The process simulator ASPEN PLUS was used for simulation of an ethanol production process based on enzymatic hydrolysis of lignocellulosic materials. Various process configurations were studied to increase the overall yield of ethanol and to reduce the energy consumption in the process. An increased utilization of the pentosan fraction was achieved by a complex recycling of streams in the process. This increased the total overall yield from 56% to 70%. Internal recycling of an ethamol containing stream increased the ethanol concentration in the distillation feed from 2.6 to 7.1 wt% which decreased the energy consumption in the distillation from 8 to 2 MW. The recycling will however result in increased concentrations of byproducts and inhibitors which requires future investigation of how these new conditions will affect the performance in the hydrolysis and fermentation steps.