Pine Wood Pellets Research Articles

Potential of Pinewood Biochar as an Eco-Friendly Reducing Agent in Iron Ore Reduction.

This study investigated the optimal proportion of biochar derived from pinewood pellets (PW) and coke as reducing agents for the carbothermal reduction of iron ore at high temperatures. Thermogravimetric analysis, elemental analysis, X-ray fluorescence, and scanning electron microscopy were used to characterize the raw materials. To determine the effect of biochar proportion on reduction efficiency, presented as metallization, metallized pellets were subjected to chemical analysis, including total iron (T.Fe) analysis, metallic iron (M.Fe) analysis, and residual Fe2O3 and FeO analysis. The results indicated that the addition of biochar derived from PW, with coke as a reducing agent, considerably increased the efficiency of carbothermal reduction. Optimal reduction conditions were established at a reduction temperature of 1300 °C and a holding time of 20 min, with 20% coke and 80% pinewood char. In summary, biochar derived from PW can be used as an alternative to coke as a reducing agent in the iron reduction process. In addition, biomass can be used as a reducing agent to mitigate carbon consumption by reducing the amount of coke required in iron production.

Fuel Wood Pellets Produced from Sawdust of Scots Pine Mature and Juvenile Wood: Self-Heating and Off-Gassing Tests at Industrial Scale

This study investigated self-heating and off-gassing of Scots pine (Pinus sylvestris) wood pellets made from sawdust generated from separated mature and juvenile wood. The pellets were produced at an industrial scale and stored in large piles of about 7.2 tonnes. The production process involved drying the sawdust using three different methods and to varying moisture contents. The results indicated significant influences of both raw material type (F(6) = 61.97, p < 0.05) and drying method (F(2) = 65.38, p < 0.05) on the self-heating of the pellets. The results from the multiple regression analysis further showed that both the raw material type and pellet moisture content significantly influenced the temperature increase, with strong correlations observed for pellets produced using low-temperature drying (F(3, 14) = 83.52, multiple R2 = 0.95, p < 0.05), and medium temperature drying (F(3, 13) = 62.05, multiple R2 = 0.93, p < 0.05). The pellets produced from fresh mature wood sawdust were found to be more prone to self-heating and off-gassing while steam drying the sawdust at high temperature and pressure led to a significant reduction in heat and gas generation across all materials. The heightened self-heating and off-gassing in mature wood pellet can be attributed to a higher proportion of sapwood in the raw material. The probable explanations to the observed differences are in line with biological mechanisms for self-heating and off-gassing, as well as the chemical oxidation of fatty and resin acids.

Experimental exploration of potassium compounds in the vicinity of a burning biomass pellet: From near-surface to downstream

The concentrations of gas-phase potassium hydroxide (KOH), potassium chloride (KCl) and atomic potassium (K(g)) were quantitatively measured from the near-surface to downstream area of burning pinewood pellets by a newly developed photofragmentation tunable diode laser absorption spectroscopy (PF-TDLAS) technique to reveal the original form of the released potassium. The novel arrangement of the PF-TDLAS system enabled a spatial resolution of ∼1 mm3, which made it possible to obtain temporal release profiles of K(g)/KOH/KCl at different heights above the burning pellet surface. Surface temperature and mass loss of the wood pellet as well as the gas temperature at measurement points were measured simultaneously. During the devolatilization stage, the release of all three potassium species was observed, with each of them accounting for ∼1/3; while in char oxidation stage, the release of KOH was dominant, but the release intensity was strongly influenced by the local oxygen content. The results from different measurement heights showed there was a notable difference in potassium release profiles of different potassium species over the near-surface area, where the detected potassium forms were the best representative of the originally released forms of potassium. For a period of time during the devolatilization stage, only K(g) was detected in the near-surface area, and the concentration was significantly lower than the downstream area where KOH and KCl coexisted. This suggested that a large amount of potassium might leave the pellet as organic-K, which cannot be detected by the PF-TDLAS method. During char oxidation stage, the total potassium concentration at the near-surface area was also lower than the downstream area, but it was due to the lack of oxygen at the measurement position. A potassium release mechanism during the devolatilization stage of biomass combustion was proposed based on the experimental measurements, and the results also indicated the importance of spatially resolved measurement.

Combustion Instability and Ash Agglomeration in Wood Pellets Boiler

The combustion instability and ash agglomeration in a wood pellet boiler were investigated in this study. The tests were conducted using the Taguchi method of orthogonal array L27(133). Several parameters are applied, including grate area (GA), primary to secondary air split ratio (SR), excess air (EA), and fuel power (P). Pine wood pellets were used, and the boiler’s nominal load was 20 kW. The results show that instability during combustion occurs since the fuel bed rises as the accumulation of the unburned wood pellets on the grate causes a slow combustion rate and pressure drop, which creates noise and disturbances. A good combination of the parameters applied to TN9 and TN20 can be useful in obtaining stable combustion. In addition, the ash agglomerations were influenced by the duration of the combustion and the temperature of the fuel bed. The largest size of the ash agglomeration was referred to as test number-TN26 (P: 16 kW, EA: 110%, SR: 30/70, and GA: 115 mm × 75 mm), which is 59 mm, and the duration time is 14,400 s (≈4 h).

Influence of Sapwood/Heartwood and Drying Temperature on Off-Gassing of Scots Pine Wood Pellets

Wood pellets produced from fresh sawdust can form and release uncontrolled gases during bulk storage, a tendency referred to as off-gassing. This study investigated the off-gassing tendencies of Scots pine wood pellets made from separated sapwood and heartwood sawdust. The effects of drying temperature, raw material storage, as well as varying proportions of sapwood and heartwood were also investigated. There was a strong linear correlation between off-gassing and sapwood content, with correlation coefficient (R) values greater than 0.9 at p < 0.001 for all the off-gases. An increase in sapwood content of the feedstock led to a significant increase in off-gassing of CO2, CO, and CH4, and O2 consumption. The drying temperature of the raw material had a significant effect on off-gassing of both sapwood (F(8, 26) = 51.32, p < 0.05) and heartwood (F(8, 26) = 334.1, p < 0.05) pellets. Increasing the drying temperature for heartwood resulted in increased off-gassing, while for sapwood, the off-gassing reduced. Storage of sapwood raw material before pelletization reduced the off-gassing of wood pellets, whereas for heartwood, it had no significant impact. Based on the results, it is suggested that a biological process, in combination with the chemical oxidation of fatty acids, lay behind the off-gassing of wood pellets.

The Use of Black Pine Bark for Improving the Properties of Wood Pellets

The requirement for alternative raw materials for fuel pellets that would enable the use of readily available low-cost renewable resources and waste materials, such as bark, has always attracted interest. The aim of the current work was to assess the effect of black pine (Pinus nigra L.) bark content (0%–100%) as well as densification temperature on the properties of black pine wood pellets produced in a single pellet die. The quality assessment of the pellets was carried out by the determination of radial compression strength, density, moisture content, ash content, and surface roughness. The results showed that adding black pine bark to the pellet feedstock resulted in the production of substantially smoother and moderately denser pellets, which also exhibited higher mechanical strength than that of the respective pellets of pure wood. Finally, it was shown that black pine bark can be a valuable raw material, which can induce improved bonding of biomass particles and may provide the opportunity to create pellets of favorable characteristics at a lower temperature compared to those made of pure wood.

Production and characterization of bio-oil from fluidized bed pyrolysis of olive stones, pinewood, and torrefied feedstock

Advancements in fluidized bed pyrolysis mechanisms and analytical methodologies are critical for progress in the biorefinery sector in general and the aviation fuel sector in particular. The statistical modelling of pyrolysis product yields and composition allowed us to observe advantages of operating temperature and feedstock selections over the torrefaction process and catalyst addition in a fluidized bed reactor. Results suggest that the chemical composition and physical properties of bio-oil from pyrolysis of olive stones at 600°C and pinewood pellets at 500°C are the most suitable for use as fuels. This work suggests that only combined use of selected gas chromatography mass spectroscopy, UV fluorescence, nuclear magnetic resonance spectroscopy, and rheology can provide comprehensive information on pyrolysis bio-oil composition. Importantly from a technological point of view, bio-oil was characterized i) by a viscosity similar to that of fossil-based oil; ii) by a low oxygen and water content; and iii) by a balanced composition of aliphatic and aromatic species. These factors indicate that bio-oil from fluidized bed pyrolysis of biomasses is a promising material for use in the aviation industry and energy production.

The Effect of Mixing Recirculated Flue Gas with Primary or Secondary Air during Biomass Combustion in Grate-Firing Boiler as the Primary Measure for NOx Reduction

Due to the pollutant regulations of the Directive (EU) 2015/2193, the need to reduce the emissions of pollutant compounds such as NOx is of a great importance for industrial boilers. This study was performed to determine the effect of primary measures in reducing said pollutants by mixing primary or secondary air with FGR and supplying the mixture for combustion. The studies were conducted on low-scale industrial biomass grate-firing furnace and boiler stand of 25 kW. Sunflower husk pellets, shredded pine bark and wood pellets were combusted during these experiments and emissions of NOx in their combustion products were analyzed. The most significant reduction of emissions was achieved by mixing primary air and FGR and supplying it to the primary combustion zone – under the grate. The emissions of NOx were reduced by 29% and 15% for shredded pine bark and sunflower husk pellets respectively. The emissions of shredded pine bark were reduced enough to meet the standards of the EU Directive, unlike those of sunflower husk pellets. The possible ways to reach greater reduction of NOx by using primary measures are implementing staged combustion, supplying pure FGR and/or mixing agriculture waste with fuels containing less N in its composition.

Study of Mass Loss and Elemental Analysis of Pine Wood Pellets in a Small-Scale Reactor

Studying the thermal decomposition of wood pellets is an important subject in order to understand the behavior of wood pellets during the combustion process. In fact, wood pellets have become an important fuel used in boiler combustion. The objective of this study is to investigate the mass loss and elemental analysis of pine wood pellets at various times and temperatures. Commercial pellets with a diameter of 6 mm were used. The experiment was conducted in the laboratory of the Engineering University of Minho. The pellets were burned in a small reactor of 1.36 kW with a maximum temperature range of 1150 °C. The data were observed at different temperatures: 264, 351, 444, 541, 650, and 734 °C, and at time intervals of 30, 60, 120, 180, 240, 300, 600, 900, 1200, and 3600 s. The results of the experiment revealed that the reaction rate increases with the temperature, and the higher the combustion temperature applied, the higher the mass loss of all substances observed. The remaining mass, as fixed carbon and ash or unburned substances, is about 3%. The residence time and temperature influence the species concentration of wood pellets.

Ash melting behaviour of reed and woody fuels blends

Ash melting behaviour is an important issue regarding operation of boilers, for instance, to avoid the agglomeration of the fluidized bed. Previous studies have shown that ash melting behaviour of the blends could differ from that of single parent fuels. This study focuses on the melting behaviour of fuel ash blends of reed, pine wood pellets and Douglas fir wood chips. For that purpose, simultaneous thermal analysis, heating microscope and scanning electron microscopy with energy dispersive X-ray analysis, X-ray diffraction, and FactSage modelling were used. The ash sample was heated up to the final temperatures stepwise, and the morphology and composition of the ash samples were examined at different temperatures. The results revealed that the melting onset for reed and woody fuels blend ashes was related to KCl-K2SO4 eutectic. The melting started at 700 °C and chlorine was released. The decomposition of CaCO3 was observed for the ashes containing wood pellets. In the case of reed and wood pellet ash, both processes performed simultaneously. The second mass loss and sulphur release were observed at 1100 °C, which is related to decomposition of K2SO4. In reed and woody fuels blend ashes, the gas release was accompanied with the melting of other substances (e.g. Si-Ca or Si-Ca-K system) and the gases were trapped into melt. The feldspars abundant in Douglas fir wood chips, could cause the sluggish melting behaviour of ash material. The FactSage modelling indicated the melting onset at lower temperatures compared to the results obtained by the other methods applied.

Influence on off-gassing during storage of Scots pine wood pellets produced from sawdust with different extractive contents

Off-gassing and self-heating are the major challenges when it comes to transportation and storage of wood pellets. The heat generated due to self-heating poses a fire risk while off-gassing of toxic gasses such as carbon monoxide (CO) and some volatile organic compounds (VOCs) is an environmental and human health risk. With the increase in production volumes of wood pellets which has subsequently increased the amounts of wood pellets in transportation and storage, there is need to find lasting solutions to off-gassing and self-heating of wood pellets. The objective of this study was to test the off-gassing abilities of Scots pine wood pellets produced from sawdust with varying amounts of extractives. The aim is to come up with raw material pre-treatment measures so as to produce wood pellets that are not liable to off-gassing. Six (6) types of sawdust raw materials namely; fresh pine sawdust (FPS), stored pine sawdust (SPS), sawdust plus pine rosin (PRS), sawdust plus linseed oil (LOS), sawdust plus tall oil (TOS) and acetone extracted sawdust (AES) were used to produce the pellets. The produced pellets were then subjected to off-gassing tests under controlled conditions using the ECOM J2KN analyser. The concentrations of carbon monoxide, carbon dioxide and methane increased with storage time but slowed down towards the end of the nine days test period. The formation of these gasses were largely dependent on the type of extractives present in the raw material and not the total extractive content. The formation of methane started later than the other gases and coincided with the time when residual oxygen was depleted.

Microbial regulation of nitrous oxide emissions from chloropicrin-fumigated soil amended with biochar

The microbial mechanism underpinning biochar’s ability to reduce emissions of the potent greenhouse gas nitrous oxide (N2O) is little understood. We combined high-throughput gene sequencing with a dual-label 15N–18O isotope to examine microbial mechanisms operative in biochar made from Crofton Weed (BC1) or pine wood pellets (BC2) and the N2O emissions from those biochar materials when present in chloropicrin (CP)-fumigated soil. Both BC1 and BC2 reduced N2O total emissions by 62.9–71.9% and 48.8–52.0% in CP-fumigated soil, respectively. During the 7-day fumigation phase, however, both BC1 and BC2 increased N2O production by significantly promoting nirKS and norBC gene abundance, which indicated that the N2O emission pathway had switched from heterotrophic denitrification to nitrifier denitrification. During the post-fumigation phase, BC1 and BC2 significantly decreased N2O production as insufficient nitrogen was available to support rapid population increases of nitrifying or denitrifying bacteria. BC1 and BC2 significantly reduced CP’s inhibition of nitrifying archaeal bacteria (AOA, AOB) and the denitrifying bacterial genes (nirS, nirK, nosZ), which promoted those bacterial populations in fumigated soil to similar levels observed in unfumigated soil. Our study provided insight on the impact of biochar and microbes on N2O emissions.

Fuel properties and combustion behaviors of fast torrefied pinewood in a heavily loaded fixed-bed reactor by superheated steam

Superheated steam (SHS) was capable of fast and uniformly torrefying heavily loaded biomass. This work detailedly investigated the torrefied biomass in terms of fuel property and combustion behavior. The reactor chamber (300 ml) was fully loaded with pinewood pellets (160 g). Overall residence times were 20, 40 and 60 min (including preheating and holding periods) under 225, 275 and 325 °C. Biomass was estimated by elements, TG, FTIR, HHV, fuel property, combustion and pyrolysis behaviors, combustion kinetics and moisture reabsorption. Holding period as short as 2 min at 325 °C with a heating rate of 15 °C‧min−1 was found to enhance energy density by 45% and generated homogeneous coal-like products with HHV of 26.76 MJ‧kg−1. Fixed carbon content increased to 64.84 wt%. The combustion activation energy increased to 79.66 kJ‧mol−1. Combustion indices and behaviors indicated that torrefied biomass had benign characteristics either for co-firing or as fuel. All suggests good potential of SHS torrefaction to obtain fuel alternatives.

Development of a small-scale reactor for upgraded biofuel pellets

The comprehensive investigation of a pyrolysis reactor has been conducted on the basis of thermal engineering design. The gas dynamics, thermodynamic, and psychrometric behaviour of the producer gas have been thoroughly assessed. The pilot-scale reactor has been programmed to operate at the temperature 973 K in the absence of an inert medium. The concentric casing of the heating filament has been used as an external source of energy. The experimental task is divided into two parts: upgradation of biomass and the decomposition of pellets in a developed small-scale pyrolysis unit for the possible gas, char, and pyrolysis oil generation. The fuel upgradation is performed via quasi-static torrefaction of pine pellets using Joule heating in the presence of nitrogen gas. The volumetric gas of nitrogen flowing across the improvised furnace is 0.70 L·min−1. The obtained results are compared with the wood pellets. The unsaturated producer gas has been found to vary accordingly to the following gas equation pv0.25=C and pv−0.69=C for the processed pine pellets and wood pellets, respectively. A relative increase of 21.00% has been seen while running the reactor with the processed pine pellets. The percentage yield of the pyrolytic oil for the processed pine and wood pellets is 10.48% and 30.00% respectively. The flame temperature and adiabatic flame temperature of the producer gas (processed pine) is lowered by 8.10% and 17.00% respectively. The energy yield of processed pinechar is found to be 122.58% higher than that of wood char.

Комплексная эффективность применения древесных гранул в энергоустановках

In advanced countries, the dramatic impact of greenhouse gases on the global climate is reduced by replacing fossil fuels with biofuels. This method is being actively encouraged. However, by-products of logging, processing and conversion of wood are classified as difficult to burn fuels due to their high moisture content, low energy density and extremely heterogeneous granulometric composition. A promising direction to increase the energy density and transportability of the timber industry by-products is their granulation. Wood pellet fuel burning in heat-generating plants results in significant increase in their energy and environmental performance. The purpose of the paper is an experimental and calculation study of the energy and environmental performance of 4 MW hot water boilers produced by Polytechnik Luft- und Feuerungstechnik GmbH in the process of burning pine and spruce wood pellets obtained from by-products woodworking. When performing studies, the components of the boiler’s heat balance, gas release, and particulate emissions were determined. Numerical modeling of thermochemical and aerodynamic processes taking place in the boiler combustion chamber was carried out by using the Ansys Fluent three-dimensional simulation software. Together with industrial-operational tests it showed the possibility to reduce the total share of flue gas recirculation into combustion chambers of boiler units to values not exceeding 0.45, in providing an acceptable temperature of combustion products at the combustion chamber outlet and maintaining minimum emissions of carbon and nitrogen monoxides. At the same time, the share of gases fed by recirculation smoke exhausters to the over-bed area of the burner should have higher values than under the reciprocating grates of boilers. Guidelines for comprehensive improvement of wood pellet combustion efficiency in combustion chamber of 4 MW hot water boilers have been developed and implemented. The priorities are: using the air passed through the cooling channels of the setting as secondary air; reducing the rarefaction in the combustion chambers to 30–70 Pa; optimizing the ratio of primary and secondary air, herewith, the share of primary air in the total flow should be 0.26–0.35. Implementation of the developed guidelines allowed to increase the boiler gross efficiency by 0.5–1.8 %, to reduce the aerodynamic resistance of the gas path by 15–20 % and to ensure consistently low emissions of carbon and nitrogen monoxides and soot particles. When designing boiler units for burning wood pellet fuel it is advisable to place heating surfaces in the combustion chamber, included in the circulation circuit of the boiler. This will increase the efficiency and life cycle of the boiler unit.

Performance evaluation of Pyrolysis system (1-5 kg/h) at different temperature

The objective of this work is to perform experimental and theoretical analysis to producebio-oil through Pyrolysis of sawdust and pinewood pellets (8mm) in fixed bed reactor using slow Pyrolysis. The experiments are performed at five different Pyrolysis temperatures 400, 425, 450, 475 and 500 °C at constant heating rate 10 °C/min in selfPyrolysis environment. Bio-oil is found to have distinct properties of being acidic, high water content to be considered as a fossil fuel, but can be used as a replacement for the furnace oil. The characterization of bio-oil carried out like calorific value, viscosity, pH, density, flash point, fire point and water content. The characterization of bio-char and Pyro-gas is also carried out. Bio-char obtained is having higher calorific value similar to bituminous coal and hence can be used for co-generation and synthesis of activated carbon. In the Pyro-gas composition, carbon monoxide (CO), hydrogen (H2) and methane(CH4) combustible gases obtained which can be used for thermal applications.

Study of the energy efficiency of wood pellets and poplar chips

Poplar is the most common type of fast-growing tree species of great economic and industrial importance. Therefore, determining the effectiveness of its energy use is an important task. A study of the operational efficiency of the Firematic 60 boiler when working on poplar chips, as well as pine wood pellets with a diameter of 6 mm and spruce wood pellets with a diameter of 8 mm was carried out. The elemental composition of burned fuels and residues was studied using an EDX-8000 X-ray fluorescence spectrometer and a Euro EA-3000 analyzer. The components of the heat balance and emission of harmful substances were determined. The emissions of particulate matter and the content of soot particles were studied. The shape and composition of soot particles were determined using a Zeiss SIGMA VP electronic scanning microscope. An energy examination showed that the boiler provides high technical and economic indicators and minimal emissions of harmful substances into the environment when burning wood pellets and poplar chips.

Energy performance and variability of an improved top-lit updraft biomass cookstove under a water boiling test protocol

ABSTRACT Several prototypes of improved biomass cookstoves have been designed to enhance the energy performance in households. In this work, a repeatability statistical analysis of a designed and built biomass cookstove based on Top-lit Updraft (TLUD) gasification is presented. The variability of the cookstove was assessed through the analysis of variance (ANOVA). The stove was tested under a modified Water Boiling Test (WBT) protocol with cold and hot starts, for this aim, three experiments were carried out, and three observations of parameters in each phase were measured or calculated. The stove operated under controlled conditions: secondary/primary airflows ratio, combustion chamber, and fuel type (pine wood pellets). Furthermore, the air velocity (≤0.25 m/s) on the hood work surface allowed having a controlled environment. The energy efficiency (~31.4 ± 0.7%), power (~9.9 ± 1.1 kW), fuel consumption (~33.7 ± 3.7 g/min), and specific fuel consumption per unit of time (~134 ± 15.81 kJ/L/min) were the response variables analyzed. It was obtained that the two phases of each stage of the modified protocol are statistically repeatable in this experimental facility leading to reliable performance of the cookstove with a confidence level of 95%.

Comparative study of the fuel quality and torrefaction performance of biomass and its molded pellets: effects of temperature and residence time

ABSTRACT Torrefaction is a promising pretreatment for upgrading biomass. Biomass pellets have been widely used in heating and power plants, but the pellets torrefaction has not been fully studied. The torrefaction performance of raw biomass samples and molded pellets of those biomass samples were compared in this study. The torrefaction was performed using a horizontal sliding tube furnace with different torrefaction severities (210°C, 240°C, 270°C, and 300°C; 15 min, 30 min, and 45 min). Three key results were obtained from this work. (i) The temperature and residence time had an obvious influence on biomass torrefaction performance. Compared to the untreated samples (rice husk particles, rice husk pellets, pine wood sawdust, and pine wood pellets), the oxygen content of the samples torrefied under the most severe torrefaction conditions (300°C and 45 min) decreased by 43.1%, 27.4%, 34.2%, and 25.3%, respectively. In contrast, the high heating value and hydrophobicity of the torrefied samples increased. (ii) The biomass source had important effects on the torrefaction results. Under the same torrefaction conditions, the mass yields and energy yields were highest for pine wood sawdust, followed by rice husk particles, pine wood pellets, and rice husk pellets. This is related to the composition and thermal decomposition of the different biomass samples. (iii) The loose raw biomass released more volatiles during torrefaction compared to biomass pellets, which were limited by heat and mass transfer, leading to complete thermal decomposition of hemicellulose and other components. Overall, the torrefaction performance of biomass varied with the temperature and residence time, and torrefaction had a greater effect on the raw biomass than on the biomass pellets.

Synergetic Effect on CO2-Assisted Co-Gasification of Biomass and Plastics

Abstract CO2-assisted co-gasification of binary mixtures of pinewood pellets (PWP) and two kinds of plastics polyethylene-terephthalate (PET) and high-density polyethylene (HDPE) were examined at 800 °C using a fixed bed reactor. Evolutionary behavior and yields of CO, H2, and CmHn were investigated for both individual feedstock and binary mixtures of biomass and plastic. Synergetic effects in co-gasification of mixtures under CO2 atmosphere were analyzed and compared between experimental and calculated results. The results showed that PET and HDPE although had similar behavior in gasification, they provided many different characteristics on blending with solid biomass in CO2-assisted co-gasification. Both PWP–PET mixture and PWP–HDPE mixture showed positive effects on hydrocarbons yield and negative effects on solid yield. For PWP–PET mixture, H2 yield showed no change compared to the calculated value; however, CO yield and CO2 consumption showed negative effects due to the blocked porosity of solid biomass from the softened PET. For PWP–HDPE mixture, H2 yield showed significant enhancement compared to the calculated value, and CO yield showed slight enhancement but a slight reduction in CO2 consumption. It was also observed that the experimental CmHn yields obtained from biomass-plastics mixtures were of higher values than the calculated values. The morphologies of solid residues for PWP, PET, PWP–PET, and PWP–HDPE were analyzed and taken as a supplement to explain the synergetic effects in the co-gasification process. These results provide an insight into energy recovery and waste treatment potential for both biomass and waste plastic using thermochemical conversion.