TWO-YEAR STORAGE STUDY WITH METHYL AND ETHYL ESTERS OF RAPESEED

Abstract

Methyl and ethyl esters, prepared from various vegetable oils by the process of transesterification, have shownmuch promise as fuels for all types of diesel engines. Very limited information is available on possible deterioration ofbiodiesel in storage. This project was designed to determine the extent of deterioration of Rape Methyl Ester (RME) andRape Ethyl Ester (REE) in storage. The study involved triplicate samples of RME and REE stored in glass and steelcontainers at room temperature (inside) and at the local ambient outdoor temperatures (outside). The study wasconducted for 24 months. At the beginning of the study and at three-month intervals, samples were taken for measurementof peroxide value, acid value, density, viscosity, and heat of combustion. At the conclusion of the study, engineperformance tests were conducted with the two year stored REE and RME, new REE and RME, and low sulfur dieselreference fuel. On the average, the esters increased over time in all of the previously mentioned properties with theexception of heat of combustion, which decreased. Regression models are presented to predict the deterioration with time.Engine power varied less than 2% for both Biodiesel fuels compared to the stored counterparts while smoke densitydecreased 3.2% for the stored RME and increased 17.5% for stored REE.