at which the effect of key factor range on a unit H 2 production cost was reversed. [ABSTRACT FROM AUTHOR]

In this study, we present an intermetallic diffusion barrier coating using a newly developed blowing coating method for a thermally stable Pd-based composite membrane on porous stainless steel (PSS). A tubular PSS sample with 1/2 inch (12.7 mm) in diameter and 450 mm in length was used for the support. The support was welded with a stainless-steel cap and a 450-mm-long stainless-steel tube for each end. Before the diffusion barrier coating, the large-sized entrance pores were gradually blocked with sub-micron (∼500 nm) and nano (50–80 nm) yttria stabilized zirconia (YSZ). 8YSZ, i.e., 8wt.% YSZ, was used for the interdiffusion barrier material and dispersed on the surface of the pre-treated PSS using the blowing coating method. The blowing coating method has 4 steps: (i) spraying the 17 wt. % 8YSZ paste on the surface of the PSS tube, (ii) blowing the paste using compressed air, (iii) drying at room temperature, and (iv) heat treatment at 923 K for 2 h in air. Steps (i) and (ii) were repeated 3 times to have a ∼240 nm thick 8YSZ layer. A thin palladium layer (∼3 μm) was deposited on the pre-treated PSS using electroless plating, and the membrane stability was tested at 673–773 K for ∼ 200 h. A hydrogen permeation flux of 9.86 × 10 −2 mol m −2 s −1 and an H 2 /N 2 selectivity of 595 were obtained at 773 K and a transmembrane pressure difference of 20 kPa. The surface and cross-sectional SEM/EDX analysis confirmed that the 8YSZ layer sufficiently prevented the interdiffusion between Pd and PSS elements, such as Fe, Cr and Ni. [ABSTRACT FROM AUTHOR]

Alkaline water electrolysis which is the most commercialized and mature technology of water electrolysis was researched to improve performance by the Korea Institute of Energy Research (KIER). In line with the trend of energy shift, renewable urea production through hydrogen production from alkaline water electrolysis was proposed in this work. To validate the process modeling of renewable urea production and hydrogen performance analysis with I–V curves was assessed. Economic and life cycle assessments were conducted to provide quantitative guidelines for renewable urea production. Absolutely, the influential factor of unit urea production cost was hydrogen from alkaline water electrolysis and environmental assessment results as well. Moreover, the guidelines for renewable urea production were provided through cost estimation and life cycle assessment. In summary, hydrogen production from alkaline water electrolysis had a significant impact on urea production and for this reason, research on alkaline water electrolysis should continue for further development. Based on experimental results, process simulation was performed, and comprehensive analysis was conducted including economic analysis and life cycle assessment. The experimental results from Korea Institute of Energy Research (KIER). [Display omitted] • Comprehensive analysis was conducted for renewable urea production. • Based on experimental results, process modeling was performed. • Technical analysis of renewable urea production was considered with I–V curve. • Economic analysis was conducted for renewable urea production. • Life cycle assessment of renewable urea production was demonstrated. [ABSTRACT FROM AUTHOR]

A numerical study of the behaviour of the multiphase flow of an anode-porous transport layer of an aqueous electrolyzer with a proton-exchange membrane (PEM) of an aqueous electrolyzer is presented. A mixture model was used to study the flow behaviour in a circular-shaped anode box to determine the efficient design of a PEM water electrolyzer. As a result of the simulation, it was found that the model pressure drop profiles obtained by computational fluid dynamics (CFD) are in good agreement with the corresponding experimental data. In addition, the performance profile was predicted considering various PEM water electrolyzer cell improvement factors compared to the Bassline model. The results of the behaviour of two-phase flows with different velocity, pressure and volume fraction profiles, as well as with porous regions in the centre, are presented, which showed a key difference in the flow profile for various inlet and outlet flow configurations. In addition, the flow volume fraction behaviour was obtained at higher and lower water and oxygen rates. Three-dimensional (3D) modelling predicted flow characteristics for three different cell configurations. In this article, we also run simulations over a wide range of flow rates. The main results of the numerical study were discussed to shed light on the design of a high-performance PEM water electrolyzer. • 3D multiphase computational fluid dynamics (CFD) analysis of PEM water electrolyser. • CFD model were verified with experiment data. • Evaluate the different configuration profile with oxygen and water flow behavior. • Key characteristics were discussed for optimum design of flow channel. [ABSTRACT FROM AUTHOR]

[Display omitted] • Comprehensive assessment in terms of 4E's analysis of CO 2 liquefaction is performed. • CO 2 liquefaction is evaluated in technical, economic, and environmental aspects. • Techno-economic and life-cycle assessments are performed for liquefaction processes. • Multi-criteria decision analysis is conducted based on the 4E's assessment results. Excessive fossil–fuel consumption to meet increased energy demand is considered as the main reason of the climatic change. To prevent this devastating change, hydrogen has gained much attention as an intermediate to replace fossil–fuel–based energy systems by sustainable green energy system. Since most of the H 2 is produced through natural gas process, a trade–off in terms of huge amounts of CO 2 emissions should be concerned. Accordingly, integration of the H 2 production and carbon capture facility actively, called blue H 2 , emerges as a workable alternative. In addition, with the rise in CO 2 demand, the liquefaction of captured CO 2 has become an attractive strategy in terms of long–term storage and transportation. Therefore, a comprehensive study is performed to assess the feasibility of an integrated system based on carbon capture using monoethanol amine and four CO 2 liquefaction systems such as Linde-Hampson, dual pressure Linde-Hampson, vapor compression refrigerant, and absorption refrigerant systems (later will use as case 1 to 4, respectively). Based on energy and exergy evaluations, case 4 reflects the higher efficiencies with specific energy consumption of 0.188 el and 0.733th GJ ton CO 2 -1 and exergy efficiency of 85.55 %. In addition, techno-economic analysis calculates unit LCO 2 production of each case; 22.19, 21.35, 21.00, and 24.60 $ ton-1 for cases 1, 2, 3, and 4, respectively. The quantified climate change impacts were estimated by life-cycle assessment; 0.629, 0.620, 0.608. and 0.674 kg CO 2 -eq kg LCO 2 -1 for cases 1, 2, 3, and 4, respectively. Furthermore, analytic hierarchy process is performed to provide comprehensive guidelines of liquefied CO 2 production under technical, economic, and environmental aspects. [ABSTRACT FROM AUTHOR]

• Two scenarios of ethylene production with seven electricity sources were performed. • This work aimed to find the proper cases for carbon–neutral ethylene production. • Economic, environmental, and technical feasibility of cases were analyzed. • Electrified steam cracking cases had the least carbon dioxide emissions. • Electrified steam cracking had a high potential for carbon neutrality. Electrification is regarded as one of the solutions for decarbonization. To reduce the emissions of carbon dioxide from the steam cracking which is a conventional ethylene production process, the electrical heating furnace can be applied to the steam cracking called the electrified furnace. Here, to determine whether the electrified steam cracking is proper for carbon neutrality, the techno-economic analysis, life cycle assessment, and the analytic hierarchy process were implemented. The analysis was proceeded by the fourteen cases divided according to steam cracking, electrified steam cracking, and seven electricity generation methods. As a result, considering the technology development level, economic feasibility, and environmental impact, the best case was the steam cracking with hydropower, and the electrified steam cracking with hydropower, solar power, and wind power had high potential. As improving the technology development of the electrified furnace, the electrified steam cracking can be expected to become the proper ethylene production process to achieve carbon neutrality. [ABSTRACT FROM AUTHOR]

The design of natural gas liquefaction process operated at offshore regards space as a design variable and requests an integrated and compact process due to space limitation. This study proposes an integrated process for natural gas liquefaction and NGLs recovery based on single mixed refrigerant (SMR) cycle. The considered SMR refrigeration cycle functions as dual mixed refrigerant (DMR) to provide two separate refrigeration levels for natural gas precooling and subcooling. NGLs recovery section includes a conventional column and a heat integrated distillation column in indirect sequence to produce lean gas, ethane liquid, LPG and gasoline. Liquefaction operating parameters were optimized using genetic algorithm in search of optimal values for profitable process with optimal energy consumption. NGLs recovery section of the proposed process is flexible, operable in both ethane recovery and ethane rejection modes. Based on base case process, the proposed process lowers energy consumption by 14%. The key features of the proposed process are cold utility recovery through self-refrigeration and ethane liquid recovery. [Display omitted] • LNG/NGLs integrated process for small-scale natural gas plant is proposed and simulated on Aspen HYSYS. • Natural gas liquefaction cycle is based on single mixed refrigerant and functions as dual mixed refrigerant. • NGLs recovery process includes a conventional distillation and a heat integrated distillation column system. • The process provides an internal cold energy recoverable to operate a refrigerated condenser. • Natural gas liquids recovery process is operable in ethane recovery and rejection modes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Techno-economic and environmental analyses were conducted for biogas valorization. • Landfill gas utilization was evaluated in economic and environmental aspects. • Various landfill gas treatment systems were considered for bio-methanol production. • Multi-criteria decision analysis was conducted to confirm the most acceptable route. With the regular increase in global solid waste, landfilling is intensively used for waste disposal. However, landfill gas (LFG) produced as a byproduct during waste decomposition in the landfills is a serious problem since it leads to damage to the eco-systems. Accordingly, it has been highlighted to convert LFG into other value-added chemicals. In this study, LFG utilization was studied in terms of conversion into methanol (MeOH) by considering different scenarios of LFG utilization. Techno-economic analysis and environmental assessment were performed to identify the economic feasibility and environmental impact of each case. From the economic analysis, bio-MeOH production costs of 879.16, 724.52, and 1,130.74 $ ton-1 for case 1, 2, and 3 was estimated with the economic infeasibility, while substantial cost reduction through projected cost analysis can lead to economic competitiveness (449.52 $ ton-1 for case 2 and 595.76 $ ton-1 for case 3). In sequence, the quantitative environmental impacts in terms of climate change impact were 2.360, 0.835, and 0.605 kg CO 2 -eq kg MeOH-1 for cases 1, 2, and 3, respectively. Based on the results of two analyses, a multi-criteria decision analysis was conducted to investigate the acceptable case of bio-MeOH production in the economic and environmental aspects. It can be concluded that the most feasible case depends on decision-makers if only economic and environmental criteria were considered. Therefore, dry reforming and membrane separation of LFG have considerable potential for bio-MeOH production in terms of LFG utilization for high weighting of economic and environmental aspects, respectively. [ABSTRACT FROM AUTHOR]

With a global trend of transition to the hydrogen-based energy system, the importance of improved systems of hydrogen production and transportation is emphasized. Especially, liquid organic hydrogen carrier is introduced due to its significant advantages when it is employed as a hydrogen energy carrier. In this study, the comprehensive preliminary feasibility study in technical, economic, and environmental aspects for hydrogen production systems using several promising systems of dodecahydro-N-ethycarbazole, Perhydro-dibenzyltoluene, methylcyclohexane, and methanol in a membrane reactor is conducted to investigate its potential to be alternative hydrogen production and transportation. With process simulation using Aspen Plus® based on detailed reaction kinetics for dehydrogenation of each dehydrogenation system and steam reforming of methanol, technical performance in terms of production rate is revealed. In addition, unit hydrogen production costs and key economic parameters for each system at various scales are estimated and compared by itemized cost estimation. Furthermore, realistic uncertainty analysis reflecting detailed distributions of each economic parameter obtained by various regression types of triangular, Epsilon skew normal, Birnbaum-Saunders, and Rayleigh and environmental assessment using SimaPro® are conducted revealing possible ranges of unit hydrogen production cost and carbon dioxide emission rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • Physical-machine learning hybrid model is proposed to predict solar PV power output. • The hybrid model is trained on a diverse dataset containing 6 different solar PV. • The model reduces error by 1.5 % and 42 % compared to the ML and physical model. • The hybrid model gives accurate result even when 97 % of the training data is loss. This research aims to develop a hybrid model combining machine learning and a physical model and demonstrate its effectiveness across diverse datasets, data scarcity scenarios, and not standard conditions. The hybridization approach involves parallel integration of physical and machine learning models, where the outputs of both models are weighted and yield improved predictions by assigning weight based on error minimization. A deep neural network serves as the machine learning model, while the single-diode model is employed as the physical model. This study utilizes six different solar PV for constructing the diverse dataset. Key findings reveal that the hybrid model can accurately predict power generation from a diverse range of solar PV, during data scarcity scenarios, and in all conditions. The model performs well in predicting solar PV power output in 6 types of solar PV with an average RMSE of 0.177 kW. The hybrid model outperforms machine learning and physical models by 1.5 % and 42 % respectively when trained on the full dataset. Moreover, when 97 % of the data is discarded intentionally, the hybrid model outperforms both machine learning and physical models by 47.7 % and 10.5 % respectively. The model also shows that it can improve the accuracy of the prediction during standard (solar irradiance = 1000 W m−2) and not standard conditions. The successful hybridization of machine learning and physical models addresses previously identified limitations in individual models. In addition, the model indicates a substantial improvement in terms of accuracy compared to prior published studies. [ABSTRACT FROM AUTHOR]

Circulating fluidized bed (CFB)-based co-pyrolysis is a promising technology for producing synthetic fuel and chemical co-products from biomass and waste feedstocks. Computational fluid dynamics (CFD) tools provide valuable insights for understanding gas-solid flow hydrodynamics, troubleshooting performance issues, and optimizing reactor operations. CFD simulations are computationally expensive and time-consuming; therefore, in this study, we developed an artificial neural network (ANN)-based machine learning model from a wide CFD simulation campaign. The CFB riser axial solid holdup profile was predicted using a two-fluid model and validated using the experimental data. Finally, a dataset connecting the input features of the model parameter-based simulations with their axial solid holdup was constructed for training the ANN. The performance of the developed model was later compared with the experimental data. The developed ANN model exhibited low mean square error values of order of 10−3 for both validation datasets to predict axial solid holdup. The ANN model performed well with an interpolated solid circulation rate of 45 kg/m2s and 62 kg/m2s and an extrapolated solid circulation rate of 30 kg/m2s and 80 kg/m2s. [Display omitted] • Introduced hybrid modeling approach to forecast CFB riser hydrodynamics. • Two-fluid model parameters with flow conditions were used as model input. • ANN model prediction performance was analyzed for different flow conditions. • CFD-ML model demonstrates successful qualitative prediction. [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) energy has come to the fore as a significant role of chemical industry in achieving a sustainable energy sector under serious environmental problems. Therefore, research for using H 2 as an energy carrier has been actively conducted. However, H 2 has very low volumetric energy density making it require conversion to other forms to acquire higher volumetric energy density. In this paper, the promising compound methanol (MeOH) was considered as a H 2 carrier owing to carbon-neutral in environmental terms. The two main overall H 2 supply scenarios were considered. The first case covers the use of MeOH produced from various types of H 2 (from steam methane reforming (SMR), coal gasification (CG), and water electrolysis (WE)), indirectly, and CO 2 electrolysis, directly, as a H 2 carrier, further converted to H 2 at desired locations. The second case covers the conversion of MeOH from four production pathways into H 2 followed by the transportation of the produced H 2 via various H 2 transportation methods such as compressed H 2 (CH 2), liquefied H 2 (LH 2), liquid organic hydrogen carrier (LOHC), and ammonia (NH 3). In this work, diverse H 2 supply scenarios considering various MeOH production methods, capacities, pathways, and distances were analyzed with unit H 2 supply cost via economic analysis. • Economic analysis was conducted for H2 supply scenarios including production and transportation. • Sensitivity analysis was performed to figure out reactant as most influential economic factor. • Unit H2 supply cost was obtained with various methanol production capacities and distances. • Technology readiness level (TRL) was considered to evaluate the feasibility of CO2 electrolysis. [ABSTRACT FROM AUTHOR]