This review is focused on potential synergy between supercritical (SC) fluid properties and processing/combustion of biodiesel fuels. These fuels are the blending additives of choice for petroleum derived diesel fuels (PDDF) due to overall better performance in the aspects of environment, safety, feedstock, and fuel quality. A typical biodiesel fuel meets commercial specifications of the American Society for Testing and Materials (ASTM D6751) or European Union (EN 14214), and is the only fuel produced on a commercial scale that qualifies as an advanced biodiesel under the Renewable Fuels Standard. Biodiesel fuels, mainly mixtures of fatty acid methyl esters (FAMEs), are currently produced by base/acid catalytic transesterification (BAC-TE) of triglyceride feedstocks with methanol. These methods require refined oil feedstocks and complex product separation/purification that leads to noncompetitive prices compared to PDDFs. Alternatively, has recently been reported a noncatalytic technology based on SC-TE processing of any lipid feedstocks. One version of this technology, the one-step SC-TE method, has reportedly major advantages over the BAC-TE, mainly due to shorter reaction times (5-9 minutes versus 1-6 hours) and the elimination of glycerol to acceptable ASTM levels in fuels of superior quality. The latter advantage originates from glycerol and polyunsaturated FAME thermal conversion to lighter fuel products. Based on a technical and economic analysis, the manufacturing cost of biodiesel fuels from a one-step SC-TE process could be about half of the BAC-TE cost. In order to optimize the biodiesel fuel production and quality leading to a more efficient and clean combustion, the connectivity between fluid properties and fuel processing/combustion is discussed. Highlights and insights from the recently case studies and real world examples of application of the principles of sustainability in the development and implementation of biodiesel fuel projects are given...
Citation: Journal of Supercritical Fluids
Pub Type: Journals
biodiesel fuels, lipid feedstocks, supercritical transesterification, fluid properties, biodiesel supercritical combustion.