Biomass Gasification Research Articles

Supercritical Fluids as Solvents for the Future

High pressure technologies involving sub and supercritical fluids offer the possibility to obtain new products with special characteristics or to design new processes, which are environmentally friendly and sustainable. Supercritical fluids are flexible tools for processing materials. Supercritical fluids have been applied to mass-transfer processes, phase-transition processes, reactive systems, materials-related processes, and nanostructured materials. In addition to extraction, application areas include impregnation and cleaning, multistage countercurrent separation, particle formation, coating, and reactive systems such as hydrogenation, biomass gasification, and supercritical water oxidation. Polymers are modified with supercritical fluids, and colloids and emulsions as well as nanostructured materials exhibit interesting phenomena when in contact with supercritical fluids that can be industrially exploited.

Hydrogen Production via Off-Sun Solar-Thermal Supercritical Water Gasification and Membrane Reforming of Piggery Waste

Supercritical water gasification (SCWG) represents an emerging technology for liquid fuel synthesis, offering large potential in significantly improving the efficiency and environmental impact of clean fuel production. Compared to conventional gasification, SCWG proceeds at much lower temperatures, allowing char and tar-free gasification of biomass and for low-quality and high-moisture content biomass to be used. As the thermochemical processes involved in SCWG and steam methane reforming (SMR) are highly endothermic, combining them with concentrated solar power (CSP) and thermal energy storage (TES) could allow the process to be driven solely by renewable energy. As such, this work models an off-sun SCWG/SMR system using novel molten salt, proposed to reach up to 600°C [1], which overcomes the previously limiting molten salt temperature of 550°C. Using an off-sun configuration, it deals with the on-sun configuration’s issues of degraded lifetime and creep-fatigue, allowing for uniform heating and a reduced load on the reactors. The novel technology of an integrated Pd-based membrane reactor, highly selective to H₂, was chosen given its ability to carry out SMR at temperatures in the viable range of new molten salts. The system uses a waste feedstock, piggery waste, to provide the dual benefit of reducing the environmental cost associated with piggery waste’s release of CH4. From the model created in Aspen Plus, a plant output of 7.2 kmolH₂/h (1,135 Nm³/h of H₂), was obtained with a flow rate of 150 kg/h of dry piggery waste, a membrane area of 131.8 m², and a 73% CH4 conversion from the feed.

Gasification of solid biomass or fast pyrolysis bio‐oil: Comparative energy and exergy analyses using AspenPlus®

AbstractThe conversion of biomass residues into syngas through gasification is attractive for energy and process industry applications. However, transportation, storage, and operational challenges limit the conventional direct solid biomass gasification process. To address these issues, the intermediate conversion of biomass to bio‐oil has emerged as a promising alternative. Bio‐oil offers improved transport and storage capabilities due to its higher mass and energy density, enabling the decoupling of solid biomass supply and syngas demand. This study compares two routes for syngas production: direct gasification of solid biomass and indirect gasification using bio‐oil from biomass pyrolysis as an intermediate with biochar and pyrolysis gas supplying thermal energy to the pyrolysis stage. Biochar combustion provides about 1.4 MJ kg−1 of dry biomass to maintain the pyrolysis temperature at 480°C. Using AspenPlus® simulations, the composition and Low Heating Value of the syngas produced by both routes are analyzed. Energy and exergy analysis at different equivalence ratios and temperatures revealed that direct gasification has higher efficiencies than indirect gasification. At 1000°C and an equivalence ratio of 0.4, the highest energy and exergy efficiencies occurred in direct gasification processes. The energy efficiency of direct and indirect gasification amounted to 62% and 53%, respectively. At the same time, the corresponding exergy efficiencies were 65% and 61%. The syngas of direct and indirect gasification processes is a starting point to produce energy, synthetic fuels, and chemicals; this study provides insights for designing and optimizing biomass gasification processes.

Electrolysis-boosted substitute natural gas from biomass: Kinetic modeling of fluidized bed gasification and system integration

The present work deals with the modeling of electrolysis-boosted biomass gasification for the production of green synthetic methane (or substitute natural gas) with a composition that enables its potential injection into the natural gas distribution grid.A kinetic and hydrodynamic model has been built to simulate a bubbling fluidized bed reactor using a mixture of steam and oxygen as gasifying agent. The model was firstly validated by comparing it with experimental results available in the open literature. Outlet temperature spans from about 730 to 1060 °C depending on the used amount of oxygen and steam within the gasifying agent, expressed through parameters like equivalence ratio and steam-to-biomass ratio.Then, process modeling for the integration between biomass gasification and high-temperature steam electrolysis has been carried out. Electrolysis has been sized to enrich the hydrogen content of the syngas, enabling a stoichiometric composition in terms of hydrogen, carbon monoxide, and carbon dioxide for the subsequent catalytic methane synthesis via carbon oxides hydrogenation. Thermal integration has been carefully designed to improve the overall process efficiency up to about 71 % (based on lower heating value of both biomass and substitute natural gas).

Experimental study on CO2 co-gasification characteristics of biomass and waste plastics: Insight into interaction and targeted regulation method

The CO2 gasification of biomass and waste plastics is one of the essential ways to utilize solid waste resources, and it is also potential negative carbon emission technology. The complex interactions in the co-gasification of biomass and waste plastics affect the quality of syngas and the efficient conversion of solid waste. In this study, sawdust, PE and PVC were selected for CO2 gasification. Firstly, the interaction and gasification characteristics were investigated by thermogravimetric experiments. Then, the impact of interaction on syngas generation and quality was studied through fluidized bed experiments. The results indicated that PE, PVC, and sawdust co-gasification exhibits both inhibitory and synergistic. PE inhibits the release of volatiles in sawdust, while PVC promotes the volatiles release. In short, PVC improves the gasification reactivity of sawdust, and PE enhances syngas quality. Adding 75 % PE, the syngas Low Heating Value by 415 % up to 30.05 MJ/kg, and Cold Gas Efficiency by 147 %. The synergistic of the sawdust/PE-PVC was manifested as the superposition and amplification of the synergistic in sawdust/PE and sawdust/PVC. Adjusting the PE and PVC proportion, syngas quality can be targeted to control. The study results exhibit new perspectives on classifying waste plastics for gasification and regulating syngas quality.

The effect of CO2 and a promoter over a Ni-based catalyst on the gas production of toluene as a model tar compound

Catalytic cracking of biomass tar can increase the gas production of biomass gasification and reduce tar content. Taking tar model compound (toluene) as the research object, HZSM-5 as the catalyst carrier, the influence of different Ni loadings, promoters, and CO2 atmosphere on the gas production trend of toluene catalytic cracking was studied. The crystal structure, specific surface area, microstructure and carbon deposition of the catalyst were investigated. When the Ni/HZSM-5 load was 8 wt%, the H2 instantaneous gas production reached highest value. When the load was increased to 10 wt%, catalyst deactivation was delayed, leading to an increase in gas production. With the addition of Ca, Mn and Fe as promoters, Ca decreased the catalytic activity of Ni/HZSM-5, leading to a decrease in H2 instantaneous gas production; however, both Mn and Fe promoted the catalytic activity of Ni/HZSM-5, with Fe resulting in the highest H2 instantaneous gas production. When 20% CO2 was introduced, Ni-Mn/HZSM-5 had the highest catalytic activity and produced the highest H2 content. The characterization of the catalysts showed the addition of CO2 effectively inhibited the formation of carbon deposits, which was beneficial to prolong the catalytic effect and increase gas production.

Advancing Process Control in Fluidized Bed Biomass Gasification Using Model-Based Deep Reinforcement Learning

This study presents a model-based deep reinforcement learning (MB-DRL) controller for the fluidized bed biomass gasification (FBG) process. The MB-DRL controller integrates a deep neural network (DNN) model and a reinforcement learning-based optimizer. The DNN model is trained with operational data from a pilot-scale FBG plant to approximate FBG process dynamics. The reinforcement learning-based optimizer employs a specially designed reward function, determining optimal control policies for FBG. Moreover, the controller includes an online learning component, ensuring periodic updates to the DNN model training. The performance of the controller is evaluated by testing its control accuracy for regulating synthetic gas composition, flow rate, and CO concentration in the FBG. The evaluation also includes a comparison with a model predictive controller. The results demonstrate the superior control performance of MB-DRL, surpassing MPC by over 15% in regulating synthetic gas composition and flow rate, with similar effectiveness observed in synthetic gas temperature control. Additionally, this study also includes systematic investigations into factors like DNN layer count and learning update intervals to provide insights for the practical implementation of the controller. The results, presenting a 50% reduction in control error with the addition of a single layer to the DNN model, highlight the significance of optimizing MB-DRL for effective implementation.

Energy Evaluation of Synthesis Gas in a Turbocharger System Employing CFD Tools

Renewable energy sources derived from biomass, such as synthesis gases, represent an opportunity to take advantage of available waste resources and contribute to global energy rationing. This study developed an analysis with computational fluid dynamics (CFD) to estimate the energy behavior of synthesis gases through a turbocharger system. The synthesis gas used to drive the turbocharger turbine was extracted from the gasification of biomass from the Colombian Caribbean. The application of models for rigid body motion, as well as models of momentum, turbulence, energy, and conservation transport of species, suggest that the energy potential available by the turbine ranges from 0.4 kW to 5.2 kW of power generation, concerning mass flow rates entering the simulated system. The main findings of the study were temperature profiles, speed profiles, rotational speed variation, torque, and mechanical power generated in the turbocharger. It is emphasized that the synthesis gas studied presents a good behavior to generate energy through a turbine system of a turbocharger device.

Comprehensive review of biomass utilization and gasification for sustainable energy production

Comprehensive review of biomass utilization and gasification for sustainable energy production

Retrofitting Biomass Combined Heat and Power Plant for Biofuel Production—A Detailed Techno-Economic Analysis

Existing combined heat and power plants usually operate on part-load conditions during low heating demand seasons. Similarly, there are boilers designated for winter use that remain inactive for much of the year. This brings a concern about the inefficiency of resource utilization. Retrofitting existing CHP plants (especially for those with spare boilers) for biofuel production could increase revenue and enhance resource efficiency. This study introduces a novel approach that combines biomass gasification and pyrolysis in a polygeneration process that is based on utilizing existing CHP facilities to produce biomethane, bio-oil, and hydrogen. In this work, a detailed analysis was undertaken of retrofitting an existing biomass combined heat and power plant for biofuel production. The biofuel production plant is designed to explore the polygeneration of hydrogen, biomethane, and bio-oil via the integration of gasification, pyrolysis, and renewable-powered electrolysis. An Aspen Plus model of the proposed biofuel production plant is established followed by a performance investigation of the biofuel production plant under various design conditions. An economic analysis is carried out to examine the profitability of the proposed polygeneration system. Results show that the proposed polygeneration system can achieve 40% carbon efficiency with a payback period of 9 years and an internal rate of return of 17.5%, without the integration of renewable hydrogen. When integrated with renewable-power electrolysis, the carbon efficiency could be significantly improved to approximately 90%; however, the high investment cost associated with the electrolyzer system makes this integration economically unfavorable.

Maximizing hydrogen-rich syngas production from rubber wood biomass in an updraft fluidized bed gasifier: An advanced 3D simulation study

BackgroundThis research focuses on biomass gasification as a solution to the global energy crisis. The study aims to optimize the production of syngas by simulating an updraft fluidized bed gasifier using rubber wood as fuel. The goal is to maximize CO and H2 at the gasifier outlet by investigating different vertical positions and angles of the biomass feed inlet. MethodsThe research utilizes 3D simulation and Computational Fluid Dynamics (CFD) through the implementation of the ANSYS Fluent® software package. Realistic assumptions and the K-epsilon turbulence model simplify the analysis. The model assumes a steady state, adiabatic conditions, homogeneous gas phase kinetics, and ideal fluid behavior. Significant findingsThe optimal biomass feed inlet position is 200 mm, yielding higher CO, while a position of 250 mm produces more H2. A 45° feed inlet angle slightly improves syngas quantities but increases CO2. Using a gasifying agent with higher CO2 enhances combustion, while limited O2 facilitates gasification. Increasing oxygen content from 20 % to 50 % raises H2O content. More steam in the inlet boosts H2 production, but excessive H2O reduces steam quality, making expensive steam less effective than air. These findings offer valuable insights for optimizing fluidized bed biomass gasification systems.

Synthetic diesel from biomass by Fischer-Tropsch synthesis

The production of liquid hydrocarbons fuel from biomass by Fischer-Tropsch synthesis has become more and more attractive due to its advantages compared to fossil diesel: environmental friendliness by recycling wood and agricultural wastes and reducing emissions of greenhouse gases (CO, CO2 ,SO2,NOx,unburned hydrocarbons and particulate matters), absence of sulphur and nitrogen, higher combustion efficiency, higher cetane number and also the compatibility with existing diesel engines and infrastructure. In this paper the Fischer-Tropsch synthesis process from biomass applied at the Güssing plant was investigated. Each stage of the installation: biomass gasification, gas cleaning and Fischer-Tropsch process, in terms of the equipment used and the parameters necessary for the synthesis, was analysed and discussed. Also, during the synthesis the gas composition of the syngas before and after each stage was analysed, using gas chromatography. The same analytical method was used in order to determine the carbon distribution of the Fischer-Tropsch fuels obtained in the process. The ASF model was applied and an α value of 0.89 was calculated for the products.

Reforming of biomass-derived producer gas using toluene as model tar: Deactivation and regeneration studies in Ni and K-Ni catalysts

Within the syngas production from biomass gasification, tar removal constitutes a chief issue to overcome for advanced catalytic systems. This work investigates the performance of Ni and Ni–K catalysts for reforming of derived-biomass producer gas using toluene as model tar. At 750 °C and 60Lg−1h−1, the stability test (70 h) revealed stable performances (CO2, CH4 and C7H8 conversions of 60, 95 and 100%, correspondingly) uniquely for the Ni–K catalyst. Although the efficient protection towards coking let by K was demonstrated, TPO studies over the post-reacted systems still evidenced the presence of carbon deposits for both samples. Conducting three successive reaction/regeneration cycles with different gasifying agents (air, steam and CO2) at 800 °C for 1h, the capability towards regeneration of both catalytic systems was assessed and the spent catalysts were characterized by XRD, SEM and TEM. While none of the regeneration treatments recovered the performance of the unpromoted catalyst, the Ni–K catalysts demonstrated the capability of being fully regenerated by air and CO2 and exhibited analogous catalytic performances after a series of reaction/regeneration cycles. Hence, it is proved that the addition of K into Ni catalysts not only enhances the resistance against deactivation but enables rather facile regenerative procedures under certain atmospheres (air and CO2).

Insights into biomass mild gasification based on mass-energy balance: Establishing condition, thermodynamic mechanisms, and product properties

To alleviate the challenge of gas and char quality competition arising from over oxidation during the biomass gasification. A new concept of biomass mild gasification based on mass and energy balance was proposed, wherein the energy produced during the oxidation stage precisely equals the energy consumed in the pyrolysis and reduction stages. An energy balance index (EBI), obtained through the combined use of TG-DSC-MS-FTIR and Gaussian model fitting to represent the relationship between mass loss and endothermic/exothermic properties among different reaction stages, was optimized by response surface methodology (RSM) to obtain the critical conditions of biomass mild gasification. Under two typical mild gasification conditions, the quality characteristics of mild gasification biochar were analyzed and the gas evolution characteristics and sequence were determined through the combination of two-dimensional correlation spectroscopy (2D COS). The results indicated that mild gasification can be achieved within a heating rate range of 21 °C/min to 26 °C/min, with the oxidation temperature ranging from 776 °C to 869 °C. Under mild gasification conditions, the biochar produced at 850 °C-20 °C/min had higher COOH content, which can regulate soil pH, promote organic matter degradation, and enhance biological activity. Under the 800 °C-25 °C/min mild gasification condition, more CO and CH4 were generated during the pyrolysis stage, but slightly more CO2 was also produced during both the pyrolysis and oxidation stages. This work provides comprehensive thinking on the precious control of gasification process, which lays a foundation for co-generation of high-quality char and gas.

Techno-Economic Evaluation of Solar Hybridized Biomass Gasification Polygeneration Plants

Techno-Economic Evaluation of Solar Hybridized Biomass Gasification Polygeneration Plants

An efficient combustion concept for low calorific gases

The main features of low calorific gases as those from biomass gasification processes, landfills, mines and sewage sludge are well known. They can be expressed as low calorific values, high water content, corrosive actions and composition changes. Due to these characteristics there are up to date no combustion systems available which are capable to utilise such gases efficiently. The ordinary combustion concepts frequently do not guarantee sufficient flame stability. The high emissions of harmful substances as CO and NOx are another problem. Because of mentioned difficulties it is necessary and also a challenge to develop an efficient and flexible combustion system which can handle these problems. Through several matching steps of numerical and experimental investigations Gaswärme-Institut e. V. Essen (GWI) developed a progressive combustion system based on the concept of continuous air staging (COSTAIR). Burner tests at a small scale thermal load of 30 kW proved a stable combustion and low NOx and CO emissions for different qualities of low calorific gases. The best design of a small scale burner was transferred to larger thermal loads by applying of scale-up criteria. Already achieved experimental results at 200 kWth confirmed the efficient performance and the high potential of the burner for use of low calorific gases.

Experimental investigation of the influence of calcium oxide on product quality, tar cracking efficiency, heating value, and syngas ratio in two-stage fixed bed gasification

ABSTRACT Biomass gasification is a thermochemical process used to generate hydrogen and methane for energy applications. This experimental study compares the products formed from sugarcane bagasse, bamboo, and rice-straw and evaluates the calorific value of the gas and the efficiency of homogeneous cracking in a novel, two-stage, downdraft, fixed-bed reactor. The formation of tar and the presence of carbon oxides (COx) in the gaseous product are some of the major problems with biomass gasification. In order to solve these issues, calcium oxide (CaO) is introduced with the feed in a 1:1 mass ratio as a CO2 sorbent, and its effect on the amount of tar is studied across the chosen biomasses. Experiments are conducted with the pyrolysis stage at 773 K and the air-gasification stage at 1073 K. The tar cracking efficiency of 97% is obtained with CaO for all biomasses. Rice-straw showed the highest syngas ratio of 1.83 and the volume of hydrogen increased by 13% after the addition of CaO, while bamboo had a 16% rise in hydrogen and showed the highest LHV of 12.21 MJ/m3, followed by bagasse with an LHV of 11.50 MJ/m3. The gasification efficiency for bamboo is the highest overall for both the processes.

Entrained flow gasification-based biomass-to-X processes: A techno-economic assessment

In the pursuit of a successful energy transition, synthetic basic chemicals and fuels, alongside renewable energies, play pivotal roles. This study focuses on the utilization of biomass as a carbon source to replace conventional fossil feedstocks, conducting detailed process simulations and techno-economic analyses for various biomass-to-x pathways. Six key products—Methanol, Dimethyl Ether, Methane (SNG), Fischer-Tropsch syncrude, Hydrogen, and Ammonia—derived from entrained flow gasification of a representative biomass are systematically compared. The uniformity of simulation detail and economic methodology enables a direct and comprehensive comparison of these products. Notably, carbon-based products exhibit up to 34% lower average investment costs compared to their hydrogen-based counterparts, namely ammonia and hydrogen. This cost discrepancy is reflected in the levelized costs of manufacturing, with hydrogen-based products emerging as the most energy-expensive. The analysis identifies variable costs as the primary contributor to overall costs with around 50%, followed by fixed investment. The study underscores the critical impact of full load hours, plant lifetime, and feedstock costs on results. This emphasise the importance of detailed planning if alternative feedstock is used to balance fuel costs and enhance plant availability. Among the evaluated products, methanol emerges as the most promising across the evaluated KPIs with costs of 283.48 € MWh−1. However, regarding hydrogen-based products, it is suggested that, especially in the context of CO2 abatement costs, a comprehensive consideration of the long-term system effects is essential to prevent misinvestments during the early stages of the energy transition. This emphasizes the need for strategic planning to ensure a sustainable and economically viable shift towards biomass-derived synthetic fuels.

Effect of particle size on the properties of biomass gasification residue pellets used as a metallurgical-grade silicon reducing agent

Due to the greenhouse effect and fossil fuel shortages, biochar became a research priority to replace charcoal for metallurgical-grade silicon reductants, but it has an uneven particle size and insufficient strength. In this study, biochar was pelletized and compared with charcoal, and the relationship between the biochar particle size and pellet strength, porosity, and reactivity was determined. The results showed that the performance of biochar pellets was better than that of charcoal. In addition, upon decreasing the biochar particle size, the pellet strength increased, the porosity decreased, and the reactivity increased. When biochar with a particle size of <100 μm was used, the strength of the pellets was 3184.63 N, the porosity was 47.85%, and the reactivity was 82.15%, which meets the requirements of metallurgical-grade silicon reducing agents. This study provides a reference for the production of biochar pellets suitable for smelting to reduce the production of greenhouse gases.

Combustion performance and flame front morphology of producer gas from a biomass gasification-based cookstove

The present work investigates the last phase of the biomass gasification-based cookstove, which is the combustion process of biomass producer gas (BGP). A constant volume combustion bomb and kinetic simulation are used to characterize the behavior of the biomass producer gas and its pollutant emissions under a conventional premixed combustion process. The BGP combustion processes of two types of biomasses available in Colombia (Pinus Patula and Cordia Alliodora) are studied under certain conditions of pressure, temperature, and equivalence ratio. To characterize the combustible mixture of gases obtained after biomass gasification, a combustion chamber with cylindrical geometry equipped with a Schlieren optical diagnostic system to visualize the combustion process, and a piezoelectric pressure transducer to register the instantaneous pressure are used. By visualizing the flame front, the flame propagation speed at which the flame propagates through the combustion chamber and the morphology of the flame are studied. Instantaneous pressure is the input of a two-zone diagnostic model through which variables, such as burning velocity, temperature, mass burned fraction, etc., are obtained to characterize the combustion process of the mentioned gasification gases. Experimental results are compared and complemented with kinetic modeling results obtained with the Cantera package using the Gri-Mech 3.0 and Aramko 1.3 kinetic mechanisms, in terms of laminar burning velocity and NO, NO2, CO, and CO2 exhaust emissions. Results show that Cordia Alliodora presents higher burning velocities than Pinus Patula BP. However, lower CO2 emissions are obtained during the Cordia Alliodora combustion, and NOx emissions are not influenced by the type of biomass considered.