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The densification of cocoa bean shells for bioenergy purposes

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The densification of cocoa bean shells into pellets was investigated to evaluate their potential as an alternative bioenergy source. The effect of shell particle size, compaction stress, compaction speed and binder addition was studied to ascertain the optimum processing conditions to produce the highest quality pellet. Compressive and tensile strength testing was employed to evaluate the mechanical integrity of the pellets, alongside their resistance to abrasion, impact and water. The results indicated that particle size reduction (to < 1 mm) and the addition of a binder were required to achieve acceptable pellet quality. Water, magnesium stearate and bentonite clay were selected as binding agents based on their industrial viability, accessibility and low cost. It was found that the addition of water or magnesium stearate was detrimental to pellet strength, whereas bentonite clay was found to enhance the strength. Pellets with added bentonite clay were subjected to combustion analysis to ascertain pellet moisture, ash content, elemental composition and calorific value. Promisingly, all pellets with added bentonite clay exceeded the 14.5 MJ kg-1 calorific value requirement set by ISO 17225-6 standards for Grade A ‘non-woody’ pellets.



Biomass densification, Compaction, Cocoa bean shell, Waste, Pellet, Combustion

Journal Title

Biomass and Bioenergy

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Elsevier BV