Björn Hedman

Cassava stems: a new resource to increase food and fuel production

Given the growing global population, mankind must find new ways to lower competition for land between food and fuel production. Our findings for cassava suggest that this important crop can substantially increase the combined production of both food and fuel. Cassava stems have previously been overlooked in starch and energy production. These food‐crop residues contain about 30% starch (dry mass) mostly in the xylem rather than phloem tissue. Up to 15% starch of the stem dry mass can be extracted using simple water‐based techniques, potentially leading to an 87% increase in global cassava starch production. The integration of biofuel production, using residues and wastewater from starch extraction, may bring added value. The cassava roots on which biofuels and other products are based can be replaced by cassava stems without land use expansion, making root starch available as food for additional 30 million people today.

EFFECT OF DRY FRACTIONATION ON PULPING CONDITIONS AND FIBRE PROPERTIES OF REED CANARY GRASS

ABSTRACT A new harvesting system and the fibre properties of reed canary grass (Phalaris arundinacea L.) makes this grass an interesting new raw material source for the pulp and paper industry in the Nordic countries. Pilot scale tests in Finland shows that high quality fine paper can successfully be produced from delayed harvested reed canary grass. Birch pulp can be replaced with reed canary grass pulp in fine paper furnish without any significant differences in the functional properties of paper. To achieve good pulp and paper properties the raw material has to be pre-treated (removal of leaves and sheaths by fractionation) before pulping. Fractionating produces a “chip” fraction of mainly internodes for pulp production and a meal fraction of leaves and sheaths that can be used as biofuel. Fractionation improves the homogeneity of the raw material and the pulp properties. Silica and other minerals, which are considered as a problem in alkaline pulping processes, are concentrated in the meal fraction. Fine material that causes poor drainage of the pulp is also removed in the fractionation process. In this work, different degrees of fractionation have been studied. Pulping conditions and fibre properties for totally unfractionated raw material up to best available raw material (manually fractionated) are compared.