Ethanol production from oil palm trunks treated with aqueous ammonia and cellulase

► Oil palm trunks were pretreated for ethanol production. ► Optimum pretreatment conditions were 80 °C, 1:12 S/L ratio, 8 h and 7% ammonia. ► Enzymatic digestibility of pretreated trunks was 95.4% of the theoretical maximum. ► SSF of pretreated trunks yielded 13.3 g/L (titer) and 78.3% (yield) of ethanol.