A review of biomass densification systems to develop uniform feedstock commodities for bioenergy application

Biofuels, Bioproducts and Biorefining

Volumn 5, Issue 6, 2011, Pages 683-707

  Tumuluru, Jaya Shankar ^a   Wright, Christopher T ^a   Hess, J Richard ^a   Kenney, Kevin L ^a  

^a IDAHO NATIONAL LABORATORY   (United States)

Author keywords

Biomass density; Biomass pre treatment; Biomass quality; Densification energy; Densification systems; Solid fuel standards

Indexed keywords

AGGLOMERATOR; AMMONIA FIBER EXPLOSION; BINDING BEHAVIORS; BINDING CHARACTERISTICS; BIO-ENERGY; BIOMASS DENSITY; BIOMASS FEEDSTOCK; BIOMASS QUALITY; END-PRODUCTS; EUROPEAN STANDARDS; FEEDSTOCK COSTS; HANDLING CHARACTERISTICS; INTERNATIONAL MARKETS; LIGNOCELLULOSIC BIOMASS; LIGNOSULFONATES; PRE-TREATMENT; PUBLIC DOMAINS; ROLLER PRESS; SCREW EXTRUDERS; SCREW PRESS; SIZE AND SHAPE; SPECIFIC ENERGY CONSUMPTION; STEAM EXPLOSION; US GOVERNMENT;

BINDERS; BINDING ENERGY; BIOMASS; BRIQUETS; DENSIFICATION; ENERGY UTILIZATION; FUELS; INTERNATIONAL TRADE; PHYSICAL PROPERTIES; PRESSES (MACHINE TOOLS); SCREWS; STANDARDS;

FEEDSTOCKS;

EID: 81255158960     PISSN: 1932104X     EISSN: 19321031     Source Type: Journal    
DOI: 10.1002/bbb.324     Document Type: Review

References (149)

1. Bapat DW, Kulkarni SV and Bhandarkar VP, Design and operating experience on fluidized bed boiler burning biomass fuels with high alkali ash, in Proceedings of the 14th International Conference on Fluidized Bed Combustion, ed by Preto FDS. ASME Publishers, New York, USA, pp. 165-174 (1997).
2. Sokhansanj S and Fenton J, Cost benefit of biomass supply and preprocessing: BIOCAP (Canada) research integration program synthesis paper. [Online]. Available at: [June 22, 2011].
3. Mitchell P, Kiel J, Livingston B and Dupont-Roc G, Torrefied biomass: A foresighting study into the business case for pellets from torrefied biomass as a new solid fuel, in All Energy 2007. University of Aberdeen, ECN, Doosan Babcock, and ITI Energy.
4. Van Loo S and Koppejan J, Handbook of Biomass Combustion and Co-Firing. Earthscan Publication Ltd, London, UK (2008).
5. Tumuluru JS, Wright CT, Kenney KL and Hess JR, A review on biomass densification technologies for energy applications. [Online]. Tech. Report INL/EXT-10-18420, Idaho National Laboratory, Idaho Falls, Idaho, USA (2010). Available at: [June 22, 2011].
6. Ndiema CKW, Manga PN and Ruttoh CR, Influence of die pressure on relaxation characteristics of briquetted biomass. Energy Convers Manage 43:2157-2161 (2002).
7. Adapa PK, Bucko J, Tabil LG, Schoenau G and Sokhansanj S, Pelleting Characteristics of Fractionated Suncure and Dehydrated Alfalfa Grinds. ASAE/CSAE North-Central Intersectional Meeting, Saskatoon, Saskatchewan, Canada, September 27-28 (2002).
8. Adapa PK, Schoenau GJ, Tabil LG, Sokhansanj S and Crerar B, Pelleting of Fractionated Alfalfa Products. ASAE Annual International Meeting, Las Vegas, Nevada, USA, July 27-30 (2003).
9. Li Y and Liu H, High pressure densification of wood residues to form an upgraded fuel. Biomass Bioenerg 19:177-186 (2000).
10. Mani S, Tabil LG and Sokhansanj S, Specific energy requirement for compacting corn stover. Bioresour Technol 97:1420-1426 (2006).
11. Tabil LG, Binding and pelleting characteristics of alfalfa. PhD dissertation, Department of Agricultural and Bioresource Engineering, University of Saskatchewan, Canada (1996).
12. Tabil LG and Sokhansanj S, Compression and compaction behavior of alfalfa grinds, Part 1: Compression behavior. Powder Handling Process 8(1):17-23 (1996).
13. Tabil LG and Sokhansanj S, Compression and compaction behavior of alfalfa grinds, Part 2: Compaction behavior. Powder Handling Process 8(2):117-122 (1996).
14. Rumpf H, The strength of granules and agglomerates, in Agglomeration, ed by Knepper WA. Interscience Publishers (1962), New York, USA, pp. 379-418.
15. Sastry KVS and Fuerstenau DW, Mechanisms of agglomerate growth in green pelletization. Powder Technol 7:97-105 (1973).
16. York P and Pilpel N, The tensile strength and compression behavior of lactose: Four fatty acids and their mixture in relation to tableting. J Pharm Pharmacol 25:1-11 (1973).
17. Pietsch WB, Size enlargement methods and equipments, part 2: Agglomerate bonding and strength, in Handbook of Powder Science and Technology, ed by Fayed ME and Otten L. Van Nostrand Reinhold Co., New York, USA, pp. 231-252 (1984).
18. Schineberger GL, Understanding Adhesives. Hitchcock Publishing Co, Wheaton, IL, USA, pp. 3.6-3.7 (1971).
19. Mani S, Tabil LG and Sokhansanj S, Compaction Characteristics of Some Biomass Grinds. AIC 2002 Meeting, CSAE/SCGR Program, Saskatoon, Saskatchewan, Canada, July 14-17 (2002).
20. Comoglu T, An overview of compaction equations. J Fac Pharm Ankara 36(2):123-133 (2007).
21. Denny PJ, Compaction equations: A comparison of the Heckel and Kawakita equations. Powder Technol 127:162-172 (2002).
22. Muñoz G and Herrera P, Multidimensional Modeling of Agricultural Fibrous Materials in Densification: Compression Stage. ASAE Paper No. 023151. American Society of Agricultural and Biological Engineers (ASABE), St Joseph, MI, USA (2002).
23. Briggs JL, Maier DE, Watkins BA and Behnke KC, Effects of ingredients and processing parameters on pellet quality. Poult Sci 78:1464-1471 (1999).
24. Wood JF, The functional properties of feed raw materials and the effect on the production and quality of feed pellets. Anim Feed Sci Technol 18:1-17 (1987).
25. Thomas M, van Zuilichem DJ and van der Poel AFB, Quality of pelleted animal feed, part 2: Contribution of processes and its conditions. Anim Feed Sci Technol 64:173-192 (1997).
26. van Dam JEG, van den Oever MJA, Teunissen W, Keijsers ERP and Peralta AG, Process for production of high density/high performance binderless boards from whole coconut husk, part 1: Lignin as intrinsic thermosetting binder resin. Ind Crops Prod 19(3):207-216 (2004).
27. Adapa PK, Tabil LG and Schoenau G, Compression characteristics of selected ground agricultural biomass. Ag Eng Int: CIGR Ejournal, Manuscript 1347, 11 (2009).
28. Kaliyan N and Morey RV, Natural binders and solid bridge type binding mechanisms in briquettes and pellets made from corn stover and switchgrass. Bioresource Technol 101:1082-1090 (2010).
29. Feed Machinery, Pellet Mill description. [Online]. Available at: [June 22, 2011].
30. Finney KN, Sharifi VN and Swithenbank J, Fuel pelletization with a binder, part 1: Identification of a suitable binder for spent mushroom compost-coal tailing pellets. Energ Fuel 23:3195-3202 (2009).
31. Leaver R. The Pelleting Process. Andritz Publications, USA (1970).
32. Samuel MA, The chemistry and technology of cereals as food and feed, 2nd ed. Springer, New York, USA (1991).
33. Grover PD and Mishra SK, Biomass briquetting: Technology and practices, in Regional Wood Energy Development Program in Asia, Tech. Report GCP/RAS/154/NET. Food and Agricultural Organization of the United Nations, Bangkok, Thailand (1996).
34. Hassan A, Biomass Briquetting in Sudan: A feasibility study. [Online]. United States Agency for International Development (USAID) (2010). Available at: [June 22, 2011].
35. Song Y, Tumuluru JS, Iroba KL, Tabil LG, Xin M and Meda V, Material and operating variables affecting the physical quality of biomass briquettes, in Proceedings of the XVIIthWorld Congress of the International Commission of Agricultural and Biosystems Engineering (CIGR). Canadian Society for Bioengineering (CSBES/CGAB), Québec City, Canada, June 13-17 (2010).
36. C.F. Nielsen A/S, Briquetting presses and total solutions. [Online]. Available at: [June 22, 2011].
37. Vanengelenhoven J, Energy tablet-making machine for biomass. [Online]. US Department of Energy. Available at: [June 22, 2011].
38. Gibson L, Energy tablets. [Online]. Available at: [June 22, 2011].
39. Sokhansanj S and Turhollow AF, Biomass densification: Cubing operations and costs for corn stover. App Eng Agr 20(4):495-499 (2004).
40. Sokhansanj S and Turhollow AF, Biomass densification: Operations and costs, in Proceedings of Bioenergy 2002 - Bioenergy for the Environment, Boise, ID, USA, Sept 22-26 (2002).
41. Yehia KA, Estimation of roll press design parameters based on the assessment of a particular nip region. Powder Technol 177:148-153 (2007).
42. Kaliyan N, Morey RV, White MD and Doering A, Roll press briquetting and pelleting of corn stover and switchgrass. Transactions of the ASABE 52(2):543-555 (2009).
43. Brewer J, Scientific principles: Materials science and technology teacher's workshop. [Online]. Available at: [June 22, 2011].
44. Olsen J, NAEMI Biomass & Business Training Workshop, Spokane, WA, USA, May 15-19 (2006).
45. Beaudequin F, Mignard B, Boillot M, Girard P and Floret J-F, Agglomeration of charcoal, in Bioenergy 84, ed by Egneus H. et al. Elsevier Science, Barking, UK (1985).
46. Reynieix M, Plancon M and Mohamed FA, Pelletization of vegetable charcoal smalls, in Biomass for Energy and Industry: 4th E.C. Conference, ed by Grassi G. Elsevier Applied Science, New York, USA (1987).
47. Siemons RV, Ahmed Dr. and Hood H, Cotton stalk charcoal agglomeration in the Sudan, Boiling Point, 198900. [Online]. Available at: [June 22, 2011].
48. Snow RH, Allen T, Ennis BJ and Litster JD, Size reduction and size enlargement, in Perry's Chemical Engineers Handbook, 7th edition, ed by Perry RH, Green DW and Maloney JO, McGraw-Hill (1997), New York, U. S. A., pp. 20-189.
49. Mort PR, Scale-up and control of binder agglomeration process-flow and stress fields. Powder Technol 189:313-317 (2009).
50. Reed TB, Trezek G and Diaz L, Biomass densification energy requirements, in Thermal Conversion of Solid Wastes and Biomass. American Chemical Society, Washington DC, USA, pp. 169-177 (1980).
51. Winter E, Fundamental considerations for preparing densified refuse-derived fuel. U.S. Environmental Protection Agency Tech. Report EPA-600/S2-81-180, Mun Env Res Lab, Cincinnati OH (1981).
52. Mewes E, Berechung der druckverteilung an stroh-und heupressen (Calculation of the pressure distribution in straw and hay balers). Landtechnische Forschung 9(6):160-170 (1959).
53. Mohsenin N and Zaske J, Stress relaxation and energy requirements in compaction of unconsolidated materials. J Agric Eng Res 11:193-205 (1975).
54. O'Dogherty MJ and Wheeler JA, Compression of straw to high densities in closed cylindrical dies. J Agric Eng Res 29:61-72 (1984).
55. Aqa S and Bhattacharya SC, Densification of preheated sawdust for energy conservation. Energy 17(6):575-578 (1992).
56. Reed TB and Bryant B, Densified biomass: A new form of solid fuel. Solar Energy Research Institute Report #SERI-35, Golden, CO (1978).
57. Miles TR and Miles Jr., TR, Densification systems for agricultural residues, in Thermal Conversion of Solid Wastes and Biomass, American Chemical Society, Washington, D. C., U. S. A., 179-191 (1980).
58. Neale MA, Straw compaction research. Agricultural Engineer, 4(4): 126-130 (1986).
59. Shepperson G and Marchant WTB, Production of grass and alfalfa cubes using an experimental ring die press, in Proceedings of the 2nd International Green Crop Drying Conference, Saskatoon, Saskatchewan, Canada, 264-270 (1978).
60. Jannasch R, Quan Y, and Samson R, A process and energy analysis of pelletizing switchgrass: Final report [Online]. Available at: (2001) [August 15, 2011].
61. Balk WA, Energy requirements for dehydrating and pelleting coastal Bermuda grass, Trans of the ASAE, 7: 349-351, 355 (1964).
62. Carre J, Hebert L, Lacrosse L and Schenkel Y, Briquetting agricultural and wood residues: Experience gained with a heated die cylindrical screw press, in Handling and Processing of Biomass for Energy: Report and Proceedings, ed by Keller P, CNRE Bulletin (FAO), no. 18, (1987) Rome, Italy, pp. 45-52. European Cooperative Networks on Rural Energy: First Workshop on Handling and Processing of Biomass for Energy, Hamburg, Germany, Sept. 14-15, 1987) Rome, Italy, pp. 45-52. European Cooperative Networks on Rural Energy: First Workshop on Handling and Processing of Biomass for Energy, Hamburg, Germany, Sept. 14-15, 1987.
63. MacMahon MJ, Additives for physical quality of animal feed, in Manufacturing of Animal Feed, ed by Beaven DA. Turret-Wheatland Ltd, Herts, Englpp. 69-70 (1984).
64. Shaw M, Feedstock and process variables influencing biomass densification. PhD dissertation submitted to Department of Agricultural and Bioresource Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada (2008).
65. Hall GE and Hall CW, Heated-die wafer formation of alfalfa and bermudagrass. Trans ASAE 11:578-581 (1968).
66. Smith IE, Probert SD, Stokes RE and Hansford RJ, The briquetting of wheat straw. J Agric Eng Res 22:105-111 (1977).
67. Kaliyan N and Morey R, Densification characteristics of corn stover and switchgrass, ASABE Paper No. 066174, ASABE Annual International Meeting, PortlOR. ASAE, St Joseph, MI, USA, July 9-12, (2006).
68. Yaman Şahan M, Haykiri-açma H, Şeşen K and Küçükbayrak S, Production of fuel briquettes from olive refuse and paper mill waste. Fuel Process Technol 68:23-31 (2000).
69. Demirbas A, Şahin-Demirbaş A and Hilal-Demirbaş A, Briquetting properties of biomass waste materials. Energ Source 26:83-91 (2004).
70. Butler JL and McColly HF, Factors affecting the pelleting of hay. Agric Eng 40:442-446 (1959).
71. Al-Widyan MI, Al-Jalil HF, Abu-Zreig MM and Abu-Handeh NH, Physical durability and stability of olive cake briquettes. Can Biosyst Eng 44: 341-345 (2002).
72. Wamukonya L and Jenkins B, Durability and relaxation of sawdust and wheat-straw briquettes as possible fuels for Kenya. Biomass Bioenerg 8(3):175-179 (1995).
73. Shrivastava M, et al., Briquetting of rice husks under hot compression, in Proceedings of the International Agricultural Engineering Conference and Exhibition. Bangkok, Thailpp. 666-672 (1990).
74. Holm JK, Henriksen UB, Hustad JE and Sørensen LH, Toward an understanding of controlling parameters in softwood and hardwood pellets production. Energy Fuels 20:2686-2694 (2006).
75. Hill B and Pulkinen DA, A study of factors affecting pellet durability and pelleting efficiency in the production of dehydrated alfalfa pellets: A special report, Saskatchewan Dehydrators Association, Tisdale, SK, Canada (1998).
76. Heffiner LE and Pfost HB, Gelatinization during pelleting. Feedstuffs, 45(23):33 (1973).
77. Tumuluru JS, Sokhansanj S, Lim CJ, Bi X, Anthony L, Staffan M, Sowlati T and Ehsan O, Quality of wood pellets produced in British Columbia. App Eng Agr 26(6):1013-1020 (2010b).
78. Kaliyan N and Morey RV, Factors affecting strength and durability of densified biomass products. Biomass Bioenerg 33(3):337-359 (2009).
79. Mani S, Tabil LG and Sokhansanj S, An overview of compaction of biomass grinds. Powder Handling Process 15(3):160-168 (2003).
80. Chirife J and Del Pilar M, Water activity, glass transition, and microbial stability in concentrated/semimoist food systems. J Food Sci 59(5):921-927 (1994).
81. MacBain R, Pelleting Animal Feed. American Feed Manufacturers Association, Arlington, VA, USA (1966).
82. Payne JD, Improving quality of pellet feeds. Mill Feed Fert 161:34-41 (1978).
83. Payne JD, Troubleshooting the pelleting process. [Online]. American Soybean Association Tech. Bulletin #MITA (P) NO. 044/11/96 (FT40-1997) (1997). Available at: [June 22, 2011].
84. Mohan D, Pittman CU and Steele PH, Pyrolysis of wood/biomass for bio-oil: A critical review. Energy Fuel 20:848-889 (2006).
85. Thomas M, van Vliet T and van der Poel AFB, Physical quality of pelleted animal feed, part 3: Contribution of feedstuff components. Anim Feed Sci Technol 70:59-78 (1998).
86. Collado LS and Corke H, Starch properties and functionalities, in Characterization of Cereals and Flours, ed by Kaletunç G and Breslauer KJ. Marcel Dekker, Inc., York, USA, pp. 473-506 (2003).
87. Thomas M, Huijnen PTHJ, van Vliet T, van Zuilichem DJ and van der Poel AFB, Effects of process conditions during expander processing and pelleting on starch modification and pellet quality of tapioca. J Sci Food Agric 79:1481-1494 (1999).
88. Alebiowu G and Itiola OA, Compression characteristics of native and pregelatinized forms of sorghum, plantaand corn starches and the mechanical properties of their tablets. Drug Dev Ind Pharm 28(6):663-672 (2002).
89. Nyanzi FA and Maga JA, Effect of processing temperature on detergent-solubilized protein in extrusion-cooked cornstarch/soy protein subunit blends. J Agric Food Chem 40:131-133 (1992).
90. Sokhansanj S, Mani S, Bi X, Zaini P and Tabil LG, Binderless pelletization of biomass, ASAE Paper No. 056061, ASAE Annual International Meeting, Tampa, FL, USA, July 17-20, 2005. ASAE, St Joseph, MI, USA (2005).
91. Crawford RL, Lignin Biodegradation and Transformation. John Wiley and Sons Inc., New York, USA (1981).
92. Updegraff DM, Semimicro determination of cellulose in biological materials. Anal Biochem 32(3):420-424 (1969).
93. Chen W, Lickfield GC and Yang CQ, Molecular modeling of cellulose in amorphous state, part I: Model building and plastic deformation study. Polymer 45:1063-1071 (2004).
94. Goldstein IS, Composition of biomass, in Organic Chemicals from Biomass, ed by Goldstein IS. CRC Press In., Boca Raton, FL, USA, pp. 9-18 (1981).
95. Nelson DL and Cox MM, Lehninger Principles of Biochemistry. W.H. Freeman and Company, New York, USA (2005).
96. Hon DNS, Cellulosic adhesives, in Adhesives from Renewable Resources, ed by Hemmingway RW and Conner AH. American Chemical Society, Washington DC, USA, pp. 289-304 (1989).
97. Lebo SE Jr, Gargulak JD and McNally TJ, Lignin Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc., New York, USA (2001).
98. Martone PT, Estevez JM, Lu F, Ruel K, Denny MW, Somerville C and Ralph J, Discovery of lignin in seaweed reveals convergent evolution of cell-wall architecture. Curr Biol 19(2):169-175 (2009).
99. Zandersons J, Gravitis J, Zhurinsh A, Kokorevics A, Kallavus U and Suzuki CK, Carbon materials obtained from self-binding sugar cane bagasse and deciduous wood residues plastics. Biomass Bioenerg 26:345-360 (2004).
100. Lehtikangas P, Quality properties of fuel pellets from forest biomass, Licentiate Thesis, Report nr 4. Department of Forest Management and Products, Uppsala (1999).
101. Lehtikangas P, Quality properties of pelletised sawdust: Logging residues and bark. Biomass Bioenerg 20:351-360 (2000).
102. Wilson TO, Factors affecting the wood pellet durability, MSc thesis. Department of Agricultural and Biological Engineering, Pennsylvania State University (2010).
103. Bradfield J and Levi MP, Effect of species and wood to bark ratio on pelleting of southern woods. For Prod J 34:61-63 (1984).
104. Tabil LG, Sokhansanj S and Tyler RT, Performance of different binders during alfalfa pelleting. Can Agric Eng 39(1):17-23 (1997).
105. Tabil LG and Sokhansanj S, Process conditions affecting the physical quality of alfalfa pellets. Am Soc Agric Eng 12(3):345-350 (1996c).
106. Anonymous, Special report, Binders. Milling 166(2):31-33 (1983).
107. Eranki PL, Bals BD and Dale BE, Advanced regional biomass processing depots: A key to the logistical challenges of the cellulosic biofuels industry. BioFPR (under review) (2011).
108. Peleg M, Flowability of food powders and methods for its evaluation-A review. J Food Process Eng 1:303-328 (1977).
109. Peleg M and Mannheim CH, Effect of conditioners on the flow properties of powdered sucrose. Powder Technol 7:45-50 (1973).
110. Bhattacharya SC, Sett S and Shrestha RM, State of the art for biomass densification. Energ Source 11:161-182 (1989).
111. Bhattacharya SC, State-of-the-art of utilizing residues and other types of biomass as an energy source. RERIC Int Energ J 15(1):1-21 (1993).
112. Liu C and Wyman CE, Partial flow of compressed-hot water through corn stover to enhance hemicellulose sugar recovery and enzymatic digestibility of cellulose. Bioresource Technol 96:1978-1985 (2005).
113. Lam PK, Sokhansanj S, Lim CJ, Bi X and Melin S, Energy input and quality of pellets made from steam exploded Douglas Fir (pseudotsugamenziesii). J Energ Fuel (2011) in press.
114. Mosier N, Henderson R, Ho N, Sedlak M and Ladisch MR, Optimization of pH-controlled liquid hot water pretreatment of corn stover. Bioresource Technol 96:1986-1993 (2005).
115. Marchessault RH, Coulombe S, Hanai T and Morikawa H, Vinylic moncmers from bioconversion of wood. 181st National Meeting of the American Chemical Society, Atlanta, GA, USA (1981).
116. Marchessault RH, Coulombe S, Morikawa H and Robert D, Characterization of aspen exploded wood lignin. Can J Chem 1082(60):2372 (1981).
117. DeLong EA, Method of rendering lignin separable from cellulose and hemicellulose in lignocellulosic material and the product so produced. Canada Patent 1096374 (1981).
118. Foody P, Optimization of steam explosion pretreatment, DOE Contract AC02-79ET23050, Final Report. 1 B80 (1980).
119. Kaar WE, Gutierrez CV and Kinoshita CM, Steam explosion of sugarcane bagasse as a pretreatment for conversion to ethanol. Biomass Bioenerg 14(3):277-287 (1998).
120. Toussaint B, Excoffier G and Vignon MR, Effect of steam explosion treatment on the physico-chemical characteristics and enzymic hydrolysis of poplar cell wall components. Anim Feed Sci Technol 32:235-242 (1991).
121. Felfli FF, Luengo CA and Beaton PA, Bench unit for biomass residues torrefaction, in Biomass for Energy and Industry: Proceedings in International Conference, ed by Kopetz H. Wurzburg, Germany, pp 1593-1595 (1998).
122. Zanzi R, Ferro DT, Torres A, Soler PB and Bjornbom E, Biomass torrefaction, in The 6th Asia-Pacific International Symposium on Combustion and Energy Utilization, Kuala Lumpur, May 20-22 (2002).
123. Bourgeois J and Doat J, Proceedings conference on bioenergy. Göteborg 3:153 (1985).
124. Arcate JR, New process for torrefied wood manufacturing. Bioenergy Update 2 (2000) [Online]. Available at: [June 22, 2011].
125. Arcate JR, Global markets and technologies for torrefied wood in 2002. Wood Energy 5:26-28 (2002. Wood Energy 5:26-28 (2002).
126. Shafizedeh F, Pyrolytic reactions and products of biomass, in Fundamentals of Biomass Thermochemical Conversion, ed by Overend RP, Milne TA and Mudge LK. Elsevier, London, UK, pp. 183-217 (1985).
127. Williams PT and Besler S, The influence of temperature and heating rate on the slow pyrolysis of biomass. Renew Energ 7:233-250 (1996).
128. Lipinsky ES, Arcate JR and Reed TB, Enhanced wood fuels via torrefaction, Fuel Chem Div Preprints 47(1):408-410 (2002).
129. Koukios EG, Progress in thermochemical, solid-state refining of biofuels: From research to commericalisation, Adv Th Ch Biomass Conv, 2, Bridgwater (1993).
130. Bergman PCA, Combined torrefaction and pelletisation: The TOP process, ECN Report # ECN-C-05-073 (2005).
131. Teymouri F, Laureano-Perez L, Alizadeh H and Dale BE, Optimization of the ammonia fiber explosion (AFEX) treatment parameters for enzymatic hydrolysis of corn stover. Bioresour Technol 96(18):2014-2018 (2005).
132. Dale BE, Densifying and handling AFEX biomass: A cooperative research project. Northern Plains Biomass Economy. Fargo, ND, USA, September 22 (2009).
133. Tumuluru JS, Kuang X, Sokhansanj S, Lim CJ, Bi X and Staffan M, Development of laboratory studies on the off-gassing of wood pellets. Can Bio Eng 52:8.1-8.9 (2010c).
134. Rhen C, Gref R, Sjöström M and Wästerlund I, Effects of raw material moisture content: Densification pressure and temperature on some properties of Norway spruce pellets. Fuel Process Technol 87(1):11-16 (2005).
135. Tumuluru JS, Tabil LG, Opoku A, Mosqueda MR and Fadeyi O, Effect of process variables on the quality characteristics of pelleted wheat distiller's dried grains with soluble (DDGS). Bio Eng 105(4):466-475 (2010d).
136. Reece FN, Temperature, pressure, and time relationships in forming dense hay wafers, Trans of the ASAE 9:749-751 (1966).
137. Israelsen M, Busk J and Jensen J, Pelleting properties of dairy compounds with molasses, alkali-treated straw and other byproducts. Feedstuffs 7:26-28 (1981).
138. Winowiski T, Wheat and pellet quality. Feed Management 39:58-64 (1988).
139. Stark CR, I. Pellet quality and its effect on swine performance; II. Functional characteristics of ingredients in the formation of quality pellets. PhD dissertation, Kansas State University, Manhattan, KS, USA (1994).
140. Cavalcanti WB, The effect of ingredient composition on the physical quality of pelleted feeds: A mixture experimental approach. PhD dissertation, Kansas State University, Manhattan, KS, USA (2004).
141. Richardson W and Day EJ, Effect of varying levels of added fat in broiler diets on pellet quality. Feedstuffs 48:24 (1976).
142. Angulo E, Brufau J and Esteve-Garcia E, Effect of a Sepiolite product on pellet durability in pig diets differing particle size and in broiler starter and finisher diets. Anim Feed Sci Technol 63:25-34 (1996).
143. Satyanarayana N, Tao Y, Glaser C, Hans-J€org G and Ay P, Increasing the calorific value of rye straw pellets with biogenous and fossil fuel additives. Energy Fuel 24:5228-5234 (2010).
144. Sadaka S and Negi S, Improvements of biomass physical and thermochemical characteristics via torrefaction process. Environ Prog Sustainable Energy 28(3):427-434 (2009).
145. Kleinschmidt C, Overview of international developments in torrefaction. Central European Biomass Conference 2011, Graz, Austria (2011, Graz, Austria (2011). [Online]. Available at: [June 22, 2011].
146. European Committee for Standardization/Technical Specification (CEN/TS), Solid biofuels: Fuel specification and Bradfield classes. Technical specification CEN/TS 14961, Brussels, Belgium (2005).
147. Sjostrom E, Wood chemistry, in Fundamentals and Applications, 2nd Edition, Academic Press, San Diego, CA, USA, pp. 292. (1993).
148. Hancock BC, Colvin JT, Mullarney MP and Zinchuk AV, The relative densities of pharmaceutical powders, blends, dry granulations, and immediate-release tablets. [Online]. Pharmaceutical Technology. (2003) Available at: [June 22, 2011].
149. Shimida Systems [Online]. Available at: [July 20, 2011].