Biomass to Liquid (BTL) is the process used to convert any biomass into a liquid biofuel.
Different Biomasses use different processes. To convert soybeans to fuel requires a process called transesterification which separates glycerin from the soybean.
According to the Farm Energy extension, “Soybeans entering the process are first cleaned and then heated and dried to obtain a 10-percent moisture content” (Erickson, 1995). Then the beans are cracked into several pieces by passing them through mechanical rolls. The soybean hulls, which account for about 8 percent of the soybean, are removed by aspiration. The hulls may be blended with the soybean meal that is later extracted in the process, or they may be further treated by toasting and grinding and then sold as animal feed.
Biomass to Liquid, BTL is a complex process.
The dehulled beans or meats are conditioned by heating, cut into flakes, and fed to the oil extraction unit, where the oil from the beans is dissolved with hexane. The oil and hexane mixture is treated with steam to separate the hexane from the oil. Once the hexane is removed, it is recycled for additional processing. Hot air and cooling water are used in the final heating and drying of the oil. The crude soybean oil is degummed and may be deodorized, bleached, and neutralized. The oil-depleted, dried soybeans are ground to a uniform size to make soybean meal, and, in some cases, the hulls are blended with the soybean meal.
Fuel use (including electricity) was the major energy input for soybean oil extraction. The NREL model assumed the highest amount of fuel used. The soybean crushing data reported by NREL were from a single performance study conducted in 1981. There have been many improvements in oil extraction technology since then. For instance, currently acceptable levels of hexane loss are less than one-third of the level reported in the NREL study (Woerfel, 1995). Data used in Pimentel’s model originated from industry interviews from 1979. Data used in Ahmed’s model were from the year 1993, which was collected through personal communications.”
