manufactured and sold in England is nearly always
manufactured from the most important indigenous oil-bearing
plant – rape. The oil is converted into a modern
diesel fuel with flow and combustion properties very
closely approximating those of conventional mineral
fuels by a simple rebuilding process of its molecular
Biodiesel thereby fulfils the highest requirements
of engine technology such as the modern high-pressure
fuel injection systems (Common Rail).
Biodiesel, is therefore a genuine alternative
to conventional diesel. However, a complete substitution
is impossible. It is estimated that five to seven
percent of the diesel fuel consumption could be replaced
by biodiesel production with indigenous raw materials.
10 percent is conceivable within the European Union.
Biodiesel is therefore now at the peak of all alternative
fuels and, together with other concepts such as hydrogen
engines and fuel cell technology, biodiesel will assume
a supporting role in the mobility of the future, when
the mineral oil wells have run dry
has a natural lead for its development in comparison
with diesel fuel. Its high cetane index, its almost
complete lack of sulphur, is significantly higher
lubricating capability and its built-in oxygen proportion
of around 11 percent make it an intrinsically modern
The higher the cetane index of a diesel fuel, the
better the ignition and combustion and the more regular
and smoother the engine runs. Commonly available diesel
fuels have a cetane index of 50 to 52, and values
of 53 to 54 are achieved by the addition of ignition
accelerators. In this, biodiesel has a natural advantage.
Its primary components are similar to cetane and this
fuel therefore has a natural cetane index of 56 to
58 and can easily fulfill the requirements of engine
manufacturers for high-quality fuels with high inflammability
low sulphur level
Whereas the sulphur content of lowsulphur diesel fuel
is reduced in the refinery in a high-energy process
with additional CO2 emission and a loss of the intrinsic
lubricating capability, biodiesel is naturally almost
free of sulphur (max. 0.001 percent and thereby at
the limit of its detectability). This characteristic
of biodiesel also allows the simple and optimum use
of an oxidation catalytic converter
Significantly Lubrication Capability
Biodiesel has a very good intrinsic lubrication capability.
Trials have shown that biodiesel lies far below the
values specified in the standard for mineral oil diesel.
The so-called HFRR value is a measure of the lubrication
capability. In general, the lower the HFRR value,
the better the fuel. Highly desulphurised mineral
oil diesel fuel has an HFRR value of 500 or higher
without additives, but the limit specified by the
standard for diesel fuel is 450. Mineral oil diesel
fuel therefore requires additives. In contrast, the
HFRR value of biodiesel is approx. 200. Biodiesel
is therefore suitable as a good lubricating additive
to conventional diesel when added in proportions of
only 1 percent. In the operation of an engine approved
for biodiesel, the engine wear is significantly reduced.
biodiesel molecule contains around 11 percent of oxygen.
This oxygen contingent leads to an improved combustion
and thereby to substantially less soot. The residues
left inside the engine by the fuel are significantly
the density of biodiesel is slightly different from
that of mineral diesel fuel, both fuels can be mixed
in any ratio due to their similar chemical structure.
The mixture is stable and cannot be separated by mechanical
methods. It is therefore also impossible to extract
biodiesel which has escaped to the engine oil with
partial flow filters. The subject of mixing will have
more importance in the future in view of the more
stringent emission requirements
compliant with EN 14124 has a flashpoint of over 110
°C and other properties which indicate a lower
potential hazard. For this reason, it is not a hazardous
material and its handling is not subject to the operational
safety rules. This is a great advantage over mineral
oil diesel in storage and handling.
the development of the European standard EN 14214,
the minimum requirements on the quality of biodiesel
were specified mutually at a European level by engine
manufacturers and the biodiesel industry. The European
standard for biodiesel has now become internationally
acknowledged and is a guideline for the standardization
activities conducted by other countries.
from all the technical advantages and features of
biodiesel, there is another more significant aspect
in its favor: its environmental friendliness. Biodiesel
and its use are the origin of local and global effects.
Its rapid biodegradability and its almost closed CO2
cycle set out the enormous bandwidth of its ecological
independent institutes have now confirmed the advantages
of the emissions from biodiesel in comparison with
conventional diesel. For example, when biodiesel is
used with a catalytic converter, only one third of
the quantity of particles is emitted in comparison
with low-sulphur diesel fuel. Unburnt hydrocarbons
are also reduced. Only slightly higher NOx values
have been noted when biodiesel is used. However, this
increase, which is caused by the higher combustion
temperature of biodiesel, is an effect not typical
of the fuel, but of the engine.
contrast, mineral oil diesel fuel is classified as
water-endangering and EN14214 Biodiesel is rapidly
biodegradable. It has been demonstrated that biodiesel
is biologically degraded by over 98 % within 21 days
whereas mineral oil diesel fuel is degraded by only
biodiesel became a serious alternative, there have
been intensive discussions of the pros and cons of
its use. Important aspects such as the material balance,
the energy and CO2 balance has been extensively analysed.
The fundamental advantage of all regenerative energy
sources is their almost completely closed CO2 cycle.
CO2 is released in all combustion processes. However,
the CO2 produced in the combustion of biodiesel has
been absorbed beforehand from the atmosphere by the
rape plant during the photosynthesis process. In contrast
to the use of fossil fuels, the combustion of biodiesel
does not make a new addition. In this way, every litre
of biodiesel which replaces fossil diesel reduces
the greenhouse effect.
it cannot be denied that future developments in Biodiesel
fuels new potentials for the use of native vegetable
oils and these oil wells will never run dry.