LIFE CYCLE ASSESSMENT OF SOYBEAN OIL PRODUCTION

A life cycle assessment (LCA) case study was conducted on the processing of soybeans to soybean oil. Three stages of soybean oil processing are studied in detail: preprocessing, extraction and separation, and postprocessing. For extraction, hexane (current industrial process) and supercritical CO₂ (research and development [R & D ] laboratory-scale process) methods are compared in detail. The initial life cycle comparison found that the laboratory-scale CO₂ system was not as good in life cycle impacts as the hexane system. However, reasonable engineering improvements typical of scale-up practices would make the CO₂ technology better than hexane and eliminate the hexane emissions. Utilization of membrane techniques to separate the small molecular CO₂ from the soybean oil hydrocarbon appears to be a much better R & D direction for development. This article illustrates the ability to use life cycle as an aid to R & D to select more advantageous directions for process improvement.