Amid the seemingly endless debate over the net energy efficiency of corn ethanol, one fact is generally accepted: recovery of ethanol by distillation and subsequent dehydration to anhydrous condition accounts for about 40% of all costs. Why? Because of the high cost of heating broth that is only 10-13% ethanol to 73 F in order to boil off an azeotropic mixture of ethanol:water (96:4 weight ratio). Then, to get to pure anydrous ethanol, molecular sieve drying is usually employed, in a separate process unit.
These two unit processes are outlined in the figure below (left, in dotted outline). Thar's extractive alternative process serves as a drop-in replacement for these units. Operational expenses are cut substantially because of lower energy costs.