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.