We report a scalable method for recovery of cellular lipids and subsequent conversion to products. When in situ transesterification was performed at high solid loadings (>20%( w/w)) by reacting microalgal biomass in acidified methanol (containing 5%(v/v) H2SO4), the released FAMEs were produced at sufficiently high concentrations such that their solubility limit in the reaction medium was exceeded. As a result, the FAMEs spontaneously formed a separate phase lighter than methanol that could be directly recovered without solvent extraction. Further, FAME production rates were easily predicted, even in concentrated biomass slurries, by models derived from fundamental reaction kinetics. Our results also suggest that un-reacted methanol and catalyst, when recovered, could be reused in subsequent reactions. Thus, this "one-pot" process represents a viable method for production of biodiesel from algal biomass since this approach (1) eliminates costs associated with co-solvent (e.g., hexane) use, recovery and storage, (2) is easily scalable by virtue of the reaction not being constrained by mass transport limitations, and (3) facilitates processing of concentrated biomass slurries that would reduce reactor volumes and minimize reactor and handling costs. (C) 2016 Z. Published by Elsevier B.V.