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Wood-Based Bioenergy

A special issue of Energies (ISSN 1996-1073). This special issue belongs to the section "A4: Bio-Energy".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 22960

Special Issue Editors

Laboratoire de Biomatériaux, Université du Québec en Abitibi-Témiscamingue, Rouyn-Noranda, QC J9X 5E4, Canada
Interests: biomaterials; biocomposites; bioenergy; materials characterization; wood processing and valorization
Special Issues, Collections and Topics in MDPI journals
Centre Technologique des Résidus Industriels (CTRI), Rouyn-Noranda J9X 0E1, Québec, Canada
Interests: bioresourced materials; wood valorization; biomass thermochemical conversion; biofuels; biochar/activated biochar; porous carbon materials; biofuel; byproduct applications

Special Issue Information

Dear Colleagues,

We invite submissions to a Special Issue of the journal Energies on the topic “Wood-Based Bioenergy”.

Today, bioenergy is of increasing interest as a renewable, environmentally friendly alternative to energy derived from fossil fuels, and it can play a significant role in reducing greenhouse gas (GHG) emissions. Bioenergy derived from wood is among the most important renewable energy options. It is obtained in three major types of fuel at different states: solid, liquid, and gaseous. Solid woody biofuels include wood, pellets, charcoal, biochar, torrefied biomass, and biocoke. Liquid biofuels from wood include lignocellulosic ethanol, butanol, biodiesel, and pyrolytic oil. Gaseous fuels from wood include biogas, syngas, and hydrogen. Bioenergy from wood is now used in many advanced applications, including transport, power and heat generation, electrodes for energy storage and batteries, etc. However, the use of wood for bioenergy is facing several environmental, technological, scientific, and economic issues. The sustainability and the future of wood bioenergy of all types depend on several complex variables, including the sustainability and management of harvested wood forest, competition for alternative wood or land utilization, demand and trade processes for bioenergy, the optimization of technological processes and energetic performance, competitiveness with alternative energies, complying with environmental legislation, etc.

This Special Issue aims to address the challenges and opportunities of the use of wood for bioenergy throughout the value chain from the supply to the energetic performance. We welcome original contributions regarding recent developments in wood-based bioenergy. The potential topics of interest include but are not limited to:

  • Issues related to wood supply for bioenergy production;
  • Thermochemical wood modification and conversion for bioenergy production;
  • New and advanced technologies and applications for wood-based bioenergy;
  • Characterization of the energetic performance of different forms of wood-based bioenergy;
  • Contribution and role of bioenergy in climate change and reduction of GHG emission.

Prof. Dr. Ahmed Koubaa
Dr. Flavia Lega Braghiroli
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • wood biomass
  • wood valorization
  • bioenergy
  • biofuel and biofuel applications
  • advanced bioenergy applications
  • wood thermochemical modification
  • calorific/energetic value
  • sustainability of wood bioenergy
  • bioenergy and climate change and greenhouse gas emissions

Published Papers (11 papers)

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Research

14 pages, 892 KiB  
Article
Chemical Elements Content and Distributions within Different Tissue Types of White Spruce
by Cyriac S. Mvolo, Emmanuel A. Boakye and Ahmed Koubaa
Energies 2023, 16(7), 3257; https://0-doi-org.brum.beds.ac.uk/10.3390/en16073257 - 05 Apr 2023
Viewed by 1327
Abstract
The relative proportions of different chemical components in wood tissues is one of the underlying factors that control wood properties. These proportions vary within and between woody tissues, and an accurate description of these variations is critical for parameterizing forest biogeochemical budgets and [...] Read more.
The relative proportions of different chemical components in wood tissues is one of the underlying factors that control wood properties. These proportions vary within and between woody tissues, and an accurate description of these variations is critical for parameterizing forest biogeochemical budgets and models. White spruce (Picea glauca (Moench) Voss) spacing intensities trials in the Petawawa Research Forest, Ontario, Canada, were sampled to evaluate variations in carbon (C), nitrogen (N), and hydrogen (H) concentrations between different tissue types, i.e., bark, cambium, knots, earlywood, latewood, and wood. Samples were freeze-dried and oven-dried to test the impact of the drying methods on these chemical elements. Freeze-dried C (51.14) and H (6.18) concentrations were significantly higher than those of oven-dried C (50.55) and H (6.06). Freeze-dried N (0.18) did not differ from oven-dried N (0.17). The spacing intensities impacted C, H, and N, with C content being higher in wider square spacings (4.3 m and 6.1 m), while the reverse was true for N and H, which exhibited higher content in smaller square spacings (1.2 m and 1.8 m). The results of this study also suggested that when it comes to the content of chemical elements, bark and knots should be treated as separate fuel types, whereas other woody tissues can be aggregated. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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15 pages, 2654 KiB  
Article
Pyrolysis of Chromated Copper Arsenate-Treated Wood: Investigation of Temperature, Granulometry, Biochar Yield, and Metal Pathways
by Mouna Gmar, Hassine Bouafif, Besma Bouslimi, Flavia L. Braghiroli and Ahmed Koubaa
Energies 2022, 15(14), 5071; https://0-doi-org.brum.beds.ac.uk/10.3390/en15145071 - 12 Jul 2022
Cited by 2 | Viewed by 1336
Abstract
Chromated copper arsenate-treated (cca) wood disposal faces environmental restrictions due to its toxicity, heavy metal leaching in storage sites, and greenhouse gas emissions during incineration. Thus, finding new management methods for this contaminated wood at the end of life is crucial. This study [...] Read more.
Chromated copper arsenate-treated (cca) wood disposal faces environmental restrictions due to its toxicity, heavy metal leaching in storage sites, and greenhouse gas emissions during incineration. Thus, finding new management methods for this contaminated wood at the end of life is crucial. This study evaluated the effect of pyrolysis temperature (300, 400, and 500 °C), particle size, biochar yield, and the behavior of arsenic (As), chromium (Cr), and copper (Cu) during treated-wood pyrolysis. The highest biochar yield was obtained at 300 °C for fine particles. The biochar retention of heavy metals decreased with increasing pyrolysis temperature. At 300 °C, the highest biochar As, Cr, and Cu retentions were 76, 91, and 83%. At 500 °C, biochar only retained 43% of the As. Additionally, heavy metal leaching from the biochar exceeded the Environmental Protection Agency’s (EPA) maximum concentration limit of 5 mg/L. High-density polyethylene encapsulation of contaminated biochar reduced the leaching of As, Cr, and Cu by 96, 95, and 91%, respectively. Thus, combining pyrolysis and plastic encapsulation to produce a composite material could be a solution for reducing waste (conversion of CCA-wood into biochar) and for the safe disposal of contaminated wood. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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13 pages, 1646 KiB  
Article
Variation of White Spruce Carbon Content with Age, Height, Social Classes and Silvicultural Management
by Cyriac S. Mvolo, James D. Stewart, Christopher Helmeste and Ahmed Koubaa
Energies 2021, 14(23), 8015; https://0-doi-org.brum.beds.ac.uk/10.3390/en14238015 - 01 Dec 2021
Cited by 1 | Viewed by 2313
Abstract
The accuracy and precision with which carbon amounts have been accounted for in forests have been questioned. As countries seek to comply with agreements to reduce global warming and industries seek to maximize bioenergy potential, this matter has increased international concern. White spruce [...] Read more.
The accuracy and precision with which carbon amounts have been accounted for in forests have been questioned. As countries seek to comply with agreements to reduce global warming and industries seek to maximize bioenergy potential, this matter has increased international concern. White spruce (Picea glauca (Moench) Voss) stand density management trials in the Petawawa Research Forest, Ontario, Canada, were sampled to evaluate carbon concentration variation within trees and plots of differing stand density. Sample-drying methodologies were also tested to compare freeze-dried carbon (FDC) and oven-dried carbon (ODC) measurements. The average FDC was 51.80 ± 1.19%, and the corrected freeze-dried carbon content (FDCCOR) was 51.76 ± 1.33%. The average ODC was 49.10 ± 0.92%, and the average volatile carbon fraction (Cvol) was 2.67 ± 1.71%. FDC was higher than ODC (mean of the differences = 2.52) and generally more variable. ODC significantly decreased radially and longitudinally. FDC was significantly affected by thinning, where heavy treatments resulted in the highest FDC amounts compared to medium, light, and control treatments. In addition to reducing carbon content (CC), drying influences wood CC in many ways that are still to be elucidated. The results of this study suggest that ODC should continue to be used within the bioenergy industry, while FDC must become the preferred standard for carbon accounting protocols. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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14 pages, 2979 KiB  
Article
Xerogel-like Materials from Sustainable Sources: Properties and Electrochemical Performances
by Gisele Amaral-Labat, Manuella Gobbo C. Munhoz, Beatriz Carvalho da Silva Fonseca, Alan Fernando Ney Boss, Patricia de Almeida-Mattos, Flavia Lega Braghiroli, Hassine Bouafif, Ahmed Koubaa, Guilherme F. B. Lenz e Silva and Maurício Ribeiro Baldan
Energies 2021, 14(23), 7977; https://0-doi-org.brum.beds.ac.uk/10.3390/en14237977 - 29 Nov 2021
Cited by 8 | Viewed by 1845
Abstract
Energy storage is currently one of the most significant technological challenges globally, and supercapacitor is a prominent candidate over batteries due to its ability for fast charging and long lifetime. Supercapacitors typically use porous carbon as electrodes, because of both the high conductivity [...] Read more.
Energy storage is currently one of the most significant technological challenges globally, and supercapacitor is a prominent candidate over batteries due to its ability for fast charging and long lifetime. Supercapacitors typically use porous carbon as electrodes, because of both the high conductivity and surface area of the material. However, the state-of-the-art porous carbon described in the literature uses toxic chemicals and complex procedures that enhance costs and pollute the environment. Thus, a more sustainable procedure to produce porous carbon is highly desirable. In this context, xerogel-like carbons were prepared by a new, cheap, simple route to polymerization reactions of tannin-formaldehyde in a bio-oil by-product. Using bio-oil in its natural pH allowed a cost reduction and avoided using new reactants to change the reactional medium. Textural properties and electrochemical performances were improved by fast activating the material per 20 min. The non-activated carbon xerogel presented a capacitance of 92 F/g, while the activated one had 132 F/g, given that 77% of the components used are eco-friendly. These results demonstrate that renewable materials may find applications as carbon electrodes for supercapacitors. Overhauling the synthesis route with a different pH or replacing formaldehyde may enhance performance or provide a 100% sustainable carbon electrode. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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15 pages, 2893 KiB  
Article
Effect of Pyrolysis Temperature and Wood Species on the Properties of Biochar Pellets
by Safa Arous, Ahmed Koubaa, Hassine Bouafif, Besma Bouslimi, Flavia Lega Braghiroli and Chedly Bradai
Energies 2021, 14(20), 6529; https://0-doi-org.brum.beds.ac.uk/10.3390/en14206529 - 12 Oct 2021
Cited by 16 | Viewed by 2140
Abstract
Thermal treatments such as torrefaction and fast pyrolysis are commonly employed methods to produce biofuels with high-energetic properties. In this study, wood chips were heat-treated at different temperatures of torrefaction (315 °C) and fast pyrolysis (400 and 454 °C) to form energetic pellets. [...] Read more.
Thermal treatments such as torrefaction and fast pyrolysis are commonly employed methods to produce biofuels with high-energetic properties. In this study, wood chips were heat-treated at different temperatures of torrefaction (315 °C) and fast pyrolysis (400 and 454 °C) to form energetic pellets. Three softwoods, jack pine (JP), balsam fir (BF), and black spruce (BS), were evaluated. Pellets are produced using 20% moisture content and 15% pyrolytic lignin as a binder. Untreated- and treated-wood residues were characterized by surface chemistry, elemental analysis, and chemical composition, whereas all pellets were characterized in terms of density, high heat value (HHV), and durability. Results showed that both thermal treatments caused significant changes in the physicochemical structure of wood residues. Using temperatures higher than 315 °C leads to the disappearance of hydroxyl groups, a decrease in oxygen and hydrogen contents, and an increase in carbon content. Regardless of the treatment temperature, pellets made from heat-treated JP had the best durability (93%). In contrast, the calorific values of wood-treated pellets reached up to 31 MJ/kg, compared to untreated-wood pellets (19 MJ/kg). Thus, the densification of the thermal-treated wood residues represents a potential approach for producing biofuels with high energetic value. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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13 pages, 2979 KiB  
Article
Analysis on the Use of Briquettes as an Alternative to Improve the Generation of Thermal Energy in the Locality of Aripuana-Brazil
by Haylemar de Nazaret Cardenas-Rodriguez, Rosa Martins, Levy Ely Lacerda Oliveira, Erik Leandro Bonaldi, Frederico de Oliveira Assuncao, Germano Lambert-Torres, Helcio Francisco Villa-Nova, Wilson Cesar Sant’Ana, Luiz Eduardo Borges-da-Silva, Clodoaldo Barboza Bomfin and Jamil Haddad
Energies 2021, 14(19), 6355; https://0-doi-org.brum.beds.ac.uk/10.3390/en14196355 - 05 Oct 2021
Cited by 4 | Viewed by 1903
Abstract
The city of Aripuana is one of the largest wood producer in the state of Mato Grosso, Brazil. Wood residues are used in the electricity generation at three thermoelectric plants in this region. However, the plants have high costs in transporting the wood [...] Read more.
The city of Aripuana is one of the largest wood producer in the state of Mato Grosso, Brazil. Wood residues are used in the electricity generation at three thermoelectric plants in this region. However, the plants have high costs in transporting the wood residues (due to poor road conditions). Hence, this paper compares the energy performance of wood residues in natura and compacted as briquettes by calculating the heating value and determining the influence of moisture content on the energy characteristics of wood residues. The goal is to demonstrate the viability of using briquettes in order to improve thermoelectric generation. The wood residues from this region are affected by the high humidity of the biome. An alternative to improve the use of energy contained in the wood residues is to produce briquettes with lower humidity. This allows one to maintain high levels of heat energy in a lower volume, facilitating handling and storage. The results show that the use of briquettes improved the performance of thermoelectric plants, generating 1 MW of electricity power with less than 1 ton of briquettes. This contributes to the preservation of the environment, reducing operating costs, transportation and storage of the raw materials. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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10 pages, 4372 KiB  
Communication
Water Resistance of Torrefied Wood Pellets Prepared by Different Methods
by Takahiro Yoshida, Katsushi Kuroda, Daisuke Kamikawa, Yoshitaka Kubojima, Takashi Nomura, Hiroki Watada, Tetsuya Sano and Seiji Ohara
Energies 2021, 14(6), 1618; https://0-doi-org.brum.beds.ac.uk/10.3390/en14061618 - 15 Mar 2021
Cited by 5 | Viewed by 1742
Abstract
Torrefaction used in combination with pelletization is a promising technology to upgrade solid biofuels and has been demonstrated worldwide. In comparison with normal biomass pellets, which disintegrate under wet conditions, one of the advantages of torrefied biomass pellets is better water resistance. An [...] Read more.
Torrefaction used in combination with pelletization is a promising technology to upgrade solid biofuels and has been demonstrated worldwide. In comparison with normal biomass pellets, which disintegrate under wet conditions, one of the advantages of torrefied biomass pellets is better water resistance. An understanding of the differences in water proof properties for torrefied biomass pellets by different production schemes can promote their further application. In the communication, various torrefied pellets were exposed to indoor and outdoor conditions, and changes in moisture content and diameter were examined. Two production schemes for the torrefied pellets were used for comparison: the torrefaction of wood chips followed by pelletization (pre-torrefaction) and the pelletization of wood chips followed by torrefaction (post-torrefaction). It was found that the post-torrefied pellets had much lower moisture levels than the pre-torrefied pellets in both indoor and outdoor tests. In the outdoor test with no-roof condition, the rate of increase in moisture content for the pre-torrefied pellets was more than double that for the post-torrefied pellets, and the post-torrefied pellets exhibited almost no diameter change. The results on the superior water resistance of post-torrefied pellets were nearly consistent with those reported in previous literature. Torrefied pellets have been considered for industrial use, such as in co-combustion and gasification on a large scale. Taking advantage of the different water resistances, torrefied pellets could also be used by personal and community consumers on a small scale for long-term indoor and outdoor storages as advanced solid biofuels with high waterproof performance, energy density, and lower biodegradation. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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9 pages, 2394 KiB  
Article
Thread Rolling: An Efficient Mechanical Pretreatment for Corn Stover Saccharification
by Likang Deng and Jun Li
Energies 2021, 14(3), 542; https://0-doi-org.brum.beds.ac.uk/10.3390/en14030542 - 21 Jan 2021
Cited by 2 | Viewed by 1482
Abstract
Sugar cane bagasse and corn stalks are rich in lignocellulose, which can be degraded into monosaccharides through enzymatic hydrolysis. Appropriate pretreatment methods can effectively improve the efficiency of lignocellulose enzymatic hydrolysis. To enhance the efficiency of enzymatic hydrolysis, thread rolling pretreatment as a [...] Read more.
Sugar cane bagasse and corn stalks are rich in lignocellulose, which can be degraded into monosaccharides through enzymatic hydrolysis. Appropriate pretreatment methods can effectively improve the efficiency of lignocellulose enzymatic hydrolysis. To enhance the efficiency of enzymatic hydrolysis, thread rolling pretreatment as a physical pretreatment was applied in this study. The influence of raw material meshes size after pretreatment was also taken as the research target. Specific surface area analysis, Scanning electron microscope (SEM), X-rays diffraction (XRD), and Fourier transform infrared (FT-IR) were used for characterizations. The results showed that, the total monosaccharide recovery rates of the raw materials, 20–40 mesh, 40–60 mesh, and 60–80 mesh enzymolysis substrates were 17.6%, 34.58%, 37.94%, and 50.69%, respectively. The sample after pretreatment showed a better recovery of monosaccharide than that of the raw material. Moreover, the enzymolysis substrates with a larger mesh exhibited a higher recovery of monosaccharide than that of the enzymolysis substrates with smaller meshes. This indicated that thread rolling pretreatment can effectively improve the efficiency of enzymatic hydrolysis. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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21 pages, 3682 KiB  
Article
Bioenergy Conversion Potential of Decaying Hardwoods
by Éloïse Dupuis, Evelyne Thiffault, Julie Barrette, Kokou Adjallé and Christine Martineau
Energies 2021, 14(1), 93; https://0-doi-org.brum.beds.ac.uk/10.3390/en14010093 - 26 Dec 2020
Cited by 8 | Viewed by 2417
Abstract
Unharvested hardwoods are abundant in eastern Canada, due to the low quality of their fiber and the absence of outlets in conventional wood transformation industries. The objective of this study was to assess the biochemical and thermochemical energy conversion potential of decaying hardwoods [...] Read more.
Unharvested hardwoods are abundant in eastern Canada, due to the low quality of their fiber and the absence of outlets in conventional wood transformation industries. The objective of this study was to assess the biochemical and thermochemical energy conversion potential of decaying hardwoods and compare their relationships with external and internal indicators of tree degradation. We characterized how wood-decay processes altered the physical and chemical properties of these woods and affected their digestibility yield and their performance according to indexes of stability and efficiency of combustion. DNA analysis on wood samples was also performed to determine the relative abundance of white-rot fungi compared to that of other saprotrophs. All properties stayed within the range of variations allowing the wood to remain suitable for conversion into bioenergy, even with increased decay. We found no significant differences in the physical and chemical properties that are crucial for energy production between wood from externally-assessed live and decayed trees. However, the proportion of wood area affected by rot was significantly associated with increased digestibility yield, and with decreased combustion reactivity. We could not detect any specific effect associated with increased relative abundance of white-rot fungi. These results suggest that the utilization of biomass from decayed hardwoods instead of live trees for bioenergy production should not alter the conversion efficiency and even potentially increase the performance of biochemical pathways, and hence, support their use as feedstock for bioenergy production. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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19 pages, 2839 KiB  
Article
Degraded Trees from Spruce Budworm Epidemics as Bioenergy Feedstock: A Profitability Analysis of Forest Operations
by Mathieu Béland, Evelyne Thiffault, Julie Barrette and Warren Mabee
Energies 2020, 13(18), 4609; https://0-doi-org.brum.beds.ac.uk/10.3390/en13184609 - 04 Sep 2020
Cited by 8 | Viewed by 2699
Abstract
Natural disturbances are common in Canadian boreal managed forests. For example, during and after insect epidemics, foresters must deal with significant amounts of degraded or dead wood that cannot be processed into sawn timber or pulp. Bioenergy could be an alternative pathway for [...] Read more.
Natural disturbances are common in Canadian boreal managed forests. For example, during and after insect epidemics, foresters must deal with significant amounts of degraded or dead wood that cannot be processed into sawn timber or pulp. Bioenergy could be an alternative pathway for this wood. A case study in Quebec (Canada) was used to evaluate the profitability of pellet production for bioenergy using degraded trees from insect epidemics. A bioenergy scenario was simulated in which degraded trees were harvested for bioenergy alongside sound wood for timber and pulp. This scenario was compared to a reference scenario in which degraded trees were left on cutovers. Using wood pellets as a case study, the results showed that at current market prices, harvesting degraded trees for pellet production is not as profitable as leaving them in the forest. Nevertheless, the overall forest operations for procuring wood for timber and pulp were still profitable, even with very high degradation levels. Procuring degraded trees reduced the overall fixed costs per harvested m3 and allowed average savings of C$2.83/harvested m3. The silvicultural savings associated with lower site preparation needs following procurement of degraded trees ranged from C$0/ha to C$500/ha, resulting in average savings of C$2.31/harvested m3. Depending on the stand conditions, the distribution of fixed costs and silvicultural savings of biomass procurement could be either low or significant. Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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16 pages, 6574 KiB  
Article
The Effect of Biomass Pellet Length, Test Conditions and Torrefaction on Mechanical Durability Characteristics According to ISO Standard 17831-1
by Hamid Gilvari, Wiebren De Jong and Dingena L. Schott
Energies 2020, 13(11), 3000; https://0-doi-org.brum.beds.ac.uk/10.3390/en13113000 - 11 Jun 2020
Cited by 22 | Viewed by 2619
Abstract
With the recent increase in biomass pellet consumption, the mechanical degradation of pellets during transport and handling has become more important. ISO standard 17831-1 is an accepted global standard that is commonly used amongst researchers and industries to determine the mechanical durability of [...] Read more.
With the recent increase in biomass pellet consumption, the mechanical degradation of pellets during transport and handling has become more important. ISO standard 17831-1 is an accepted global standard that is commonly used amongst researchers and industries to determine the mechanical durability of pellets. However, the measured mechanical durability sometimes fails to match the certificate accompanying the shipment. In such cases, pellet length specifications are suspected to play a role. This paper studies the effect of pellet length on mechanical durability for various types of commercially produced biomass pellets. In addition, the effect of test conditions and torrefaction on the mechanical durability of biomass pellets has been investigated. To study the effect of pellet length, pellets were classified into three groups: shorter than 15 mm, 15 to 30 mm, and longer than 30 mm, and their length distributions were measured using an in-house image processing tool. Then, the mechanical durability of pellets was measured using ISO standard 17831-1. The mechanical durability results were compared to random-sized pellet samples. To study the effect of test conditions, the mechanical durability test was operated at different time intervals to elucidate the effect of tumbling at different conditions. The results show that the mechanical durability depends highly on the length distribution of the pellets, with a difference between categories of up to 13%. It was also observed that the mechanical durability remains relatively constant after a specific time interval. Based on the results, we highly recommend modifying the current ISO standard to account for the pellet length distribution (PLD). Full article
(This article belongs to the Special Issue Wood-Based Bioenergy)
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