by volume above the limit. Malta has the highest FAME
content at 11.2% by volume.
In the RED, there is a provision that biofuels made
from wastes, residues, non-food cellulosic material and
ligno-cellulosic material count twice toward the required
percentage of energy from renewable sources. France
has limits on how much used cooking oil methyl ester
and animal fat methyl ester can go into a biofuel, but the
United Kingdom has no such restrictions. Customers in
the U.K. have, however, reported more problems than
those in Germany or France.
Crépeau shared data showing a correlation between
the cloud point and the amount of saturated FAME in a
biofuel. (The cloud point is the temperature below which
the waxes in a biofuel start to solidify, giving the fuel a
cloudy appearance.) Animal fat methyl ester and palm
oil methyl ester bring about a similar high cloud point
because of their high saturated FAME content, between 40
and 50%.
FILTER PLUGGING ISSUES
Concawe has investigated the effect that FAME has
on diesel fuel filters. “You would expect that FAME
would lengthen the regeneration intervals of the diesel
particulate filter [DPF] due to lower loading on the DPF, so
we did a study to investigate that,” Hamje said. Here she
refers to the filter that removes soot from the exhaust gas
of a diesel engine. Most filters are designed to burn off the
particulate matter in a process known as regeneration.
Concawe found that increasing FAME to 50% in the fuel
blend increases the kilometres that can be driven between
filter regenerations, as well as reduces fuel consumption
by about 1%. The higher the FAME blend, the more FAME
builds up in the lubricant over time, Hamje said. She
clarified that in general, less regeneration is preferable
because it means there is less deposit on the catalyst, and
less fuel burned in the regeneration process. It should
also be considered, though, that FAME-containing fuels
do get consumed at a slightly higher rate because of their
higher oxygenate content.
Crépeau also referred to lab data on diesel fuel filter
plugging and FAME content. He said that customers were
complaining of filter plugging issues at temperatures
above the cloud point, so a rig test was conducted. When
the filters were analysed, mostly saturated FAME was
found inside. It was also found that monoglycerides do not
