Solar distillation of fuel alcohol. Final report

The objective of this project was to demonstrate the application of solar energy to the distillation of ethanol for use as a fuel or fuel additive. An experimental facility was constructed to study the distillation of ethanol from a low concentration in water (10 to 20%) to a high concentration (>90%) using solar energy as the only heat source. Concentrating solar collectors were used to supply energy to a thermocline storage tank which provided a near constant temperature energy source to drive a laboratory scale distillation column. Various tests were performed on each component of the system to study its behavior. The data gathered during these tests were compared to predicted performance from theoretical considerations. Close agreement between theory and experiment was obtained in all cases. In the laboratory, energy was supplied at slightly above 210/sup 0/F to a column of 20 actual trays and a still concentration of 10% ethanol to yield a 90% ethanol distillate. Obviously, solar energy can successfully be utilized for the distillation of fuel alcohol. In an example scenario, 7500 Btu per pound of distillate are found to be needed to produce 90% ethanol. If combusted, this distillate would yield 1.7 times the energy usedmore » to produce it.« less