When a new type of fuel is introduced, it is necessary to ensure
that exhaust gas aftertreatment systems work properly with these
fuels. Today diesel particulate filter (DPF) is an inherent part of
current diesel engine's exhaust gas aftertreatment system due
to stringent exhaust emission limits. The functioning of DPF
depends on the composition of soot particulates of exhaust gas,
whereas the type of soot depends on the fuel used.
To avoid clogging, DPF has to be regenerated regularly. This
regeneration is usually increasing fuel consumption, so the longer
the regeneration interval is, the better is fuel economy. Fuel
quality and engine-out particulate emissions are important factors
affecting to the need of regeneration. Renewable fuels burn cleanly
and produce less particulate emissions than ordinary diesel fuel.
Therefore, the increase of exhaust backpressure is slower enabling
longer regeneration frequency.
Hydrotreating of vegetable oils is an industrial scale
alternative to esterification for producing biobased diesel fuels.
Hydrotreated vegetable oils (HVO) consist of high cetane number
paraffinic hydrocarbons that are free of aromatics and sulfur. HVO
is superior to ester-type biodiesel (FAME) when considering
stability, NOx emissions, tendency to dilute engine oil
and winter conditions.