In Sweden, stump fuel extraction for energy purposes is not a well-established practice and this major resource is currently left in the forest. The stump fuel supply chain is both challenging and complex, due to distance between resource and end user, material bulkiness, and the number of subprocesses involved. This study examined the impact of different aspects such as site characteristics, fuel quality, biomass losses, and machine performance on fuel cost. Two systems, including transport of comminuted and uncomminuted fuel, were studied. Discrete-event simulation was used to model systems and to analyse the dynamics of the supply chain and its various components. For a distance of 10？km, transportation of uncomminuted fuel gave the lowest costs. For distances from 30 to 70？km, site size (odt) determined whether to comminute or not before transport. For longer distances, comminution before transport proved to be necessary. Well-planned stump storage was shown to reduce the delivery costs significantly, while high moisture content (>45%) had detrimental effects on system costs per unit energy delivered. However, the most influential parameters were productivity level and site characteristics (distance and site size). 1. Introduction Conventional bioenergy assortments, mainly forest industry by-products such as black liquor, bark, sawdust, and shavings, are already utilised to a great extent in Sweden. The potential for growth and development in the bioenergy sector lies in primary forest fuels, for example, small trees, logging residues, and tree stumps, in other words materials previously left in the forest. The largest volume of biomass is in the tree stump assortment, which is currently almost unused [1, 2]. If properly handled, trees stumps are a high-quality fuel [3]. Today softwood tree stumps are harvested on a limited scale in Sweden, but national potential of 20.7？TWh per year has been reported [2]. Due to the stumps geometry of root system, spruce-dominated final felling stands are mainly considered suitable for stump extraction [4]. Extraction can be based on energy and silvicultural considerations [5]. Heat and combined heat and power plants (CHP) are the main consumers of stump fuel today [6]. Other future areas of potential application include biorefineries, liquid biofuel production, and thermal treatment plants [7–9]. Stumps are usually harvested using an excavator in the snow-free season when the ground is not frozen, that is, late spring, summer, and early autumn in the Nordic countries [6]. For both practical and environmental
References
[1]
J. Routa, A. Asikainen, R. Bj？rheden, J. Laitila, and D. R？ser, “Forest energy procurement: state of the art in Finland and Sweden,” Wiley Interdisciplinary Reviews: Energy and Environment, vol. 2, no. 6, pp. 602–613, 2013.
E. Anerud and R. Jirjis, “Fuel quality of norway spruce stumps-influence of harvesting technique and storage method,” Scandinavian Journal of Forest Research, vol. 26, no. 3, pp. 257–266, 2011.
[4]
T. Kalliokoski, P. Nygren, and R. Siev？nen, “Coarse root architecture of three boreal tree species growing in mixed stands,” Silva Fennica, vol. 42, no. 2, pp. 189–210, 2008.
[5]
L. N. Eriksson and L. Gustavsson, “Biofuels from stumps and small roundwood—Costs and CO2 benefits,” Biomass and Bioenergy, vol. 32, no. 10, pp. 897–902, 2008.
[6]
K. K？rh？, “Industrial supply chains and production machinery of forest chips in Finland,” Biomass and Bioenergy, vol. 35, no. 8, pp. 3404–3413, 2011.
[7]
K. Tran, X. Luo, G. Seisenbaeva, and R. Jirjis, “Stump torrefaction for bioenergy application,” Applied Energy, vol. 112, pp. 539–546, 2013.
[8]
D. Eriksson, F. Weiland, H. Hedman et al., “Characterization of Scots pine stump-root biomass as feed-stock for gasification,” Bioresource Technology, vol. 104, pp. 729–736, 2012.
[9]
Y. Pu, D. Zhang, P. M. Singh, and A. J. Ragauskas, “The new forestry biofuels sector,” Biofuels, Bioproducts and Biorefining, vol. 2, no. 1, pp. 58–73, 2008.
[10]
J. Hj？ltén, F. Stenbacka, and J. Andersson, “Saproxylic beetle assemblages on low stumps, high stumps and logs: implications for environmental effects of stump harvesting,” Forest Ecology and Management, vol. 260, no. 7, pp. 1149–1155, 2010.
[11]
J. D. Walmsley and D. L. Godbold, “Stump harvesting for bioenergy—a review of the environmental impacts,” Forestry, vol. 83, no. 1, pp. 17–38, 2010.
[12]
A. Eriksson, L. Eliasson, and R. Jirjis, “Simulation-based evaluation of supply chains for stump fuel,” International Journal of Forest Engineering, vol. 25, pp. 1–14, 2014.
[13]
U. J. Wolfsmayr and P. Rauch, “The primary forest fuel supply chain: a literature review,” Biomass and Bioenergy, vol. 60, pp. 203–221, 2014.
[14]
M. Bertilsson, “Grovkrossning av stubbar [Stump shredding—a study in productivity],” Institutionen f？r Skoglig Resurshush？llning, Sveriges Lantbruksuniversitet, Arbetsrapport, vol. 335, 2011.
[15]
H. von Hofsten and P. Granlund, Effektivare Transporter om Stubbarna Grovkrossas P？avl？gg, Haulage Gain from Crushing Stumps to Coarse Chips at Landing, Resultat Skogforsk, 2010.
[16]
H. von Hofsten and M.-？. Brantholm, “Kostnader och produktivitet i stubbsk？rd—en fallstudie (Productivity and costs in stump harvest systems—a case study),” Skogforsk Arbetsrapport 795, 2013.
[17]
J. Laitila, T. Ranta, and A. Asikainen, “Productivity of stump harvesting for fuel,” International Journal of Forest Engineering, vol. 19, pp. 37–47, 2008.
[18]
M. Laihanen, A. Karhunen, and T. Ranta, “Possibilities and challenges in regional forest biomass utilization,” Journal of Renewable and Sustainable Energy, vol. 5, no. 3, Article ID 033121, 2013.
[19]
R. Jirjis, “Storage and drying of wood fuel,” Biomass and Bioenergy, vol. 9, no. 1–5, pp. 181–190, 1995.
[20]
M. Nylinder and T. Th？rnqvist, Lagring av stubbved i fingerad milj？, Institutionen f？r skogsproduktion, Rapport 121, Sveriges lantbruksuniversitet, Garpenberg, Sweden, 1981.
[21]
J. Laurila and R. Lauhanen, “Moisture content of norway spruce stump wood at clear cutting areas and roadside storage sites,” Silva Fennica, vol. 44, no. 3, pp. 427–434, 2010.
[22]
P. Rauch, “Stochastic simulation of forest fuel sourcing models under risk,” Scandinavian Journal of Forest Research, vol. 25, no. 6, pp. 574–584, 2010.
[23]
R. H. Ballou, Business Logistics Management, Prentice Hall, Englewood Cliffs, NJ, USA, 1992.
[24]
J. Allen, M. Browne, A. Hunter, J. Boyd, and H. Palmer, “Logistics management and costs of biomass fuel supply,” International Journal of Physical Distribution & Logistics Management, vol. 28, pp. 463–477, 1998.
[25]
D. Athanassiadis, O. Lindroos, and T. Nordfjell, “Pine and spruce stump harvesting productivity and costs using a Pallari KH 160 stump-lifting tool,” Scandinavian Journal of Forest Research, vol. 26, no. 5, pp. 437–445, 2011.
[26]
S. C. Grado and M. Jeya Chandra, “A factorial design analysis of a biomass to ethanol production system,” Biomass and Bioenergy, vol. 15, no. 2, pp. 115–124, 1998.
[27]
M. R. Ghaffariyan, M. Acuna, and M. Brown, “Analysing the effect of five operational factors on forest residue supply chain costs: a case study in Western Australia,” Biomass and Bioenergy, vol. 59, pp. 486–493, 2013.
[28]
M. Acuna, L. Mirowski, M. R. Ghaffariyan, and M. Brown, “Optimising transport efficiency and costs in Australian wood chipping operations,” Biomass and Bioenergy, vol. 46, pp. 291–300, 2012.
[29]
H. An and S. W. Searcy, “Economic and energy evaluation of a logistics system based on biomass modules,” Biomass and Bioenergy, vol. 46, pp. 190–202, 2012.
[30]
J. Banks, J. Carson, B. Nelson, and D. Nicol, Discrete-Event System Simulation, Pearson Education, Upper Saddle River, NJ, USA, 2010.
[31]
L. Eliasson, P. Granlund, H. von Hofsten, and R. Bj？rheden, “Studie av en lastbilsmonterad kross—CBI 5800 (Study of a truck-mounted CBI 5800 grinder),” Arbetsrapport 775-2012, 2012.
[32]
M. Nordstr？m, B. Hannrup, E. Anerud, T. Johannesson, H. von Hofsten, and L. Eliasson, “Validation of functions for calculating the quantity of forest fuel in stump harvest—a pilot study,” Skogforsk Arbetsrapport 780-2012, 2012.
[33]
H. von Hofsten, T. Johannesson, and E. Anerud, “Impact of stump splitting on harvest productivity,” Skogforsk Arbetsrapport, vol. 759, 2012.
[34]
H. von Hofsten, T. Johannesson, and E. Anerud, Comparative Study of Two Stump Lifting Heads, Biorex 50 and the Rotary Stump Cutter—Effects on Stump Procurement System from Lifting to Grinding on Landing, vol. 783 of Arbetsrapport Skogforsk, 2012.
[35]
T. Ranta and S. Rinne, “The profitability of transporting uncomminuted raw materials in Finland,” Biomass and Bioenergy, vol. 30, no. 3, pp. 231–237, 2006.
[36]
W. E. Walker, P. Harremo？s, J. Rotmans, et al., “Defining uncertainty: a conceptual basis for uncertainty management in model-based decision support,” Integrated Assessment, vol. 4, pp. 5–17, 2003.
[37]
W. L. Oberkampf, S. M. DeLand, B. M. Rutherford, K. V. Diegert, and K. F. Alvin, “Error and uncertainty in modeling and simulation,” Reliability Engineering and System Safety, vol. 75, no. 3, pp. 333–357, 2002.
[38]
K. K？rh？ and A. Mutikainen, “Testing two novel stump lifting heads in a final felling Norway spruce stand,” in Proceedings of the 4th International Bioenergy Conference—Sustainable Bioenergy Business (Bioenergy '09), M. Savolainen, Ed., vol. 44, pp. 441–448, FINBIO, Jyv？skyl？, Finland, August 2009.
[39]
O. Korpinen, T. Ranta, E. J？ppinen, E. H？m？l？inen, and J. Laitila, “Forest fuel supply chain based on terminals and stumps,” in Proceedings of the International Bioenergy Conference and Exhibition, M. Savolainen, Ed., Finnish Forest Research Institute, Jyvaskyla, Finland, September 2007.
[40]
A. Leinonen, R. Impola, and S. Rinne, “Harvesting of stumps for fuel,” in Bioenergy in Wood Industry, pp. 209–216, 2005.
[41]
E. Anerud, “Stumps as fuel—the influence of handling method on fuel quality,” Acta Universitatis Agriculturae Sueciae, vol. 2012, article 85, 2012.
[42]
T. Th？rnqvist, Logging Residues as a Feedstock for Energy Production—Drying, Storing, Handling and Grading, Sveriges Lantbruksuniversitet, Uppsala, Sweden, 1984.
[43]
S. van Loo and J. Koppejan, The Handbook of Biomass Combustion and Co-Firing, Earthscan, Sterling, Va, USA, 2008.
[44]
O. Balci, “Validation, verification, and testing techniques throughout the life cycle of a simulation study,” Annals of Operations Research, vol. 53, no. 1, pp. 121–173, 1994.
[45]
M. Pettersson and T. Nordfjell, “Fuel quality changes during seasonal storage of compacted logging residues and young trees,” Biomass and Bioenergy, vol. 31, no. 11-12, pp. 782–792, 2007.
[46]
J. S？derstr？m, Grot ur Br？nslekvalitetsynpunkt—En Studie i Attityders Inverkan, Efokus AB, 2009.
[47]
K. K？rh？, “Comparison of two stump-lifting heads in final felling Norway spruce stand,” Silva Fennica, vol. 46, no. 4, pp. 625–640, 2012.
[48]
V. Lazdans, H. von Hofsten, A. Lazdins, and D. Lazdina, “Productivity and costs of stump harvesting for bioenergy production in Latvian conditions,” in Proceedings of the 8th International Scientific Conference Engineering for Rural Development, pp. 28–29, Jelgava, Latvia, May 2009.
[49]
B. Nordén, Sammanst？llning av Studier P？krossar Och Flisare 2007–2009, Skogforsk, 2009.
[50]
A. Asikainen and P. Pulkkinen, “Comminution of Logging Residues with Evolution 910R chipper, MOHA chipper truck, and Morbark 1200 tub grinder,” International Journal of Forest Engineering, vol. 9, no. 1, 1998.
[51]
J.-E. Liss, “Studier p？ nytt fordon f？r transport av skogsflis,” Dalarna University, Wood Technology, Report, Arbetsdokument, Institutionen f？r Matematik, Naturvetenskap och Teknik, Falun, Sweden, 2006.
[52]
R. Mortazavi and J. Johansson, “Road transport vehicles for hauling uncomminuted forest energy products in Sweden,” International Journal of Forestry Research, vol. 2013, Article ID 402349, 7 pages, 2013.
[53]
D. Lindberg, Stubbtransporter och Br？nslekvalitet hos Stubbved [Stump Transport and Fuel Quality in Stumpwood], Arbetsrapport 220, Institutionen f？r Skoglig Resurshush？llning, Sveriges Lantbruksuniversitet, 2008.
