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  • 1.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Kartläggning och nulägesbeskrivning av pelletskedjan2011Report (Other academic)
  • 2.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Lösningarna finns! Är pelletsproducenterna medvetna om problemen?2011In: Bioenergi: utmaningar och möjligheter / [ed] Delin, Karin, Persson, Lars, Wikström, Per-Arne, Gävle: Region Gävleborg , 2011, p. 25-29Chapter in book (Other academic)
    Abstract [sv]

    Sverige är inte längre världsledande som pelletsproducent. USA producerar allra mest pellets i världen. Kanada och Ryssland producerar också allt mer pellets. Ingen av dessa länder har någon omfattande inhemsk konsumtion. I stort sett all pellets exporteras och det sker huvudsakligen till Europa. Sannolikt kommer det att leda till att priset på pellets i Europa sjunker, med följd att lönsamheten för svenska pelletsproducenter minskar.

  • 3.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Varför får inte villaägaren driva kvalitetsutvecklingen på bränslepellets?2011In: Bioenergi: utmaningar och möjligheter / [ed] K. Delin, L. Persson, P.-A. Wikström, Gävle: Region Gävleborg , 2011, p. 31-33Chapter in book (Other academic)
  • 4.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Nordgren, Daniel
    Innventia, Box 5604, SE-11486 Stockholm, Sweden.
    Tomani, Per
    Innventia, Box 5604, SE-11486 Stockholm, Sweden.
    The effects of kraft lignin additives on wood fuel pellet quality, energy use and shelf life2013In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 112, no 0, p. 64-69Article in journal (Refereed)
    Abstract [en]

    In 2011, the total consumption of pellets in Sweden amounted to 1.9 million tons, which represents an energy value of 9 TWh. The pellets are used in large-scale as well as in small-scale applications, and increased demands on pellet quality are likely to force pellet producers to improve on the pellet properties. One way of increasing pellet quality is by using additives. The purpose of this article, therefore, is to examine kraft lignin as an additive. Pelletswere produced in a small industrial pellet press located at KarlstadUniversity, Karlstad, Sweden, and 1–4% of kraft lignin was added to the pellets. The results indicate that the addition of an increased amount of kraft lignin to the pellets increases their mechanical durability and their lengths. The results also indicate that dry kraft lignin yields pellets with higher durability as compared to wet kraft lignin. The energy demand was unaffected by the increased use of kraft lignin. The general results presented in this paper are useful for producers of lignin, pellet producers and end-users of pellets, who are interested in developing their products and/or improving the production processes.

  • 5.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodesson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Tillsatser som kvalitetshöjare för pellets2011Report (Other academic)
  • 6.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    From sawdust to pellets. Still a challenge...2012In: Public Service Review European Union, no 33, p. 398-399Article in journal (Other academic)
  • 7.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    How residence time in the mixing conditioner affects the quality in wood fuel pellets2016Conference paper (Other academic)
  • 8.
    Berghel, Jonas
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The amount of dust and rejects as well as the electricity consumption during production decreases with the use of adequate additives2017Conference paper (Other academic)
  • 9.
    Frodeson, Stefan
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Granström, Karin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Romlin, Carl
    Drinor AB, Karlstad.
    Thelander, Alexander
    Drinor AB, Karlstad,.
    The Potential for a Pellet Plant to Become a Biorefinery2019In: Processes, ISSN 2227-9717, Vol. 7, no 4, p. 1-11, article id 233Article in journal (Refereed)
    Abstract [en]

    The use of bioenergy has increased globally in recent years, as has the utilization of biomaterials for various new product solutions through various biorefinery concepts. In this study, we introduce the concept of using a mechanical dewatering press in combination with thermal drying in a pellet plant. The purpose of the study is to increase the understanding of the effects a mechanical dewatering press has in a pellet production chain and investigate whether a pellet plant could thus become a biorefinery. The evaluations in this study are based on industrial data and initial tests at the university. The results show that the concept of using the mechanical dewatering press together with a packed moving bed dryer reduces energy use by 50%, compared to using only a packed moving bed dryer. The press water could be used as a raw material for biogas, bioplastics, and biohydrogen. Hence, this study points out the possibilities of a pellet plant increasing the efficiency of the drying step, while moving towards becoming a biorefinery.

  • 10.
    Granström, Karin
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Steam Drying of Sawdust for Pellets Production2003Conference paper (Other (popular science, discussion, etc.))
  • 11.
    Granström, Karin
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Williams, Helen
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Sandberg, Maria
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    The importance of a holistic perspective when investigating agricultural products as additives in sustainable pellets development2012Conference paper (Refereed)
  • 12.
    Kjeang, Are
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Govindarajan, Venkatesh
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology. Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Palm, Jenny
    2 IIIEEE, International Institute for Industrial Environmental Economics, Lund University, Lund, Sweden..
    Energy consulting services in the information age: literature review2017In: Energy, Sustainability and Society, ISSN 2192-0567, Vol. 7, no 30, p. 1-10Article in journal (Refereed)
  • 13.
    Renström, Roger
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Experimental data from a spouted bed dryer as a basis for design of a two stage dryer2011In: Proceedings of the 5th Nordic Drying Conference, NDC / [ed] Alves-Filho, O., Eikevik, T.M. & Goncharova-Alves, S., 2011Conference paper (Refereed)
  • 14.
    Sandberg, Maria
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Miljöaspekter på produktion och lagring av träpellets2011Report (Other academic)
  • 15.
    Stahl, Magnus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Granstrom, Karin
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Improvement of Wood Fuel Pellet Quality Using Sustainable Sugar Additives2016In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 11, no 2, p. 3373-3383Article in journal (Refereed)
    Abstract [en]

    The global production and use of wood fuel pellets has increased significantly in recent years. The raw material and the energy required to dry it are the main production costs. Therefore, it is crucial to minimize energy consumption, production costs, and the environmental impact associated with wood pellets. However, these changes should not negatively affect the quality of the pellets. One way to achieve these goals is to use additives. This work investigates how different types of sugar additives affect both the energy needed by the pellet press and the durability and oxidation of the produced pellets. When sugar was used as an additive, the energy use was practically unaffected. When molasses and SSL were added, a small decrease in energy use was observed (6 to 8%) for admixtures up to 1 wt.%; however, when more molasses was added, the energy use increased. Using these additives increased the bulk density (7 to 15 %) and durability (10 to 20 %) of the pellets. The storage of the pellets also caused a small increase in durability (1 to 3 %). Volatile organic compounds were produced as oxidation peaks within the first two months of storage; thereafter, the peaks tapered off.

  • 16.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Drying Parameter Variation and Wood Fuel Pellets Quality'Pilot Study with a new Pelleting Equipment Set up2006Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    The new pelleting equipment set up, in combination with an integrated automatic control system and the existing pilot-scale dryer, in the laboratory at the Department of Environmental and Energy Systems at Karlstad University in Sweden, make it possible to run a variety of tests. With the integrated control system the possibility to make adjustments throughout the chain with the aim to decrease the energy demand and improve the pellet quality with focus on the strength of the pellet, moisture content etc are possible. Thus, we have an unique possibility to control the whole production chain, from wet sawdust to pellets. Publications that combine the drying of the raw material with the quality properties of wood fuel pellets are rare. Therefore, research that aims at investigating dryer performance and its effects on chosen pellet quality parameters is to be performed. From now on our department have the tools and possibility to contribute to that field of research

  • 17.
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energy reduction in wood fuel pellet production: Verringerung des Energieverbrauchs bei der Produktion von Holzpellets2012In: 12th Pellets Industry Forum Proceedings: Internationaler Fachkongress zum Pelletsmarkt, Pforzheim, Germany: Solar Promotion , 2012, p. 85-90Conference paper (Refereed)
    Abstract [en]

    The wood fuel pellet industry demands energy efficient solutions for their production since these not only save energy but also money. One way of achieving this is to use additives. Choosing the right additive can save money but also increase the quality of the pellets, a win win situation. In this work, it is investigated how different kind of additives affect the energy use of the pelletizing equipment and also how it affects the durability of pellets. The best results were achieved using oxidized cornstarch as an additive during pellet production, it not only decreases the energy used the most but also produce the pellets with highest durability.

  • 18.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Improving Wood Fuel Pellets for Household Use: Perspectives on Quality, Efficiency and Environment2008Doctoral thesis, comprehensive summary (Other scientific)
    Abstract [en]

    Bioenergy is one of many contributors to reducing the use of fossil fuels in order to mitigate climate change by decreasing CO2-emissions, and the potential for biofuels are large. The wood fuel pellets are a refined biofuel made of sawdust, which is dried and compressed to achieve improved fuel and transportation properties. In 2007 the amount of wood fuel pellets used for heating purposes in Sweden was 1715000 tons.

    The aims of this work was: to examine the moisture content and emission of monoterpenes during the drying and pelletising steps of the pellets production (Paper I); to investigate how the recirculation of drying gases affects the energy efficiency of rotary dryers and how the energy efficiency is related to the capacity of the dryer. (Paper II); to analyse the causes of the problems encountered by household end-users of pellets and investigate whether an improved pellet quality standard could reduce these problems (Paper III); to investigate how the energy consumption of the pelletising machine and chosen pellet quality parameters were affected using an increased amount of rapeseed cake in wood fuel pellets (Paper IV); and to identify gaps of knowledge about wood fuel pellet technology and needs for further research on quality, environmental and health aspects throughout the wood fuel pellet chain, from sawdust to heat. (Paper V).

  • 19.
    Ståhl, Magnus
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Minska energianvändningen i pelletspressen och öka pelletskvaliteten2013Conference paper (Other academic)
    Abstract [en]

    The wood fuel pellet industry demands energy efficient solutions for their production since these not only save energy but also money. One way of achieving this is to use additives. Choosing the right additive can save money but also increase the quality of the pellets, a win win situation. In this work, it is investigated how different kind of additives affect the energy use of the pelletizing equipment and also how it affects the durability of pellets. The best results were achieved using oxidized cornstarch as an additive during pellet production, it not only decreases the energy used the most but also produce the pellets with highest durability.

  • 20.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Theoretical Effects of Recirculation of Drying Gases in a Co-current Rotary Dryer2005Conference paper (Other (popular science, discussion, etc.))
    Abstract [en]

    The most energy demanding process in manufacturing of biofuels is drying. When drying is needed it is together with the raw material the main cost factors for pellet production. The most common drying technique used in the Swedish pellet industry for drying sawdust is a direct-fired rotary dryer. Recirculation of drying gases can contribute to energy efficient operation of dryers.



    Improvements due to recirculation of drying gases are elucidated in four system configuration scenarios using a mathematical model. The results indicate that for different scenarios the dew point of the gases leaving the dryer may be unaffected or increase significantly when the recirculation ratio increases. The latter is important for the district heating demand as a higher dew point implies that the energy recovered in the condenser becomes more useful especially at higher return flow temperatures. Optimisation of the drying process regarding dryer capacity and energy recovery is suggested

  • 21.
    Ståhl, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Wood Fuel Pellets: Sawdust Drying in the Energy System2005Licentiate thesis, monograph (Other academic)
    Abstract [en]

    In 2004, the amount of wood fuel pellets used in Sweden was 1 256 000 tons, it was mostly used in large scale burning for district heating. Over the last 10 years, a significant increase in pellet production has occurred and today the preferred raw materials for pellet production, i.e., dry sawdust and wood shavings, are insufficient. New raw materials could be used. However, the quality demanding residential customer that uses a pellet burner or a pellet stove with limited emission control prefers stem wood pellets. One solution could be to increase the drying of wet raw materials, such as wood chips.

    The most common technique in Sweden for the drying of sawdust is to use a directly fired co-current rotary dryer, although steam drying does occur when co-generation is possible. In the production chain for pellets, the drying process is the most energy consuming process and, together with the raw material, it is the main cost factor for the manufacturer. Thus, it is important to run the drying process as energy efficiently and environmentally friendly as possible. This thesis, therefore, discusses the effects of the drying of sawdust, which is the primary raw material for wood pellets.

    In the work described in Paper I, the moisture content and emission of terpenes during the drying and pelleting steps of the pellets production are examined. Furthermore, the effects on pellet quality are examined. In the work described in Paper II, the recirculation of drying gases in a rotary dryer is examined from the point of view of energy savings and dryer capacity.

    The drying process also affects the pellet quality. Drying of sawdust can be used to control quality properties, such as moisture content and emissions of Volatile Organic Compounds (VOC). Almost all of the monoterpenes are emitted during the drying and pelleting steps causing environmental and health related problems (see Paper I).

    Energy savings can be made using recirculation of the drying gases. Increased recirculation could mean higher dew points in the emitted drying gases, which increases the chances to use the energy from the emitted drying gases for secondary processes connected to the dryer system, such as district heating. However, there is a conflict between recirculation ratio/recovered energy and drying performance (see Paper II)

  • 22.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Energy Efficient Pilot-Scale Production of Wood Fuel Pellets made from a Raw Material Mix Including Sawdust and Rapeseed Cake2011In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 35, no 12, p. 4849-4854Article in journal (Refereed)
    Abstract [en]

    Presently, most fuel pellets are made from sawdust or shavings. In Sweden, these materials are used to the maximum extent. As the demand for pellets increases, the supply of sawdust will be insufficient and other raw materials or mixes of raw materials will be used. This work investigates sawdust mixed with rapeseed cake. The latter is a residual product from the production of chemically unmodified oil refined from cold-pressed rape oil. At the Department of Energy, Environmental and Building Technology at Karlstad University, Sweden, a complete pilot-scale pellet production unit is located. The pellets are produced and tested for mechanical durability, length, bulk density and moisture content according to the Swedish Standard for pellets. During production, the load current, the die pressure and the die temperature were measured along with other parameters. The main purpose was to examine how the mixture of rapeseed cake and pine sawdust affected the energy consumption of the pelletising machine and mechanical durability of mixed fuel pellets. The results show that the energy consumption decreased and the amount of fines increased with increasing rapeseed cake in the wood fuel pellets. These results indicate that we must compromise between a decrease in the use of energy and a decrease in durability.

  • 23.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Validation of a Developed Mathematical Model by Studying the Effects of Recirculation of Drying Gases2008In: Drying TechnologyArticle in journal (Refereed)
  • 24.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Validation of a Developed Mathematical Model Studying the Effects of Recirculation of Drying Gases2006Conference paper (Refereed)
    Abstract [en]

    Drying is a costly and energy consuming process. Consequently, it is of great practical importance to improve its energy efficiency. Our objective, therefore, is to develop and validate a theoretical drying model by studying the recirculation of drying gases. The results show that the amount of recovered energy over the condenser and the dryer efficiency increase with increased recirculation, implying an energy efficient operation. The validation shows that the model correlates well with industrial data. Accordingly, it should be possible to use the model industrially to predict capacity changes and energy recovered when changes in drying gas recirculation are made

  • 25.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Validation of a Mathematical Model by Studying the Effects of Recirculation of Drying Gases2008In: Drying Technology, ISSN 0737-3937, E-ISSN 1532-2300, Vol. 26, no 6, p. 786-792Article in journal (Refereed)
  • 26.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Additives for wood fuel pellet production - A win, win, win situation2016Conference paper (Other academic)
    Abstract [en]

    The production and use of wood-fuel pellets, preferably made from sawdust or shavings, have increased significantly worldwide in recent years. If wood-fuel pellets should continue to be a successful biofuel at the energy market there are several factors to take into consideration. The pellet production industry already tries to reduce the production cost, since it is a low margin business. Further, it tries to produce pellets from a broader raw material base and at the same time satisfy the customer requirements while producing a sustainable product. The wood fuel pellet industry has the possibility to meet all these criteria; however, it also has the potential for improvements.

    This work focuses on energy efficiency, technical aspects and environmental factors, i.e., the electricity consumption, the physical and mechanical properties of the pellets, and the CO

    2 equivalent emitted during production, respectively. 20 various additives, with an admixture of up to 2 % (wt.), have been tested during wood fuel pellet production at Karlstad University. This work presents the benefits of using different additives in pellet production and the cost associated with different additives. The results shows that additive from the sea and from farmlands (algae, rape seed cake and grass) decrease the energy use in the pellet press but unfortunately also decrease the durability. Additives from wood (resins, lignin) and molasses increases the durability of the pellet but shows almost no or little change in electricity consumption. However, using starch grades, white sugar or spent sulphite liquor as an additive increases the mechanical properties while it decreases both the electricity consumption and the climate impact, hence a win-win-win situation. To justify the use of additives from a climate impact perspective in regions with an OECD European electricity mix or the Swedish electricity mix, the usage of additives from the rest products where the CO2 equivalent emissions are allocated to the main product are crucial.

    In conclusion, it is necessary to do research that systematically investigates the consequences of using additives for wood fuel pellets to continuously be a successful biofuel at the energy market

  • 27.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Research Experience From The Use Of Different Additives In Wood-Fuel Pellet Production2017In: International Journal of Energy Production and Management, ISSN 2056-3272, E-ISSN 2056-3280, Vol. 2, no 3, p. 288-293Article in journal (Refereed)
    Abstract [en]

    The use of wood-fuel pellets has increased signi cantly worldwide in recent years, especially in the United Kingdom. If wood-fuel pellets should continue to be a successful biofuel at the energy market, the pellet production industry has to reduce the production cost, since it is a low-margin business. Further, improved pellets regarding storability and strength of the pellets are crucial to manage the overseas transportation that causes material losses. In addition, the industry tries to produce pellets from a broader raw material base and at the same time satisfy the customer requirements while produc- ing a sustainable product. The wood-fuel pellet industry has the possibility to meet all these criteria; however, it also has the potential for improvements. Using additives in pellet production is one way to meet the criteria. In conclusion, it is necessary to do the research that systematically investigates the consequences of using additives for wood-fuel pellets, and this work presents a compilation of results and experiences from more than 20 different additive studies and the test bed for pellet produc- tion research at Karlstad University– a pellet production unit adapted for additives studies. Additives, with an admixture of up to 2% (wt.), have been tested in the NewDeP (New Development for Pellet Technology) pilot plant for pellet production at Karlstad University. The research has focused on the electricity consumption, the physical and mechanical properties of the pellets, and the CO2 equivalents emitted during production. The results showed that the additives Wetland grass, Algae, Turpentine and Lignin decreased the electricity consumption in the pellet press but unfortunately also decreased the durability. The additives Resins, Molasses, White sugar, Native potato starch and Oxidized potato starch increased the durability of the pellet but showed almost no change in the electricity consumption. However, Oxidized corn starch, Spent sulphite liquor and Native wheat starch as additives increased the mechanical properties while it decreases both the electricity consumption and the climate impact, hence a Win-Win-Win situation. 

  • 28.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Frodeson, Stefan
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Effects on Pellet Properties and Energy Use When Starch Is Added in the Wood-Fuel Pelletizing Process2012In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 26, no 3, p. 1937-1945Article in journal (Refereed)
    Abstract [en]

    The production and use of wood-fuel pellets have increased significantly worldwide in recent years. The increased use of biomaterials has resulted in higher raw material prices, and there are no signs that indicate a decrease in raw material competition. Additives can be used for different purposes. Partly, they are used to facilitate the use of new raw materials to increase the raw material base, and partly, they are used to decrease the energy use in the pelletizing process. They are also used to increase durability or shelf life. Consequently, it is necessary to do research that systematically investigates the consequences of using additives. In this work, it is investigated how various percentages of different kinds of starch influence pellet properties, including shelf life and energy use in the pelletizing process. Four different starch grades were used: native wheat starch, oxidized corn starch, native potato starch, and oxidized potato starch. The pellets were produced in a small industrial pellet press located at Karlstad University, Karlstad, Sweden. The result shows that starch increases the durability of the pellets. Oxidized starches increase the durability more than native starches, and the best results were obtained by adding oxidized corn starch. The durability did not decrease with storage time when the pellets were stored indoors during 7 months. The oxidation process was not consistently altered by the addition of starch. The energy consumption of the pellet press decreases when starch is added. Again, the oxidized corn starch showed the best result; when 2.8% of corn starch was added, the average energy consumption was reduced by 14%

  • 29.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Energy reduction in wood-fuel pellet production2013In: Forest bioenergy review, ISSN 2045-8614, Vol. 4, no 19, p. 6-Article in journal (Other academic)
  • 30.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Improvement of Wood Fuel Pellets Quality Using Sustainable Sugar Additives2015In: Proceedings of ECOS 2015 – The 28th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, Pau, France, 2015, p. 1-8Conference paper (Refereed)
  • 31.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Williams, Helén
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Energy efficiency, greenhouse gas emissions and durability when using additives in the wood fuel pellet chain2016In: Fuel processing technology, ISSN 0378-3820, E-ISSN 1873-7188, Vol. 152, p. 350-355Article in journal (Refereed)
    Abstract [en]

    The use of renewable resources for bioenergy should be performed to support sustainable development. Since the use of bioenergy has increased significantly worldwide in recent years and biomass is made of limited resources it must be used efficiently and with a low environmental impact The wood fuel pellet industry has the possibility to meet these criteria; however, it also has the potential for improvements. This work investigates how the additives, cornstarch and molasses, affect: the electricity consumption of the pellet press, the emission of Carbon dioxide equivalents (CO2 eq.) from the production of wood fuel pellets in three different countries with different emissions from electricity, the durability of the pellets and its effects on energy efficiency. The results show that pellet production is more energy efficient when additives are used, and that the amount of CO2 eq. increases with an increased use of additives. In countries with a low usage of fossil fuels for electricity production, the global warming impact gets higher due to the additives; while in countries that use a lot of fossil fuels to produce electricity, the global warming impact will be reduced because of the additives by up to 1%. The increased global warming impact from the additives can be balanced by the decrease in the reduced amount of rejected material within the production. That is because the durability of the pellets increases with an increasing amount of additive.

  • 32.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Williams, Helén
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Sustainable improvements in the wood fuel pellet chain2014In: The Sustainable Energy and Environmental Protection, 2014Conference paper (Refereed)
    Abstract [en]

    A path towards sustainability should include growth with sustainable means such as the concept of Bioeconomy. The use of renewable resources for bioenergy should be performed to support sustainable development; however, biomass is made of limited resources and must be used efficiently and with a low environmental impact. The wood fuel pellet industry has the possibility to meet these criteria, but also has the potential for improvements. Earlier work on wood fuel pellet production has concluded that using oxidised cornstarch as an additive during pellet production decreases the energy used and also produces pellets with high durability. This work presents how additives such as cornstarch and molasses, affect the electricity use of the pellet press and also affect the emission of CO2 eq. from wood fuel pellet production. The results are presented for two different locations of the pellet plant, since the results will depend on how the electricity used is produced, e.g. using more or less renewable or fossil fuels in the electricity mix. 

  • 33.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Frodeson, Stefan
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Berghel, Jonas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences (from 2013).
    Olsson, Stefan
    Stora Enso.
    Using Secondary Pea Starch in Full-Scale Wood Fuel Pellet Production Decreases the Use of Steam Conditioning2019In: World Sustainable Energy Days 2019: European Pellet Conference, 2019Conference paper (Refereed)
  • 34.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Industrial processes for biomass drying and their effects on the quality properties of wood pellets2002Conference paper (Refereed)
  • 35.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Granström, Karin
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Berghel, Jonas
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Renström, Roger
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Industrial processes for biomass drying and their effects on the quality properties of wood pellets2004In: Biomass and Bioenergy 27:621-628, 2004, Vol. Vol.27, p. 621-628Article in journal (Refereed)
    Abstract [en]

    This paper contributes to the discussion of how different kinds of industrial scale dryers for biomass influence the quality properties of wood pellets. It also discusses how the drying technique can affect the environment. The most common biomass drying processes in use, i.e., convection dryers are discussed. The discussion of drying techniques is based on advantages and disadvantages with a focus on the drying medium,temperature and residence time. The choice of drying technique is particularly important if the end-users choice of pellets is made due to the specific requirements for the heating system used. Some specific parameters were tested in order to investigate how the choice of drying technique affects the pellet quality. The parameters tested were moisture content and the emissions of volatile hydrocarbons. Pellets available on the market were chosen for the tests. The amount of volatile hydrocarbons left in sawdust after drying vary with drying technique, as emissions of terpenes are larger in dryers with long residence times. Low emissions of volatile hydrocarbons would improve the energy content of the sawdust, and by decreasing air pollution improve the work environment and the environment in the surroundings of the dryers

  • 36.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Wikström, Fredrik
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Swedish Perspective on Wood Fuel Pellets for Household Heating: A Modified Standard for Pellets Could Reduce End-User Problems2009In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 33, no 5, p. 803-809Article in journal (Refereed)
    Abstract [en]

    The use of wood fuel pellets has increased significantly over the past few years, and since 2006 the households use the major part of the pellets available in Sweden. During the same period, the oil heating has decreased. Many former oil users that were used to almost maintenance-free heating systems now use pellets. Despite significant improvements of pellet quality and storage and burner equipment, there are still some problems that the household pellets user encounters. In this work, common end-user problems are identified. The cause of each problem, as well as whether a modified Swedish standard for pellets could reduce some of the problems encountered, is analysed. The results show that the most serious problems originate from the crumbling of pellets. We conclude that many of the problems could be avoided by modifying the Swedish standard, e.g., the quality parameters could be set using intervals instead of threshold values.

  • 37.
    Ståhl, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Wikström, Fredrik
    Karlstad University, Faculty of Technology and Science, Department of Energy, Environmental and Building Technology.
    Wood Fuel Pellet Technology Research: Quality and Environmental AspectsManuscript (Other academic)
1 - 37 of 37
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