Reconsideration of regulated contamination limits to improve filterability of biodiesel and blends with diesel fuels

For the fulfillment of the Directive EU/2001/2018 targets for 2030, one of the main restrictions in the development of biodiesel fuels from sustainable feedstocks are currently the filterability problems. Contaminants such as saturated monoglycerides, sodium soaps and free steryl glucosides in biodiesel fuels have been found to clog fuel filters in vehicles, fuel dispensers and other industrial equipment which reduces the lifetime of the filters, and may result in fuel starvation, with engine operating difficulties and possible fuel-injection equipment damage. From a distilled biodiesel fuel spiked with these contaminants and subsequently blended with diesel fuel, samples fulfilling quality standards were prepared. filter blocking tendency, cold soak filtration test and total contamination tests were measured. It was found that filterability properties were affected always by the highest contaminant contents, both individually and synergistically. Total contamination test presented inconclusive results. The following conclusions were achieved: i) improvements in the precision of filterability and total contamination methods should be searched; ii) future regulations of biodiesel fuels should limit the free steryl-glucoside, saturated monoglyceride and sodium soap contents; iii) the current biodiesel fuel standards around the world do not secure the filterability properties, which could cause premature fuel filter clogging.