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Biomethane potential (BMP) is often used to evaluate the biogas potential during anaerobic digestion (AD). However, BMP tests are complex and time-consuming. Therefore, the present study presents a hybrid model in machine learning (ML) for evaluating and predicting BMP based on biomass biochemical composition. Generative adversarial network (GAN) is combined with different ML models to model and predict BMP for different biomass materials. The models were trained on 64 experimental datasets (original datasets) and a combination of a GAN and the original datasets (augmented datasets). The gradient boost regression (GBR) model performed very well on the training set with both datasets compared to the support vector machine (SVM), Artificial neural network (ANN), and random forest (RF). RF and GBR models performed very well when trained with the combined GAN and original datasets, with RF slightly outperforming GBR on the test datasets (R2 score of 0.9106 vs. 0.9177). This indicates that the models benefit from the additional data generated by the GAN. The GBR model trained with the GAN and original datasets combined outperformed the RF model on the test set, with an R2 score of 0.9177 vs. 0.9106. A comparison between three different hyperparameter optimization methods (grid search, particle swarm optimization, and Bayesian optimization) showed that the grid search optimized model offers a balanced performance with an R2 score of 0.9994 and a marginal improvement on the test set with an R2 of 0.9213. Feature analysis results demonstrate that cellulose has the most influence on BMP. [ABSTRACT FROM AUTHOR]

Biomass valorisation for bioenergy is crucial for establishing a sustainable low-carbon circular bioeconomy and addressing societal and environmental challenges. As global demand for renewable energy grows, effective waste management using biomass becomes increasingly vital. However, successful implementation requires addressing specific local, scientific, and conceptual challenges, including technological intricacies, resource availability, scalability, and environmental impacts. Advancements in chemical looping gasification and chemical looping combustion are reviewed here as essential components of bioenergy with carbon capture and storage technologies. Chemical looping technologies have substantially contributed to decarbonising various industries, supported by precise trends. The review highlights the potential of chemical looping combustion and gasification in biomass utilisation for generating bioenergy and mitigating carbon emissions. Moreover, the advantages of chemical looping processes enhance their feasibility and applicability across different contexts including (1) significant increase in biomass conversion efficiency through chemical looping gasification, leading to substantial reductions in greenhouse gas emissions, (2) progress in chemical looping combustion, enhancing carbon capture and storage capabilities and contributing to a closed carbon cycle, (3) detailed insights into integrating chemical looping technologies into industrial sectors. [ABSTRACT FROM AUTHOR]

Definition: Active learning strategies are increasingly implemented in chemical engineering education, yet challenges persist in stimulating student participation and motivation. The rigorous demands placed on students in this field, from complex practical requirements to extensive programming and computational skills, underscore the need for innovative educational tools. Gamification emerges as a pivotal instrument in this context, fostering active student engagement, enhancing practical application of knowledge, increasing motivation, and providing a more precise assessment of student comprehension. These educational games serve as a powerful adjunct to traditional teaching strategies, equipping students with necessary skills for their future careers in the field. These games include laboratory course games, process simulators, games used in foundational courses, and those centered around reaction kinetics. This entry primarily investigates the various games employed to bolster student learning during chemical engineering laboratory courses. A thorough analysis is conducted on the survey of existing games used specifically in chemical engineering labs. The gamut of games discussed includes escape games, along with Virtual Reality (VR) and Augmented Reality (AR) games, all aiming to enhance laboratory experiences in areas such as fluid mechanics, organic reactions, and process control. This entry concludes by examining the prospective trajectory of gamification in chemical engineering labs, offering insights into future potential and advancements in this innovative educational approach. [ABSTRACT FROM AUTHOR]

Canola meal is a low-value agricultural residue obtained after oil extraction from canola, the utilization of which requires further attention. On the other hand, plastic waste disposal is also another leading issue that creates severe environmental challenges. Supercritical water gasification is considered an environmentally friendly technology to produce hydrogen from plastic residues and organic wastes. This study deals with hydrothermal co-gasification of canola meal and plastic wastes (i.e., low-density polyethylene) while exploring the influence of temperature (375–525°C), residence time (15–60 min) and plastic-to-biomass ratio (0:100, 20:80, 50:50, 80:20 and 100:0) on hydrogen yield. Maximum hydrogen yield (8.1 mmol/g) and total gas yield (17.9 mmol/g) were obtained at optimal temperature and residence time of 525°C and 60 min, respectively. A change in the gas yield with variable plastic-to-biomass ratio showed synergistic effects between both feedstocks. The trend of catalytic performance towards improving hydrogen yield was in the following order: WO 3 –TiO 2 (18.5 mmol/g) > KOH (16.9 mmol/g) > TiO 2 (9.5 mmol/g) > ZrO 2 (7.8 mmol/g) > WO 3 –ZrO 2 (7.4 mmol/g). • Canola meal and plastic waste were co-gasified in supercritical water for H 2 production. • Synergistic effects occurred during co-gasification of canola meal and plastic waste. • Effects of temperature, reaction time and plastic-to-biomass ratio were studied. • WO 3 –TiO 2 catalyst improved H 2 yields and carbon gasification efficiency. • Aliphatics, aromatics and organic compounds were obtained as intermediate products. [ABSTRACT FROM AUTHOR]

Waste biomass has the potential to produce renewable fuels and fine chemicals. Biofuels derived from agricultural, forestry, and energy crop systems are promising resources to address climate change and minimize greenhouse gas emissions. The recent advances in various thermochemical technologies for the conversion of waste biomass to value‐added biofuel products are discussed. A summarized outline of thermochemical technologies such as torrefaction, liquefaction, pyrolysis, and gasification is provided. An overview of different types and sources of biomass as well as their physicochemical properties is presented. The thermochemical conversion products and their environmental benefits are considered as well. [ABSTRACT FROM AUTHOR]

Waste biomass can be converted to green fuels and value-added products via thermochemical and biological conversion processes. The thermochemical processes endure limitations such as high processing costs due to high-temperature requirements. In contrast, the challenges of biological processes include low product yield and long processing time. Integrating different technologies, especially thermochemical and biological conversion processes, helps to enhance resource utilization and promote a circular economy. The combination of different technologies would help alleviate their limitations. In this respect, the integration of biological processes (e.g., syngas fermentation and anaerobic digestion) and thermochemical processes (e.g., pyrolysis, gasification, hydrothermal carbonization etc.) was the focus of this review. Integrated conversion processes often reduce the environmental impact compared to a standalone process. Hybrid pyrolysis-anaerobic digestion processes are promising from economics and ecological perspectives. However, more studies are required to understand how to effectively recycle and utilize the residue from pyrolysis and other thermochemical processes. Hydrothermal liquefaction (HTL) and pyrolysis are promising bio-oil production. However, HTL-derived oils are characterized by higher heating values and lower oxygen contents. The maturity level of most biological processes for waste biomass valorization is in the range of technology readiness level (TRL) 4-5. In contrast, thermochemical processes are expected to reach a TRL of 9 in the next two decades through detailed research and development. Moreover, the TRL of integrated processes described in the present study should also be assessed to evaluate their maturity and commercialization potential. The study will help researchers and policymakers to identify the knowledge gaps in integrating thermochemical and biological conversion processes. Motivation and novelty statement: The present review is the first of its endeavor to present the advances, progress, and prospects of combining thermochemical and biological conversion processes for biofuels and value-added chemicals production. Most of the studies available in the literature focus on the advances in thermochemical or biological processes as a standalone conversion pathway despite many possible integration scenarios available. Therein lies the motivation for the present study. The current review is helpful for new researchers and policymakers to acquire the fundamental knowledge and possible pathways to unlock full biomass conversion pathways. Therefore, the authors made a significant effort to explain each conversion pathway in the first few sections before outlining their advantages and limitation. The final section was entirely on the different possible integration scenarios followed by process integration challenges. This study aims to open up the possibility of future research and help researchers identify the knowledge gaps in integrating thermochemical and biological conversion processes. [ABSTRACT FROM AUTHOR]

[Display omitted] Waste biomass can be converted to green fuels and value-added products via thermochemical and biological conversion processes. The thermochemical processes endure limitations such as high processing costs due to high-temperature requirements. In contrast, the challenges of biological processes include low product yield and long processing time. Integrating different technologies, especially thermochemical and biological conversion processes, helps to enhance resource utilization and promote a circular economy. The combination of different technologies would help alleviate their limitations. In this respect, the integration of biological processes (e.g., syngas fermentation and anaerobic digestion) and thermochemical processes (e.g., pyrolysis, gasification, hydrothermal carbonization etc.) was the focus of this review. Integrated conversion processes often reduce the environmental impact compared to a standalone process. Hybrid pyrolysis-anaerobic digestion processes are promising from economics and ecological perspectives. However, more studies are required to understand how to effectively recycle and utilize the residue from pyrolysis and other thermochemical processes. Hydrothermal liquefaction (HTL) and pyrolysis are promising bio-oil production. However, HTL-derived oils are characterized by higher heating values and lower oxygen contents. The maturity level of most biological processes for waste biomass valorization is in the range of technology readiness level (TRL) 4–5. In contrast, thermochemical processes are expected to reach a TRL of 9 in the next two decades through detailed research and development. Moreover, the TRL of integrated processes described in the present study should also be assessed to evaluate their maturity and commercialization potential. The study will help researchers and policymakers to identify the knowledge gaps in integrating thermochemical and biological conversion processes. The present review is the first of its endeavor to present the advances, progress, and prospects of combining thermochemical and biological conversion processes for biofuels and value-added chemicals production. Most of the studies available in the literature focus on the advances in thermochemical or biological processes as a standalone conversion pathway despite many possible integration scenarios available. Therein lies the motivation for the present study. The current review is helpful for new researchers and policymakers to acquire the fundamental knowledge and possible pathways to unlock full biomass conversion pathways. Therefore, the authors made a significant effort to explain each conversion pathway in the first few sections before outlining their advantages and limitation. The final section was entirely on the different possible integration scenarios followed by process integration challenges. This study aims to open up the possibility of future research and help researchers identify the knowledge gaps in integrating thermochemical and biological conversion processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Economic and environmental assessment of waste-tires to sustainable aviation fuel was studied. • Results from pyrolysis-hydroprocessing and gasification – Fischer–Tropsch process were compared. • Economically both methods are promising with lower global warming potential. • Pyrolysis had a superior energy conversion efficiency compared to gasification. The aviation industry is a major source of greenhouse gas emissions, making it critical to transition from traditional fossil jet fuels to eco-friendly sustainable aviation fuels (SAF). This change is essential to achieve the goal of net-zero emissions by 2030. Moreover, Waste tires presents a significant environmental challenge due to their durability and difficulty of disposal. Their toxic and flammable nature complicates storage and processing. To address these challenges, waste tires can be processed to SAF using thermochemical processes such as pyrolysis to bio-oil and hydroprocessing, or gasification to syngas and Fischer-Tropsch synthesis (GFT). While waste tires appear to be a viable feedstock,there have not been studies to date that thoroughly compared the most efficient thermochemical process of converting waste tires to SAF. This study compares the economic and environmental impacts of two waste tire based SAF production methods (Pyrolysis/hydroprocessing and GFT). Economically, both methods are more favorable compared to other SAF pathways such as alcohol to jet (ATJ) or hydroprocessing of esters and fatty acids (HEFA). Pyrolysis SAF costs more (0.78 USD/l) than GFT SAF (0.66 USD/l). Pyrolysis is sensitive to hydrogen costs, with a 30% price fluctuation significantly impacting its minimum fuel selling price (MFSP). In contrast, the GFT method is more influenced by catalyst costs. Environmentally, pyrolysis emits less CO 2 (34.3 kg CO 2 eq/kg SAF) compared to GFT (58.6 kg CO 2 eq/kg SAF) but has a higher potential environmental impact in several categories, except for terrestrial ecotoxicity, where both methods are similar. Although pyrolysis has a lower global warming potential (GWP), it presents higher risks in toxicity and photochemical pollution. [ABSTRACT FROM AUTHOR]

Summary: Rapid industrialization, increasing fuel prices, exhausting fossil fuel resources and greenhouse gas emissions are some of the factors instilling the search for alternative sources of energy and chemicals. Lignocellulose biomass‐derived biofuels and biochemicals have emerged as clean products to complement fossil‐based resources and reduce environmental impacts. Lignocellulosic biomasses are renewable, inexpensive and abundantly available resources to produce a wide variety of liquid, gaseous and solid biofuels and industrially relevant biochemicals. Different biological (e.g., fermentation and anaerobic digestion), thermochemical (e.g., liquefaction, gasification and pyrolysis) and catalytic (e.g., transesterification) conversion technologies can be used to produce fuel and chemical products from lignocellulosic biomass. This article makes a comprehensive review of different biofuels (e.g., biodiesel, bio‐oil, bioethanol, biobutanol, biogas, hydrogen, syngas and jetfuel) and value‐added biochemicals (e.g., propylene, ethylene, benzene, 5‐hydroxymethylfurfural, levulinic acid, succinic acid, maleic acid, fumaric acid, phenols and other aromatic compounds) from lignocellulosic biomass. Additionally, the current status, challenges and future perspectives for the production and utilization of biofuels and biochemicals are systematically discussed. [ABSTRACT FROM AUTHOR]

The increasing world population, as well as demands for energy and industrial commodities, have led to an overall rise in anthropogenic greenhouse gas emissions. Moreover, demands for fossil fuels and petrochemicals are also gradually escalating in the developing and underdeveloped countries to sustain the transportation sector, industrial power generation and commodity chemical production. To address these challenges and to meet the Paris Agreement on climate change, there has been a growing interest in the development of renewable energy resources. Hydrogen is considered a strong candidate for the next-generation energy infrastructures as an energy carrier and vector, as well as a precursor or auxiliary component for several industrial processes. This review outlines current researches and applications of hydrogen in the processing and upgrading of hydrocarbon fuels, fuel cells, platform chemicals synthesis, pharmaceuticals, aerospace and maritime uses, metallurgy and electronics. Besides, applications of hydrogen as a direct fuel, synthesis of liquid hydrocarbons via Fischer-Tropsch process and syngas fermentation to alcohols are also reviewed. The specific utilization of hydrogen in the metallurgical industry is highlighted for metal reduction and in the oxyhydrogen flame for cutting and welding of metals. Besides, the article also describes the use of hydrogen in pharmaceutical industries for drug discovery. Finally, a variety of socio-economic aspects of hydrogen as a renewable fuel is also outlined in this article. Image 1 • Hydrogen is a clean energy carrier and vector with diverse industrial applications. • Hydrogen is used in power-to-gas systems, production of liquid hydrocarbons and fuel upgrading. • Hydrogen is applied in drug manufacturing, medical imaging and biomedical studies. • Oxy-hydrogen flames are used for welding, cutting metals and metal reduction. • Clean hydrogen is produced from gasification, electrolysis, photocatalysis, dark/photo-fermentation and biophotolysis. [ABSTRACT FROM AUTHOR]

Oil refineries are collectively responsible for about 4–6% of the global CO 2 emissions, largely because of the regenerator part of the Fluid Catalytic Cracking (FCC) unit (25–35%). An advanced combustion technology, also called chemical looping combustion (CLC), has been recently presented as a novel CO 2 capture process for FCC units; however, no study provides the economic feasibility of a CLC-FCC unit. In this study, a techno-economic feasibility of the novel CLC-FCC unit was presented for the first time based on a case study with 50,000 barrels feed per day. A rigorous mass and energy balance estimation shows that 96 vol% of coke regeneration (combustion) was achieved in the FCC regenerator by using a stoichiometrically required amount of metal oxide (CuO modified catalysts) at 750 °C for 45 min. The preliminary energy penalty calculations of the proposed CLC-FCC unit (0.21 GJ/ton CO 2) is relatively lower compared to the post-combustion (3.1–4.2 GJ/t CO 2) via amine solvent and oxy-fuel combustion (1.8–2.5 GJ/t CO 2) units reported in the literature. The equipment purchase cost (EPC) is 1.1 times higher than a standalone FCC unit due to the increase in the number of processing equipment required. The cash flow analysis results reveal a yearly basis average CO 2 capture cost of 0.0106 US$/kg of CO 2 (∼10.6 US$/ton CO 2) for the CLC-FCC unit, which is lower compared to the other conventional CCS technologies i.e. oxy-fuel combustion and post-combustion. Factors such as EPC, capital expenditure (CAPEX), and discount rate significantly influenced the capture cost. In contrast, the CO 2 capture cost is not influenced by a change in oxygen carrier and electricity cost. • Designed a novel Chemical Looping Combustion - Fluid Catalytic Cracking Unit • Performed a case study on CLC-FCC with a feed rate of 50,000 barrels of VGO • Performed a detailed tecnho-economic analysis on the designed CLC-FCC • CO 2 capture cost of the CLC-FCC concept was determined as ∼10.6 US$/ton CO 2 • Designed CLC-FCC provides 1.1 times higher EPC than conventional FCC unit [ABSTRACT FROM AUTHOR]

The accurate determination of biomass composition can enhance the efficacy of biofuel yield evaluations and provide valuable estimates for process economic viability. This study proposes a generative adversarial algorithm (GAN)-based machine learning (ML) model (hybrid deep learning method) for predicting the composition of lignocellulosic biomass, which includes cellulose, hemicellulose, and lignin content. The model employs proximate and ultimate analyses of biomass as input features, while comparing the performance of three different ML models, with random forest (RF) outperforming all other models). The implementation of the GAN significantly enhanced the model's performance. For the test dataset, the R2 values experienced an increase across all biomass components, with cellulose demonstrating the most noteworthy improvement, elevating from 0.7233 to 0.854. To further enhance the predictive capabilities of the model, hyperparameter optimization was performed. Before optimization, the RF model displayed strong correlations between predicted and actual values. However, post-optimization improvements were relatively minimal, with Grid Search and Bayesian Optimization yielding only marginally better results than Randomized Search. Additionally, an interpretable analysis was conducted to provide a deeper understanding of the relationship between proximate and ultimate analysis, and the structural composition of biomass. The findings presented in this study could prove useful in assessing the potential of biomass for the production of bio-based chemicals and biofuels. • GAN based Machine learning (ML) model for biomass composition prediction proposed. • Assessed three hyperparameter optimization methods' impact. • Random forest (RF) outperforms other models. • GAN data generation greatly enhances RF model performance. • R2 values for cellulose increased from 0.7233 to 0.854 with the use of GAN data. [ABSTRACT FROM AUTHOR]

Hydrothermal gasification in subcritical and supercritical water is gaining attention as an attractive option to produce hydrogen from lignocellulosic biomass. However, for process optimization, it is important to understand the fundamental phenomenon involved in hydrothermal gasification of synthetic biomass or biomass model compounds, namely cellulose, hemicellulose and lignin. In this study, the response surface methodology using the Box-Behnken design was applied for the first time to optimize the process parameters during hydrothermal (subcritical and supercritical water) gasification of cellulose. The process parameters investigated include temperature (300–500 °C), reaction time (30–60 min) and feedstock concentration (10–30 wt%). Temperature was found to be the most significant factor that influenced the yields of hydrogen and total gases. Furthermore, negligible interaction was found between lower temperatures and reaction time while the interaction became dominant at higher temperatures. Hydrogen yield remained at about 0.8 mmol/g with an increase in the reaction time from 30 min to 60 min at the temperature range of 300–400 °C. When the temperature was raised to 500 °C, hydrogen yield started to elevate at longer reaction time. Maximum hydrogen yield of 1.95 mmol/g was obtained from supercritical water gasification of cellulose alone at 500 °C with 12.5 wt% feedstock concentration in 60 min. Using these optimal reaction conditions, a comparative evaluation of the gas yields and product distribution of cellulose, hemicellulose (xylose) and lignin was performed. Among the three model compounds, hydrogen yields increased in the order of lignin (0.73 mmol/g) < cellulose (1.95 mmol/g) < xylose (2.26 mmol/g). Based on the gas yields from these model compounds, a possible reaction pathway of model lignocellulosic biomass decomposition in supercritical water was proposed. Image 1 • Hydrothermal gasification was studied by response surface methodology using Box-Behnken design. • Cellulose, hemicellulose and lignin were gasified in subcritical and supercritical water. • Process parameters e.g. temperature, reaction time and feed concentration were studied. • Temperature was found to be the most significant factor impacting H 2 yields. • Maximum H 2 yields were obtained from xylose (2.26 mmol/g) followed by cellulose (1.95 mmol/g) and lignin (0.73 mmol/g). [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO 2) is the largest anthropogenic greenhouse gas (GHG) on the planet contributing to the global warming. Currently, there are three capture technologies of trapping CO 2 from the flue gas and they are pre-combustion, post-combustion and oxy-fuel combustion. Among these, the post-combustion is widely popular as it can be retrofitted for a short to medium term without encountering any significant technology risks or changes. Activated carbon is widely used as a universal separation medium with series of advantages compared to the first generation capture processes based on amine-based scrubbing which are inherently energy intensive. The goal of this review is to elucidate the three CO 2 capture technologies with a focus on the use of activated carbon (AC) as an adsorbent for post-combustion anthropogenic CO 2 flue gas capture prior to emission to atmosphere. Furthermore, this coherent review summarizes the recent ongoing research on the preparation of activated carbon from various sources to provide a profound understanding on the current progress to highlight the challenges of the CO 2 mitigation efforts along with the mathematical modeling of CO 2 capture. AC is widely seen as a universal adsorbent due to its unique properties such as high surface area and porous texture. Other applications of AC in the removal of contaminants from flue gas, heavy metal and organic compounds, as a catalyst and catalyst support and in the electronics and electroplating industry are also discussed in this study. Unlabelled Image [ABSTRACT FROM AUTHOR]

The superabsorbent polymer (SAP) of the disposable diaper, which could serve as a substrate for pathogen growth, was valorized into nanostructured carbon through chemical activation for electrochemical hydrogen storage. The Box-Behnken experimental design was employed to elucidate the effects of activation conditions. Optimization results show that activation temperature and KOH:SAPC molar ratio had a greater impact on the textural and morphological characteristics of the nano-activated carbon. The best electrode material exhibited a surface area of 2552 m2/g, a total pore volume of 1.28 cm³/g, a total micropore volume of 0.871 cm³/g, and a pore size of 1.32 nm. The galvanostatic charge/discharge curves indicate that only higher current densities of 1 and 2 A/g could achieve a faster release of stored hydrogen in approximately 4 min. The best material stored hydrogen mainly through the electric double-layer mechanism, and the specific capacity reached 1878 mAh/g (6.60 wt% of H 2), which ranks among the best-reported hydrogen storage capacities with activated carbon. • Diaper waste was used as a sustainable precursor to prepare activated carbon. • Abundant micropores and high surface area allowed high hydrogen storage capacity. • Higher current density achieved faster release of adsorbed hydrogen atoms. • The mechanism of hydrogen storage is mainly electric double layer. [ABSTRACT FROM AUTHOR]

This study examined the effectiveness of a 915 MHz atmospheric pressure microwave torch for bulk syngas or hydrogen generation via noncatalytic greenhouse gas (GHG) reforming and its flexibility regarding the amount of soot formed by the process. The investigation shows that plasma-GHG reforming for mass hydrogen generation is feasible without a catalyst at high gas flow rate and microwave power. The best hydrogen production rate and energy yield were 1672 g (H 2)/h and 41.8 g (H 2)/kWh, respectively, at 160 lpm gas flow rate and 40 kW microwave power at a CH 4 /CO 2 ratio of 1. The conversion rates of CH 4 and CO 2 under the same conditions were 95.59% and 95.59%, respectively. The plasma reforming method employed in this study shows its excellent potential for industrial application. [Display omitted] • Greenhouse gases (GHG) reforming for mass hydrogen generation. • Investigated a 915 MHz atmospheric pressure microwave plasma torch for GHG reforming. • Attained hydrogen production rate and energy yield of 1672 g (H 2)/h and 41.8 g (H 2)/kWh. • CH 4 and CO 2 conversion of 95.6% and 95.4%, respectively, were realized. [ABSTRACT FROM AUTHOR]

[Display omitted] • The economic studies of two scenarios for resource recovery from pot ale was studied. • A high-fidelity simulation process model was developed with Aspen Plus simulation by using experimental data. • The minimum selling price of biomethane ranges between 142 U.S.$/ MWh to 148.9 U.S.$/MWh. • Ammonia produced from scenario 2 is estimated at a minimum selling price of 720 U.S.$/tons. • The potential environmental impact index was used to compare the environmental friendliness of the process. The necessity to decarbonise the whiskey distillery industry and minimize environmental pollution has triggered interest in the conversion of co-products such as pot ale into green fuels and chemicals. The disposal of pot ale to the environment creates severe environmental challenges due to its harmful composition. This study assesses the economic and environmental impacts of a novel integrated process for biomethane production and ammonia recovery from pot ale. Two scenarios were comprehensively studied. Scenario 1 includes the alkali pre-treatment, anaerobic digestion (AD) unit and biomethane purification unit. In contrast, scenario 2 introduces an additional gas–liquid stripping unit for efficient ammonia recovery from pot ale. Both scenarios were profitable from an economic standpoint. Scenarios 1 and 2 had a biomethane minimum selling price (MSP) of 142 U.S.$/ MWh and 148.9 U.S.$/MWh respectively. Ammonia produced from scenario 2 is estimated at a minimum selling price of 720 U.S.$/tons. The undiscounted net present value (NPV) of scenario 1 (10.4 million U.S.$) is greater than scenario 2 (6.7 million U.S.$). Also, Scenario 1 had a shorter payback period (PBP) (12.8 years) compared to scenario 2 (14.1 years). A local sensitivity analysis shows that factors such as raw material cost and fixed capital investment influenced the biomethane MSP. The environmental impact assessment of the two scenarios using the waste reduction algorithm confirms the environmental benign nature of the process. The total potential environmental impacts (PEI)/y for scenario 1 with coal as an energy source inside the system is 8494 PEI/y while the use of oil as an energy source produces a lower PEI of 8488 PEI/y. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalytic biodiesel (BD) synthesis, cavitation and acoustic reactors was reviewed. • The stability of biomass-derived catalysts is limited due to high ash content. • Hydrotalcites require harsh conditions to tailor BD synthesis. • Cavitation phenomenon propagates faster BD synthesis using acoustic reactors. • Enhanced mixing of BD-oil-catalyst can be attained using microfluidic reactors. Biodiesel production can be achieved through different processes and different reactor types as well as varying reaction parameters such as catalyst dose, oil: alcohol ratio, reaction time, mixing intensity, free fatty acid content (<3% required) and reaction temperature. The present review presents the advances in catalytic biodiesel production with emphasis on the current challenges, and prospects in homogeneous and heterogeneous catalysts. Particularly, alkaline earth metal, metal mixed oxides, carbon-based and biomass-derived catalysts, and ionic liquids are discussed in detail. In addition, microfluidic, and acoustic reactors such as ultrasonic and hydrodynamic cavitation reactors are reviewed. The results from conducted studies revealed calcium oxide (CaO)-based catalysts derived from either residual biomass sources or synthetic chemicals are more favorable for biodiesel synthesis. Hydrotalcite catalysts and ionic liquids require harsh conditions such as higher temperature, higher oil: methanol ratio, and longer reaction time to achieve appreciable yield. The micro-reactors and cavitation reactors provide a faster reaction rate compared to conventional reactors because there is a drastic reduction in the time it takes for miscibility and diffusion of the reactant molecules and hence, eliminates the high energy requirement for mixing. The hydrodynamics reactor presents lower erosion challenges and energy input per unit of reactants when compared with the ultrasonic reactor. It is hoped that this study will provide detailed and recent knowledge on heterogeneous catalysts, microfluidic, and cavitation reactors for biodiesel synthesis. [ABSTRACT FROM AUTHOR]

• Hydrothermal gasification can effectively produce H 2 -rich syngas from waste biomass. • Modeling and optimization of hydrothermal gasification can improve its efficiency and economics. • Thermodynamic, kinetic and computational fluid dynamics modeling are popular modeling approaches. • Optimization approaches include univariate, factorial, Taguchi, and response surface methodology. • Machine learning and artificial neural networks are prospective modeling approaches. [Display omitted] Hydrothermal gasification of biomass is an alternative method of producing hydrogen-rich syngas. Modeling and optimization of hydrothermal processes are important to evaluate the economic feasibility of the process. Furthermore, developing a mathematical model to represent the many underlying mechanisms during hydrothermal gasification could contribute to lower process expenditures, improve efficiency and provide an in-depth understanding of the process. The present study outlines different modeling and optimization strategies for hydrothermal gasification of biomass and waste materials to produce hydrogen-rich syngas. The modeling techniques (e.g. thermodynamic, kinetic and computational fluid dynamic modeling) and process optimization approaches (e.g. univariate, factorial, Taguchi, response surface methodology and mixture design of experiments) are discussed in this review comprehensively together with their merits and limitations. The knowledge gaps and prospects of modeling and optimization of hydrothermal conversion are also elucidated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design for hydrothermal gasification of 56,000 metric tons/year of soybean straw. • Aspen Plus-designed plant can process 170 metric tons/day of soybean straw. • Breakeven cost of H 2 was U.S. $1.94/kg excluding storage and transportation cost. • Tax rate and costs of feedstock, catalyst and labor impact breakeven cost of H 2. • Cash flow analysis was used to evaluate profitability of the project. This paper proposes a conceptual design for the catalytic supercritical water gasification of soybean straw. The design consists of four process units for pretreatment, gasification, separation, purification and combustion. The economic feasibility of hydrogen production was evaluated based on a comprehensive cash flow analysis. The economic analysis suggested a minimum selling price of U.S. $1.94/kg for hydrogen. The cost of hydrogen produced is relatively lower compared to that of other biomass conversion processes. Besides, the net rate of return (NRR) estimated was 37.1%. A positive NRR value indicates that the project is profitable from an economic perspective. Sensitivity analysis indicates that the minimum selling price of hydrogen is affected by the feedstock price, utility cost, tax rate and labor cost. Moreover, feedstock price and labor cost show the greatest effect. Other factors such as land cost, working capital and utility cost showed the least effect on the minimum selling price. [ABSTRACT FROM AUTHOR]

The emerging Schiff base‐derived metal complexes are the building blocks for biomedical applications. Herein, novel Schiff base N,N′‐[(1Z,2Z)‐1,2‐diphenylethane‐1,2‐diylidene]bis(6‐nitro‐1,3‐thiazol‐2‐amine) and corresponding Cu(II), Ni(II), Mn(II), and Co(II) metal complexes were successfully synthesized and characterized. The characterization of ligand and corresponding metal complexes was carried out by employing elemental analysis, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy, Fourier transform infrared spectroscopy (FTIR) analysis, molar conductance, magnetic susceptibility measurements, electronic spectra, electronic paramagnetic resonance (EPR) and density functional theory (DFT) studies. DFT calculations at B3LYP/6‐311+G** level of theory have been executed to examine the equilibrium geometry of the ligand and metal complexes. Furthermore, total energy, highest‐occupied molecular orbital (HOMO) and lowest‐unoccupied molecular orbital (LUMO), and Mulliken atomic charges were reckoned. Tetrahedral geometry was observed in the case of the Ni(II) complex, and octahedral geometries were discerned for Cu(II), Mn(II), and Co(II), complexes. Docking studies were performed against the newly synthesized analogs with the active site of Escherichia coli (PDB ID: 3t88), Staphylococcus aureus (PDB ID: 3q8u), Candida Albicans (PDB ID: 3qlw), and Aspergillus flavus (PDB ID: 4ynt) receptors to recognize the interactions between complexes and identify their probable binding sites. Synthesized analogs were examined for in vitro antimicrobial activity employing both minimum inhibitory concentration and disk diffusion method against the aforementioned pathogens. The result for these pathogens suggested metal compounds evince higher activity in comparison to the free ligand. [ABSTRACT FROM AUTHOR]

Due to the increasing world population and environmental considerations, there has been a tremendous interest in alternative energy sources. Hydrogen plays a major role as an energy carrier due to its environmentally benign nature. The combustion of hydrogen releases water vapor while it also has a vast industrial application in aerospace, pharmaceutical, and metallurgical industries. Although promising, hydrogen faces storage challenges. Underground hydrogen storage (UHS) presents a promising method of safely storing hydrogen. The selection of the appropriate cushion gas for UHS is a critical aspect of ensuring the safety, efficiency, and reliability of the storage system. Cushion gas plays a pivotal role in maintaining the necessary pressure within the storage reservoir, thereby enabling consistent injection and withdrawal rates of hydrogen. One of the key functions of the cushion gas is to act as a buffer, ensuring that the storage pressure remains within the desired range despite fluctuations in hydrogen demand or supply. This is achieved by alternately expanding and compressing the cushion gas during the injection and withdrawal cycles, thereby effectively regulating the overall pressure dynamics within the storage facility. Furthermore, the choice of cushion gas can have significant implications on the performance and long-term stability of the UHS system. Factors such as compatibility with hydrogen, cost-effectiveness, availability, and environmental impact must be carefully considered when selecting the most suitable cushion gas. The present study provides a comprehensive review of different types of cushion gases commonly used in UHS, including nitrogen, methane, and carbon dioxide. By examining the advantages, limitations, and practical considerations associated with each option, the study aims to offer valuable insights into optimizing the performance and reliability of UHS systems. Ultimately, the successful implementation of UHS hinges not only on technological innovation but also on strategic decisions regarding cushion gas selection and management. By addressing these challenges proactively, stakeholders can unlock the full potential of hydrogen as a clean and sustainable energy carrier, thereby contributing to the global transition towards a low-carbon future. [ABSTRACT FROM AUTHOR]

The demand for sustainable energy sources has increased owing to environmental concerns, such as climate change, rising energy demand and rapid industrialization. Biomass utilization for bioenergy and value‐added chemical production has become essential for creating a circular low‐carbon bioeconomy and sustainable waste management techniques. This review focuses on thermochemical processes and analyzes the trends of biomass utilization for energy production in the EU over the last decade. It discusses the current state‐of‐the‐art of gasification, pyrolysis, advanced combustion and liquefaction technologies, and presents the individual challenges and prospects of each process. A comprehensive overview of previous studies related to each conversion technology is provided to pave the way for future thermochemical, biochemical and integrated biomass valorization studies. Additionally, the review discusses biomass thermochemical conversion processes, which are combined with carbon capture, such as gasification, liquefaction and pyrolysis. These processes offer the potential to achieve negative net atmospheric carbon emissions, which can contribute to global warming mitigation efforts. [ABSTRACT FROM AUTHOR]

• Soybean straw and flax straw were gasified under hydrothermal conditions. • Optimal temperature (500 °C), biomass-to-water ratio (1:10), biomass particle size (0.13 mm) and residence time (45 min). • Higher H 2 yield from soybean straw (6.62 mmol/g) than flax straw (3.82 mmol/g). • KOH catalyst enhanced H 2 and total gas yields from soybean straw and flax straw. • Experimental results show a slight deviation from thermodynamic yields. Biofuels produced from lignocellulosic feedstocks are gaining popularity because of the elevating energy demand, increasing greenhouse gas emissions, escalating fuel prices and dwindling fossil fuel resources. Therefore, it has become important to seek alternative energy resources from renewable waste biomass. In this study, agricultural crop residues such as soybean straw and flax straw were gasified in subcritical water (300 °C) and supercritical water (400 and 500 °C) for H 2 production. To maximize the non-catalytic process, the impacts of temperature (300–500 °C), biomass-to-water ratio, BTW (1:5 and 1:10), biomass particle size (0.13 mm and 0.8 mm) and residence time (30–60 min) on H 2 production were studied at a pressure range of 22–25 MPa. Maximum H 2 yield and total gas yields of 6.62 mmol/g and 14.91 mmol/g, respectively were obtained from soybean straw at the highest temperature (500 °C), lower feed concentration (1:10 BTW), smaller particle size biomass (0.13 mm) and longer residence time (45 min). To evaluate the drift in the experimental H 2 yield from the theoretical values, thermodynamic modeling using Gibbs free minimization method was performed. The experimental results showed slight deviations from the thermodynamic models due to the temperature gradient and absence of agitation in the tubular batch reactor. However, the KOH catalyst was found to elevate the H 2 , CO 2 and CH 4 yields for soybean straw and flax straw. The findings suggest that supercritical water gasification could be an efficient green technology for H 2 production from waste biomass. [ABSTRACT FROM AUTHOR]

Lignocellulosic feedstocks such as forestry biomass and agricultural crop residues can be utilized to generate biofuels and biochemicals. In addition, a large amount of non-plant residues or biogenic wastes is also generated worldwide that has huge potentials but remains underutilized. Converting these organic waste materials through thermochemical and biochemical processes into biofuels is widely regarded as a remedial approach to address waste management and clean energy problems. One of such thermochemical biomass-to-gas technologies is hydrothermal gasification in the presence of subcritical or supercritical water, which utilizes the unique fluid properties of water to disintegrate effectively the organic wastes into hydrogen-rich syngas. This paper reviews the thermophysical chemistry of subcritical and supercritical water as well as their role in generating syngas from the hydrothermal decomposition of biogenic, polymeric and organic wastes such as municipal solid waste, animal manure, food waste, industrial effluents, sewage sludge, mixed plastics, waste tires and petrochemical wastes. The paper also describes different technologies used for syngas cleaning and conditioning together with gas-to-liquid technology such as Fischer-Tropsch synthesis to produce hydrocarbon fuels. The current progress, challenges and knowledge gaps in the research and development of hydrothermal gasification of biogenic wastes are also discussed. Image 1 • Hydrothermal gasification is an alternative method for waste-to-energy conversion. • Supercritical water gasification can effectively decompose biogenic wastes to H 2. • Integrated gasification, syngas cleaning and Fischer-Tropsch process are beneficial. • Catalysts can enhance H 2 yields from hydrothermal gasification of biogenic wastes. • Water-gas shift, methanation and hydrogenation reactions impact syngas yields. [ABSTRACT FROM AUTHOR]

Mechanical, physical, and corrosion properties of pure aluminum cannot meet the requirements of the modern industries. This has led to increase in demand for aluminum alloys and aluminum matrix composites with enhanced properties. These properties make them suitable for most applications. This article analyzes the physicomechanical and microstructural properties of stir cast Al6063 alloy matrix reinforced with different weight fractions (2, 4, and 6 wt.%) of sawdust ash (SDA). The density, porosity, hardness, tensile strength, and impact strength of the unreinforced alloy and developed composite samples were evaluated while microstructural analysis was also carried out. The results showed reduced density values with increased SDA contents while percentage porosity ranged between 1.56 and 2.23%. The hardness (88.3–106.93 BHN) and tensile strength (112.13–132.71 MPa) of the composites were 21.09% and 18.35% better than those of Al6063 alloy. However, the impact strengths (45.48–35.51 J) of the composites were lower when compared to the unreinforced Al6063 alloy with a reduction of 21.92%. Microstructural images showed evenly distributed reinforcement particles within the matrix, while the XRD analysis also revealed the presence of different intermetallic phases in the composite samples. The micrographs of the composites showed plastic deformation during straining. The findings from the study indicate that SDA particulates incorporated into alloy matrix influenced the properties with increased hardness and tensile strength and reduced impact strength. Hence, the aluminum matrix composites will be suitable for use in lightweight engineering applications. [ABSTRACT FROM AUTHOR]

Definition: Gas–liquid mass transfer is a major issue during various bioprocesses, particularly in processes such as syngas fermentation (SNF). Since SNF involves the movement of gases into the fermentation broth, there is always a rate-limiting step that reduces process efficiency. Improving this process could lead to increased efficiency, higher production of ethanol, and reduced energy consumption. One way to improve fluid transfer between gas and liquid is by incorporating nanoparticles (NPs) into the liquid phase. This entry describes recent advances in using NPs to improve gas–liquid mass transfer during SNF. The entry also describes the basics of SNF and the impact of NPs on the process and suggests areas for future research. For example, carbon nanotubes have been found to elevate the available surface area needed for gas–liquid transfer, thus improving the process efficiency. Another area is the use of NPs as carriers for enzymes involved in syngas fermentation. [ABSTRACT FROM AUTHOR]

The use of coal for energy generation is facing serious scrutiny because of environmental concerns. As a result, there is a growing global interest in biomass, a renewable and readily available energy source. However, the utilization of biomass comes with significant drawbacks, including its heterogeneity, low bulk density, and calorific value. Biomass also has a low energy content, high moisture, poor grindability, and high volatile matter, which affect its handling, bulk transportation, and storage. Torrefaction technology has been employed in previous works to improve the properties of biomass for subsequent handling and transportation and for low-cost energy generation. Since coal is a promising precursor for energy generation, it is imperative to compare the physicochemical properties of coal with that of torrefied biomass. Therefore, this study aims to conduct a comprehensive comparison between various grades of coal and torrefied biomass. The review revealed that torrefied biomass could replace coal, as its properties are similar to those of coal, except for high-grade coals. The proximate and ultimate analyses of coals (lignite and bituminous) were found to be comparable to various torrefied biomass materials. The fuel ratio (0.5–2.0), and higher heating values (16,100–19,000 kJ/kg) of coal and torrefied biomass were within the range useful for coal-fired plants. Additionally, ash analyses, ash fusion temperature, hygroscopic tendency, functional group study, and microstructural comparison were reviewed in this study. The results from various studies have shown close similarities with only small disimilarities in the fuel properties between coal and torrefied biomass. Therefore, torrefied biomass is proposed as a complimentary feedstock to coal in various applications. [Display omitted] • The similarity and disparity between torrefied biomass and coal are discussed. • Proximate, ultimate, calorific, and FTIR analyses of torrefied biomass and coal were discussed. • Fuel ratio, ash content, and grindability values of torrefied biomass and coal were discussed. • Present grade of coal with similar properties to torrefied biomass and application in thermal plants. • Recommend partial or total replacement of coal with torrefied biomass in co-fired plants. [ABSTRACT FROM AUTHOR]

Organic acids are important compounds with numerous applications in different industries. This work presents a comprehensive review of the biological synthesis of oxalic acid, an important organic acid with many industrial applications. Due to its important applications in pharmaceuticals, textiles, metal recovery, and chemical and metallurgical industries, the global demand for oxalic acid has increased. As a result, there is an increasing need to develop more environmentally friendly and economically attractive alternatives to chemical synthesis methods, which has led to an increased focus on microbial fermentation processes. This review discusses the specific strategies for microbial production of oxalic acid, focusing on the benefits of using bio-derived substrates to improve the economics of the process and promote a circular economy in comparison with chemical synthesis. This review provides a comprehensive analysis of the various fermentation methods, fermenting microorganisms, and the biochemistry of oxalic acid production. It also highlights key sustainability challenges and considerations related to oxalic acid biosynthesis, providing important direction for further research. By providing and critically analyzing the most recent information in the literature, this review serves as a comprehensive resource for understanding the biosynthesis of oxalic acid, addressing critical research gaps, and future advances in the field. [ABSTRACT FROM AUTHOR]

[Display omitted] • The study integrates Machine Learning with process simulation to model waste biomass pyrolysis. • Key properties like H/C ratio, O/C ratio, and yields of oil, gas, and char yield were used as output for the model. • Hyperparameter optimization significantly improved the performance of some models. • AdaBoost model's R2 increased from 0.81 to 0.90 because of hyperparameter optimization. • A publicly available graphical user interface was developed based on the ML model results. Waste biomass pyrolysis is a promising thermochemical conversion process for the production of biofuels and sustainable materials. However, it is challenging to accurately predict the properties and yield of products formed during pyrolysis. Machine learning (ML) is a useful tool for predicting the performance of a process. In the present study, ML algorithms integrated with process simulation were explored to accurately model waste biomass pyrolysis based on properties such as H/C, O/C, oil yield, gas yield, and char yield. Six different ML models including Random Forest (RF), Gradient Boosting Regressor (GBR), eXtreme Gradient Boosting (XGBoost), Adaptive Boosting (AdaBoost), Artificial Neural Network (ANN), and Stochastic Gradient Descent (SGD) were used to model pyrolysis process. It was found that the out-of-the-box (without optimization) models for RF, XGBoost, ANN, and GBR performed the best and did not benefit from hyperparameter optimization. The GBR was identified as the most effective among various ML models. It accurately predicted yields of gas, biochar, bio-oil yields, and their H/C and O/C compositions. GBR effectively demonstrated the complex relationships between these variables. The box plot showing the root mean squared logarithmic error (RMSE) revealed that the GBR model had the best overall performance with a value less than 0.03. Also, the partial dependence plot and SHAP feature importance were evaluated to better understand each feature's effect on the output. Lastly, a shareable graphical user interface (GUI) was created to enable researchers explore and predict pyrolysis yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • Metal oxides are efficient catalysts due to their hydrothermal stability. • Promoters can increase catalytic activity and minimizes coking in thermochemical reactions. • Alkali-based catalysts increase H 2 yield in catalytic gasification. • Cobalt catalysts are efficient over iron catalysts in Fischer-Tropsch synthesis. • Catalytic liquefaction increases hydrocarbons content and heating value of bio-crude oil. The increase in the global population and industrialization has induced an unprecedented increase in biogenic wastes. These biogenic wastes are a potential source of energy and a suitable alternative to energy from non-renewable fossil fuels. Thermochemical technologies are effective ways to transform wastes biomass into biofuels and value-added biochemicals. However, non-catalytic thermochemical conversion technologies are associated with challenges such as low yield, undesirable byproducts and higher levels of heteroatoms affecting the quality of final fuel products. Therefore, there is a need for innovative catalytic approaches to mitigate such challenges. In this review article, various catalyst and their synthesis pathways have been highlighted with specific applications in thermocatalytic conversion technologies. Furthermore, a state-of-the-art review was performed to discuss the impacts of catalysts on the production of biofuels and biochemicals via pyrolysis, gasification, liquefaction, Fischer-Tropsch synthesis and polysaccharides conversion. In addition, an attempt has been made to address the challenges posed by catalysts and their synthesis routes by evaluating the effect of different process parameters. [ABSTRACT FROM AUTHOR]

The densification parameters for sub-bituminous coal briquette were optimized in this study to obtain maximum drop to fracture (DF), water resistance index (WRI), and cold crushing strength (CCS). Full factorial experimental design was used to optimize the compaction pressure (14 and 56 MPa), particle size (0.5 - 1 mm), and external moisture content (3 - 10%). Briquettes were produced with a pitch binder and cured at 300°C for 60 minutes in an inert environment of a tubular furnace. The DF, WRI and CCS of the coal briquettes were carried out and mathematical models were developed between the dependent and independent variables. The results showed that particle size has the largest influence on the physicomechanical properties, whereas the pressure and moisture content have minimal impact. Lower particle size implied better physicomechanical properties for the coal briquettes. The optimum process parameters for maximum physicomechanical properties were pressure of 56 MPa, particle size of 0.5 mm, and moisture content of 10%. The maximum DF, WRI, and CCS obtained for the coal briquettes were 170 times/2m, 97.78%, and 7.94 MPa, respectively. The mathematical models developed were validated and found useful at 95% confidence level. Coal briquettes useful for energy generation was successfully developed. [ABSTRACT FROM AUTHOR]

Nanomaterials are beginning to play an essential role in addressing the challenges associated with hydrogen production and storage. The outstanding physicochemical properties of nanomaterials suggest their applications in almost all technological breakthroughs ranging from catalysis, metal-organic framework, complex hydrides, etc. This study outlines the applications of nanomaterials in hydrogen production (considering both thermochemical, biological, and water splitting methods) and storage. Recent advances in renewable hydrogen production methods are elucidated along with a comparison of different nanomaterials used to enhance renewable hydrogen production. Additionally, nanomaterials for solid-state hydrogen storage are reviewed. The characteristics of various nanomaterials for hydrogen storage are compared. Some nanomaterials discussed include carbon nanotubes, activated carbon, metal-doped carbon-based nanomaterials, metal-organic frameworks. Other materials such as complex hydrides and clathrates are outlined. Finally, future research perspectives related to the application of nanomaterials for hydrogen production and storage are discussed. [Display omitted] • Different routes for renewable H 2 production are discussed. • A comparison of the H 2 storage capabilities of various nanomaterials is presented. • New technological advances on nanomaterial applications for H 2 storage are explained. • Computational methodologies for H 2 storage are evaluated. • Future research recommendations are presented based on identified literature gaps. [ABSTRACT FROM AUTHOR]

Hydrothermal flames are formed in supercritical water in the presence of a fuel and an oxidant (usually air or oxygen). Integrating hydrothermal flames as the heat source for supercritical water oxidation helps to minimize the reaction time (to milliseconds), improve the reaction kinetics and reduce the chances of corrosion and reactor plugging. This review outlines state-of-the-art research on hydrothermal flames including the impacts of process parameters on flame ignition. The ignition and sustainability of hydrothermal flames are dependent on several factors such as the type of fuel and its concentration, type of oxidant (air and oxygen) as well as the temperatures and flow rate of the feed and oxidant. The article describes some novel applications of hydrothermal flames for clean energy production, geothermal energy recovery, deep well spallation, wastewater treatment, degradation of recalcitrant nitrogen-containing compounds and heavy oil upgrading. Finally, the challenges and future perspectives of hydrothermal flame applications are discussed. This review also highlights some technical considerations relating to hydrothermal flames such as the choice of organic solvent and its characteristics, preheating, ignition mechanism, flame stability and propagation, advanced reactor configurations, mixing with subcritical and supercritical components, recirculation zones, cooling mechanisms, corrosion and salt precipitation. [Display omitted] • Hydrothermal flames are produced by supercritical water, fuel and oxidant. • Hydrothermal flames can treat nuclear, biohazardous waste and wastewater. • Hydrothermal flames can recover renewable energy and upgrade heavy oils. • The review elucidates the applications of hydrothermal spallation drilling. • Preheating, ignition mechanism and stability of hydrothermal flames are reviewed. [ABSTRACT FROM AUTHOR]

The current study focused on characterizing lean grade coal and carbonized biomass (at 400oC) for energy generation. Samples were pulverized using a ball mill and then mixed with a mechanical mixer at two mixing ratios. Proximate, ultimate and calorific value analyses were carried out on the samples using different ASTM standards and some available linear regression models. Lean grade coal has the highest ash content (79.58%) while raw biomass has the least (2.29%). Carbonized biomass samples have the highest heating value (9.49 MJ/kg). The O/C and H/C atomic ratios shows that carbonized biomass is the best fuel compared to coal and blended samples. The FTIR spectra of coal and blended samples shows peaks representing Si-O-Si while C-H bonds were the predominant ones in raw and carbonized samples. Lean grade coal and blended samples contain silicon as displayed by the EDX spectra. The coal and blended samples have grey-like silica and carbide microstructure. The coal and blended samples are not good for energy generation but may serve well as raw material for silicon recovery. Carbonized biomass has good fuel properties that can be useful in existing coal-fired plants. [ABSTRACT FROM AUTHOR]

This study analyses the impact of particle polydispersity using the Eulerian-Eulerian (EE) and Lagrangian-Eulerian (LE) modelling approaches in the context of wellbore cleaning operations in the drilling industry. Spherical particles of sizes 0.5 mm, 0.75 mm and 1 mm are considered, whereas a Power Law rheological model is used for the fluid phase description. The EE approach implemented herein applies the Kinetic Theory of Granular Flow (KTGF) in ANSYS Fluent® and accounts for the particle size differences by representing them as different phases within the computational domain. With the LE approach, we employ the Dense Discrete Phase Model (DDPM) and capture this difference with the aid of a size distribution model (the Rosin-Rammler model). The findings of our computational experiments show considerable differences in key variables (the pressure drop, and particle deposition tendencies) between monodispersed and polydispersed transport scenarios. • A comparison between monodispersed and polydispersed transport is presented. • Considerable differences in cuttings transport velocity exist between the LE & EE method. • Increased particle deposition is observed with monodispersed transport in this study. • The pressure drop is overpredicted when monodispersity is assumed. [ABSTRACT FROM AUTHOR]

• The cubic EoS applied, successfully predicted MEG and Methanol compositions. • PSRK mostly overpredicted the compositional distributions in the respective phases. • The CPA EoS with Infochem mixing rules was found to be the most accurate EoS. • Prediction accuracies showed no convincing dependence on operating conditions. This study presents a comparative computational examination of different cubic equations of state (EoS) on hydrate inhibition fluid systems involving real reservoir fluids. Two gas hydrate inhibitors (Monoethylene glycol – MEG and methanol) were considered alongside 4 cubic EoS namely; Cubic-Plus-Association (CPA) EoS coupled with Infochem mixing rules, Soave-Redlich-Kwong (SRK) EoS coupled with the Huron-Vidal (HV) mixing rule, Peng Robinson EoS coupled with the HV mixing rule and the Predictive-Soave-Redlich-Kwong EoS with the PSRK-type mixing rule. Pressure-Temperature (PT) – flash calculations were carried out using MultiflashTM software (version 6.1) and the obtained results were compared with experimental data from various literature. The tested Cubic EoS successfully modelled the distribution of water, a hydrate inhibitor and hydrocarbons in the complex mixtures at different conditions with the CPA EoS performing best. The PSRK EoS produced results farthest from experimental data. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Subsurface hydrogen production technologies were introduced. • The potential of the approach to significantly reduce CO 2 emissions was highlighted. • An overview of major barriers to subsurface technologies was provided. • Finally, the operational challenges faced in subsurface hydrogen production were addressed. Subsurface technologies present an excellent opportunity to produce hydrogen from hydrocarbon resources. It refers to the production of hydrogen directly from underground resources, particularly hydrocarbon resources. This method often involves injecting steam or oxygen into the reservoirs to initiate reactions that produce hydrogen. In some cases, subsurface method can also involve the process of in-situ gasification (ISG), and in-situ combustion (ISC) (also known as subsurface combustion and gasification). The produced hydrogen is extracted from the reservoir, leaving the carbon dioxide and other byproducts underground. This approach could offer a sustainable and carbon-free pathway to produce hydrogen because of reduced CO 2 emissions compared to conventional methods. A comprehensive review of the status and progress of ISC and ISG of hydrocarbon for hydrogen production is presented. The advantages and limitations of the technologies were discussed as well as the underlying reaction mechanism. Techno-economic and lifecycle assessment studies of ISG and ISC are presented. One of the main economic limitations of subsurface hydrogen production is the high cost of building and operating the required infrastructure. However, utilizing pre-existing horizontal wells for air or oxygen injection can significantly reduce the initial infrastructure investment costs. Moreover, the overall process cost of ISG can vary significantly due to various factors, including membrane costs, oxygen production costs and the cost of hydrocarbon. The findings from the environmental evaluation indicate that the primary contributors to greenhouse gas emissions in subsurface technologies are the CO 2 emissions produced during gas combustion for heat generation and the electricity consumed during the gasifying agents' preparation stage. Subsurface methods for producing hydrogen encounter numerous challenges, including choosing the right locations and selecting cost-effective drilling techniques. [ABSTRACT FROM AUTHOR]

Corn husk, an abundant agro-industrial waste was employed to produce activated carbon for energy storage. The sponge-like activated carbons were produced with environmentally friendly potassium carbonate (K 2 CO 3) at different impregnation ratio (corn husk:K 2 CO 3 ; 1:1 to 1:3) and activation temperatures (500–800 °C). The obtained activated carbon was used to produce electrodes for supercapacitor application. The results revealed that corn husk: K 2 CO 3 ratio of 1:2 and 650 °C promoted mainly nanopores (0.773 nm) with appreciably higher specific surface area (1115 m2/g) and a sponge morphology. The electrochemistry performance test on the materials shows specific capacitances of up to 269 F/g at 5 mV/s scan rate for a material obtained at 650 °C. The textural characteristics, morphology, and heteroatoms of sulfur and nitrogen significantly promoted higher energy storage capacity. This activated carbon was employed to assemble a symmetric supercapacitor in acidic electrolyte (0.5 M H 2 SO 4) that delivered up to ~10 Wh/kg and was very stable, maintaining about 99.5 % of its original energy after 20,000 charge/discharge cycles. [Display omitted] • Corn husk, an abundant waste is suitable to be used as activated carbon precursor. • K 2 CO 3 allows to activate carbons, with a low environmental impact. • 650 °C was the optimal temperature to obtain carbons for supercapacitors. • Corn husk activated carbons contained O, N and S as heteroatoms. • The supercapacitor maintained 99 % of its energy after 20,000 cycles. [ABSTRACT FROM AUTHOR]

Chemical looping gasification (CLG) is a promising thermochemical process for the production of H 2. CLG process is mainly based on oxygen transfer from an air reactor to a gasification reactor using solid metal oxides (also called oxygen carriers, (OC)) as oxidants. The unique oxygen separation system of CLG makes it an advanced process with a smaller carbon footprint compared to the conventional gasification process. The other advantages of CLG includes increased efficiency, reduced greenhouse gas emissions, and improved process stability compared to conventional biomass gasification. Although CLG is a promising technology, it still faces several challenges such as high capital cost, OC durability, complex reaction mechanism and scalability issues. Some of these challenges can be addressed by understanding the impact of various process conditions on H 2 yield and char formation during CLG. The present study proposes a novel integrated process simulation and experimental studies to generate large dataset used for interpretable machine learning (ML) analysis. Three different ML models including support vector machine (SVM), random forest (RF), and gradient boost regression (GBR) were used to develop models for predicting the H 2 and char yield during CLG. The GBR outperformed other models for the prediction of H 2 and char yield during CLG with R2 value > 0.9. Among the experimental conditions, the temperature (T) and steam to biomass ratio (SBR) were the most relevant parameters affecting H 2 and char production. Biomass ash, C, volatile matter (VM) and H content also influenced H 2 and char formation. Overall, a combination of SHAP and partial dependence plot helped address the black box challenges of ML models. [Display omitted] • Process simulation was combined with experiments to understand chemical looping gasification. • Temperature and steam to biomass ratio affects hydrogen and char formation. • GBR outperformed RF and SVM in predicting hydrogen and char yield. • Ash content of biomass influenced char formation during chemical looping gasification. [ABSTRACT FROM AUTHOR]

[Display omitted] • The application of ozone for decontamination in various industries is reviewed. • The effectiveness of ozone against the SARS-CoV-2 virus on surfaces is discussed. • Ozone therapy is highlighted as a viable method for SARS-CoV-2 viral treatment. • Further investigations on gaseous ozonation of PPE & textile materials are required. Ozone – a powerful antimicrobial agent, has been extensively applied for decontamination purposes in several industries (including food, water treatment, pharmaceuticals, textiles, healthcare, and the medical sectors). The advent of the COVID-19 pandemic has led to recent developments in the deployment of different ozone-based technologies for the decontamination of surfaces, materials and indoor environments. The pandemic has also highlighted the therapeutic potential of ozone for the treatment of COVID-19 patients, with astonishing results observed. The key objective of this review is to summarize recent advances in the utilisation of ozone for decontamination applications in the above-listed industries while emphasising the impact of key parameters affecting microbial reduction efficiency and ozone stability for prolonged action. We realise that aqueous ozonation has received higher research attention, compared to the gaseous application of ozone. This can be attributed to the fact that water treatment represents one of its earliest applications. Furthermore, the application of gaseous ozone for personal protective equipment (PPE) and medical device disinfection has not received a significant number of contributions compared to other applications. This presents a challenge for which the correct application of ozonation can mitigate. In this review, a critical discussion of these challenges is presented, as well as key knowledge gaps and open research problems/opportunities. [ABSTRACT FROM AUTHOR]

[Display omitted] • A conceptual mobile autothermal methane pyrolysis unit for onsite hydrogen production was proposed. • The design combines methane pyrolysis and char gasification in an energy efficient way. • The levelized cost of hydrogen (LCOH) obtained from the conceptual design ranged from 1.3 to 1.47 U.S.$/kg. • The proposed design's net present value (NPV) was in the range of 3.76 – 4.35 M.U.S.$. • Compared to onsite hydrogen production, the mobile design is profitable. The present study proposes a conceptual mobile autothermal methane pyrolysis unit for onsite hydrogen production. Considering the shortage of hydrogen pipeline infrastructure between production plants and fuelling stations in most places where hydrogen is required, it is imperative to create alternative hydrogen production means. The design combines a catalytic plasma methane pyrolysis unit with a steam char gasification setup, combustion, and biomethanation unit for hydrogen production. The reactor design includes Ni - Br in a bubble column acting as a catalyst. Energy and exergy calculations followed by a comprehensive economic analysis were appraised to evaluate the efficiency and performance of the integrated process. The levelized cost of hydrogen (LCOH) from the conceptual design ranged from 1.3 to 1.47 U.S.$/kg, while the proposed design's net present value (NPV) was in the range of 3.76 – 4.35 M.U.S.$. Factors such as equipment purchase cost (EPC) and feedstock cost significantly influenced the NPV and LCOH. In addition, a positive NPV and lower LCOH outline the proposed design's profitability. Finally, an optimized methane conversion of 76.8 % was obtained from the study. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design of an integrated catalytic deoxygenation and hydrothermal gasification was performed. • Using experimental data, a high-fidelity process model was created with Aspen Plus. • Exergy analysis results showed that the deoxygenation reactor's exergy efficiencies are superior. • Equipment and raw material costs have superior effect influences on economic viability. Several technologies have been developed to produce sustainable aviation fuel (SAF), the hydroprocessing of esters and fatty acids (HEFA) representing one of the most mature pathways. Although HEFA has been widely adopted by industry, this pathway is mainly reliant on the hydrodeoxygenation (HDO) reaction, which requires large amounts and high pressures of hydrogen gas that reduces the cost-effectiveness of the process. In this study, the economic, environmental, and exergy analyses of two alternative scenarios for the catalytic production of SAF were considered. In both scenarios, SAF is produced through the catalytic deoxygenation of tall oil fatty acid (TOFA) via decarboxylation/decarbonylation (deCO x) – an approach requiring smaller amounts and lower pressures of hydrogen, feedstocks of lower purity and cost, and simpler supported metal catalysts relative to HDO. The material and energy balance was calculated using Aspen Plus process simulation software. Scenario 1 comprises a plant in which the catalytic deoxygenation of TOFA via deCO x is performed using hydrogen gas obtained commercially, while scenario 2 integrates catalytic deoxygenation with a plant that produces hydrogen gas via hydrothermal gasification. The study revealed that both scenarios were economically feasible relative to other pathways for SAF production, with the minimum fuel selling price (MFSP) of scenario 2 (USD$ 0.39/L) being lower than that of scenario 1 (USD$ 0.62/L). In addition to being the most economically viable, scenario 2 was also found to be preferable from an environmental standpoint since it also shows a lower global warming potential (GWP). Discounted cash flow analysis (DCFA) was used to determine other economic indicators such as net present value (NPV), internal rate of return (IRR), net rate of return (NRR) and payback period (PBP), which was estimated to be approximately 3 years for both scenarios. Finally, sensitivity analysis confirms that the raw materials and equipment purchase costs have the greatest impact on the MFSP. [ABSTRACT FROM AUTHOR]