Bioethanol is largely produced by fermentation of sugars obtained through appropriate treatment of biomass feedstocks.  The most common way of separating and purifying ethanol from fermentation broths is by distillation.  In this process, the broth is heated to boiling, and the ethanol separates from the liquid phase by evaporation; the ethanol vapor is then condensed to get the final product.  Distillation is usually a very energy intensive process.  A cheaper and more energy efficient alternative to distillation (based on membrane technology) is being developed by researchers from the Agricultural Research Service (ARS) of the United States Department of Agriculture (USDA).  The equipment is called “spiral wound liquid membrane module”.  In their process, the fermentation broth (which is about 5% to 10% ethanol) enters the membrane module, where a first set of membrane containing a solvent extracts the ethanol from the broth.  In a second set of membranes, the ethanol is separated by evaporation in a vacuum. Finally, the ethanol vapor is condensed to obtain the final product.  More details of their innovative process can be obtained from the USDA-ARS website (URL above)..