The design principles for one particularly efficient distillation arrangement employing available technology are illustrated. The newly developed temperature dependent UNIQUAC vapor/liquid equilibrium computation methods are utilized in the design of a minimum cost distillation plant for the production of 100 million liters per year of 95 wt % ethanol product. Vacuum distillation and vapor reuse methods are employed. These methods combine synergistically to reduce the distillation energy requirement in concentrating dilute beer feeds. The vapor reuse methods are then extended to demonstrate how 99.9 wt % ethanol are then produced at virtually no additional energy cost.