assessed the homogeneous base and acid
catalyzed, heterogeneous and supercritical processes for biodiesel
production from waste vegetable oil using Hysys Plant. This study
showed the heterogeneous acid catalyst process had the lowest
total capital investment (TCI), calculated as 0.63 million dollars for
an 8000 tons/year production plant and manufacturing costs, and
was the only process that had a positive after-tax rate of return,
whereas the supercritical process had the highest TCI of all the
assessed process with 2.15 million