Wood Gasification Research Articles

Compact Biomass Power Plant with Wood Gas Engine

Compact Biomass Power Plant with Wood Gas Engine

Different aspects of biochar addition on semi-dry anaerobic digestion of organic fraction of municipal solid waste in continuous mode

This study investigated the use of biochar, derived from a wood gasifier, in semi-dry anaerobic digestion of organic fraction of municipal solid waste (OFMSW). The experiment was conducted in three phases, without biochar and changing the hydraulic retention time (HRT) from 50 to 15 days until first acidification condition (on pH = 6.5), with biochar at an optimal concentration of 30 g/L in HRT= 20–10 day. Also, countermeasures for the acidified reactor with biochar during the dormancy period were investigated. The results demonstrated that adding biochar led to a rapid recovery of the acidified reactor, improved stability parameters, and removed foaming as a disturbance. Biochar addition (30 g/L) enhanced the organic loading rate (OLR) up to 11 kgVS/m3.day with an HRT of 20 days leading to specific methane production of 383 L/kgVS and a volumetric production increase of biomethane by 85 %. However, at higher OLRs with HRT of 10 days, acidification condition resurfaced leading to homogeneous foaming. Excess adding of biochar did not have significant treatment effects but necessitated a no-feeding period (about 45 days) and gentle stirring with long intervals for stable conditions. Overall, the use of biochar along with the OFMSW biogas plant was demonstrated to enhance production efficiency.

Environmental, economic, and eco-efficiency assessment of residential heating systems for low-rise buildings

Transitioning from fossil fuels to renewable heating is essential for rapidly reducing greenhouse gas emissions. Besides greenhouse gas emissions, other environmental and economic impacts are crucial for successfully implementing renewable heating systems. This study evaluates 13 residential heating systems' environmental, economic, and eco-efficiency performance for a typical German two-story dwelling. The life cycle assessment method is employed to quantify the environmental impacts. Assuming a sustainable supply of biomass-based fuels, biomass heating systems exhibit the lowest environmental impacts, whereas gas heating systems are associated with high environmental impacts. Among heat pump systems, the water-source heat pump demonstrates the lowest environmental impact. Additionally, integrating a PV system into heat pump systems reduces the environmental impacts across all heat pumps. The evaluation indicates that the air-source heat pump is the most economical system, while the pellet boiler with solar thermal support and the heat pump with ice storage incur the highest costs. However, the cost differences among the heating systems are relatively small, making it challenging to establish a clear ranking based solely on economic evaluation. An eco-efficiency assessment, which combines environmental and economic aspects into a single indicator, reveals that the most eco-efficient systems are the air-source heat pump, both with and without a PV system, and the wood gasifier heating system. In contrast, the ice-storage heat pump and the pellet heating with solar thermal support show the lowest eco-efficiency.

Gas component effect on energy loss of reciprocated engine operated by bio-syngas from wood gasifier

AbstractTo convert woody biomass into electricity with small capacity and high efficiency, it is reasonable to gasify the woody biomass and operate a reciprocating engine. On the other hand, bio-syngas produced from woody biomass have a low calorific value. Therefore, if the concepts of the thermal efficiency and the losses (the cooling loss, the combustion loss, the pumping loss, the exhaust loss, etc.) obtained by conventional fossil fuels are applied as these are, it is not possible to predict the thermal efficiency appropriately. In this paper, the bio-syngas as the reference is produced in a self-made gasification system, and the thermal efficiency and the losses of the reciprocating engine are experimentally examined to evaluate the significant effect of combustible components on these indicators. The combustible components are hydrogen, methane, and carbon monoxide. The nitrogen fraction in the bio-syngas is adjusted to control the low heating value. A commercially available small general-purpose spark-ignition reciprocating engine (GP-SIRE) was modified and used as the experimental engine. The results showed that (1) the operation with the referenced bio-syngas exhibits higher thermal efficiency (more than 10 points) than that with the conventional methane, and that (2) there is a trade-off between the combustion loss and the cooling loss.

In-situ biomethanation of high CO content syngas in agricultural biogas digesters

To meet global energy demands, syngas with high CO content (>50 %) generated from hydrothermal gasification of agricultural residues or wood, could be utilized as a co-substrate in anaerobic digestion (AD) processes for conversion into CH4. This study investigated in-situ biomethanation using synthetic gas (55 % CO, 35 % H2, and 15 % CO2), mimicking wood gasification syngas, during AD of cow manure, the most abundant agricultural waste. A continuously stirred tank reactor (CSTR) served as a control and was fed only cow manure, while the other two reactors were fed syngas with or without gas recirculation at different gas loading rates (GLRs).In-situ syngas injection in AD of cow manure at GLRs ≤0.3 L LRV−1 d−1 improved overall CH4 productivity compared to the control (0.35 ± 0.1 vs. 0.29 ± 0.1 L LRV−1 d−1), though the CH4 content (45 ± 5 %) was lower than the control reactor (62 ± 3 %), indicating a need for biogas upgrading. Gas recirculation enabled higher CO and H2 conversion efficiencies of 99–100 % but considerably decreased CH4 productivity from cow manure. In-situ biomethanation enhanced the relative abundance of hydrogenotrophic methanogens, highlighting their role in syngas conversion to CH4.

Following fuel conversion during biomass gasification using tunable diode laser absorption spectroscopy diagnostics

The efficiency of the gasification process and product quality largely depend on the degree of fuel conversion. We present the real-time in-situ tunable diode laser measurements of main carbon and oxygen-containing species in the hot reactor core of a pilot-scale entrained flow biomass gasifier (EFG). The concentrations of CO, CO2, CH4, C2H2, H2O, soot, and gas temperature were measured during the air and oxygen-enriched gasification of stem wood at varying equivalence ratios. The experiments were made at the upper and lower optical ports inside a 4 m long, ceramic-lined, atmospheric EFG, allowing to access the degree of the fuel conversion inside the reactor. The exhaust composition was measured by micro-GC, FTIR, and low-pressure impactor. There was a good agreement between the data measured inside the reactor and at the exhaust for oxygen-enriched gasification implying that the chemical reactions are practically frozen downstream the optical ports. For air, the data indicated that the gasification reactions are still active at the measurement locations. Significant concentrations of C2H2, up to 5000 ppm, were found inside the reactor.

ТЕПЛОФИЗИЧЕСКАЯ МОДЕЛЬ И РЕЗУЛЬТАТЫ ЭКСПЕРИМЕНТАЛЬНОГО ИССЛЕДОВАНИЯ ГАЗИФИКАЦИИ ДРЕВЕСНЫХ И РАСТИТЕЛЬНЫХ ОТХОДОВ

The article compares the calculation results using the developed thermophysical composition model for the study of thermal gasification of wood and plant waste – renewable natural energy resources in a gas generator with the reverse combustion process and forced steam-air blast, which allows to achieve minimal formation of a by-product – resin. Based on the thermophysical model, the optimal consumption of solid fuel – wood and plant waste and oxidizer – atmospheric air is determined. The work can be used by technical engineers at enterprises in Russia and abroad for the environmentally friendly disposal of wood and plant waste in autonomous energy technology installations with combustion gas generators to generate thermal and electrical energy for the consumer. In particular, large volumes of wood and plant waste accumulate at wood processing and agricultural enterprises in the Tyumen region, which are an additional cheap source of energy.

Wood Gasification: A Promising Strategy to Extend Fuel Reserves after Global Catastrophic Electricity Loss

Wood Gasification: A Promising Strategy to Extend Fuel Reserves after Global Catastrophic Electricity Loss

Wood Chipper Design for Biofuel Production in a Global Catastrophic Loss of Infrastructure Scenario

A variety of events such as high-altitude electromagnetic pulses, extreme solar storms, and coordinated cyber attacks could result in a catastrophic loss of infrastructure on a continental or global scale. The lengthy repair of critical infrastructure creates a need for alternative fuels such as wood gas. Wood gas is produced by heating wood in a low-oxygen environment and can be used to power combustion engines. This work investigates a novel wood chipper, designed as an energy-efficient tool for producing wood gas stock, wood chips, aiming to speed up the transition to alternative fuel. A prototype is built and tested to determine the energy efficiency and production rate of the device. The results suggest that the wood chipper could produce one cord of wood chips, 3.6 m3, in less than a day and is a viable alternative to other manual wood-processing methods. In addition, the global scaling up of production of the wood chipper is considered, indicating that the mass production of the wood chipper could accelerate the transition of wood gas production methods from manual to machine-driven immediately after a catastrophic event.

El gas del agua: entre la alternativa y la decepción a mediados del siglo XIX

By the middle of the 19th century, gas lighting had reached a good level of implementation in some European countries. In France, lighting based on coal distillation had been implemented in many towns, resisting the emergence of other alternatives such as wood gas or resin gas. However, some drawbacks remained that led some inventors to make advances in obtaining hydrogen gas from water. The procedure was not unknown, but it had not gone beyond the laboratory phase. The transition to the industrial phase occurred in the 1850s with the work of some French inventors and with its subsequent application in some factories in this country. In this paper we study the advances and resistance that were generated in France in the development of water gas in those years. In addition, we delve into the repercussions that these new techniques had in Spain, either in the proposed applications or in those carried out.

In-situ electrochemical impedance analysis of a commercial SOFC stack fueled by real wood gas

The combination of solid oxide fuel cells (SOFCs) and wood gasification has the potential to significantly increase renewable electricity production and decrease emissions. Depending on the quality of the wood gas, degradation processes have a significant impact on the reliability and lifetime of the SOFC. Using electrochemical impedance spectroscopy (EIS) and subsequent distribution of relaxation times (DRT) analysis, the impact on the degradation of coupling wood gasification with a commercial SOFC stack is determined in this study. The thermal behavior of the SOFC stack under various operating conditions, as well as various synthetic wood gas mixtures classified by their hydrogen-to-carbon (H/C) ratio, was assessed. The decrease in the H/C ratio from 8 to 1, observed during syngas and real wood gas operation, leads to a rightward shift in the Nyquist plots, suggesting an increase in the SOFC stack's impedance. Correlations between variations in the H/C ratio and their effects on anodic electrooxidation, ionic conduction, gas transport, and diffusion were identified using DRT analysis to interpret the EIS results. By incorporating an upstream desulfurization system and ensuring an H/C ratio greater than 2, the coupling of biomass gasification with the SOFC stack was stable to degradation issues.

Design and operation of a local cogeneration plant supplying a multi-family house (9,5 kW electrical / 35 kW thermic power) – a field report

In the paper at hand a small cogeneration plant that is suitable to supply heat and electric power to a three family house is presented. The plant is capable of delivering 9.5 kW electrical power to the mains and 30 kW thermal power used for heating the domestic hot water and the building respectively. Woodchips, a renewable energy carrier, are used to power the plant, so it is CO2 neutral. Powering an internal combustion engine with wood gas made from woodchips has turned out to be the right technology for small cogeneration plants. Such units are not available from stock; hence a prototype has been constructed. More than two years of operation experience with this prototype show the practicability of the system. The amount of maintenance work is acceptable and will be reduced in the future by optimization. Measurements concerning the electrical as well as the thermal efficiency are presented. During these measurements further room for improvement has been discovered to maximise output power and to lower losses. In summary it figured out that the plant operates reliable with acceptable amount of maintenance work. And, if we don’t calculate the amount of development work for the prototype, it is profitable.

Investigations on the Release of Heavy Metals during the Gasification of Simulated Waste Wood

Investigations on the Release of Heavy Metals during the Gasification of Simulated Waste Wood

Synthesis of syngas from municipal solid waste in a fluidized bed gasifier

In this study, three representative materials, wood, paper, and cloth from municipal solid waste, were studied separately in an atmospheric fluidized bed gasifier. The effects of different feedstock, equivalence ratio, gasification temperature, and calcium carbonate presence on syngas composition, the lower heating value, and carbon conversion efficiency were investigated at different operating temperatures (800-950?C), and the equivalence ratio range from 0.2 and 0.5. As the equivalence ratio increased, the yields of syngas and its lower heating value decreased, whereas the CO2 yield and carbon conversion efficiency increased generally from wood gasification. Higher gasification temperature favored enhancing the CO and H2 yield and lowering the CO2 yield while the lower heating value and carbon conversion efficiency of syngas increased. Different variations of CO2 yield and the lower heating value of syngas were observed in different feedstock gasification. CaCO3 was more supportive for enhancing the yields of syngas components (H2, CO, and CH4) and lowering the CO2 yield, while a lower heating value of syngas was also increased from different feedstock gasification. However, an optimum temperature of 900?C was the highest lower heating value of syngas, reaching 8000 kJ/Nm3 from wood gasification.

Model Forecasting of Hydrogen Yield and Lower Heating Value in Waste Mahua Wood Gasification with Machine Learning

Biomass is an excellent source of green energy with numerous benefits such as abundant availability, net carbon zero, and renewable nature. However, the conventional methods of biomass combustion are polluting and poor efficiency processes. Biomass gasification overcomes these challenges and provides a sustainable method for the supply of greener fuel in the form of producer gas. The producer gas can be employed as a gaseous fuel in compression ignition engines in dual‐fuel systems. The biomass gasification process is a complex as well as a nonlinear process that is highly dependent on the ambient environment, type of biomass, and biomass composition as well as the gasification medium. This makes the modeling of such systems quite difficult and time‐consuming. Modern machine learning (ML) techniques offer the use of experimental data as a convenient approach to modeling and forecasting such systems. In the present study, two modern and highly efficient ML techniques, random forest (RF) and AdaBoost, were employed for this purpose. The outcomes were employed with results of a baseline method, i.e., linear regression. The RF could forecast the hydrogen yield with R2 as 0.978 during model training and 0.998 during the model test phase. AdaBoost ML was close behind with R2 at 0.948 during model training and 0.842 during the model test phase. The mean squared error was as low as 0.17 and 0.181 during model training and testing, respectively. In the case of the low heating value model, during model testing, the R2 was 0.971 and RF and AdaBoost, respectively, during model training and 0.842 during the model test phase. Both ML techniques provided excellent results compared to linear regression, but RFt was the best among all three.

Effects of inherent AAEMs on catalytic gasification of biomass with large particle size under oxygen-steam atmosphere

Oxygen-steam gasification of biomass is a promising technology because of its ability to improve syngas quality and reduce energy consumption. In this study, a fixed-bed reactor is employed to assess the effects of inherent alkali and alkaline earth metals (AAEMs) on the catalytic gasification of candlenut wood with large particle size under the oxygen-steam atmosphere. Two grain directions, radial and axial, are considered for candlenut wood. Various characterization techniques, SEM, X-ray CT, BET, and FTIR, are employed to analyze biochar samples. GC-MS and GC are determined to tar and syngas respectively. The results show that char yield from biomass with axial grain is higher. Acid-washing removes alkali metals (K and Na) better from biomass with axial grain than radial grain, and vice versa for alkaline earth metals (Ca and Mg). In terms of the gasified chars derived from acid-washed biomass, AAEMs content gradually decreases along the end surface and radial direction, which could also be observed from the 3D reconstruction of X-ray CT images. In all samples, micropores (0–10 µm) dominate and are distributed along the grain direction. In general, pores of 20–30 µm and above 30 µm comprise a minor proportion. Inherent AAEMs facilitate an augmentation in char yield as well as BET and total pore volume of gasified char. AAEMs and grain direction have a slight effect on functional groups of gasified chars. Certain organic matter species and content in tar are remarkably affected by the grain direction, since the discrepancies of pore structure and specific surface area. Acid-washing pretreatment augments the content and organic species of M2-M4 compounds (containing 2–4 benzene rings) in the tar. K and Na significantly boost the char steam gasification, water-gas shift, and steam-tars reforming reactions. A decrement in concentrations of H2 (14.49% and 13.35%), CH4 (0.51% and 0.89%), and CO2 (2.32% and 1.37%) in syngas derived from acid-washed samples are acquired, respectively, compared to that of biomass samples with radial and axial grains. However, a reduction of 4.09% and 1.53% in syngas calorific value could be obtained. The CnHx volume fraction is significantly affected by grain direction and AAEMs, with axial grain yielding a higher volume fraction of C2H4 (49.07%), C2H2 (71.29%), and C3H8 (127.36%) from acid-washed sample than that of radial grain.

An econometric analysis of the sawmill by-product market to explore bioeconomy options in Austria

Bioeconomy strategies promote higher shares of biomass products in material and energy sectors. Deploying by-products from sawmills is therefore of major interest. This study aims at analyzing market characteristics and implications of bioeconomy strategies by combining three methods: First, an econometric supply and demand model for sawmill by-products (SBP) was estimated based on data from 2001 to 2020. Second, the model was used to analyze a reference and a bioeconomy scenario. Third, a use case was analyzed dealing with the integration of wood gasification and BioSNG (Synthetic Natural Gas) production into Austrian flows of SBP. The results indicate that SBP supply reacts unit-elastic to sawnwood exports, while both supply and demand respond inelastic to SBP prices. Demand is positively inelastic related to SBP as input in panel and pellet production. In a bioeconomy scenario, long-term supply would exceed demand, resulting in additional SBP to be used for gasification. A 100 MW BioSNG plant converting these SBP could provide 528 MWh BioSNG per year. This is a 11 % share of the Austrian target value of 5 TWh green gas.

Conversion in a char bed reactor of tars and syngas from a wood gasifier

Cleaning syngas, particularly reforming tars, is still a major bottleneck to the development of gasification. In this work, syngas was simultaneously sampled and analysed downstream and upstream of a tar conversion reactor using a real syngas produced with a commercial gasifier.At 800 °C and 2 s residence time, tar conversion reached 51a% compared with only 11 % in an inert bed. The tar content in the syngas decreased from 8.1 to 4.2 g/Nm3. Almost all the tertiary tars were converted, and only benzene, toluene, and naphthalene persisted. The energy content of the syngas increased by 5 % thanks to simultaneously increase of the LHV and syngas flowrate. LHV's increase in mainly due to H2 production.

Improvement of syngas quality from two-stage downdraft wood gasification through steam and oxygen injection

The transition from fossil fuels to clean energy sources requires the supply of gaseous fuels from renewable origin for a number of applications. Such applications include in particular high-temperature heat for industries, and Combined Heat and Power (CHP) for flexible, decentralized power production. Gasification of lignocellulosic biomass is a good candidate to this end, converting solid biomass such as wood residues into a more versatile and CO2-neutral gaseous fuel. Today, the use of syngas remains limited due to its relatively low energy density and challenges related to its residual tar content.To improve the quality of syngas on these two aspects, we have studied the injection of steam and oxygen in a pilot two-stage downdraft gasifier. Replacing secondary air by oxygen enhances the Lower Heating Value (LHV) by 65%, while steam injection boosts the H2/CO ratio and damps the temperature rise due to oxygen. The gasification efficiency is enhanced by both oxygen and steam. As a drawback, oxy-steam conditions yield more Class III and IV tars in the syngas. The combined use of oxygen and steam can enhance the volumetric power of syngas-based CHP engines, and provide a sustainable fuel for high-temperature industrial applications.In future research, longer runs should be done to confirm the effects of steam and oxygen on conversion efficiency. The injection of steam and oxygen at the primary stage should also be studied. The presented results will help choosing whether to use oxygen and steam in downdraft gasification applications, and support the validation of numerical models.

Characteristics of gasification chars – Results from a screening campaign

Despite several useful characteristics like high carbon content, large BET surface area and narrow particles size distribution, the solid residues from wood gasification, i.e. gasification chars, are rarely used and commonly considered as wastes. Furthermore, marketing of these materials is hampered by a limited knowledge base on their characteristics from different gasification technologies, an incomplete understanding on influencing factors and a lack of standardization both for the material itself and the analytical procedures that have to be employed for their characterization. To provide a basis for standardization and future utilization perspectives, a screening was performed covering a wide range of gasification technologies. The samples were analyzed for ash content, moisture, volatiles, fixed carbon and elemental composition as well as the content of polycyclic aromatic hydrocarbons (PAHs) and volatile aromatic hydrocarbons. In total, analysis data of 118 gasification char samples from plants of 17 different gasification plant manufacturers have been evaluated. The results indicate a wide variation in the characteristics of gasification chars both with respect to ash and carbon content, i.e. 3.9%–100% and 0.9–92.5%, respectively. Particularly high levels of organic contaminants are associated with samples originating from cold gas filtration with PAH contents of up to 130 g kg−1 and post-treatment would be necessary in most cases to qualify these materials for material applications. Hot gas filtration and thermal post-treatment was found to result in gasification chars with substantially lower levels of organic contaminants. For these materials, the PAH contents rarely exceeded 2 g kg−1.