NOVELTY - Production of a biodiesel product comprising a fatty acid ethyl ester product, comprises (a) processing a raw material source comprising an average of at least 0.5 wt.% of free fatty acids in total oil; (b) extracting the free fatty acids and other reactive lipids from the raw material source and reacting the free fatty acids and other reactive lipids with ethanol using an acid catalyst and a base catalyst to form the fatty acid ethyl ester product; (c) transesterifying any unreacted lipids with ethanol using a base catalyst; and (d) separating the ester product from a glycerin byproduct.    USE - The process is useful for small-scale in situ biodiesel production.    ADVANTAGE - The process can be carried out in a simple and cost-effective manner.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a biodiesel product formed by the process; and    (2) a biodiesel production plant producing a biodiesel product comprising a fatty acid ethyl ester product, comprising a raw materials preparation unit receiving and processing at least one raw material source comprising an average of at least 0.5 wt.% of free fatty acids in total oil, an acid-enhanced solvency and expression-based extractor and in situ reactor unit receiving the raw material source from the raw materials preparation unit and converting the free fatty acids and other reactive lipids in the raw material source to the fatty acid ethyl ester product by acid catalysis and base catalysis with ethanol, an ethanol and catalyst preparation unit supplying ethanol, acid catalyst, and base catalyst to the acid-enhanced solvency and expression-based extractor and in situ reactor unit, and a separation and refining unit receiving a liquid stream comprising the fatty acid ethyl ester product and glycerin from the acid-enhanced solvency and expression based extractor and in situ reactor unit and separating the fatty acid ethyl ester product from the glycerin and impurities in the liquid stream.