NOVELTY - Production of monoesters from triglyceride-containing stream comprising vegetable or animal fats and/or oils, comprises a transesterification process or a fatty acid olefin reaction process. The transesterification process and the fatty acid olefin reaction process uses olefin-containing stream derived from a petroleum or natural gas liquids process plant.    USE - The process is used for producing monoesters which may be employed as biodiesel (claimed). The produced ester can be used for fuel for heating systems, ecological solvents, basic compounds for production of sulfonates of fatty alcohols, amides and ester dimers.    ADVANTAGE - In the case of diesel fuel applications, a product having a lower cloud point is produced than when biodiesel is produced using methanol. The process avoids the possibility of environmental issues resulting from methanol release on biodegradation of biodiesel produced using methanol. It improves the economics of biodiesel production by utilizing lower cost raw materials and/or centralizing production in a refinery or petrochemical plant.    DETAILED DESCRIPTION - Production of monoesters from triglyceride-containing stream comprising vegetable or animal fats and/or oils, comprises a transesterification process or a fatty acid olefin reaction process. The transesterification process comprises hydrolyzing olefins in an olefin containing stream comprising at least one olefin selected from ethylene, propylene, butylenes, amylene and/or hexane, the olefin-containing stream being derived from a petroleum or natural gas liquids process plant, where the olefins are converted to the corresponding alcohol; reacting the corresponding alcohol with triglyceride in the triglyceride containing stream in the presence of a homogeneous or heterogeneous catalyst to produce monoesters and glycerin; and separating the monoesters from the glycerin and optionally purifying the monoesters. The fatty acid olefin reaction process comprises hydrolyzing the triglyceride-containing stream to produce fatty acids and glycerins; and reacting the fatty acids with olefins in an olefin containing stream comprising at least one olefin selected from ethylene, propylene, butylenes, amylene and/or hexane. The olefin-containing stream is derived from a petroleum or natural gas liquids process plant in the presence of a catalyst to produce monoesters.