Advances in the thermo-chemical production of hydrogen from biomass and residual wastes: Summary of recent techno-economic analyses

Gasification of biomass for syngas production: Research update and stoichiometry diagram presentation

Gasification is a thermal process that converts organic materials into syngas, bio-oil, and solid residues. This mini-review provides an update on current research on producing high-quality syngas from biomass via gasification. Specifically, the review highlights the effective valorization of feedstocks, the development of novel catalysts for reforming reactions, the configuration of novel integrated gasification processes with an assisted field, and the proposal of advanced modeling tools, including the use of machine learning strategies for process design and optimization. The review also includes examples of using a stoichiometry diagram to describe biomass gasification. The research efforts in this area are constantly evolving, and this review provides an up-to-date overview of the most recent advances and prospects for future research. The proposed advancements in gasification technology have the potential to significantly contribute to sustainable energy production and reduce greenhouse gas emissions.

Copyrolysis of Waste Cartons and Polyolefin Plastics under Microwave Heating and Characterization of the Products

Municipal organic solid waste contains many recoverable resources, including biomass materials and plastics. The high oxygen content and strong acidity of bio-oil limit its application in the energy field, and the oil quality is mainly improved by copyrolysis of biomass with plastics. Therefore, in this paper, a copyrolysis method was utilized to treat solid waste, namely, common waste cartons and waste plastic bottles (polypropylene (PP) and polyethylene (PE)) as raw materials. The products were analyzed by Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, GC, and GC/MS to investigate the reaction pattern of the copyrolysis. The results show that the addition of plastics can reduce the residue content by about 3%, and the copyrolysis at 450 °C can increase the liquid yield by 3.78%. Compared with single waste carton pyrolysis, no new product appeared in the copyrolysis liquid products but the oxygen content of the liquid decreased from 65% to less than 8%. The content of CO₂ and CO in the copyrolysis gas product is 5-15% higher than the theoretical value; the O content of the solid products increased by about 5%. This indicates that waste plastics can promote the formation of l-glucose and small molecules aldehydes and ketones by providing H radicals and reduce the oxygen content in liquids. Thus, copyrolysis improves the reaction depth and product quality of waste cartons, which provides a certain theoretical reference for the industrial application of solid waste copyrolysis.

Sustainable production of biofuels and bioderivatives from aquaculture and marine waste

The annual global fish production reached a record 178 million tonnes in 2020, which continues to increase. Today, 49% of the total fish is harvested from aquaculture, which is forecasted to reach 60% of the total fish produced by 2030. Considering that the wastes of fishing industries represent up to 75% of the whole organisms, the fish industry is generating a large amount of waste which is being neglected in most parts of the world. This negligence can be traced to the ridicule of the value of this resource as well as the many difficulties related to its valorisation. In addition, the massive expansion of the aquaculture industry is generating significant environmental consequences, including chemical and biological pollution, disease outbreaks that increase the fish mortality rate, unsustainable feeds, competition for coastal space, and an increase in the macroalgal blooms due to anthropogenic stressors, leading to a negative socio-economic and environmental impact. The establishment of integrated multi-trophic aquaculture (IMTA) has received increasing attention due to the environmental benefits of using waste products and transforming them into valuable products. There is a need to integrate and implement new technologies able to valorise the waste generated from the fish and aquaculture industry making the aquaculture sector and the fish industry more sustainable through the development of a circular economy scheme. This review wants to provide an overview of several approaches to valorise marine waste (e.g., dead fish, algae waste from marine and aquaculture, fish waste), by their transformation into biofuels (biomethane, biohydrogen, biodiesel, green diesel, bioethanol, or biomethanol) and recovering biomolecules such as proteins (collagen, fish hydrolysate protein), polysaccharides (chitosan, chitin, carrageenan, ulvan, alginate, fucoidan, and laminarin) and biosurfactants.

Gasification of Solid Fuels (Coal, Biomass and MSW): Overview, Challenges and Mitigation Strategies

Currently, hydrogen energy is the most promising energy vector, while gasification is one of the major routes for its production. However, gasification suffers from various issues, including slower carbon conversion, poor syngas quality, lower heating value and higher emissions. Multiple factors affect gasification performance, such as the selection of gasifiers, feedstock’s physicochemical properties and operating conditions. In this review, the status of gasification, key gasifier technologies and the effect of solid-fuel (i.e., coal, biomass and MSW) properties on gasification performance are reviewed critically. Based on the current review, the co-gasification of coal, biomass and solid waste, along with a partial utilisation of CO2 as a reactant, are suggested. Furthermore, a technological breakthrough in carbon capture and sequestration is needed to make it industrially viable.

Catalytic pyrolysis of lignocellulosic biomass for bio-oil production: A review

Catalytic pyrolysis has been widely explored for bio-oil production from lignocellulosic biomass owing to its high feasibility and large-scale production potential. The aim of this review was to summarize recent findings on bio-oil production through catalytic pyrolysis using lignocellulosic biomass as feedstock. Lignocellulosic biomass, structural components and fundamentals of biomass catalytic pyrolysis were explored and summarized. The current status of bio-oil yield and quality from catalytic fast pyrolysis was reviewed and presented in the current review. The potential effects of pyrolysis process parameters, including catalysts, pyrolysis conditions, reactor types and reaction modes on bio-oil production are also presented. Techno-economic analysis of full-scale commercialization of bio-oil production through the catalytic pyrolysis pathway was reviewed. Further, limitations associated with current practices and future prospects of catalytic pyrolysis for production of high-quality bio-oils were summarized. This review summarizes the process of bio-oil production from catalytic pyrolysis and provides a general scientific reference for further studies.

Biomass Gasification in Downdraft Gasifiers: A Technical Review on Production, Up-Gradation and Application of Synthesis Gas

Rapid climate change and forecasted damage from fossil fuel combustion, forced researchers to investigate renewable and clean energy sources for the sustainable development of societies throughout the world. Biomass-based energy is one of the most important renewable energy sources for meeting daily energy needs, which are gaining in popularity daily. Gasification-based bioenergy production is an effective way to replace fossil fuels and reduce CO2 emissions. Even though biomass gasification has been studied extensively, there is still much opportunity for improvement in terms of high-quality syngas generation (high H2/CO ratio) and reduced tar formation. Furthermore, the presence of tar has a considerable impact on syngas quality. Downdraft gasifiers have recently shown a significant potential for producing high-quality syngas with lower tar concentrations. This article presents a comprehensive review on the advancement in biomass downdraft gasification technologies for high-quality synthesis gas. In addition, factors affecting syngas production and composition e.g., equivalency ratio, temperature, particle size, and gasification medium on synthesis gas generation are also comprehensively studied. The up-gradation and various applications of synthesis gas are also discussed in brief in this review article.

Advanced Steam Reforming of Bio-Oil with Carbon Capture: A Techno-Economic and CO2 Emissions Analysis

A techno-economic analysis has been used to evaluate three processes for hydrogen production from advanced steam reforming (SR) of bio-oil, as an alternative route to hydrogen with BECCS: conventional steam reforming (C-SR), C-SR with CO2 capture (C-SR-CCS), and sorption-enhanced chemical looping (SE-CLSR). The impacts of feed molar steam to carbon ratio (S/C), temperature, pressure, the use of hydrodesulphurisation pretreatment, and plant production capacity were examined in an economic evaluation and direct CO2 emissions analysis. Bio-oil C-SR-CC or SE-CLSR may be feasible routes to hydrogen production, with potential to provide negative emissions. SE-CLSR can improve process thermal efficiency compared to C-SR-CCS. At the feed molar steam to carbon ratio (S/C) of 2, the levelised cost of hydrogen (USD 3.8 to 4.6 per kg) and cost of carbon avoided are less than those of a C-SR process with amine-based CCS. However, at higher S/C ratios, SE-CLSR does not have a strong economic advantage, and there is a need to better understand the viability of operating SE-CLSR of bio-oil at high temperatures (>850 °C) with a low S/C ratio (e.g., 2), and whether the SE-CLSR cycle can sustain low carbon deposition levels over a long operating period.

Gasification kinetics of Barapukurian coal char using carbon dioxide and steam reactants

Gasification of coal is a cost-effective and sustainable technology to produce syngas and hydrogen with integrated carbon capture and storage system. This study investigates the gasification characteristics of Barapukurian bituminous coal (BBC) char under carbon dioxide (CO2) and steam atmosphere using a thermogravimetric analyser (TGA). The char was prepared through a rapid pyrolysis process in a high temperature entrained flow gasifier at a temperature of 1200 °C. TGA experiments were conducted under atmospheric pressure over 700–1200 °C. Factors affecting intrinsic gasification kinetics, such as diffusion and mass transfer limitations, were optimised before conducting TGA experiments at various temperatures. Three established kinetic models of the volumetric model (VM), grain model (GM) and random pore model (RPM) fitted well with the experimental data. The activation energy determined from CO2 gasification was 1.20–1.25 times higher than that of steam gasification, indicating a higher reactivity under steam than CO2. The order of reaction using CO2 and steam was determined to be 0.67 and 0.95 at 900 °C.

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LaFeO3 Modified with Ni for Hydrogen Evolution via Photocatalytic Glucose Reforming in Liquid Phase

In this work, the optimization of Ni amount on LaFeO3 photocatalyst was studied in the photocatalytic molecular hydrogen production from glucose aqueous solution under UV light irradiation. LaFeO3 was synthesized via solution combustion synthesis and different amount of Ni were dispersed on LaFeO3 surface through deposition method in aqueous solution and using NaBH4 as reducing agent. The prepared samples were characterized with different techniques: Raman spectroscopy, UltraViolet-Visible Diffuse Reflectance Spettroscopy (UV–Vis-DRS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence (XRF), Transmission Electron microscopy (TEM), and Scanning Electron microscopy (SEM) analyses. For all the investigated photocatalysts, the presence of Ni on perovskite surface resulted in a better activity compared to pure LaFeO3. In particular, it is possible to identify an optimal amount of Ni for which it is possible to obtain the best hydrogen production. Specifically, the results showed that the optimal Ni amount was equal to nominal 0.12 wt% (0.12Ni/LaFeO3), for which the photocatalytic H2 production was equal to 2574 μmol/L after 4 h of UV irradiation. The influence of different of photocatalyst dosage and initial glucose concentration was also evaluated. The results of the optimization of operating parameters indicated that the highest molecular hydrogen production was achieved on 0.12Ni/LaFeO3 sample with 1.5 g/L of catalyst dosage and 1000 ppm initial glucose concentration. To determine the reactive species that play the most significant role in the photocatalytic hydrogen production, photocatalytic tests in the presence of different radical scavengers were performed. The results showed that •OH radical plays a significant role in the photocatalytic conversion of glucose in H2. Moreover, photocatalytic tests carried out with D2O instead of H2O evidenced the role of water molecules in the photocatalytic production of molecular hydrogen in glucose aqueous solution.

Fast hydropyrolysis of biomass Conversion: A comparative review

Recent studies show that fast hydropyrolysis (i.e., pyrolysis under hydrogen atmosphere operating at a rapid heating rate) is a promising technology for the conversion of biomass into liquid fuels (e.g., bio-oil and C₄₊ hydrocarbons). This pyrolysis approach is reported to be more effective than conventional fast pyrolysis in producing aromatic hydrocarbons and also lowering the oxygen content of the bio-oil obtained compared to hydrodeoxygenation (a common bio-oil upgrading method). Based on current literature, various non-catalytic and catalytic fast hydropyrolysis processes are reviewed and discussed. Efforts to combine fast hydropyrolysis and hydrotreatment process are also highlighted. Points to be considered for future research into fast hydropyrolysis and pending challenges are also discussed.

Advances in production of bioplastics by microalgae using food waste hydrolysate and wastewater: A review

Microalgae have emerged as an effective dual strategy for bio-valorisation of food processing wastewater and food waste hydrolysate which favours microalgae cultivation into producing value-added by products mainly lipids, carbohydrates, and proteins to the advantages of bioplastic production. Moreover, various microalgae have successfully removed high amount of organic pollutants from food processing wastewater prior discharging into the environment. Innovation of microalgae cultivating in food processing wastewater greatly reduced the cost of wastewater treatment compared to conventional approach in terms of lower carbon emissions, energy consumption, and chemical usage while producing microalgae biomass which can benefit low-cost fertilizer and bioplastic applications. The study on several microalgae species has all successfully grown on food waste hydrolysates showing high exponential growth rate and biomass production rich in proteins, lipids, carbohydrates, and fatty acids. Multiple techniques have been implemented for the extraction of food wastes to be incorporate into the bioplastic production.

Co-Gasification Characteristics of Coal and Biomass Using CO2 Reactant under Thermodynamic Equilibrium Modelling

This study assessed the entrained flow co-gasification characteristics of coal and biomass using thermodynamic equilibrium modelling. The model was validated against entrained flow gasifier data published in the literature. The gasification performance was evaluated under different operating conditions, such as equivalence ratio, temperature, pressure and coal to biomass ratio. It is observed that the lower heating value (LHV) and cold gas efficiency (CGE) increase with increasing temperature until the process reaches a steady state. The effect of pressure on syngas composition is dominant only at non-steady state conditions (<1100 °C). The variation in syngas composition is minor up to the blending of 50% biomass (PB50). However, the PB50 shows a higher LHV and CGE than pure coal by 12%and 18%, respectively. Overall, biomass blending of up to 50% favours gasification performance with an LHV of 12 MJ/kg and a CGE of 78%.

Comparative Techno-Economic and Exergetic Analysis of Circulating and Dual Bed Biomass Gasification Systems

In this work, the techno-economic and exergy analyses of two gasification technologies with integration into heat and power combined cycles are presented: i). Circulating fluidized bed (CFB) and ii). Dual fluidized bed (DFB) systems. As feedstock, lignocellulosic biomass (sugarcane bagasse, SCB) was considered. The gasification process of the fluidized-bed systems (circulating and dual bed) and the syngas conversion were performed using Aspen Plus® software. The process design includes biomass drying and gasification, syngas cleaning, combustion, power generation, and heat recovery. The SCB-DFB system has the lowest irreversibility rate and, as a result, the highest overall performance and power generation (achieving 32% in the gasification system and 53% of exergy efficiency when coupled with the combined cycle). From the techno-economic assessment, the SCB-DFB system has the lowest total production costs per unit of energy. Hence, the dual fluidized bed systems could be a more competitive technology for the agro-industrial sector to generate power from lignocellulosic materials.

Techno-economic study for a gasification plant processing residues of sewage sludge and solid recovered fuels

The energetic valorisation of wastes through gasification is a promising solution with a better environmental impact in terms of pollutant emissions compared with incineration, landfilling, and heat and power generation from fossil fuels. However, techno-economic studies are imperative to define the viability of these technologies and to optimise heat and power consumptions and costs. This work intended to develop a techno-economic analysis for a small-scale gasification plant processing mixtures of solid recovered fuels and sewage sludge, assuming a capacity of 883 kg/h and two different sale scenarios: (A) production of electric energy, and (B) production of hydrogen. Gasification tests and mass and energy flow analyses were carried out for the economic assessment. The results showed that both scenarios presented viability for implementation. Although scenario A was more attractive in the short-term period due to the lower payback period (9 year) and higher internal rate of return (IRR, 7.5%), the other option was more favourable at the end of plant's life once the net present value was greater (1,801,700 €). Based on the results of a sensitivity analysis, a conclusion could be drawn that the economic indicators payback period and IRR were most influenced by capital expenditures applied in the plant.

Theoretical study on the adsorption mechanism of PbCl2/CdCl2 by kaolinite during municipal solid waste pyrolysis

In the process of municipal solid waste (MSW) pyrolysis, kaolinite possesses an outstanding trapping effect on semi-volatile metal vapors (Pb, Cd) through physical and chemical adsorption. In this paper, the microscopic mechanism of PbCl₂ and CdCl₂ adsorption on the surface of Al rings and Si rings of kaolinite was investigated by combining Monte Carlo method with density functional theory (DFT). The calculations indicate that the continuously enriched pore structure in the process of dehydroxylation indirectly influences the adsorption of PbCl₂/CdCl₂ by kaolinite. Under the non-bond interaction and electron transfer induction, PbCl₂ molecules are more conveniently adsorbed on the Al-(001) surface than CdCl₂, while the adsorption sites of CdCl₂ molecules are more widely distributed on the Si-(001) surface. Moreover, the transform in the Al-coordination and the exposed active oxygen atoms significantly affect the adsorption activity of kaolinite (the capability to gain and lose electrons). Considering the energy barrier and electrophilic nucleophilic sensitivity, it is more feasible for PbCl₂/CdCl₂ to be adsorbed near IV/V-coordinated Al and active O under Van der Waals action. Subsequently, IV/V-coordinated Al will act as an electron acceptor, and the active oxygen atoms after dehydrogenation will serve as an electron donor. Under the induction of the energy difference of frontier orbitals, the electrons transfer will encourage the formation of more stable adsorption states. The results shed new light on strengthening the adsorption activity of kaolinite to PbCl₂/CdCl₂ in the process of MSW pyrolysis.

Photocatalytic reforming of aqueous phase obtained from liquefaction of household mixed waste biomass for renewable bio-hydrogen production

In this study, hydrothermal liquefaction of household waste was performed to produce valuable liquid hydrocarbons with aqueous phase as by-product. Photocatalytic reforming of aqueous phase was carried out for hydrogen production. Liquefaction of 15 g waste at temperature of 320 °C and solvent to biomass ratio of 13.33 mL/g produced bio-oil of 32.4 wt% and hydrogen 21 wt% in gas product. Hydrogen production from aqueous phase was studied in presence of various concentrations of activated carbon doped Fe/TiO₂ catalyst (0.2-1 wt%). Hydrogen yield was 32 wt% when 0.6 wt% of catalyst was used to reform aqueous phase. To ease of operation in economical manner the reusability study of the catalyst was evaluated and it was found to be active for three consecutive cycles. As outcome of this study, household waste can serve for a whooping amount of hydrogen (53 wt%) production via liquefaction and photocatalytic reforming process.

Resource recovery and biorefinery potential of apple orchard waste in the circular bioeconomy

In this review investigate the apple orchard waste (AOW) is potential organic resources to produce multi-product and there sustainable interventions with biorefineries approaches to assesses the apple farm industrial bioeconomy. The thermochemical and biological processes like anaerobic digestion, composting and , etc., that generate distinctive products like bio-chemicals, biofuels, biofertilizers, animal feed and biomaterial, etc can be employed for AOW valorization. Integrating these processes can enhanced the yield and resource recovery sustainably. Thus, employing biorefinery approaches with allied different methods can link to the progression of circular bioeconomy. This review article mainly focused on the different biological processes and thermochemical that can be occupied for the production of waste to-energy and multi-bio-product in a series of reaction based on sustainability. Therefore, the biorefinery for AOW move towards identification of the serious of the reaction with each individual thermochemical and biological processes for the conversion of one-dimensional providences to circular bioeconomy.

Gas-pressurized torrefaction of biomass wastes: The optimization of pressurization condition and the pyrolysis of torrefied biomass

A novel gas-pressurized (GP) torrefaction with high oxygen removal efficiency at mild temperature was proposed in our previous work. However, the optimal condition of the GP torrefaction and subsequent pyrolysis of the torrefied biomass were not clear. In this work, the effect of pressure on the GP torrefaction and pyrolysis product properties of the torrefied biomass were studied in detail. The results show that the pressure increasing from 1.7 MPa to 5.0 MPa just slightly contributed to further oxygen removal, and 1.7 MPa was thus selected as the optimum pressure. The GP torrefaction significantly improved the product property of biomass pyrolysis compared to the conventional torrefaction (AP torrefaction). The acids content in bio-oil was reduced from 15-20% to less than 5%, and the calorific value of biogas increased to as high as 16.57-19.31 MJ/Nm³. Furthermore, an overall conversion mechanism of combined GP torrefaction and subsequent pyrolysis of biomass was proposed.

Progress in waste valorization using advanced pyrolysis techniques for hydrogen and gaseous fuel production

Hydrogen and gaseous fuel derived from wastes have opened up promising alternative pathways for the production of renewable and sustainable fuels to substitute classical fossil energy resources that cause global warming and pollution. Existing review articles focus mostly on gasification, reforming and pyrolysis processes, with limited information on particularly gaseous fuel production via pyrolysis of various waste products. This review provides an overview on the recent advanced pyrolysis technology used in hydrogen and gaseous fuel production. The key parameters to maximize the production of specific compounds were discussed. More studies are needed to optimize the process parameters and improve the understanding of reaction mechanisms and co-relationship between these advanced techniques. These advanced techniques provide novel environmentally sustainable and commercially procedures for waste-based production of hydrogen and gaseous fuels.

Slow pyrolysis of municipal solid waste (MSW): A review

In recent years, extensive studies have been carried out to improve our knowledge of the reactor operations and system performance in thermal pyrolysis of municipal solid wastes (MSW). However, the fundamentals of MSW pyrolysis and their engineering applications remain unsatisfactorily explored. This paper is a review of the pyrolysis of MSW and synergistic co-pyrolysis of the constituents of MSW with reference to pyrolytic performance, the distribution and energy content of the end products, and the mechanisms of the synergistic effects. The prospects for, and challenges of, the MSW pyrolysis process are provided. A MSW pyrolytic process with maximal energy recovery and minimal carbon footprint is proposed.

A review on the production of renewable aviation fuels from the gasification of biomass and residual wastes

This article reviews the production of renewable aviation fuels from biomass and residual wastes using gasification followed by syngas conditioning and Fischer-Tropsch catalytic synthesis. The challenges involved with gasifying wastes are discussed along with a summary of conventional and emerging gasification technologies. The techniques for conditioning syngas including removal of particulate matter, tars, sulphur, carbon dioxide, compounds of nitrogen, chlorine and alkali metals are reported. Recent developments in Fischer-Tropsch synthesis, such as new catalyst formulations are described alongside reactor technologies for producing renewable aviation fuels. The energy efficiency and capital cost of converting biomass and residual wastes to aviation fuels are major barriers to widespread adoption. Therefore, further development of advanced technologies will be critical for the aviation industry to achieve their stated greenhouse gas reduction targets by 2050.

Sustainable Biomass Activated Carbons as Electrodes for Battery and Supercapacitors-A Mini-Review

Some recent developments in the preparation of biomass carbon electrodes (CEs) using various biomass residues for application in energy storage devices, such as batteries and supercapacitors, are presented in this work. The application of biomass residues as the primary precursor for the production of CEs has been increasing over the last years due to it being a renewable source with comparably low processing cost, providing prerequisites for a process that is economically and technically sustainable. Electrochemical energy storage technology is key to the sustainable development of autonomous and wearable electronic devices. This article highlights the application of various types of biomass in the production of CEs by using different types of pyrolysis and experimental conditions and denotes some possible effects on their final characteristics. An overview is provided on the use of different biomass types for the synthesis of CEs with efficient electrochemical properties for batteries and supercapacitors. This review showed that, from different biomass residues, it is possible to obtain CEs with different electrochemical properties and that they can be successfully applied in high-performance batteries and supercapacitors. As the research and development of producing CEs still faces a gap by linking the type and composition of biomass residues with the carbon electrodes' electrochemical performances in supercapacitor and battery applications, this work tries to diminish this gap. Physical and chemical characteristics of the CEs, such as porosity, chemical composition, and surface functionalities, are reflected in the electrochemical performances. It is expected that this review not only provides the reader with a good overview of using various biomass residues in the energy storage applications, but also highlights some goals and challenges remaining in the future research and development of this topic.

Metabolic flux and functional potential of microbial community in an acidogenic dynamic membrane bioreactor

In this study, a laboratory-scale acidogenic dynamic membrane bioreactor (DMBR) was operated with or without alginate immobilization under various hydraulic retention times. The interactions between biofilm formation, metabolic flux and predicted functional genes were investigated in the DMBR. Regardless of the alginate immobilization, hydrogen yield was increased after biofilm was formed on a supporting material. Metabolic flux shifts from homoacetogenic to hydrogenic pathways along with biofilm formation was confirmed by flux balance analysis for metabolites. KEGG ortholog count prediction of functional genes from microbial consortia using bioinformatics package (PICRUSt). Predicted enzymes showed similar levels of functional gene expression regardless of the immobilization status. PICRUSt result showed strong evidence of the functional relationship among hydrogen production, biofilm formation, and metabolic pathway. Taken together, this study provides to estimate characteristics of biofilm formation changes and to better understand the microbial metabolism of DMBR.