Published November 2003
In 1900 Rudolf Diesel demonstrated his new compression-ignition engine with peanut oil as fuel. The vegetable oil was supplanted by petroleum-based "diesel" which was less viscous and lower in cost. Today biodiesel (fatty acid alkyl esters) is being promoted as a "green" fuel substitute for petroleum-based diesel. Biodiesel has a number of advantages. It is produced from renewable resources such as vegetable oils and animal fats improving energy security. When blended with petroleum-based diesel up to 20% (B20) by volume it can operate in existing diesel engines without engine modification. It is low in sulfur and particulates reducing these two sources of emissions. It does not require changes in infrastructure (R0205009).
Consumption of petroleum-based diesel and its bio-based counterpart have experienced substantial growth in Europe. Tax incentives enacted in the EU for biodiesel relative to gasoline have resulted in a dramatic expansion of usage and production to fill the demand. In 1992 production of biodiesel was 35,000 tons/yr in 1992 to 2 million tons/yr in 2003 (R0205001). Under consideration by EU is a directive for a minimum fuel content from renewable resources with the goal to increase content from today's <1% to 5.75% by 2010. This corresponds to biodiesel consumption of 9 million tons/yr (R0205003, R0205014, R0205015). The annual consumption of diesel in the US approaches 40 billion gallons. Annual US production of vegetable oils (primarily soybean oil) and animal fats, the feedstock for biodiesel is nearly 35 billion pounds (CEH, Fats and Oils Industry Overview, 220.5000A). If it were all fats and oils converted this volume represents a potential of 4.7 billion gallons of biodiesel (B100). While it will not all be converted, the potential impact of widespread commercialization of biodiesel could be significant.
The production of fuels from renewable resources is encouraged in the US through a series of tax incentives and subsidies. In the United States the Commodity Credit Corporation (CCC) of the USDA administers the subsidy program of approximately $1.50 per gallon (R0205009). The pending Senate's 2003 energy bill (S 1548) contains additional tax incentives for the production of biodiesel (R0205019) broadening the appeal of this fuel alternative.
In this review we analyze the technical and economics aspects for the production of 220 million lb/yr (100,000 t/yr) of "biodiesel" (fatty acid methyl esters) using heterogeneous catalysis. The review is based primarily on patents issued to Institut Francais du Petrole (IFP) and licensed by its subsidiary Axens.
This review will be of interest to fuel, methanol and oleochemical producers.