A small solar energy collector was run to heat lignocellulosic hydrolyzates through an exchanger, and the heated hydrolyzate was concentrated by vacuum membrane distillation (VMD). Under optimal conditions of velocity of 1.0 m/s and 65 degrees C, glucose rejection was 99.5% and the flux was 8.46 L m(-2) h(-1). Fermentation of the concentrated hydrolyzate produced 2.64 times the amount of ethanol as fermentation using the original hydrolyzate. The results of this work indicated the possibility to decrease the thermal energy consumption of lignocellulosic ethanol through using VMD. (C) 2012 Elsevier Ltd. All rights reserved.