Submitted to: Progress in Energy and Combustion Science (PECS)
Publication Type: Review Article
Publication Acceptance Date: November 18, 2009
Publication Date: December 24, 2009
Citation: Knothe, G.H. 2010. Biodiesel and Renewable Diesel: A Comparison. Progress in Energy and Combustion Science (PECS). 36:364-373. Technical Abstract: The search for alternatives to petroleum-based fuels has led to the development of fuels from various sources, including renewable feedstocks such as fats and oils. Several types of fuels can be derived from these triacylglycerol-derived feedstocks. One of them is biodiesel, which is defined as the mono-alkyl esters of vegetable oils or animal fats. Biodiesel is produced by transesterifying the oil or fat with an alcohol such as methanol under mild conditions in the presence of a base catalyst. Another kind of product that can be obtained from lipid feedstocks is a fuel whose composition simulates that of petroleum-derived diesel fuel. This kind of fuel, probably best termed "renewable diesel," is produced from the fat or oil by a hydrodeoxygenation reaction at elevated temperature and pressure in the presence of a catalyst. This article discusses in a general and comparative fashion aspects such as fuel production and energy balance, fuel properties, environmental effects including exhaust emissions and co-products. The questions if these fuels compete with or complement each other, what the effect of production scale may be and others are addressed.