NOVELTY - Continuously producing bio-diesel by a transesterification of animal-derived triglycerides, comprises reacting a first stream comprising the triglycerides with a second stream comprising ethanol, and/or methanol in the presence of fluid carbon dioxide (CO2) within a pressurized conduit for a period of time sufficient to produce bio-diesel and glycerol at a pressure of at least 1000 psia and a temperature of at least 80?OF.    USE - The method is useful for producing bio-diesel from triglycerides.    ADVANTAGE - The method is capable of producing bio-diesel from triglycerides with high purity and without contaminant. The method is less time consuming, and easily processed in an economical manner.    DETAILED DESCRIPTION - Continuously producing bio-diesel by a transesterification of animal-derived triglycerides, comprises: reacting a first stream comprising the triglycerides with a second stream comprising ethanol, and/or methanol in the presence of fluid carbon dioxide (CO2) within a pressurized conduit for a period of time sufficient to produce bio-diesel and glycerol at a pressure of at least 1000 psia and a temperature of at least 80?OF; or rotating the first and second discs in opposite directions, transferring a first stream through at least one of the first or second central conduits, and transferring a second stream through at least one of the first and second central conduits, the streams contact and react to form bio-diesel, and glycerol in the annular space between the first and second discs; or rotating the first and second flanges in opposite directions, rotating the third and fourth flanges in opposite directions, transferring a first stream, and transferring a second stream through at least one of the third and fourth conduits, thus the streams contact and react to form bio-diesel, and glycerol in the annular space between the third and fourth flanges; or rotating the third and fourth flanges in opposite directions, transferring a first stream comprising triglycerides, and transferring a second stream through at least one of the first and second conduits, thus the streams are transferred to spaces around the tapered rollers, where they are compressed to generate sufficient heat and pressure to produce supercritical conditions under which the triglycerides and ethanol, and/or methanol react to form bio-diesel and glycerol. An INDEPENDENT CLAIM is included for an apparatus for combining or mixing fluids.