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  • 1.
    Nilsson, Bengt
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Nilsson, Daniel
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Distribution of logging residues at the clear-felled site after fuel adapted logging operations2015In: Papers of the 23rd European Biomass Conference: Setting the course for a biobased economyExtracted from the Proceedings of the International Conference held in Viennna, Asutria1-4 June 2015 / [ed] Obernberger I, Baxter D, Grassi A, Helm P, ETA-Florence Renewable Energies , 2015, p. 270-272Conference paper (Refereed)
    Abstract [en]

    During extraction of logging residues previous studies in Sweden have shown that up to 50% of the available logging residues will not reach the energy-conversion site. The remaining potential of the logging residues are therefore lost by handling either at the clear-felled site, during transportation or due to decomposition. An outtake of 100% is not possible or desired, since the Swedish Forest Agency recommends that at least 20% of the logging residues should be left at the clear-felled site after a fuel adapted logging operation. In this study the losses at the clear-felled area is examined by studying the distribution of the remaining logging residues under and between the harvester heaps as well amount of logging residues that are left at the roadside landing after comminution. The results show that most of the reaming logging residues are well distributed at the clear-felled area between the harvester heaps. Additional logging residues are left at the clear-felled area since the forwarder cannot gather all logging residues from under the harvester heaps. In addition to this a not insignificant amount of logging residues are left at the roadside landing.

  • 2.
    Nilsson, Bengt
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Nilsson, Daniel
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Distributions and Losses of Logging Residues at Clear-Felled Areas during Extraction for Bioenergy: Comparing Dried- and Fresh-Stacked Method2015In: Forests, ISSN 1999-4907, E-ISSN 1999-4907, Vol. 6, no 11, p. 4212-4227Article in journal (Refereed)
    Abstract [en]

    It is well known that a large proportion of available logging residues intended for extraction will not reach the energy-conversion industry, because some are lost during transportation or left on the clear-felled area. However, there is little understanding of where logging residue losses occur in the supply chain. In this study, the distribution of logging residues for two methods (dried- and fresh-stacked method) to extract logging residues were studied in one clear-felled area. In addition, residue fractions were examined in a detailed comparison. Even though the fresh-stacked method left somewhat more logging residues at the clear-felled area, the differences are small between the methods. Approximately 30% of the total amount of logging residues was left behind between the harvester heaps, with an additional 10%-15% under these heaps and approximately 2%-3% beneath the windrows. The final product that was delivered to the energy-conversion industry was very similar, regardless of the extraction method used. The delivered chipped logging residues had moisture contents of 37% and 36% following fresh- and dried-stacked methods respectively, and in both cases the needle content in the processed logging residues was approximately 10%. However, the total amount of fine fractions (needles and fines) was slightly higher following dried-stacking.

  • 3.
    Nilsson, Daniel
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Lagring av flisade skogsbränslen: - med avseende på att minska energi- och kvalitetsförändringar2011Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
  • 4.
    Nilsson, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Nilsson, Bengt
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Nutrient removal after whole-tree harvesting with the traditional Swedish dried-stacked method for removal of logging residues2015In: Papers of the 23rd European Biomass Conference: Setting the course for a biobased economyExtracted from the Proceedings of the International Conference held in Viennna, Asutria1-4 June 2015 / [ed] Obernberger I, Baxter D, Grassi A, Helm P, ETA-Florence Renewable Energies , 2015, p. 9-13Conference paper (Refereed)
    Abstract [en]

    Bioenergy from logging residues is an important contributor to Swedish energy supplies. Logging residues where long defined and regarded as the unmerchantable aboveground biomass left behind in the clear-felled area, consisting of branches, tops and small trees that are gathered after the round wood harvest, but logging residues are nowadays regarded as a third assortment next to timber and pulpwood with high economic value. However long-term experiments on removal of logging residues from Norway spruce (Picea abies (L.)Karst) stands have shown both growth reductions and growth increase in the next generation, because of decreasing amounts of nutrients. So an increased removal of logging residues requires some sort of compensation of nutrients. Therefore it is of importance to investigate how much nutrients that is removed from the stand after whole-tree harvesting.

    In this study the removal of the nutrients nitrogen (N), phosphorus (P), calcium (Ca), potassium (K) and magnesium (Mg) have been investigated by laboratory analysis of the nutrients together with the actual removal of stemwood, bark and logging residues. The study has also investigated the distribution of nutrients at the clear-felled area.

    The results show that approximately half of the total nutrient removed in whole tree harvesting is done with the removal of stemwood and bark. The results also show that approximately 30% of the total amount of nutrients is left at the clear-felled area.

  • 5.
    Nilsson, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Nilsson, Bengt
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Bergh, Johan
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Amount of nutrients extracted and left behind at a clear-felled area using the fresh-stacked and dried-stacked methods of logging residue extraction2018In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 33, no 5, p. 437-445Article in journal (Refereed)
    Abstract [en]

    Nutrient removal has been one of the key issues since the harvesting of logging residues started in Sweden. This study examined the actual removal of nutrients by measuring the amounts of biomass removed (from a forest products perspective) combined with their respective nutrient concentrations (N, P, Ca, K and Mg), from a clear-felled area when using the dried-stacked and fresh-stacked methods. The most important finding is that the two methods were very similar regarding nutrients remaining at the clear-felled area. Of the nutrients remaining there, most were found to be well distributed between the harvester heaps. Both methods fulfilled the requirements of the Swedish Forest Agency. A sensitivity analysis showed that even if the dried-stacked method left more needles, or the fresh-stacked method extracted more logging residues, there would only be a small impact on the levels of nutrients removed. The sensitivity analysis also showed that the amount of logging residues remaining between the harvester heaps seems to be much more important for nutrients left behind, regardless of extraction method. With this in mind, it is highly probable that improvements to the extraction of logging residues, without increasing nutrient removal, can be made.

  • 6.
    Nilsson, Daniel
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nylinder, Mats
    The Swedish University of Agricultural Sciences.
    Fryk, Hans
    The Swedish University of Agricultural Sciences.
    Nilsson, Jonaz
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Mätning av grotflis2012Report (Other academic)
    Abstract [sv]

    Handeln av grotflis, flis från grenar och toppar vid slutavverkning, har ökatkraftigt under de senaste åren. Inmätningen sker vanligtvis vidmottagningsplatsen och betalningen sker vanligen utifrån energiinnehåll meduppgift om fukthalt.Syftet med denna studie har varit att jämföra olika mätmetoder för grotflissom bygger på volym, vikt och olika sätt att uppskatta fukthalten. Den metodsom antas som facit bygger på 10 prover per container vilket innebär 30prover per leverans. Detta ”facit” har jämförts med sex alternativa sätt attberäkna lassens energivärde. En av metoderna är den som tillämpas av VMFSyd och en annan är en metod som bygger på en finsk modell att uppskattafukthalten. Studien är avgränsad till 44 leveranser grotflis, i huvudask frånbarrträd, under vinter och sommarförhållanden och transporten har skett iekipage om tre fliscontainrar.Medelfukthalten för de vinterkörda leveranserna bestämdes via 10 prov percontainer, LNU/SLU, till 39,3 % medan VMF Syd uppmätte enmedelfukthalt på 38,7 %, via den finska metoden uppskattades fukthalten förde vinterkörda leveranserna till 45,5 %. Medelfukthalten för desommarkörda leveranserna bestämdes av LNU/SLU till 27,9 %, av VMFSyd till 27,0 % meden uppskattningen via den finska metoden gav enmedelfukthalt på 30 %.De vinterkörda ekipagen hade enligt det antagna facit, LNU/SLU, ettenergiinnehåll i medeltal på 104,2 MWh medan energiinnehållet enligtfukthalten från VMF blev energiinnehållet i medeltal 105,7 MWh och dåfukthalten bestämdes med den finska metoden blev energiinnehållet imedeltal 90,8 MWh. För de sommarkörda leveranserna blev energiinnehålleti medeltal 110,8 MWh enligt LNU/SLU, 112,5 MWh enligt VMF Syd och105,7 MWh enligt den finska metoden.När det gäller de olika mätmetoderna visade det sig att M6, energivärde direkt ifrån mätsedel, var den bästa med en kvotspridning på 6,4 % ijämförelse med antaget facitvärde beräknat enligt LNU/SLU. Anledningentill detta är att denna mätning baseras på av fukthalten och beräknat effektivtvärmevärde för varje enskild leverans medan de andra bygger på ett beräknat”erfarenhetstal” för energiinnehåll per ton respektive per m3s förleveranserna i studien. Om mätningen istället baseras på erfarenhetstalistället för fukthaltsmätning visar resultaten att volymmätning ger en mindrekvotspridning, runt 10 %, jämfört med viktbaserad mätning där kvotspridningen hamnar på ca 17 % jämfört med facit. Fukthaltsmätningenligt den finska metoden ger en kvotspridning på ca 15 %.Volymminskningen under transport för alla leveranser i studien uppmättes imedeltal till strax över 2 % och resultaten visar också att den störstavolymminskningen, ca 70 %, sker redan under de första kilometrarna.Skillnaden mellan VMFs volymmätning och den mer noggrannavolymmätningen utförda av LNU/SLU visade sig vara endast 0,5 %. Men dålassen krattats för att möjliggöra denna mätning har även VMFs inmätningförenklats.

  • 7.
    Nilsson, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Pettersson, Roger
    Linnaeus University, Faculty of Technology, Department of Mathematics.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Nylinder, Mats
    The Swedish University of Agricultural Sciences.
    The importance of accurate measurement of comminuted logging residues’ moisture contents for small-scale forest owners2016In: Drewno, ISSN 1644-3985, Vol. 59, no 198, p. 99-110Article in journal (Refereed)
    Abstract [en]

    Bioenergy from logging residues is an important contributor to Swedish energysupplies. Thus, accurate measurements of delivered logging residues’ energycontents are very important for both sellers and buyers. Deliveries’ energycontents are highly correlated with their moisture contents, and thus aredetermined in southern Sweden (and elsewhere) by measuring their masses andmoisture contents. There is insufficient knowledge, however, about the variation inmoisture content within and between deliveries, and hence the minimum numberof samples needed to obtain the required precision. Thus, these variations wereexamined in detail in the presented study. Nested analysis of the variance of theacquired data shows that at least nine samples are required to obtain estimates ofa delivery’s moisture content with a 3% margin of error. For high volume trade,such as that between forest companies and the energy-conversion industry,current measurement practices are sufficiently accurate. For private forest ownersmaking single deliveries, however, higher precision is required as inaccuratemeasurements can strongly affect prices.

  • 8.
    Nilsson, Daniel
    et al.
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Technology, Department of Forestry and Wood Technology.
    Lagring av flisad grot vid värmeverk: en jämförande studie mellan vinter och sommar förhållanden2013Report (Other academic)
    Abstract [sv]

    Företrädare för den energiomvandlande industrin upplever i vissa fall attdet är skillnader i den inmätta energimängden och den energimängd somlevereras ut till kund. Detta gäller även vid beaktande av verkningsgrad iförbränningsanläggningen.Syftet med studien har varit att identifiera och storleksbestämma deskillnader i energiinnehåll hos två stackar om vardera 1000 m3s flisad grotsom mättes in vid leverans, samt efter tre månaders lagring strax innanförbränning. Studien är genomförd under två tidsperioder den enarepresenterande vinter- och den andra sommarförhållande, dålagringsegenskaperna skiljer sig åt beroende på årstid.Medelfukthalten för groten som flisades under den frusna delen av åretbestämdes vid leverans till 41,5 % och var efter tre månaders lagring 42,8%. Substansförlusten noterades till 5,6 % och energiförlusten till 6,1 %.För den grot som flisades under sommarförhållanden bestämdesmedelfukthalten vid leverans till 32,2 % och efter tre månaders lagringhade medelfukthalten i stacken ökat till 44,6 %. Substansförlusternanoterades till 10,1 % och energiförlusten till 14,1 % under de tresommarmånaderna.Den grot som flisades under vinterförhållanden visade vid leverans på ettfuktigare material jämfört med den grot som flisades och levereades undersommarförhållanden. Däremot ökade fukthalten endast marginellt hosbränslet som flisades under vinterförhållandena medan fukthalten ökadeavsevärt under lagringen för bränslet som flisades undersommarförhållandena.Substansförlusterna i stacken med vinterflisad grot såväl som i stackenmed sommarflisad grot visade sig ligga väl i paritet med vad tidigare 

    studier visat med substansförluster på i storleksordningen 2 – 3 % permånad under de tre månader som studien pågick. Energiförlusterna vardäremot betydligt högre för den stack med sommarflisad grot vilket varväntat då både substansförlusterna och fukthaltsökningen var större.

  • 9.
    Sandberg, Dick
    et al.
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Azoulay, Michel
    Baudin, Anders
    Blom, Åsa
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Carlsson, Bo
    Linnaeus University, Faculty of Science and Engineering, School of Natural Sciences.
    Eliasson, Lars
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Johansson, Jimmy
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Kifetew, Girma
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nilsson, Bengt
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nilsson, Daniel
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nilsson, Jonaz
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Nordvall, Hans-Olof
    Thörnqvist, Thomas
    Linnaeus University, Faculty of Science and Engineering, School of Engineering.
    Utvändiga träfasader: Inverkan av materialval, konstruktion och ytbehandling på beständigheten hos fasader av gran och tall2011Report (Other academic)
    Abstract [en]

    The external façade must give expression to a building through both design and colour, and it must also protect the insulating layers in the wall from external influences. These functions can be fulfilled by almost all materials. If wood is to be competitive in this context, the wood material, the façade design and the surface treatment system must be chosen and interact in such a way that the façade is given a long life with little need for maintenance. A wooden façade will then in a broad sense be both economically and aesthetically attractive for the user.

    This study illustrates the state of knowledge regarding the outdoor use of pine (Pinus sylvestris L.) and spruce (Picea abies L. Karst.) facings above ground. Specifically, it deals with the use of wooden facings with regard to the choice of material, façade design, surface treatment and recycling. The market demands wooden facing systems, and the requirements emphasized by the actors on the market, e.g. the builders, real estate administrators, architects, designers, frame suppliers, contractors and representatives for the single-family timber housing industry can be summed up as follows:

    • There must be a specified life-time and given time intervals for maintenance of the wooden facings. (Shall be similar to those of competitive materials)
    • The supplier of the facing system should shoulder the long-term responsibility for its maintenance.
    • Flexibility, the supplier shall be able to replace or renovate the facings when necessary.
    • Building requirements, the wooden facing materials must be able to interact with other, specially fire-classified, materials.
    • The facing system shall have an attractive appearance.

    The primary market for the new facing systems should be multi-family houses but not necessarily multi-family houses of wood. The focus shall lie in the flexibility of the facing system in architectural expression, and in relation to other materials and systems. New building is important, but the million program, renovation and additions (ROT) and greater energy efficiency are also important spheres.

    The Swedish market is small (currently ca. 70 000 m3 wood for façades), but it should nevertheless be given priority before the Nordic countries, and thereafter Switzerland, Austria and Germany. The literature describes more or less well-founded recommendations for prolonging the life of wooden facing materials and extending their maintenance intervals, although some of the recommendations are directly conflicting.

    Many details relating to materials choice, façade design and surface treatment are important for the durability of wooden facings. It is difficult to separate the most important factors, but without taking into consideration aspects such as costs, availability and other factors of a practical nature, the following key factors can be identified as important for an environmentally correct and durable façade of pinewood or spruce:

    Choice of material

    • The wood shall have a high proportion of heartwood, preferably exclusively heartwood
    • The wood shall have vertical annual rings.

    Handling from forest to the façade

    • The wood shall be handled so that it does not suffer mechanical damage or microbial attack, or become wet or soiled, i.e. a rapid and correct handling with good packaging.

    Design

    • The façade shall start at least 30 cm above the ground level.
    • The façade shall be ventilated so that moisture can rapidly dry out. Ventilation of the space behind the facing is an easy way of achieving this.
    • Water run-off – no horizontal surfaces.
    • Flexibility –both in the construction and in the architectural design. There is a demand for facing systems which can be simply “hung onto” existing buildings.

    Surface treatment

    • Sealed end-grain sections – sealing of the end-grain surface to prevent moisture absorption into the wood is decisive for the life-time of the wood material. Nailing can open up new end-grain surfaces and should thus be carried out carefully and only after due consideration.
    • Rounded edges – increase the covering ability of paint and reduce the risk of mechanical damage to the facing boards.
    • Choice of surface treatment – vital for the performance of the facings. The wooden facings shall be delivered as part of the complete maintenance package.

    Nowadays there are many types of surface treatment where nano-technology is used to create an added value in a surface compared with what the more traditional products can offer. Nano-based surface-treatment products are already on the market, and they are said to make the surfaces dirt- and water-repellent, to prevent the growth of algae, fungi and moss, to improve UV- and temperature-resistance and colour permanence, to improve scratch- and abrasion-resistance, and to have anti-graffiti qualities etc. However, most of these products are new and for some of them there are still question marks with regard to their long-term performance and technical life-time, as well as their serviceability and thereto related economy seen from a life-cycle perspective for the product or system for which the surface treatment constitutes only a part.

    A cost analysis carried out as a part of the study makes the assessment that the new nano-technology-based surface-treatment systems could lead at most to a reduction of 15 %. in maintenance costs. The assumption is then that the façade needs to be cleaned every fifth or seventh year when a traditional painting system is used.

    According to the Swedish Standard, recovered wood from a wooden façade is defined as tree fuel and is generally designated recycled wood or, when the material is in a disintegrated form, as recycled chips,

    There is a major problem in recovering energy from recycled wood when a part of the material has been treated in some way, e.g. impregnated with a wood-protection agent or surface-treated, or when it contains other design components of e.g. plastic or metal. Recycled chips are a very good fuel for energy recovery provided the plant has adequate flue-gas cleaning and the ash is handled in a correct manner. Contaminated ash constitutes a problem, since it is classified as dangerous waste and cannot therefore be returned to the forest. If the content of heavy metals is not too high, the ash can be used as a covering and filling material. Otherwise, the ash must be deposited as landfill. A better sorting of household waste and an overhaul of the regulations would mean that the cleaned recycled wood could be burned in conventional biofuel boilers and that the contaminated portion could be burned separately.

     

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