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Journal of Energy in Southern Africa

On-line version ISSN 2413-3051
Print version ISSN 1021-447X

J. energy South. Afr. vol.22 n.4 Cape Town  2011


The technical pre-feasibility to use briquettes made from wood and agricultural waste for gasification in a downdraft gasifier for electricity generation



Pholoso MalatjiI; Ntshengedzeni Sampson MamphweliII; Martina MeinckenI

IDepartment of Forest and Wood Science, Stellenbosch University
IIInstitute of Technology, University of Fort Hare,




Biomass can be converted to energy through various thermochemical and biological processes. Gasification is one of the thermochemical processes that has recently gained popularity, because it achieves higher conversion efficiencies than, for example, incinerators, boilers or furnaces. Fixed-bed downdraft gasifiers are preferred for electricity generation, because they produce very little tar, but on the other hand, they are limited with regard to biomass properties, such as particle size, bulk density and moisture content. Biomass material with a heterogeneous size is usually processed into pellets or briquettes, which have to be mechanically strong enough to be handled. Cohesive strength is provided by residual moisture and lignin present in most biomass. However, the briquetting process becomes more complicated if one wants to add agricultural waste products that do not necessarily contain lignin as binders. The aim of this work was to process wood chips, grape skins and chicken litter into briquettes that are mechanically stable and have a sufficiently high energy content, as well as adequate bulk density for gasification. The performance of these briquettes in a downdraft gasifier was simulated with a program developed for wood, which was modified to optimise the briquette yield. The results showed a gasification performance comparable to solid pine wood, implying that the blended briquettes could be used as fuel for a downdraft biomass gasifier. Unfortunately, the briquettes proved too instable to experimentally verify the performance in a gasifier. This paper describes the properties of the briquettes as well as the gasification simulation results.

Keywords: gasification performance, simulation, various biomass, briquettes



Full text available only in pdf format.



The authors wish to acknowledge T. H. Jayah, Lu Aye, R. J Fuller and D. F Stewart for provision of the downdraft gasifier simulation program.



Demirbas A., (2004). Combustion characteristics of different biomass fuels, Progress in Energy Combustion Science 30 219-230.         [ Links ]

Hagström P, (2006). Biomass potential for heat, electricity and vehicle fuel in Sweden, PhD dissertation, Department of Bioenergy, Swedish University of Agricultural Sciences, Acta Universitatis Agriculturae Sueciae Vol. 11.         [ Links ]

Higman C., van der Burgt M., (2003). Gasification, Elsevier Science, Burlington, USA, p. 67-70.         [ Links ]

Jayah T.H., Lu A., Fuller R.J., Stewart D.F, (2003). Computer simulation of a downdraft wood gasifier for tea drying, Biomass and Bioenergy 25, p. 459-465.         [ Links ]

Kaliyan N., and Morey V. N., (2009). Factors affecting strength and durability of densified biomass products, Biomass and Bioenergy 33 337-359.         [ Links ]

Kaupp A., (1982). Myths and Facts About Gas Producer Engine Systems, presented at the First International Producer Gas Conference, Colombo, Sri Lanka, 8-12 November 1982.         [ Links ]

Maciejewska A., H. Veringa, J. P M. Sanders, and S. D. Peteves, (2006). Co-firing of biomass with coal: Constraints and role of biomass pre-treatment, Luxembourg: Office for Official Publications of the European Communities, 113.         [ Links ]

Malatji P., and Meincken M., (2009). Processing of wood an agricultural waste for gasification, presented at the South African Chemical Engineering Conference, 20-23 September 2009, Somerset West, South Africa.         [ Links ]

Mamphweli N.S., and Meyer E.L., (2009). Implementation of the biomass gasification project for community empowerment at Melani village, Eastern Cape, South Africa, Renewable Energy 34, p. 2923-2927.         [ Links ]

Mamphweli N. S., and Meyer E.L., (2010). Evaluation of the conversion efficiency of the 180Nm3/h Johansson Biomass gasifier, International Journal of Energy and Environment 1, p. 113-120.         [ Links ]

Quaak P, Knoef H., and Stassen H. E., (1999). Energy from biomass: a review of the combustion and gasification technologies, World Bank Technical Paper No 422, Washington DC, USA.         [ Links ]

Rajvanshi A. K., (1986). Biomass Gasification, Alternative Energy in Agriculture, Vol. II, CRC Press, p. 83-102.         [ Links ]

Raveendran K., Ganesh A., and Khilar K. C., (1996). Pyrolysis characteristics of biomass and biomass components, Fuel 75 987-998.         [ Links ]

Remulla J. A., (1982). Gas Manufactures in the Philippines: Status and Prospects, presented at the Technical Consultation Meeting between the Peoples Republic of China and Philippines, 20-23 June 1982.         [ Links ]

Sims C. H., Hassler C. C., and Bean T. L., (2008). Wood Densification, West Virginia University Publication No. 838, 1988., accessed 14/08/2008.         [ Links ]

Shaw M. D., (2008). Feedstock and Process Variables Influencing Biomass Densification, MSc thesis, Department of Agricultural and Bioresource Engineering, University of Saskatchewan, Canada.         [ Links ]

Stassen H. E., (1995). Small scale biomass gasifiers for heat and power: a global review, World Bank Technical Paper No. 296, Washington DC, USA.         [ Links ]

Strehler A., (2000). Technologies of Wood Combustion, Ecological Engineering (Supplement) 16 25-40.         [ Links ]

Walker C. F. J., (2006). Primary Wood Processing: Principles and practice, Springer, Netherlands, p 596.         [ Links ]

Wilaipon P., (2008). Physical Characteristics of Maize Cod Briquettes under Moderate Die Pressure,, visited 10/03/2008.         [ Links ]

White J. W., and McGrew W., (1976). Clean fuels from Biomass, Sewage, Urban Refuse, Agricultural wastes. Symposium Papers presented at the Institute of Gas Technology, Orlando, USA, January, p. 459.         [ Links ]



Received 28 October 2010
Revised 2 June 2011

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