The purpose of this article is
to know all about transesterified lipids. For hydrogenated alkane renewable diesel, see
Vegetable oil refining. For biomass and organic waste-to-fuel production, see
Biomass to liquid. For unmodified vegetable oil used as motor fuel, see
Vegetable oil used as fuel.
Bus run by biodiesel
Biodiesel refers to a vegetable oil-
or animal fat-based diesel fuel consisting of long-chain alkyl (methyl, propyl
or ethyl) esters. Biodiesel is typically made by chemically reacting lipids
(e.g., vegetable oil, animal fat (tallow)) with an alcohol.
Biodiesel is
meant to be used in standard diesel engines and is thus distinct from the
vegetable and waste oils used to fuel converted diesel engines. Biodiesel can
be used alone, or blended with petrodiesel. Biodiesel can also be used as a low
carbon alternative to heating oil.
The National Biodiesel Board (USA) also has
a technical definition of "biodiesel" as a mono-alkyl ester.[1]
Blends
Blends of
biodiesel and conventional hydrocarbon-based diesel are products most commonly
distributed for use in the retail diesel fuel marketplace. Much of the world
uses a system known as the "B" factor to state the amount of
biodiesel in any fuel mix:[2]
• 100% biodiesel is referred to as
B100, while
• 20% biodiesel, 80% petrodiesel is
labeled B20
• 5% biodiesel, 95% petrodiesel is
labeled B5
• 2% biodiesel, 98% petrodiesel is
labeled B2
Blends of less
than 20% biodiesel can be used in diesel equipment with no, or only minor
modifications,[3] although certain manufacturers do not extend warranty
coverage if equipment is damaged by these blends. The B6 to B20 blends are
covered by the ASTM D7467 specification.[4] Biodiesel can also be used in its
pure form (B100), but may require certain engine modifications to avoid
maintenance and performance problems[citation needed]. Blending B100 with
petroleum diesel may be accomplished by:
• Mixing in tanks at manufacturing
point prior to delivery to tanker truck
• Splash mixing in the tanker truck
(adding specific percentages of biodiesel and petroleum diesel)
• In-line mixing, two components
arrive at tanker truck simultaneously.
• Metered pump mixing, petroleum
diesel and biodiesel meters are set to X total volume, transfer pump pulls from
two points and mix is complete on leaving pump.
Applications
Biodiesel can be
used in pure form (B100) or may be blended with petroleum diesel at any
concentration in most injection pump diesel engines. New extreme high-pressure
(29,000 psi) common rail engines have strict factory limits of B5 or B20, depending
on manufacturer.[citation needed] Biodiesel has different solvent properties
than petrodiesel, and will degrade natural rubber gaskets and hoses in vehicles
(mostly vehicles manufactured before 1992), although these tend to wear out
naturally and most likely will have already been replaced with FKM, which is
nonreactive to biodiesel. Biodiesel has been known to break down deposits of
residue in the fuel lines where petrodiesel has been used.[5] As a result, fuel
filters may become clogged with particulates if a quick transition to pure
biodiesel is made. Therefore, it is recommended to change the fuel filters on
engines and heaters shortly after first switching to a biodiesel blend.[6]
Distribution
Since the
passage of the Energy Policy Act of 2005, biodiesel use has been increasing in
the United States.[7] In the UK, the Renewable Transport Fuel Obligation
obliges suppliers to include 5% renewable fuel in all transport fuel sold in
the UK by 2010. For road diesel, this effectively means 5% biodiesel.
[edit] Vehicular
use and manufacturer acceptance
In 2005,
Chrysler (then part of DaimlerChrysler) released the Jeep Liberty CRD diesels
from the factory into the American market with 5% biodiesel blends, indicating
at least partial acceptance of biodiesel as an acceptable diesel fuel
additive.[8] In 2007, DaimlerChrysler indicated its intention to increase
warranty coverage to 20% biodiesel blends if biofuel quality in the United
States can be standardized.[9]
The Volkswagen
Group has released a statement indicating that several of its vehicles are
compatible with B5 and B100 made from rape seed oil and compatible with the EN
14214 standard. The use of the specified biodiesel type in its cars will not
void any warranty. [10]
Starting in
2004, the city of Halifax, Nova Scotia decided to update its bus system to
allow the fleet of city buses to run entirely on a fish-oil based biodiesel.
This caused the city some initial mechanical issues, but after several years of
refining, the entire fleet had successfully been converted.[11][12]
In 2007,
McDonalds of UK announced it would start producing biodiesel from the waste oil
byproduct of its restaurants. This fuel would be used to run its fleet.[13]
Railway usage
British train
operating company Virgin Trains claimed to have run the world's first
"biodiesel train", which was converted to run on 80% petrodiesel and
only 20% biodiesel, and it is claimed it will save 14% on direct emissions.[14]
The Royal Train
on 15 September 2007 completed its first ever journey run on 100% biodiesel
fuel supplied by Green Fuels Ltd. His Royal Highness, The Prince of Wales, and
Green Fuels managing director, James Hygate, were the first passengers on a
train fueled entirely by biodiesel fuel. Since 2007, the Royal Train has
operated successfully on B100 (100% biodiesel).[15]
Similarly, a
state-owned short-line railroad in eastern Washington ran a test of a 25%
biodiesel / 75% petrodiesel blend during the summer of 2008, purchasing fuel
from a biodiesel producer sited along the railroad tracks.[16] The train will
be powered by biodiesel made in part from canola grown in agricultural regions
through which the short line runs.
Also in 2007,
Disneyland began running the park trains on B98 (98% biodiesel). The program
was discontinued in 2008 due to storage issues, but in January 2009, it was
announced that the park would then be running all trains on biodiesel
manufactured from its own used cooking oils. This is a change from running the
trains on soy-based biodiesel.[17]
Aircraft use
A test flight
has been performed by a Czech jet aircraft completely powered on biodiesel.[18]
Other recent jet flights using biofuel, however, have been using other types of
renewable fuels.