Abstract: Embodiments of the present invention concern methods, compositions, and apparatus for the continuous conversion of algal lipids into biodiesel. In some embodiments, the biodiesel is formed in a multi-step sequence, the first steps occurring in the presence of water and a strong acid wherein the lipids are released from the algae by means of mechanical and chemical action and are then hydrolyzed to free fatty acids. In a subsequent step, this free fatty acid mixture is reacted with methanol to generate fatty acid methyl esters (also known as biodiesel). Such methods produce biodiesel from algal lipids without the requirement for separate algal cell lysis or lipid extraction or purification prior to the acid catalysis sequence. In other embodiments, the multi-step acid catalysis sequence occurs at 100° C. at two atmospheres of pressure.