Pelleting torrefied biomass at pilot-scale – Quality and implications for co-firing

The co-firing of solid biofuels in coal plants is an attractive and fast-track means cutting emissions but its potential linked to biomass densification. For torrefied materials this topic under-represented literature. This pilot-scale (121–203 kg h−1) pelleting study generated detailed knowledge on the densification compared untreated biomass. Four feedstock with high supply availability (beech, poplar, wheat straw corn cob) were studied their forms. Systematic methods used produce 180 batches 8 mm dia. pellets using press channel length (PCL) moisture content (MC) ranges 30–60 7.3–16.6% (wet basis) respectively. Analysis showed that moderate degrees torrefaction (250–280 °C, 20–75 min) strongly affected behaviour. highest quality black had a mechanical durability bulk density range 87.5–98.7% 662–697 m−3 Pelleting energy varied from −15 +53 kWh t−1 increases production fines. Optimal MC PCL reduced significantly for pellet was characterised by decrease increase density. Energy densities 11.9–13.2 GJ (as received) obtained.