The potential of biodiesel with improved properties to an alternative energy mix

Abstract

Fuels derived from renewable biological sources (biomass) are prominent among the sustainable energy sources. Biodiesel, the mono-alkyl esters of vegetable oils or animal fats, is one of the significant biomass-derived fuels. It is obtained from vegetable oils or other triacylglycerol feedstocks by transesterification with an alcohol giving glycerol as co-product. While biodiesel is technically competitive with petrodiesel fuel, problems that have beset biodiesel include poor cold flow and oxidative stability. These problems are to a great extent due to most biodiesel fuels containing mainly the same five C16 and C18 fatty acid esters. Five methods, including fatty acid profile modifications, exist for overcoming these problems. Properties of neat esters show that enriching acids such as decanoic or palmitoleic acids in feedstocks may improve biodiesel properties. The alcohol also plays a role with esters other than methyl imparting more favorable properties to biodiesel. The technical problems of biodiesel also afflict feedstocks, perhaps more severely, with claimed high production potential. Thus, algae-based biodiesel fuels would likely possess worse cold flow and oxidative stability than most vegetable oil-based biodiesel. Hydrodeoxygenation of vegetable oil feedstocks yields renewable diesel, whose composition thus resembles petrodiesel. Properties, including mass and energy balance of biodiesel and renewable diesel are compared as are potential uses. Biodiesel has a favorable balance compared to other biomass-derived fuels, also when including co-products. For fuels such as biodiesel and others to be more competitive, fuel properties as well as economics and production potential need to be improved. © Springer 2011.