The HG substrate containing 180–220 g l−1 total
sugars is already used to achieve a corresponding
ethanol concentration of 10–12% (v/v). Low gravity
fermentation significantly increases the energy consumption
in the downstream processes such as the
distillation and waste distillage treatment. The VHG
substrate containing over 250 g l−1 total sugars is
encouraged as a focus for further research into ethanol
fermentations.