Notes on this draft:
This draft is provided with suggested visuals, mostly photography. We will
schedule this photography after other drafts in this series are reviewed unless we
can find or purchase stock photos that sill suffice.
This is V1.1 of the diesel fuel module rearranged -- with one exception -- to the
revised outline from the client.
I did not move "low sulfur diesel" and "ultra-low sulfur diesel" fuels to the
alternative fuels section. They are not alternative fuels. Low sulfur diesel is the
regular diesel you buy at the pump every day. Ultra-low sulfur diesel is what
you'll buy at the pump when the new regulations take effect later this year.
Also, while I moved "diesel fuel grades" under diesel properties, I really think they
need to stand on their own as an /H1/ heading.
Finally, I have a section -- contaminants -- which is not on the outline. I came
across this subject while writing and it's in the spot in the copy I feel is most
Diiesel Fuels V-1 3/7/06 1
ELECTRICAL AND ELECTRONIC SYSTEMS
The student will be able to:
1. Describe various diesel fuel properties
2. Describe various diesel fuel additives
3. Describe various alternative fuels used in diesel engines
4. Describe various performance combustion supplements
Terms to Learn
Additives Liquefied natural gas (LNG)
Aromatic content Liquefied petroleum gas (LPG)
Bacteria Low-sulfur fuel
Biodiesel Non-taxed dyes
British Thermal Unit (BTU) Particulate mater
Cetane Pour point
Cloud point Specific gravity
Compressed natural gas (CNG) Sulfur
Contaminants Sulfur dioxide
Diesel fuel grades Volatility
Flash point Ultra-low sulfur fuel
Heat Valve Water injector
(Insert still of diesel fuel pump at gas station)
Diesel fuel is produced from petroleum and is sometimes called petrodiesel. It’s
basically a mixture of hydrocarbons (hydrogen and carbon) extracted from crude
oil through a process called distillation.
Diiesel Fuels V-1 3/7/06 2
During the combustion process, the chemical energy of the fuel is converted into
mechanical energy to power the vehicle.
Compared to gasoline, Diesel fuel contains approximately 18% more energy per
unit of volume. This, combined with the greater fuel efficiency of diesel engines,
contributes to a diesel engine’s relatively better fuel economy compared to a
gasoline engine. Diesel fuel is also simpler to refine than gasoline.
One of the drawbacks of diesel fuel is that it contains higher quantities of sulfur
which result in harmful exhaust emissions.
Strict EPA standards control the amount of sulfur allowed in diesel fuel. To
reduce the sulfur content, the fuel undergoes special processing after distillation.
/H2/ Low Sulfur Diesel Fuel
(Insert still of truck on highway belching black diesel smoke.)
The sulfur level in diesel fuel has been identified as a major contributor to harmful
diesel exhaust particulate and sulfur dioxide emissions.
In October 1993, the EPA limited the sulfur content in diesel fuels intended for
highway vehicles to 500 parts per million (PPM). This was a significant reduction
from the previous standard of 5000 PPM.
This was done to reduce exhaust emissions, particularly particulate mater and
(Insert still of petroleum refinery plant.)
Sulfur content is reduced during refining with one of the most effective processes
being “hydrotreating.” This process involves the introduction of hydrogen into the
refining process to remove sulfur and reduce aromatic hydrocarbons.
Lowering the sulfur content of diesel fuel reduces its “lubricity” or its ability to
lubricate moving arts, especially those in the fuel injection pump and injectors.
Most fuel providers added a lubricity additive into the blend and there are
aftermarket lubricity enhancers available.
/H2/ Ultra-Low Sulfur Diesel Fuel
Ultra-low sulfur is the new standard mandating the sulfur content in diesel fuel
sold for highway vehicles in the United States.
Diiesel Fuels V-1 3/7/06 3
The allowable sulfur content is 15 parts per million (PPM) which is a drop from
the 500 PPM previously allowed.
This new standard will greatly reduce emissions of sulfur compounds (blamed for
acid rain). In fact, the EPA estimates that once this new ultra-low standard is
fully implemented, nitrogen oxide emissions will be reduced by 2.6 million tons
each year. Soot and particulate matter will be reduced by 110,000 tons per year.
In addition to reducing emissions of sulfur compounds, this new fuel standard will
allow the use of far more advanced emission control systems that would not
survive under the previous fuel standard.
These advanced systems can greatly reduce emissions of oxides of nitrogen and
The switch to an ultra-low sulfur standard will further reduce the lubricating
properties of the fuel. Diesel fuel providers will include an additive to restore the
lubricity to required levels to prevent engine damage and maintain service
In addition, the processing used to produce ultra-low sulfur fuel reduces the
aromatics and density of the fuel, which in turn results in a reduction of energy
content (BTU/gallon and a slight drop in fuel mileage.
/H3/ Ultra-Low Sulfur Fuel Introduction Schedule
Ultra-low sulfur fuel will be the only diesel fuel legally available for highway use
starting in 2006.
The new ultra-low sulfur fuel will introduced progressively throughout North
H4/ United States (Except California)
Refinery: June 1, 2006
Terminal: September 1, 2006
Retailer: October 15, 2006
Refinery: June 1, 2006
Terminal: July 15, 2006
Retailer: September 1, 2006
Diiesel Fuels V-1 3/7/06 4
Refinery: June 1, 2006
Terminal: July 15, 2006
Retailer: September 1, 2006
/H1/ Diesel Fuel Properties
The refiner of diesel fuel has several methods of achieving the desired
• Choice of crude oil
• Refinery processing
• Refinery blending
/H2/ Diesel Fuel Grades
Diesel fuel has been categorized by the American Society of Testing Materials
into three classifications or grades. These grades are numbers 1D, 2D and 4D.
Grades 1D and 2D are used in diesel vehicles. Grade 4D is blended for use in
marine applications and large stationary diesel engines that operate at a constant
speed. 4D diesel is not suitable for use in vehicles.
The higher the grade number, the heavier the fuel. Generally speaking, heavier
diesel fuels produce more energy. However, the higher viscosity of a heavier
diesel fuel can inhibit its flow properties in cold weather which can hamper
starting and negatively impact overall engine performance.
/H3/ Diesel Fuel #1
1D is the most refined diesel fuel among the three grades and it is the most
volatile. It’s intended for high-rpm engines that experience frequent changes in
speed and load.
/H3/ Diesel Fuel #2
2D is the grade most commonly used in diesel vehicles, especially in warm to
moderate climates. However, some diesel engines require Number 1D fuel in
order to perform satisfactorily. Always follow the engine manufacturer’s fuel
/H2/ Heat Value
Heat value is the amount of energy stored in one gallon of diesel fuel. The heat
value indicates how well the engine converts the heat energy of combustion into
actual work. Heat value is measured in British Thermal Units (BTUs).
Diiesel Fuels V-1 3/7/06 5
The higher the heat value per gallon of fuel, the more power derived from each
gallon of fuel used.
The BTU content of number 2D diesel fuel is generally higher than that of
number 1D diesel fuel.
/H2/ Specific Gravity
Diesel fuel specific gravity refers to a comparison of the density of fuel versus the
density of water. In other words, specific gravity refers to the ratio of fuel density
to water density.
Water is the standard in this comparison and is assigned a specific gravity of
(Insert still of hydrometer.)
Diesel fuel is lighter than water and therefore its specific gravity will always be
less than one. Specific gravity can be measured with a common hydrometer.
The specific gravity of diesel fuels ranges from 0.8 to 0.94.
Why is this important? Heavier fuels (higher specific gravity) generally have a
higher Heat Value than lighter fuels. This means that specific gravity is a good
indicator of the amount of BTUs present in a diesel fuel. More BTUs equal more
energy and better performance.
(Insert still or illustration of injector spray pattern.)
Specific gravity also has an effect on the spray penetration of the fuel as it is
injected into the combustion chamber. This in turn can impact ignition and
burning characteristics as well as lubrication properties.
You may encounter another scale to measure specific gravity devised by the
American Petroleum Institute (API). On the API scale, diesel fuels range from 20
to 45. Again, the higher the number, the more BTUs contained in the fuel.
/H2/ Cetane Number
The cetane number refers to the ignition quality and is a measure of the ease
with which the liquid diesel fuel is vaporized and ignited in the diesel engine. The
higher the cetane number, the easier the fuel ignites when subjected to the
elevated temperatures and pressures in the engine’s combustion chamber.
A higher cetane number is beneficial during engine starting and warm-up, as well
as in cold weather and in service with prolonged low engine loads.
Diiesel Fuels V-1 3/7/06 6
The cetane rating scale runs from 0 to 100, with 100 being the highest ignition
quality. A high cetane number also equates to lower exhaust emissions.
Typically, diesel vehicle fuels have a cetane number between 40 and 55. A
cetane rating of 40 or above is currently the standard for all on-highway diesel
engines. However, a 50 cetane rating or higher is required in certain areas.
In addition, newer diesel engines may require a higher cetane fuel rating. The
engine service manual will specify which cetane number is required.
Volatility refers to a liquid fuel’s ability to vaporize. Diesel fuel must vaporize in
order to ignite during the engine’s combustion process.
Volatility is measured by the air-vapor ratio formed at a specific temperature.
Diesel fuel volatility is represented by a 90% distillation temperature which is the
temperature at which 90% of the diesel fuel is distilled off
/H2/ Cloud Point
The cloud point is the temperature at which crystals of paraffin wax begin to
appear in the fuel. Another term for cloud point is “wax appearance point.”
(Insert still of container of diesel fuel at cloud point.)
Diesel fuel contains paraffin wax which is desirable as a source of energy and is
normally dissolved in the fuel as a liquid. In cold temperatures, the wax begins to
congeal and solid wax crystals can form in the fuel. These crystals can plug fuel
lines and engine filters which in turn inhibit fuel flow and negatively impact engine
You can actually detect the presence of these wax crystals by a cloudy look to
As a general rule of thumb, if the fuel’s cloud point is at least 10 degrees below
the ambient temperature, the engine performance should not suffer.
Grade 2D diesel fuel has a cloud point of approximately 10 degrees Fahrenheit
(-12 degrees Celsius). Grade 1D has a cloud point of 20 degrees Fahrenheit
(-28.8 degrees Celsius).
Special winter fuel blends, special additives and fuel heaters are all effective
methods of preventing wax formation.
Diiesel Fuels V-1 3/7/06 7
/H2/ Pour Point
Pour point is simply the lowest temperature at which fuel can flow.
The pour point of diesel fuel is 5 degrees Fahrenheit (8.8 degrees Celsius) above
the temperature at which the fuel will not flow. Pour point is also approximately
10 degrees lower than the cloud point.
In other words, as temperatures drop below freezing, wax crystals begin to form
as the fuel reaches its cloud point. If the temperature continues to drop, the fuel
will reach and exceed its pour point becoming too thick to flow and eventually
becomes a solid.
There are additives available which can improve fuel flow and lower the pour
point in extremely cold temperatures.
Viscosity is the degree to which a fluid resists flowing when a force is applied.
Viscosity has an impact on:
• Injector spray atomization
• Ignition characteristics
• Burn efficiency
Viscosity is measured by heating the fuel to a specific temperature (generally 100
degrees Fahrenheit, 38 degrees Celsius) and measuring its flow rate through a
standardized orifice. Viscosity is expressed in either centistokes (cSt) or
seconds Saybolt Universal (SSU).
Diesel fuel viscosity generally falls within a range of 2.4 to 4.1 cSt or 34 SSU.
Any fuel with a lower viscosity is too thin for diesel operation and its use could
lead to engine damage, specifically to the injectors and other fuel system
Diesel fuel also has a low viscosity index. This means the fuel is thin and flows
easily when hot and thickens as the temperature drops.
Diesel fuel can be too thin or too thick for proper engine operation so viscosity is
a critical property in blending diesel fuel.
In diesel engines, fuel pumps and fuel injectors are lubricated by the diesel fuel.
Diiesel Fuels V-1 3/7/06 8
(Insert still of diesel pump)
Diesel fuel lubricity is the measure of a diesel fuels ability to lubricate and reduce
wear on the metal parts of these fuel system components.
/H2/ Flash Point
The flash point of a fuel is the temperature at which vapors formed above the
surface of a liquid fuel will ignite when exposed to an open flame.
Flash point has a minimal effect on engine performance and is more relevant in
the handling and storage of the fuel.
/H2/ Sulfur Content
All diesel fuels contain varying amounts of various sulfur compounds.
Excessive amounts of sulfur in fuel can lead to a number of engine reliability and
performance problems. These include:
• Accelerated piston, piston ring and cylinder wear.
• Varnish formation on piston skirts
• Crankcase oil sludge
• Corrosive damage to finished surfaces, bearings and other engine
• Higher exhaust emissions
• Damage to catalytic converter
To minimize these potential problems and reduce exhaust emissions, regulations
require a sulfur content no greater than .05% in highway diesel fuels.
Sulfur is removed from diesel fuels through a process called hydrotreating. The
process uses hydrogen along with a catalyst at temperatures between 500 – 800
degrees Fahrenheit (260 – 427 degrees Celsius) to create a reaction.
The resulting reaction forms hydrogen sulfide which is separated from the
hydrocarbon thereby lowering the sulfur content of the fuel.
Reducing sulfur will in turn reduce sulfur dioxide emissions and sulfate particles
for reduced harmful exhaust emissions.
/H3/ Reduced Lubricity
Diiesel Fuels V-1 3/7/06 9
One drawback of reducing the sulfur content of fuel is the corresponding drop in
lubrication. Sulfur is the primary lubricating property in diesel fuel and lack of
adequate lubrication can reduce the service life of engine components such as
fuel injectors and injection pumps.
Restoring lubricity is addressed in the blending process and through fuel
/H2/ Aromatic Content
Aromatic content is the presence of the benzene family in hydrocarbon
compounds that occur naturally in the refining of diesel fuel. Other aromatic
compounds of toluene, xylene and naphthalene are also present in the chemical
make-up of the fuel.
The aromatic content of diesel fuel is a product of the distillation process and
contributes to harmful exhaust emissions. To reduce these harmful emissions,
most state regulations now mandate a maximum aromatic content of 35% in on-
highway diesel fuels.
California regulations restrict the aromatics content to less than 10% in order to
Reducing aromatic content to 10% greatly reduces the lubricity of the fuel so
many refiners treat the fuel with a lubricity additive.
Note that diesel fuels with low sulfur, low aromatic content and a high cetane
number enhance engine performance because of improved combustion. The
result is easier engine start-up, smoother running, reduced engine noise and less
/H2/ Carbon Residue
Carbon residue refers to carbon deposits left in the combustion chamber. These
deposits can be caused by incomplete combustion or the use of residual blend
(Insert still of combustion chamber with heavy carbon build-up.)
Excessive carbon deposits can have a negative impact on engine performance.
Soot ash is another type of potentially harmful residue and results from either the
base crude oil or oil additives.
Soot ash can accelerate the wear on components such as fuel injectors, pistons
and piston rings thereby reducing the service life of the engine.
Diiesel Fuels V-1 3/7/06 10
Currently, regulations call for a maximum of .001% soot ash content in on-
highway diesel fuels.
/H1/ Fuel Contaminants
Fuel contamination is common problem in diesel fuels and can affect engine
performance, engine reliability and service life.
Water is the most common type of contamination in diesel fuel and can be the
Water in a diesel fuel system is found in two forms, free and dissolved. Free
water generally comes from one of three sources:
1. Bulk storage tanks
3. Dissolved water
(Insert photo of bulk storage tank.)
As fuel is removed from storage tanks or vehicle fuel tanks, it’s replaced by air
which contains water vapor or humidity. This water vapor is eventually
condensed into liquid water.
The second type of water found in diesel fuel systems is dissolved water.
Dissolved water is found in virtually all diesel fuels. Currently, there is no method
of removing dissolved water from diesel fuel.
Since water is heavier than diesel fuel, it collects at the bottom of the fuel tank or
This water can be mixed with the fuel when the tank bottoms become agitated.
This can occur when a tank is dispensing or receiving fuel.
Water in the fuel can reduce engine power and lead to the corrosion of fuel
Since water cannot pass easily through nozzle orifices, water will accumulate,
vaporize and then cause the tip to blow off the end of an injector.
Diiesel Fuels V-1 3/7/06 11
In extremely cold temperatures, water in a fuel tank can turn to ice. Since ice is
lighter than diesel fuel, it can actually float through the fuel system. This can
create blockages in fuel separators, fuel filters and in extreme conditions, fuel
Plugged fuel filters when the ambient temperature is above 10-degrees
Fahrenheit are generally caused by frozen water and not the fuel itself.
Water also reduces the lubricity of the fuel which can result in seizure and
scoring of moving metal surfaces.
Water can combine with sulfur in the fuel to form a strong corrosive acid.
Water causes rusting of iron components, which in turn produces abrasive iron
oxide particles. Significant quantities of these particles contribute to premature
wear of close-tolerance, moving fuel system components.
Finally, water in fuel contributes to the growth of micro-organisms which can
multiply and eventually plug fuel filters.
/H2/ Fungus and Bacteria
Initially, diesel fuel is sterilized thanks to the high temperatures involved in
refinery processing. However, fuel can quickly become contaminated with
microorganisms present in air or water. These microorganisms contain bacteria
(yeasts) and fungi (molds).
While bacteria and fungi can occur in working fuel tanks, storage tanks where
fuel is held for an extended period of time are a much better growth environment
for this type of contaminant.
Fungus and bacteria are introduced to diesel fuel through air or water and will
spread throughout a fuel system when moisture is present. They actually feed
on the hydrocarbons found in diesel oil.
The presence of fungus and bacteria will shorten the service life of the engine
filters. The only way to prevent these contaminants is through the use of a
biocide fuel additive.
If the contamination has been progressing for a prolonged period of time, a
heavy biofilm may accumulate on the surface of the tank which will prevent the
biocide additives from neutralizing the contaminants. In that case, the tank must
be drained and manually cleaned.
/H1/ Diesel Fuel Additives
Diiesel Fuels V-1 3/7/06 12
(Insert still of a variety of aftermarket additive products.)
For general use, in healthy engines operating in moderate temperatures, no fuel
additives are generally required. In addition, premium brands and
knowledgeable suppliers will often add the additives they feel will best meet the
prevailing conditions or improve the quality of the fuel they sell.
However, even with a high quality fuel, engine performance, cold weather
operation, fuel stability, engine service life and other diesel fuel characteristics
can be improved through the use of additives.
Additives may be added to diesel fuel at the refinery, during distribution, at the
terminal, by the marketer or the ultimate end-user customer. Any additives
added to the fuel after it leaves the terminal are referred to as “aftermarket
/H2/ Non-taxed Dyes
Diesel fuel sold for use on highways is subject to the Federal Highways Fuel Tax
and is clear or amber in color.
Diesel fuel for stationary, commercial marine engines, agricultural and
construction equipment and off-road use is not taxed. Neither is the fuel used in
government agency and Red Cross vehicles. This non-taxed fuel is dyed bright
blue or red to indicate that the tax has not been paid.
(Insert still of container filled with dyed fuel.)
The dye used to mark these fuels is so concentrated that that even a small
amount of dye will mark a large quantity of fuel.
Since it is illegal to use these fuels on highway vehicles, there are hefty fines for
an operator caught using non-taxed fuels.
Also note that off-road diesel fuel has a higher sulfur content which can lead to
catalytic converter failure when used in an engine intended for highway use.
/H2/ Cetane Booster
This additive raises the cetane number of the fuel for faster start-ups, more
efficient ignition, improved power and performance. In some cases, this additive
can also reduce combustion noise and smoke.
/H2/ Biocide Contaminant Control
Diiesel Fuels V-1 3/7/06 13
Biocides are most effective in the prevention of bacteria and fungi as they work to
neutralize the growth of these contaminants. These additives can also be used
with varying degrees of success when bacteria and fungi microorganisms reach
However, if contamination is extreme, the fuel tanks, filters and other fuel system
will have to be cleaned manually.
/H2/ Injector Cleaner (Detergent)
Fuel and crankcase lubricants can form deposits on the fuel injector nozzles.
Excessive deposits can alter the injector spray pattern and reduce the efficiency
of the combustion process and ultimately, the engine’s performance.
Injector deposits can also result in increased exhaust emissions.
Injector cleaners have the ability to bond to an existing deposit and an agent that
dissolves the deposits so they can be burned in the combustion process.
This additive also reduces the opportunity for deposits to form on the injector
/H2/ Lubricity Improvers
Lubricity additives are used to compensate for the poor lubrication qualities of
low sulfur and ultra low sulfur diesel fuels.
Lubricity additives contain a polar group of agents that is attracted to metal
These agents cause the additive to form a thin surface film which acts as a
boundary lubricant when two metal surfaces come into contact.
/H2/ Smoke Suppressants
Smoke suppressants use organometallic compounds as combustion catalysts to
increase the efficiency of the combustion process.
Adding these compounds to a fuel can help to reduce exhaust smoke
particulates, black smoke and carbon dioxide.
/H2/ Corrosion Inhibitors
The presence of water in diesel fuel will ultimately lead to corrosion in pipes,
tanks and other steel fuel system components.
Diiesel Fuels V-1 3/7/06 14
Rust particles will form and break off which can plug fuel filters and increase fuel
pump and injector wear reducing their service life.
Over time, this corrosion will eventually eat holes in the steel components
Corrosion Inhibitors are compounds that that attach to metal surfaces and form a
barrier that prevents corrosion.
/H1/ Winter Fuel Blends
Diesel fuel number 2D loses its ability to flow at temperatures below 20-degrees
Fahrenheit. This is caused by the formation of wax crystals.
(Still of diesel fuel pump in snowy environment.)
Most fuel companies offer a “winter blend” of the diesel fuel they sell during
winter months in cold climates. In other words, Maine may receive a “winter
blend” during winter months while the blend in Florida may not change
throughout the year.
Generally speaking, number 2D diesel fuel performs satisfactorily at or above 10-
In formulating their “winter bend,” oil companies adjust the cloud point (the
temperature at which crystals of paraffin wax begin to appear in the fuel) to suit
the various climatic conditions in different locations and during different times of
Lower the cloud point during winter months is generally done by the addition of
heavier components (napthalenes and aromatics) and other fluidity improver
Some winter blends mix a small amount of Diesel number 1D fuel with 2D fuel.
The addition of about 15% to 20% diesel number 1D to diesel fuel number 2 will
reduce the cloud point of the fuel by about 5 degrees Fahrenheit.
Winter fuel is lighter than summer fuel and is less economical. Both power and
overall mileage suffers when diesel number 1 is added to the blend.
/H2/ Winterizing Additives
A number of aftermarket additives can be added to diesel fuel to minimize fuel
system problems in low-temperature environments.
/H3/ De-icing Additives
Diiesel Fuels V-1 3/7/06 15
Water in diesel fuel freezes at low temperatures. If enough water is present in
the fuel, the resulting ice crystals can block the flow of fuel to the engine by
plugging fuel lines and fuel filters.
De-icing additives incorporating low molecular weight alcohols or glycols can be
added to diesel fuel to prevent ice formation.
They prevent ice formation by giving the resulting additive/water mixture a lower
freezing point than plain water.
/H3/ Low Temperature Additives (Cold Flow Improvers)
These additives (also known as Anti-gel agents) are designed to lower the diesel
fuel’s pour point or cloud point, or improve its cold-flow properties.
They contain polymers which interact with the wax crystals that form in diesel fuel
when it’s cooled below its cloud point.
The polymers minimize the effect of the wax crystals on fuel flow by modifying
their size, shape and formation.
To be effective, these additives must be blended into the fuel while the fuel is
above its cloud point and before the wax crystals have formed.
/H1/ Alternative Fuels
Thanks to the constantly fluctuating price and uncertain availability of petroleum-
based fuels, along with more stringent emissions standards, research is
expanding in the development of alternate fuels.
A number of alternative fuels are currently available but questions of easy
availability, engine modifications, cost and fuel mileage have yet to be answered
limiting their use and overall acceptance in the marketplace.
Biodiesel is a non-fossil fuel obtained from vegetable oil and anima fats.
Biodiesel fuels are biodegradable, non-toxic and have significantly fewer
emissions than petroleum based (petrodiesel) fuels when consumed.
Biodiesel can be made from a number of sources.
• Soybean, rapeseed, mustard, palm oil and hemp.
• Waste vegetable oil
Diiesel Fuels V-1 3/7/06 16
• Animal fats (tallow, lard and yellow grease)
Plants offer the most promising sustainable source of biodiesel fuels. Plants use
photosynthesis to convert solar energy into chemical energy. It’s this chemical
energy that’s released when Biodiesel is burned.
Biodiesel has combustion properties very similar to regular diesel fuel including
viscosity, combustion energy and cetane ratings. It offers the same btu/gallon
ratio as #1 diesel while offering better lubricity.
It can accommodate winterizers and has a gel point slightly higher than diesel #2.
Biodiesel offers a number of environmental benefits:
• It reduces carbon monoxide (CO) emissions by approximately 50% and
carbon dioxide emissions by 78% compared to pretodiesel.
• It contains fewer aromatic hydrocarbons: 56% les benzofluoranthene and
71% less Benzopyrenes.
• It has zero sulfur emissions.
• It reduces the emission of particulates by up to 65%.
Biodiesel can be mixed with regular diesel fuel in any amount, although the most
popular blend is 20 – 30% soybean oil to 70-80% #1 diesel fuel.
As a blend, little or no alteration to the fuel injection system is necessary which
In addition to its advantages, Biodiesel also has a number of drawbacks to
consider. For example, an important point to remember when switching to or
blending Biodiesel is that this alternative fuel has solvent properties that can
clean out the deposits built up from petrodiesel use and can clog fuel filters.
Also note that Biodiesel can harm the rubber gaskets and hoses found in
vehicles manufactured before 1992.
Biodiesel is “hydrophilic” which means it has an affinity for water which as you’ve
read earlier, can cause numerous problems in the fuel system.
Finally, Biodiesel fuel currently costs significantly more than convention petro-
/H2/ Compressed Natural Gas (CNG)
Natural gas is a cleaner alternative to conventional diesel fuel and it produces
very low particulate and nitrogen dioxide emissions.
Diiesel Fuels V-1 3/7/06 17
(Insert still of CNG tank.)
As the name implies, compressed natural gas is compressed and stored in high-
Compressed natural gas is composed primarily of methane and hydrocarbon and
it offers a high carbon-to-hydrogen ratio. Hydrogen is an excellent fuel that
produces good power, good fuel economy and minimal pollution.
Because CNG is a gas, it does not have to be vaporized as a liquid fuel does.
CNG enters the combustion chamber as a vapor making the combustion process
significantly more efficient.
/H2/ Liquefied Natural Gas
Liquefied natural gas is made through a process called liquefaction. Natural gas
is refrigerated to minus 260 degrees Fahrenheit to condense it into a liquid.
The liquefaction process removes most of the water vapor, butane, propane and
other trace gasses. The resulting LNG is more than 98% pure methane.
The LNG returns to a vapor as the temperature rises.
/H2/ Liquefied Petroleum Gas
Liquefied petroleum gas (LPG) is a mixture of gasses produced from petroleum
and made up primarily of propane and butane.
LPG is stored under pressure to keep it in a liquid state. Because the pressure
needed to liquefy the gas is considerable, the containers holding it must be
constructed of heavy steel.
LPG reverts back to a gas when the pressure is sufficiently reduced.
The advantage of converting this gas to a liquid is in transportation and storage.
The fuel is 250 times more dense as a liquid than it is as a fuel meaning more
liquid fuel can be carried and stored in a smaller container.
LPG has combustion qualities that equal or surpass diesel fuel.
It burns with little air pollution, generates minimal solid residue in the engine and
does not dilute the engine lubricants.
/H2/ Water Injection
Diiesel Fuels V-1 3/7/06 18
While water in the fuel is a problem, water in the combustion chamber can
actually enhance performance while reducing emissions.
In certain situations, the introduction of vaporized water into the cylinder at time
of combustion can lower Nitrogen Oxide emissions and soot formation. Water
injection can also result in better fuel economy.
(Insert still of water injection kit or actual engine installation.)
Water helps to cool the inlet charge of fuel which reduces high combustion
temperatures and minimizes detonation.
Water can also be mixed with other additives such as methanol, propane and
CNG to produce more power and torque.
Several after market companies make water injection kits designed for diesel
engines. Care should be used when using water injection as it has the potential
to reduce performance and damage the engine if not installed and calibrated
Diiesel Fuels V-1 3/7/06 19