7-17: Estimating bioenergy potentials of common African agricultural residues

Monday, April 29, 2013
Exhibit Hall
Sune Tjalfe Thomsen1, Zsófia Kádár1 and Jens Ejbye Schmidt2, (1)Department of Chemical and Biochemical Engineering,, Technical University of Denmark (DTU), Kgs. Lyngby, Denmark, (2)Masdar Institute, Abu Dhabi, United Arab Emirates
Asking a bioenergy researcher about the composition of wheat straw, he would know it by heart. But if enquiring about typical African biomasses – it would be another case. Until now, biomasses common to African countries have not at all received the same scientific attention as biomasses from Europe, North America or Brazil. For that reason, it is difficult to estimate bioenergy potentials in the African region. In this study 13 different African agricultural residues: yam peelings, cassava peelings, cassava stalks, plantain peelings, plantain trunks, plantain leaves, cocoa husks, cocoa pods, maize cobs, maize stalks, rice straw, groundnut straw and oil palm empty fruit bunches, were analysed to establish detailed compositional mass balances, enabling estimations of accurate bioenergy potentials for bioethanol and biogas.

The composition of the residues shows significant differences. Yam, cassava, and plantain peelings have very high bioenergy potentials of up to 41 g bioethanol (100 g TS)-1 and 439 L methane (kg TS)-1 due to a high starch content, while plantain trunks have the highest amount of cellulose, 46 g (100 g TS)-1, which can hold potentials in relation to biomaterials as well as bioenergy. Cocoa pods are unusual rich in lignin, thus poor in carbohydrates and will therefore not be optimal for fermentative processes such as in biogas and bioethanol production.

The findings in this study will be linked to results from project partners who have assessed availability of the agricultural residues, possible low tech pretreatment technologies, and sustainability of the agricultural systems.