This work aims to present implementation of renewable fuel production from sweet sorghum on a farm scale. High concentrations of sugar in stalks, simple downstream technology, and minimum upkeep of feedstock make sweet sorghum an ideal candidate for decentralized energy production. The Alcohol Separation Unit (ASU) at Oklahoma State University (OSU) serves as both a research and demonstration prototype unit, first of its kind to study bioethanol production from fermented sweet sorghum liquid feedstock. This pilot plant has been built to establish a robust downstream separation strategy crucial for on-farm bioethanol production. The study investigates four key aspects of the process – equipment and instrumentation, safety, operation and maintenance, and finally economics. The Alcohol Separation Unit has a two-column distillation set up for concentrating ethanol, with associated heat exchangers, pumps, and storage units. Each unit has been designed to work with the sweet sorghum liquid feedstock. This pilot plant was commissioned in Fall 2013. A total of 5000 gallons of sweet sorghum feed containing 5 wt% ethanol have been successfully processed at the pilot plant and 190 proof ethanol was produced in October 2013. The total mass balance closes at 92% and ethanol purities of 193.6 proof at 74oF with rectifier column conditions of 0.8 psig and 171oF were established during processing. Overall economics of the pilot plant indicate fixed capital costs at 403,000 USD. Major unit operation equipment (columns, heat exchangers, storage tanks) makes approximately 50% of the costs. Major energy usage at the pilot plant for ethanol production is steam, which accounts for 75% of total operating costs of 68,000 USD.
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