Wang, P.S., Thompson, J. & Van Gerpen, J. J Am Oil Chem Soc (2011) 88: 563. doi:10.1007/s11746-010-1691-x
When used as a biodiesel fuel, isopropyl esters are expensive compared to the more common methyl esters. However, isopropyl esters have better cold flow properties than methyl esters, allowing the use of highly saturated feedstocks such as tallow or lard. It has not been determined if isopropyl esters can be part of an economical biodiesel (B100) blend for a specified cloud point, which allows for an objective material cost comparison. This work explores this question through the use of an empirical cloud point model that has been developed and validated. Constrained cost minimization was performed using the cloud point model and historical prices for alcohols and triglycerides. Case studies using 2003 and 2006 average prices are presented. The results indicate that an expensive component such as isopropyl ester can be part of an economical blend under the market conditions. For isopropyl esters to be feasible as an economical blend component, they have to be derived from a highly saturated feedstock that is less expensive than soybean oil by $0.10/lb. This price differential is most applicable to a biodiesel blend that has a cloud point between 5 and 10 °C.