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Siwale, W., Frodeson, S., Finell, M., Arshadi, M., Henriksson, G. & Berghel, J. (2023). Influence of Sapwood/Heartwood and Drying Temperature on Off-Gassing of Scots Pine Wood Pellets. Bioenergy Research
Open this publication in new window or tab >>Influence of Sapwood/Heartwood and Drying Temperature on Off-Gassing of Scots Pine Wood Pellets
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2023 (English)In: Bioenergy Research, ISSN 1939-1234, E-ISSN 1939-1242Article in journal (Refereed) Epub ahead of print
Abstract [en]

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. 

Place, publisher, year, edition, pages
Springer, 2023
Keywords
Biofuel pellets, Bulk storage, Gas emissions, Carbon oxides, Methane, Feedstock composition
National Category
Energy Systems
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-96667 (URN)10.1007/s12155-023-10668-6 (DOI)001064448400001 ()2-s2.0-85170075647 (Scopus ID)
Funder
Swedish Energy Agency, 47997-1Vinnova, 2021-03727Karlstad University
Available from: 2023-09-11 Created: 2023-09-11 Last updated: 2023-10-19Bibliographically approved
Siwale, W., Frodeson, S., Finell, M., Arshadi, M., Jonsson, C., Berghel, J. & Henriksson, G. (2023). Variations in Extractive Content of Scots Pine Sapwood and Heartwood and the Effect on Off-Gassing During Storage of Wood Pellets. In: Proceedings of the 2023 SWST International Conference, Asheville, North Carolina, USA, June 25 - 30, 2023.: . Paper presented at SWST 66TH International Convention. 25-30 June, 2023. Asheville, North Carolina, USA..
Open this publication in new window or tab >>Variations in Extractive Content of Scots Pine Sapwood and Heartwood and the Effect on Off-Gassing During Storage of Wood Pellets
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2023 (English)In: Proceedings of the 2023 SWST International Conference, Asheville, North Carolina, USA, June 25 - 30, 2023., 2023Conference paper, Oral presentation with published abstract (Other academic)
Keywords
Fuel Pellets, Off-gas Emissions, Methane, Carbon Oxides, Wood Extractives, Sapwood, Heartwood
National Category
Renewable Bioenergy Research
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-96495 (URN)
Conference
SWST 66TH International Convention. 25-30 June, 2023. Asheville, North Carolina, USA.
Available from: 2023-08-28 Created: 2023-08-28 Last updated: 2023-08-31Bibliographically approved
Berghel, J., Ståhl, M., Frodeson, S., Pichler, W. & Weigl-Kuska, M. (2022). A comparison of relevant data and results from single pellet press research is Mission Impossible: A review. Bioresource Technology Reports, 18, Article ID 101054.
Open this publication in new window or tab >>A comparison of relevant data and results from single pellet press research is Mission Impossible: A review
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2022 (English)In: Bioresource Technology Reports, ISSN 2589-014X, Vol. 18, article id 101054Article in journal (Refereed) Published
Abstract [en]

A global increase in the wood fuel pellet market requires knowledge of new biomasses pelleting abilities. As large-scale industrial tests of new materials are costly, tests in e.g., a single pellet press (SPP) are desirable. SPPs have many different configurations and it typically produces one pellet at a time and can give results of its pelletability. This review has surveyed the research that has been carried out of SPPs to ascertain the feasibility of comparing their obtained data and the results. The results show that it is almost impossible to compare the data and results of the various different SPP studies, e.g., some information from the data used was missing, resulting in that only 27 out of 70 papers were comparable. One solution could be the introduction of a common SPP testing method using a determined set of data that enables a reference pellet to be produced in every study.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Presses (machine tools); Testing, Densifications; Dies diameter; Fuel pellet; Industrial tests; Large-scales; Pellet press; Pelletisation; Pellets markets; Piston velocity; Testing method, Pelletizing, feasibility study; review
National Category
Engineering and Technology Energy Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-90615 (URN)10.1016/j.biteb.2022.101054 (DOI)2-s2.0-85128933469 (Scopus ID)
Note

cited By 0

Available from: 2022-06-20 Created: 2022-06-20 Last updated: 2022-10-21Bibliographically approved
Siwale, W., Frodeson, S., Berghel, J., Henriksson, G. & Finell, M. (2022). Effect of Sterilization and Contamination of Sawdust on Methane and Carbon Oxides Emissions of Scots Pine Wood Pellets. In: : . Paper presented at World Sustainable Energy Days 2022/European Pellet Conference, Wels, Austria, April 5-8, 2022..
Open this publication in new window or tab >>Effect of Sterilization and Contamination of Sawdust on Methane and Carbon Oxides Emissions of Scots Pine Wood Pellets
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2022 (English)Conference paper (Other academic)
National Category
Renewable Bioenergy Research
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-94176 (URN)
Conference
World Sustainable Energy Days 2022/European Pellet Conference, Wels, Austria, April 5-8, 2022.
Available from: 2023-04-03 Created: 2023-04-03 Last updated: 2023-05-09Bibliographically approved
Siwale, W., Frodeson, S., Berghel, J., Henriksson, G., Finell, M., Arshadi, M. & Jonsson, C. (2022). Influence on off-gassing during storage of Scots pine wood pellets produced from sawdust with different extractive contents. Biomass and Bioenergy, 156, Article ID 106325.
Open this publication in new window or tab >>Influence on off-gassing during storage of Scots pine wood pellets produced from sawdust with different extractive contents
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2022 (English)In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 156, article id 106325Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2022
Keywords
Carbon dioxide, Carbon monoxide, Methane, Off-gassing, Wood extractives, Wood pellets, Acetone, Health risks, Heating, Pelletizing, Storage (materials), Volatile organic compounds, Wood, Environmental health risks, Extractives content, Fire risks, Offgassing, Pine sawdust, Scots pine wood, Self-heating, Toxic gas, Wood pellet, carbon, pine, Pelleting, Voc
National Category
Energy Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-88950 (URN)10.1016/j.biombioe.2021.106325 (DOI)2-s2.0-85121003662 (Scopus ID)
Available from: 2022-03-03 Created: 2022-03-03 Last updated: 2022-10-12Bibliographically approved
Siwale, W., Frodeson, S., Finell, M., Arshadi, M., Jonsson, C., Henriksson, G. & Berghel, J. (2022). Understanding Off-Gassing of Biofuel Wood Pellets Using Pellets Produced from Pure Microcrystalline Cellulose with Different Additive Oils. Energies, 15(6), Article ID 2281.
Open this publication in new window or tab >>Understanding Off-Gassing of Biofuel Wood Pellets Using Pellets Produced from Pure Microcrystalline Cellulose with Different Additive Oils
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2022 (English)In: Energies, E-ISSN 1996-1073, Vol. 15, no 6, article id 2281Article in journal (Refereed) Published
Abstract [en]

Fuel wood pellets have the tendency of undergoing self-heating and off-gassing during storage and transportation. Self-heating can lead to spontaneous combustion and cause fires while toxic gasses such as carbon monoxide and some volatile organic compounds released due to off-gassing are a human health and environmental hazard. Previous research suggests that the self-heating and off-gassing of wood pellets are as a result of the oxidation of wood extractives. The aim of this study was to identify the extractives, i.e., fatty and resin acids that are responsible for the emissions of carbon monoxide, carbon dioxide and methane from wood pellets by testing the off-gassing tendencies of pellets produced from synthetic microcrystalline cellulose and different additive oils. The additive oils were intentionally selected to represent different types of wood extractives (mainly fatty and resin acids) and they included: tall oil, pine rosin, linseed oil and coconut oil. The highest mean concentrations of carbon monoxide, carbon dioxide and methane were recorded from cellulose pellets with added linseed oil. The concentrations of carbon monoxide and methane for the other four pellet types were negligible and there was no carbon dioxide emission. Pellets with added linseed oil had high off-gas emissions due to the high content of unsaturated fatty acids compared to other pellet types.

Place, publisher, year, edition, pages
MDPI, 2022
Keywords
off-gassing, cellulose pellets, additive oils, fatty and resin acids, solid biofuels, wood pellets, self-heating
National Category
Energy Engineering
Research subject
Chemistry; Energy Technology
Identifiers
urn:nbn:se:kau:diva-89516 (URN)10.3390/en15062281 (DOI)000775539800001 ()2-s2.0-85127671377 (Scopus ID)
Available from: 2022-04-14 Created: 2022-04-14 Last updated: 2023-08-28Bibliographically approved
Anukam, A., Berghel, J., Henrikson, G., Frodeson, S. & Ståhl, M. (2021). A review of the mechanism of bonding in densified biomass pellets. Renewable & sustainable energy reviews, 148, Article ID 111249.
Open this publication in new window or tab >>A review of the mechanism of bonding in densified biomass pellets
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2021 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 148, article id 111249Article in journal (Refereed) Published
Abstract [en]

The production of durable biomass pellets have always been challenged by several factors including the lack of understanding of the mechanism involved in how particles combine to form pellets under standard conditions of the pellet press. This is because contributing factors span several molecular, microscopic, and even nanoscopic levels as biomass undergoes pelleting. The characteristics of the bonds formed between the combining particles and their relevance to the quality of pellets remains vague, no matter how quality is defined. However, even though few researchers have attempted to explain the mechanism of bonding in densified biomass pellets using different theories, none of their hypotheses supports particle bonding from a structural chemistry perspective. There are still no clear explanations which consider the role of molecular structure and the interactions of substances as milled biomass undergo pelleting. In view of these arguments therefore, this review presents an in-depth analysis of a structural chemistry perspective of the mechanism of bonding and the use of additives in densified biomass pellets and helps identify research areas needed to facilitate better understanding of bonding in densified biomass pellets. The status of current research in biomass pelleting, types of materials suitable as additives and their structural characteristics, as well as the current technical specifications of using additives are also discussed.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Additives, Attraction forces, Functional groups, Pellets quality, Press configuration, Structural chemistry
National Category
Energy Engineering Energy Systems
Research subject
Energy Technology; Chemistry
Identifiers
urn:nbn:se:kau:diva-85355 (URN)10.1016/j.rser.2021.111249 (DOI)000674459200004 ()2-s2.0-85107655065 (Scopus ID)
Available from: 2021-07-02 Created: 2021-07-02 Last updated: 2022-05-11Bibliographically approved
Frodeson, S., Anukam, A., Berghel, J., Ståhl, M., Kudahettige-Nilsson, R. L., Henriksson, G. & Aladejana, E. B. (2021). Densification of Wood-Influence on Mechanical and Chemical Properties when 11 Naturally Occurring Substances in Wood Are Mixed with Beech and Pine. Energies, 14(18), Article ID 5895.
Open this publication in new window or tab >>Densification of Wood-Influence on Mechanical and Chemical Properties when 11 Naturally Occurring Substances in Wood Are Mixed with Beech and Pine
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2021 (English)In: Energies, E-ISSN 1996-1073, Vol. 14, no 18, article id 5895Article in journal (Refereed) Published
Abstract [en]

The need to increase the use of renewable biomasses for energy supply, such as fuel pellets is significant. However, different types of biomasses have different mechanical properties to be pelletized, which entails a limitation in available raw materials for pellet producers. Within this study eleven different pure substances from biomasses were separately mixed with European beech and Scots pine, to identify its impact on the densification process. Beech and pine pellets were used as control materials against their corresponding pellets mixed with substances representing: cellulose, hemicelluloses, other polysaccharides, lignin, protein, and extractives. The mechanical properties were investigated as well as FT-IR and SEM analyses on the pellets. The results showed that the addition of the substances xylan and galactan created the hardest pellets for both pine and beech and that adding extractives to wood affects pine more than beech in relation to hardness. The FT-IR data could not provide clear explanations as to the variation in hardness and springback behavior through the identification of major functional groups in each pellet. It can be concluded that biomass residues rich in xylan and galactan increase pellet quality in terms of strength and durability without affecting the production process.

Place, publisher, year, edition, pages
MDPI, 2021
Keywords
pellets, single pellet press, chemical composition, pelletization
National Category
Energy Engineering
Research subject
Energy Technology
Identifiers
urn:nbn:se:kau:diva-86165 (URN)10.3390/en14185895 (DOI)000699255600001 ()2-s2.0-85115399049 (Scopus ID)
Available from: 2021-10-11 Created: 2021-10-11 Last updated: 2023-08-28Bibliographically approved
Henriksson, L., Frodeson, S., Berghel, J., Andersson, S. & Ohlson, M. (2019). Bioresources for Sustainable Pellet Production in Zambia: Twelve Biomasses Pelletized at Different Moisture Content. BioResources, 14(2), 2550-2575
Open this publication in new window or tab >>Bioresources for Sustainable Pellet Production in Zambia: Twelve Biomasses Pelletized at Different Moisture Content
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2019 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 14, no 2, p. 2550-2575Article in journal (Refereed) Published
Abstract [en]

The use of charcoal and firewood for cooking is common in Zambia,and its utilization is suchthat the deforestation rate is high, energy utilization is low, and unfavorable cooking methods lead to high death rates due to indoor air pollution mainly from particulate matter and carbon monoxide.Byusing an alternative cooking method, such as pellet stoves, it is possible to offer a sustainable solution, provided that sustainable pelletproduction can be achieved. In this study, 12different available biomaterials were pelletizedina single pellet unitto investigate their availability as raw materials for pellet production in Zambia. The study showedthat sicklebush and pigeon pea generatedthe same pelleting properties correlated withcompression and frictionand that both materials showedlow moisture uptake. The study also identifiedtwo groups of materials that broadenedthe raw material base and helpedto achieve sustainable pellet production.Group 1consisted of materials with equal pelletingabilities (miombo, peanut shell, pigeon pea,and sicklebush) andGroup 2 consistedof materialsthat showed low impact of varying moisture content(eucalyptus, miombo, peanut shell, pigeon pea, and sicklebush). The hardest pellet was made from Tephrosia, which wasfollowed by Gliricidia.

Place, publisher, year, edition, pages
North Carolina: North Carolina State University, 2019
Keywords
Biomass pellets, Single pellet press, Densification, Backpressure, Chemical composition
National Category
Paper, Pulp and Fiber Technology Energy Systems Other Environmental Engineering
Research subject
Environmental and Energy Systems
Identifiers
urn:nbn:se:kau:diva-71412 (URN)000466449000010 ()
Note

DOI: 10.15376/biores.14.2.2550-2575

Available from: 2019-03-02 Created: 2019-03-02 Last updated: 2021-06-30Bibliographically approved
Anukam, A. I., Berghel, J., Frodeson, S., Bosede Famewo, E. & Nyamukamba, P. (2019). Characterization of pure and blended pellets made from Norway spruce and pea starch: A comparative study of bonding mechanism relevant to quality. Energies, 12(23), 1-22, Article ID 4415.
Open this publication in new window or tab >>Characterization of pure and blended pellets made from Norway spruce and pea starch: A comparative study of bonding mechanism relevant to quality
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2019 (English)In: Energies, E-ISSN 1996-1073, Vol. 12, no 23, p. 1-22, article id 4415Article in journal (Refereed) Published
Abstract [en]

The mechanism of bonding in biomass pellets is such a complex event to comprehend, as the nature of the bonds formed between combining particles and their relevance to pellet quality are not completely understood. In this study, pure and blended biomass pellets made from Norway spruce and pea starch were characterized using advanced analytical instruments able to provide information beyond what is visible to the human eye, with intent to investigate differences in bonding mechanism relevant to quality. The results, which were comprehensively interpreted from a structural chemistry perspective, indicated that, at a molecular level, the major disparity in bonding mechanism between particles of the pellets and the quality of the pellets, defined in terms of strength and burning efficiency, were determined by variation in the concentration of polar functional groups emanating from the major organic and elemental components of the pellets, as well as the strength of the bonds between atoms of these groups. Microscopic-level analysis, which did not provide any clear morphological features that could be linked to incongruity in quality, showed fracture surfaces of the pellets and patterns of surface roughness, as well as the mode of interconnectivity of particles, which were evidence of the production of pellets with dissimilarities in particle bonding mechanism and visual appearance.

Place, publisher, year, edition, pages
MDPI, 2019
Keywords
Biomass, Combustion efficiency, Functional groups, Pellet strength, Pelleting, Advanced Analytics, Chemical bonds, Efficiency, Plants (botany), Starch, Surface roughness, Analytical instrument, Combustion efficiencies, Comparative studies, Elemental components, Morphological features, Polar functional groups, Structural chemistry, Pelletizing
National Category
Energy Engineering Bioenergy
Research subject
Energy Technology
Identifiers
urn:nbn:se:kau:diva-76601 (URN)10.3390/en12234415 (DOI)000514090100013 ()2-s2.0-85076133821 (Scopus ID)
Available from: 2020-01-30 Created: 2020-01-30 Last updated: 2023-08-28Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9707-8896

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