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In light of resource depletion, energy scarcity, and toxic waste management, gasification is regarded as a viable waste-to-energy conversion method. Moreover, the Gasifier-Engine-Genest combo provides a suitable alternative for distributed electric power, waste conversion, and alleviating electricity scarcity. Despite an abundance of research report, it is not usually acknowledged as a viable alternative to traditional energy sources. Thus, to promote Gasification, efficient technology is required to maximize the yield of syngas with clean and improved calorific value. Furthermore, there is a void in the prior study that summarises the various types of biomasses and their pre-treatment, as well as the progression of conventional gasification to advanced gasification for the improvement of syngas quality and respective critical applications. Moreover, this is necessary in order to organise the conditions and biomass for gasification, which are many and frequently scattered in the literature. Hence, this study summarises the detailed review of recent novel concepts development over conventional techniques of biomass gasification. Recent reports on feed material properties of diverse biomass, as well as pre-treatment employing biomass torrefaction for gasification, are presented in this paper in order to evaluate their potential. In addition, a literature review of the various categories of gasification, the gasification processes, and the impact of technology on the quality of syngas, power generation and distribution were reported. In conclusion, it is proposed that enhanced gasification technology be employed to implement sustainable development in order to reduce the existing reliance on non-renewable energy sources. [ABSTRACT FROM AUTHOR]

• Study evaluates generation from biomass gasification. • Syngas is used within poly-generation systems to generate sustainable fuels. • The article considers recycling of multiple sources of biomass to generate syngas. • A new poly-generation process to produce urea, liquids fuels and power is proposed. • A novel hybrid environmental and economic optimisation methodology is proposed. The production of renewable chemicals and fuels is driving modern society towards a type of sustainable development which involves a decreasing dependency on fossil fuels and the minimisation of waste. Biomass, a waste by-product from the urban environment, is a carbon dioxide neutral organic fuel that can potentially serve as a feedstock for the production of sustainable power and heat. Gasification is preferred over the other thermal conversion options for biomass processing whereby the product synthesis gas can be utilised to power generators/turbines and generate clean energy, ammonia and methanol. Incidentally, efficient and economically sound biomass driven supply chains can be integrated into an existing petrochemical infrastructure. Moreover, the potential production volumes of fuels and green chemicals can also be increased by the addition of multiple biomass sources, thereby creating potential positive scale effects. This study proposes a new poly-generation process that utilises multiple sources of biomass feedstock to produce high quality urea, methanol, Fisher-Tropsch liquids and power. Four flowsheet configurations are simulated using Aspen Plus software and the built-in capabilities of the activated analysis using Aspen Process Economic Analyzer and Aspen Energy Analyzer to perform the economic, energy and environmental impact calculations. The results demonstrate that the methanol production technique is the most economic process pathway with a net profit of approximately $0.035 per kg of biomass input, whilst the urea process pathway presents the lowest environmental impact solution with approximately 0.71 kg of CO 2 -e per kg of biomass input. These results are relative and can be analysed from different perspectives based on the market demand of the products and their applications and local need. For instance, considering at the economic and environmental indicators relative to the production capacity, production of liquid fuels achieve net profits of approximately $0.27 per kg of product, whilst urea production demonstrates the lowest environmental emissions of approximately 3.93 kg of CO 2 -e per kg of product. [ABSTRACT FROM AUTHOR]

• Critical analysis of thermochemical conversion technologies for BECCS. • The potential of BECCS for CO 2 negative emissions. • Highlighting the technical maturity of technologies regarding BECCS. • Critical discussion about CO 2 capturing techniques in terms of BECCS. • Highlighting the issue and recommendation for BECCS commercialisation. The future of the global environment is at threat due to global warming and climate change primarily driven by greenhouse gas emissions. Bioenergy with carbon dioxide capture and storage/utilisation (BECCS/U) through its CO 2 negative emission capacity is considered a principal component of global mitigation strategies as agreed in the Paris climate change agreement. In this study, the current global status and efforts to implement BECCS systems are comprehensively reviewed. The potential for thermochemical conversion processes (combustion, gasification, pyrolysis, and liquefaction) to manifest within BECCS systems is analysed, in addition to their integration potential with carbon dioxide capture methods. Outcomes suggest that gasification and combustion processes when integrated with CO 2 capture and storage (CCS), within combine heat and power (CHP) configurations, biomass integrated gasification combine cycle (BIGCC) and chemical looping cycle (CLC) are mature technologies. Furthermore, this review indicates that pyrolysis and liquefaction process are commercial and lab-scale respectively. When integrated within BECCS systems, pyrolysis systems are at the pilot level and liquefaction processes are at lab scale. Moreover, a comprehensive discussion on the negative emission potential from various BECCS configurations is provided, highlighting their role in advancing bio-refineries through waste management and conversion to value-added products such as biochar, ethanol, bio diesel etc. The pyrolysis process has CO 2 mitigation potential of 2.2 GtCO 2 /year by 2020-2050. Finally, an insight into the commercial barriers and future perspectives of BECCS technologies, role of international supply chains therein, and the need for effective stakeholder management to facilitate BECCS systems within global trade. [Display omitted] [ABSTRACT FROM AUTHOR]

• Hydrogen rich syngas can be produced from gasified waste biomass. • Optimum feedstock blending options are utilised to maximise hydrogen production. • A hybrid environmental and economic optimisation methodology is implemented. • Steam gasification demonstrates excellence in providing hydrogen-rich syngas. • Date pits indicates high potential in maximising the hydrogen content in syngas. Concerns related to global warming and the depletion of fossil fuels have propelled the global community to explore alternative renewable energy sources. Biomass is a nonconventional and renewable energy resource that can potentially be utilised for the production of sustainable heat and power. The thermal gasification process is an effective biomass conversion and utilisation method producing syngas as the product gas. This study details a biomass gasification process and subsequent optimisation, considering multiple parameters, including the type of feedstock and gasifying agent (gasifier) to maximise hydrogen production. Aspen Plus software is used to develop three agent-based biomass gasification models considering the characteristics of certain materials from Qatar built environment. The ultimate goal of the study is to optimise the gasification processes to yield different biomass blending options satisfying the maximisation of hydrogen generation through different scenarios. The capabilities of the built-in activated analysis package using Aspen Energy Analyser and Aspen Process Economic Analyser are utilised to evaluate the environmental and economic perspectives. The results demonstrate the excellence of steam-only biomass gasification in providing profitable and cleaner products. The yield of hydrogen production from blending of biomass feedstock achieved a high fraction of 5.23% with the steam-only gasification, while the yield increased from 1.63% to 5.22% for the oxygen/steam gasification when maximising the hydrogen fraction. Moreover, the selective limiting of biomass capacity enhances the quality of syngas through enriching the hydrogen production and lowers the need for subsequent adjustment and the manipulation of gasifying agent quantity and operating energy. [ABSTRACT FROM AUTHOR]

• The study evaluates generation of sustainable products from biomass gasification. • Two types of gasifying medium; oxygen and steam, are compared. • The article considers recycling of a blended feed of multiple biomass sources. • Aspen plus is utilised to simulate and integrate the different processes. • Poly-generation of Fisher-Tropsch liquids, methanol, urea and power is considered. Economically, fossil fuels remain the main source of energy despite their high emissions of greenhouse gases. However, biomass, a renewable fuel with CO 2 neutrality, has experienced widespread attention as a potential contributor to sustainable development of the energy sector. Gasification is an important thermochemical process that converts biomass feedstock into H 2 -rich combustible gases, which are favoured by wide downstream applications. The use of pure steam or oxygen as a gasifying agent is preferred to increase the yield of combustible gases. Consequently, hydrogen is utilised as an important intermediary in the generation of value-added products such as urea, fuels and power. This study compares the biomass gasification using oxygen-only and steam-only gasifying agents. Moreover, the study examines a poly-generation system that consumes biomass feedstock of multiple sources to produce high grade Fisher-Tropsch liquids, methanol, urea, and power. To achieve this aim, four Aspen Plus simulation flowsheets are developed considering both gasifiying agents and compared utilising the built-in economic and environmental capabilities. The results obtained from the economic and environmental evaluation demonstrate the excellence of steam-only biomass gasification in providing profitable and cleaner products. The methanol production using steam gasification is the most economical solution with a net profit per input of $0.12 per kg of biomass input and the lowest emissions pathway with 0.68 kg of CO 2 -e per biomass input. The relative nature of the results can offer diverse perspectives depending on the market situation of the products. Consequently, analysing the results relative to production capacity, power generation using steam gasification achieves a net profit approximated at $0.80 per kg of product, whilst methanol production using steam gasification remains the lowest environmental impact solution with 2.32 kg of CO 2 -e per output product. [ABSTRACT FROM AUTHOR]

Considering changes in the global climate, there is an impetus to diversify away from fossil fuels as part of efforts to reduce greenhouse gas emissions. Biomass, as a source of energy, has the potential to generate sustainable power and fuels and contribute towards a cleaner future. In fact, the utilisation of biomass as a carbon dioxide neutral organic source in an integrated system generates valuable products, and reduces waste and the consumption of non-renewable resources. Gasification, the preferred option for converting biomass to combustible gas, provides higher electrical efficiencies than combustion, whereby the syngas generated from the gasification process can be utilised to generate clean energy. In addition, syngas can be utilised for the production of ammonia and methanol thus reducing their respective dependencies on natural gas. This study will detail an optimised biomass gasification process considering multiple parameters, including the thermodynamic operating conditions, the type of gasifier (gasifying agent) and feedstock. Fundamentally, this study considers the process pathways for the recycling of multiple sources of biomass to generate high energy syngas from the available biomass options when used in combination as blends or individually. To achieve this aim, an Aspen Plus simulation model is developed for four different biomass agent-based gasification techniques using the biomass characteristics of certain Qatar biomass materials, which include date pits, manure and sewage sludge. Outcomes of the study included an optimisation of the gasification processes to yield different blending options of the biomass feedstock satisfying the downstream operations of power and fuels production. The results demonstrate the domination of date pits for two of the considered configurations with over 99% w/w date pit feed composition. Moreover, the sensitivity analysis conducted on the different configurations highlighted specific optimum operation points in terms of temperature, pressure, and oxygen and steam feed ratios. The hydrogen content in the generated syngas, considered important for the downstream production, yields a peak at approximately 850 °C and 1 bar with a modified equivalence ratio of approximately 2.5, and a ratio of oxygen supplied by an air-steam combination of approximately 0.6. The process can be further optimised by considering trade-offs between product purity or yield, profit, operating efficiency, quality of raw materials blends, and carbon footprint. • Biomass as a source of energy has the potential to generate sustainable products. • Syngas is an important intermediary in the production of power, fuels and chemicals. • Different pathways for recycling of multiple biomass sources are evaluated. • Optimum biomass feedstock blending options are determined. • The effect of changing key gasification performance parameters is analysed. [ABSTRACT FROM AUTHOR]

• Integration of biomass gasification with power devices was reviewed for clean electricity generation. • The electrical efficiency ranges from 40% to 60% for SOFC-gasification systems. • The overall electrical efficiency is approximately 60–90% for integrated systems using CHP. • The technical maturity of biomass gasification systems with all approaches was analyzed. • The pros and cons, as well as the current status of each configuration, were analyzed. The integration of biomass based gasification with power systems can enable carbon neutral electricity. This study examines the power generation process from syngas derived from biomass gasification using syngas generators, gas and steam turbines, and combined heat and power (CHP). The efficiency of electricity generation using syngas in a combustion engine ranges from approximately 20 % to 35 %. It is considered cost-effective due to its ability to tolerate syngas with impurities. Conversely, the use of steam and gas turbines also falls within this efficiency range, ranging from 20 to 35 %, although, in specific instances, efficiencies up to 50 % have been reported. The integrated CHP system enhances the overall system efficiency, achieving levels as high as 90 %, whereas it is within the range of 40–60 % without CHP. This review also evaluates the potential for clean electricity generation through the integration of fuel cells (FC) with the gasification system, specifically, the solid oxide fuel cell (SOFC) by considering both experimental and modelling studies. The electrical efficiency of power production using SOFC falls within the range of 30–60 % using syngas derived from a gasification system. However, for hydrogen, higher efficiencies up to 90 % have been observed. The power generation is approximately 0.85kWel using syngas produced from gasification of one kg biomass/h. The power generation capacity is normally in the range of 200 kW to 2 MW. Moreover, Technology readiness level (TRL) for these technologies, with a particular focus on FC technology is also analysed. Finally, this review examines the current state of the art, challenges, and future prospects of technologies. [ABSTRACT FROM AUTHOR]

Renewable fuel generation and reducing reliance on fossil fuels are essential components of sustainable development. Manufacturing and use of petrochemicals are such an important economic pillar of contemporary civilisation. Therefore, there is a strong incentive to allocate alternative production pathways in order to conserve scarce resources. In order to minimise global emissions, it is also necessary to utilise environment wastes to generate value-added goods. This study demonstrates the sustainability assessment of various biomass gasification utilisation strategies developed through the poly-generation process. The superstructure network, which consists of different biomass feedstock (sources) and prospective uses (sinks) among the various gasification alternatives (pools), is examined to find the most cost-effective and ecologically beneficial production routes. Superstructure optimisation aids decisions on biomass feedstock mixing and subsequent utilisation, while taking both economic and environmental concerns into account. The results indicated the importance of biomass feedstock blending in enhancing the profitability of the process and lowering the requirement of gasifying agents. The findings indicated the domination of the power generation technique at 95.9% for oxygen gasification and methanol production for both oxygen/steam and steam-only gasification options at 92.5% when economic objective is considered. However, when the environmental objective is considered, urea generation turned to dominate the utilisation allocation at 94.9% for oxygen gasification, and methanol dominated the allocation at 92.5% for oxygen/steam and steam-only gasification options. Nevertheless, when both objectives are considered concurrently, urea dominated the strategies in all scenarios with a varying allocation of 38%–95%. The former solution maximiser the net profit at 0.124 $/kg biomass, and minimised net emissions at 0.58 kg CO 2 /kg biomass. Additionally, the study highlights the excellence of steam-only gasification over oxygen/steam and oxygen-only gasification options in delivering value-added products with higher profits and lower emissions. [ABSTRACT FROM AUTHOR]

The gasification of biomass as a source of energy has gained much attention due to their potential in generating valuable downstream products. In this study, the production of downstream methanol using sorption enhanced steam gasification of palm oil wastes is configured through the Aspen Plus® simulator. The CO 2 capture is accomplished by deploying CaO, which is an economically viable technique. For this purpose, the flowsheet configuration for methanol production is evaluated from techno-economic and environmental feasibility perspectives using built-in Aspen Plus techniques considering the impact of three key operating parameters; temperature, steam flowrate and CaO flowrate on methanol production. The results of the economic and environmental assessments demonstrate a reduction in CO 2 emissions with respect to the optimum CaO case at 52.7 tonnes CO 2 -e/h, and in comparison with the base case (90.7 tonnes) and the case without adsorbent regeneration (53.3 tonne) for the Palm kernel shell (PKS) biomass feedstock. Whereas, the reduction in CO 2 emissions for empty fruit bunches (EFB) biomass feedstock with respect to optimum CaO case is approximated at 61.8 tonne CO 2 -e/h, and in comparison with the base case (86.6 tonne CO 2 -e/h) and the case without adsorbent regeneration (62.6 tonne CO 2 -e/h). This reduction is also associated with an increase in the capital cost at $120.2 and $119.7 million, and the total annualised cost at $155.4 and $153.1 million of the optimum CaO case for PKS and EFB, respectively. Whereas, $119.1 and $107 million in capital costs with $146 and $139 million in annualised costs are reported for the base case and $118.9 and $117.3 capital costs with $146.7 and $142.3 million annualised costs reported for the case without adsorbent regeneration with respect to PKS and EFB feedstocks, respectively. However, it is also associated with a comparable net profit per methanol production at $201, $132 and $208 million, respectively for the three cases of PKS feedstock, and $170, $130 and $179 million respectively for the three cases of EFB feedstock. The use of CaO and regeneration slightly increases the cost, however, it significantly reduces the CO 2 emissions. • Integrated gasification-methanol production model is simulated using Aspen plus®. • 60 tonne/hr CaO is found to maximise methanol production at reduced CO 2 emissions. • A techno economic and environmental analysis is performed. • The maximum methanol production profit is $208/tonne for PKS and $179/tonne for EFB. • Optimisation and sensitivity of scenarios is utilised to maximise production. [ABSTRACT FROM AUTHOR]

Hydrogen is a zero-emission green fuel containing sufficient energy potentially suitable for electricity generation. Currently, large quantities of hydrogen are produced using classical fossil fuels. Nevertheless, the finite quantities of these resources have compelled the global community to look into using more sustainable and environmentally friendly resources such as bio-based waste. There are several approaches, to convert biomass to hydrogen, among which the thermochemical and biological processes are considered as the most important ones. The aim of this review paper is twofold, namely, (a) to evaluate hydrogen production and biomass processing methods to give a better insight into their potential merits and identify gaps for sustainable hydrogen generation, and (b) to evaluate current and future opportunities in membrane technology for hydrogen separation and purification from biomass processing. By fulfilling these gaps, the objectives of economical, sustainable, and environmentally-friendly resources for hydrogen production and separation can be recommended. • Thermochemical conversion technologies for hydrogen production. • Gasification technologies review for hydrogen production. • Biological routes for hydrogen production. • Potential of membrane applications for hydrogen separation from syngas. • Prospective of hydrogen as future of energy. [ABSTRACT FROM AUTHOR]

Sustainable energy resources are a solution to the increasing energy demand caused by the accelerating population growth and the national development in the emerging countries. Biomass wastes, such as municipal solid wastes, sewage sludge, and agriculture wastes have potential to be converted into energy via thermochemical processing methods - pyrolysis and gasification. These waste treatment methods are environmentally friendly compared to direct burning and other advantages include: a reduced carbon footprint, waste emission reduction, abundant availability, and comparable energy efficiencies. The types and quantity of value-added products depend on process types and operating parameters - temperatures, catalyst, particle size and waste type. This review focuses on the production of gaseous fuel, especially syngas, from the co-conversion of biomass with other waste using the co-gasification and co-pyrolysis processes. This review critically discusses experimental and modelling studies and the key parameters - synergistic effects, reactor types, catalyst types, blending ratio, pre-treatments processes, performance efficiencies, and gasifying agents. Results reflect that mixing coal with biomass significantly reduces SO 2 , NOxs, and tar yields while increasing gas yields. The co-conversion of biomass and plastics enhances gas yields; steam with oxygen is found the best gasifying agent; while acid pretreatment and catalysts improves gas yields and reduces tar content. The review proposes future research to improve efficiencies and gas yields, thereby providing cleaner and sustainable energy for future generations, while maintaining an effective sustainable waste management scenario. Future work should study techno-economic feasibility, and environmental sustainability (using life cycle assessments) for large scale adoption of energy technologies. • A critical review of various feedstock blends for co-gasification and co-pyrolysis. • Co-conversion modelling, experimental and techno-economic studies are reviewed. • Analysis of the impact of blending ratio, catalysts, and pre-treatment on gas yield. • Effect of blend of plastic with biomass on efficient utilization. • Highlights for the challenges, future prospects and policy implications for technology upscaling. [ABSTRACT FROM AUTHOR]

The fruit of oil-palm trees is used to extract millions of tons of palm oil annually across the globe. The extraction of palm oil leaves behind various residues such as empty fruit bunches, mill sludge and fibers, shells, and palm kernel cake. Considering the large amounts of solid organic wastes that are produced in oil palm mills, there is a need for their recovery and utilization. Palm kernel shells (PKS) are the most difficult fraction of the solid waste to decompose. In this work, PKS solid residues which had been subjected to thermal treatment in a gasifier were used as raw materials for the production of a calcium oxide (quicklime/burnt lime) catalyst. The produced catalyst was fully characterized by SEM–EDX, XRF, XRD, CHNS, TGA, and BET analyses. In addition, the basic strength and basicity of the catalyst were determined. The catalytic activity of the CaO-based catalyst was verified in transesterification of sunflower oil with methanol. The effect of the catalyst loading on the fatty acid methyl esters (FAME) formation at a methanol-to-sunflower oil ratio (9:1) at 60 °C was studied. The results show that the calcium carbonate contained in the palm kernel shell biochars is a promising source for calcium oxide catalyst production. [ABSTRACT FROM AUTHOR]

Gasification has emerged as a prominent technique to convert biomass, coal, plastic, and municipals wastes sludge (generated from agriculture, industrial, and domestics, urban centers) into energy in the form of gaseous products. However, co-gasification of these materials has many advantages, such as desired product yield and uninterrupted feedstock supply as well as the sustainable utilization and disposal of these wastes. Numerous reviews have been documented based on the gasification of individual materials of biomass and coal, nevertheless, very few reviews have been reported on the process of co-gasification. In co-gasification, the effect of parameters becomes very important when dealing with the co-gasification of different mixed materials. The objective of this review to study the effect of temperature, blending ratio, and equivalence ratio (ER) on catalytic co-gasification of biomass-coal, biomass-plastic, biomass-sewage sludge, and mixed plastic blends. In addition, the effects of these parameters on gaseous products, heating values, tar formation, and gasification performance have been analyzed. It is also important to specify the ranges of parameters for the feed combinations in catalytic co-gasification that will provide a guideline for researchers and commercial enterprises to investigate co-gasification. For temperature from 650 to 750 °C found good for hydrogen rich syngas production. Whereas, the ratio of biomass 50% or above and ER of 0.20 and 0.25 were found good for higher hydrogen and lower CO 2 and tar production. Moreover, the current issues are related to technology, operational problems, policy requirements and route map for commercial success of co-gasification technology have been highlighted. Image 1 • Impact of temperature, blending ratio, and EQ ratio in co-gasification are reviewed. • Temperature (650–750 °C) is found good for higher H 2 production in co-gasification. • EQ ratio range (0.2–0.25) for gas composition and (0.3) for heating values and CCE. • Biomass content above 50% in blend found effective for gas composition. • The research gaps and technical issues highlighted for commercialization. [ABSTRACT FROM AUTHOR]

• Study on air catalytic gasification of PKS using downdraft fixed-bed gasifier. • Effect of temperature, air flowrate, catalyst were evaluated on gas composition. • Time series ANN modelling approach to predict the gaseous flowrate. • Good agreement found amongst developed NARX neural networks model and experiment data. The air gasification of Palm Kernel Shells (PKS) using coal bottom ash (CBA) as a catalyst has been performed in a fixed-bed gasifier. The impact of three process parameters, namely, temperature (575–775°C), air flowrate (1.5–45 litter/min) and catalyst loading (0–30 wt.%) has been investigated on the product gas yield. The composition of the H 2 product is computed to be a maximum of 28 vol.% at 875°C. The air flowrate has a direct relation with H 2 production. The catalysts used have demonstrated a positive impact on the carbon conversion efficiency, showing the increase in carbon-containing gases in the product gas due to the increases in gas yield. A Non-linear Autoregressive Network with exogenous inputs (NARX) neural network has been used to predict the gaseous flowrate dynamically in order to improve gasification performance. The predicted results from the NARX network demonstrate good agreement with the experimental study with R 2 ≥ 0.99. [ABSTRACT FROM AUTHOR]

• An ASPEN plus model for coconut coir pith and its char gasification was developed. • Sensitivity analysis was conducted for both coconut coir pith and its char. • Techno-economic analysis of coconut coir pith and its char gasification was done. • Steam gasification of char can generate syngas of high yield and quality. • Coconut coir pith char gasification is more economical than coir pith gasification. The study on the steam gasification of biomass char is important to evaluate the performance of steam gasification of biomass and its char. A validated ASPEN plus model was used to investigate the effects of temperature (1023, 1073, 1123, 1173, and 1223 K) and steam-to-feed ratio (0.5, 1.0. 1.5. 2.0, and 2.5) on the syngas output and its composition using steam gasification of coir pith and its char. The study also compared the output and composition of syngas of both processes conducted at 1123 K and 0.75 (steam-to-feed ratio). The techno-economic analysis of both gasifications at the above condition was also investigated. The sensitivity analysis indicated that the temperature has both positive and negative influences; while increasing the steam-to-feed ratio has only a positive influence on the syngas output. Further, it was observed that the increase in temperature increased the yield of H 2 and CO, but it decreased the yield of CO 2 and CH 4. Meanwhile, it was noted that the increase in steam-to-feed ratio increased the yield of H 2 and CO 2 however, it decreased the yield of CO and CH4. The comparative study indicated that the coir pith char gasification generated 27% more syngas output and 25% more H 2 + CO composition than the coir pith gasification. The techno-economic analysis indicated that the coir pith char steam gasification can generate 1.12 times more revenue than coir pith steam gasification. It can be concluded that the biomass char gasification is more advantageous than biomass only gasification. [ABSTRACT FROM AUTHOR]