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Diesel fuel , also called diesel oil, is any liquid fuel specifically designed for use in a diesel engine, a type of internal combustion engine in which fuel ignition takes place without a spark as a result of compression of the inlet air and then injection of fuel. Therefore, diesel fuel needs good compression ignition characteristics. The most common type of diesel fuel is a specific fractional distillate of petroleum
fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
, but alternatives that are not derived from petroleum, such as
biodiesel Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil wit ...
,
biomass to liquid Biomass to liquid (BtL or BMtL) is a multi-step process of producing synthetic hydrocarbon fuels made from biomass via a thermochemical route. Main processes According to a study done by the U.S. Department of Agriculture and the Department of En ...
(BTL) or
gas to liquid Gas to liquids (GTL) is a refinery process to convert natural gas or other gaseous hydrocarbons into longer-chain hydrocarbons, such as gasoline or diesel fuel. Methane-rich gases are converted into liquid synthetic fuels. Two general strategies e ...
(GTL) diesel are increasingly being developed and adopted. To distinguish these types, petroleum-derived diesel is sometimes called petrodiesel in some academic circles. In many countries, diesel fuel is standardised. For example, in the European Union, the standard for diesel fuel is
EN 590 EN 590 is a standard published by the European Committee for Standardization that describes the physical properties that all automotive diesel fuel must meet if it is to be sold in the European Union and several other European countries. Based on ...
. Diesel fuel has many colloquial names; most commonly, it is simply referred to as ''diesel''. In the United Kingdom, diesel fuel for on-road use is commonly called ''diesel'' or sometimes ''white diesel'' if required to differentiate it from a tax-advantaged agricultural-only product containing an identifying coloured dye known as ''red diesel''. The official term for white diesel is ''DERV'', standing for ''diesel-engine road vehicle''. In Australia, diesel fuel is also known as distillate (not to be confused with "distillate" in an older sense referring to a different motor fuel), and in Indonesia, it is known as Solar, a trademarked name from the country's national petroleum company Pertamina. The term gas oil ( French: ''gazole'') is sometimes also used to refer to diesel fuel. Ultra-low-sulfur diesel (ULSD) is a diesel fuel with substantially lowered sulfur contents. As of 2016, almost all of the petroleum-based diesel fuel available in the United Kingdom, mainland Europe, and North America is of a ULSD type. Before diesel fuel had been standardised, the majority of diesel engines typically ran on cheap
fuel oils Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
. These fuel oils are still used in watercraft diesel engines. Despite being specifically designed for diesel engines, diesel fuel can also be used as fuel for several non-diesel engines, for example the Akroyd engine, the
Stirling engine A Stirling engine is a heat engine that is operated by the cyclic compression and expansion of air or other gas (the ''working fluid'') between different temperatures, resulting in a net conversion of heat energy to mechanical work. More specif ...
, or boilers for steam engines.


History


Origins

Diesel fuel originated from experiments conducted by German scientist and inventor
Rudolf Diesel Rudolf Christian Karl Diesel (, ; 18 March 1858 – 29 September 1913) was a German inventor and mechanical engineer who is famous for having invented the diesel engine, which burns diesel fuel; both are named after him. Early life and educatio ...
for his compression-ignition engine he invented in 1892. Originally, Diesel did not consider using any specific type of fuel, instead, he claimed that the operating principle of his rational heat motor would work with any kind of fuel in any state of matter. However, both the first diesel engine prototype and the first functional Diesel engine were only designed for liquid fuels. At first, Diesel tested crude oil from
Pechelbronn Merkwiller-Pechelbronn () is a commune in the Bas-Rhin department in Grand Est in north-eastern France. It is notable as the original home of oil sands mining. Oil sands were mined from 1745 in Merkwiller-Pechelbronn, initially under the dire ...
, but soon replaced it with
petrol Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...
and kerosene, because crude oil proved to be too viscous, with the main testing fuel for the Diesel engine being kerosene. In addition to that, Diesel experimented with different types of
lamp oil Kerosene, paraffin, or lamp oil is a combustible hydrocarbon liquid which is derived from petroleum. It is widely used as a fuel in aviation as well as households. Its name derives from el, κηρός (''keros'') meaning "wax", and was regis ...
from various sources, as well as different types of petrol and
ligroin Ligroin is the petroleum fraction consisting mostly of C7 and C8 hydrocarbons and boiling in the range 90‒140 °C (194–284 °F). The fraction is also called heavy naphtha. Ligroin is used as a laboratory solvent. Products under the name ...
, which all worked well as Diesel engine fuels. Later, Diesel tested coal tar
creosote Creosote is a category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood or fossil fuel. They are typically used as preservatives or antiseptics. Some creosote types were ...
, paraffin oil, crude oil,
gasoil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
, and
fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
, which eventually worked as well. In Scotland and France,
shale oil Shale oil is an unconventional oil produced from oil shale rock fragments by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock (kerogen) into synthetic oil and gas. The resulting oil c ...
was used as fuel for the first 1898 production Diesel engines because other fuels were too expensive. In 1900, the French Otto society built a Diesel engine for the use with crude oil, which was exhibited at the
1900 Paris Exposition The Exposition Universelle of 1900, better known in English as the 1900 Paris Exposition, was a world's fair held in Paris, France, from 14 April to 12 November 1900, to celebrate the achievements of the past century and to accelerate developme ...
Rudolf Diesel: ''Die Entstehung des Dieselmotors'', Springer, Berlin/Heidelberg 1913, p. 115 and the 1911 World's Fair in Paris. The engine actually ran on
peanut oil Peanut oil, also known as groundnut oil or arachis oil, is a vegetable oil derived from peanuts. The oil usually has a mild or neutral flavor but, if made with roasted peanuts, has a stronger peanut flavor and aroma. It is often used in Americ ...
instead of crude oil, and no modifications were necessary for peanut oil operation. During his first Diesel engine tests, Diesel also used illuminating gas as fuel, and managed to build functional designs, both with and without pilot injection. According to Diesel, neither was a coal-dust–producing industry existent, nor was fine, high quality coal-dust commercially available in the late 1890s. This is the reason why the Diesel engine was never designed or planned as a coal-dust engine. Only in December 1899, did Diesel test a coal-dust prototype, which used external mixture formation and liquid fuel pilot injection. This engine proved to be functional, but suffered from piston ring failure after a very few minutes due to coal dust deposition.


Since the 20th century

Before diesel fuel had been standardised, diesel engines typically ran on cheap fuel oils. In the United States, these were distilled from petroleum, whereas in Europe, coal-tar creosote oil was used. Some diesel engines were fuelled with mixtures of several different fuels, such as petrol, kerosine, rapeseed oil, or lubricating oil, because they were untaxed and thus cheap. The introduction of motor-vehicle diesel engines, such as the
Mercedes-Benz OM 138 The Mercedes-Benz OM 138 is a diesel engine manufactured by Daimler-Benz. In total, 5,719 units were produced between 1935 and 1940.According to Oswald, 1,082 engines were made for the L 1100 and 2,670 were made for the L 1500. Daimler says t ...
, in the 1930s meant that higher quality fuels with proper ignition characteristics were needed. At first no improvements were made to motor-vehicle diesel fuel quality. After World War II, the first modern high quality diesel fuels were standardised. These standards were, for instance, the DIN 51601, VTL 9140-001, and NATO F 54 standards.Hans Christian Graf von Seherr-Thoß (auth.): Die Technik des MAN Nutzfahrzeugbaus. In: MAN Nutzfahrzeuge AG (ed.): Leistung und Weg: Zur Geschichte des MAN Nutzfahrzeugbaus. Springer, Berlin/Heidelberg 1991. . p. 437 In 1993, the DIN 51601 was rendered obsolete by the new EN 590 standard, which has been used in the European Union ever since. In sea-going watercraft, where diesel propulsion had gained prevalence by the late 1970s due to increasing fuel costs caused by the
1970s energy crisis The 1970s energy crisis occurred when the Western world, particularly the United States, Canada, Western Europe, Australia, and New Zealand, faced substantial petroleum shortages as well as elevated prices. The two worst crises of this period w ...
, cheap
heavy fuel oil Heavy Fuel Oil (HFO) is a category of fuel oils of a tar-like consistency. Also known as bunker fuel, or residual fuel oil, HFO is the result or remnant from the distillation and cracking process of petroleum. For this reason, HFO is contaminate ...
s are still used instead of conventional motor-vehicle diesel fuel. These heavy fuel oils (often called Bunker C) can be used in diesel-powered and steam-powered vessels.Günter Mau: Handbuch Dieselmotoren im Kraftwerks- und Schiffsbetrieb, Springer-Vieweg, Braunschweig/Wiesbaden 1984, . p. 13


Types

Diesel fuel is produced from various sources, the most common being petroleum. Other sources include biomass,
animal fat Animal fats and oils are lipids derived from animals: oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides. Although many animal parts and secretions may yield oil, in commercial ...
,
biogas Biogas is a mixture of gases, primarily consisting of methane, carbon dioxide and hydrogen sulphide, produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste and food waste. It is a ...
,
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbon di ...
, and coal liquefaction.


Petroleum diesel

Petroleum diesel, also called petrodiesel, fossil diesel, or mineral diesel, is the most common type of diesel fuel. It is produced from the
fractional distillation Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to ...
of crude oil between at
atmospheric pressure Atmospheric pressure, also known as barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as , which is equivalent to 1013.25 millibars, ...
, resulting in a mixture of carbon chains that typically contain between 9 and 25 carbon atoms per molecule.


Synthetic diesel

Synthetic diesel can be produced from any carbonaceous material, including biomass, biogas, natural gas, coal and many others. The raw material is gasified into
synthesis gas Syngas, or synthesis gas, is a mixture of hydrogen and carbon monoxide, in various ratios. The gas often contains some carbon dioxide and methane. It is principly used for producing ammonia or methanol. Syngas is combustible and can be used as ...
, which after purification is converted by the Fischer–Tropsch process to a synthetic diesel. The process is typically referred to as biomass-to-liquid (BTL),
gas-to-liquid Gas to liquids (GTL) is a refinery process to convert natural gas or other gaseous hydrocarbons into longer-chain hydrocarbons, such as gasoline or diesel fuel. Methane-rich gases are converted into liquid synthetic fuels. Two general strategies e ...
(GTL) or coal-to-liquid (CTL), depending on the raw material used. Paraffinic synthetic diesel generally has a near-zero content of sulfur and very low aromatics content, reducing unregulated emissions of toxic hydrocarbons, nitrous oxides and particulate matter (PM).


Biodiesel

Biodiesel Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil wit ...
is obtained from vegetable oil or animal fats (bio lipids) which are mainly fatty acid methyl esters (FAME), and transesterified with methanol. It can be produced from many types of oils, the most common being
rapeseed Rapeseed (''Brassica napus ''subsp.'' napus''), also known as rape, or oilseed rape, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed, which naturally contains ...
oil (rapeseed methyl ester, RME) in Europe and soybean oil (soy methyl ester, SME) in the US. Methanol can also be replaced with ethanol for the transesterification process, which results in the production of ethyl esters. The transesterification processes use catalysts, such as sodium or potassium hydroxide, to convert vegetable oil and methanol into biodiesel and the undesirable byproducts glycerine and water, which will need to be removed from the fuel along with methanol traces. Biodiesel can be used pure (B100) in engines where the manufacturer approves such use, but it is more often used as a mix with diesel, BXX where XX is the biodiesel content in percent.Bosch Automotive Handbook, 6th edition, pp. 327–328 FAME used as fuel is specified in DIN EN 14214 and ASTM D6751 standards. Fuel Injection Equipment (FIE) manufacturers have raised several concerns regarding biodiesel, identifying FAME as being the cause of the following problems: corrosion of fuel injection components, low-pressure fuel system blockage, increased dilution and polymerization of engine sump oil, pump seizures due to high fuel viscosity at low temperature, increased injection pressure, elastomeric seal failures and fuel injector spray blockage. Pure biodiesel has an energy content about 5–10% lower than petroleum diesel. The loss in power when using pure biodiesel is 5–7%. Unsaturated fatty acids are the source for the lower oxidation stability. They react with oxygen and form peroxides and result in degradation byproducts, which can cause sludge and lacquer in the fuel system. As biodiesel contains low levels of sulfur, the emissions of
sulfur oxide Sulfur oxide refers to many types of sulfur and oxygen containing compounds such as SO, SO2, SO3, S7O2, S6O2, S2O2, etc. Sulfur oxide (SO''x'') refers to one or more of the following: * Lower sulfur oxides (S''n''O, S7O2 and S6O2) * Sulfur mon ...
s and
sulfate The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...
s, major components of
acid rain Acid rain is rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). Most water, including drinking water, has a neutral pH that exists between 6.5 and 8.5, but acid ...
, are low. Use of biodiesel also results in reductions of unburned hydrocarbons,
carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simpl ...
(CO), and particulate matter. CO emissions using biodiesel are substantially reduced, on the order of 50% compared to most petrodiesel fuels. The exhaust emissions of particulate matter from biodiesel have been found to be 30% lower than overall particulate matter emissions from petrodiesel. The exhaust emissions of total hydrocarbons (a contributing factor in the localized formation of smog and ozone) are up to 93% lower for biodiesel than diesel fuel. Biodiesel also may reduce health risks associated with petroleum diesel. Biodiesel emissions showed decreased levels of
polycyclic aromatic hydrocarbon A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. ...
(PAH) and nitrated PAH compounds, which have been identified as potential
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive substa ...
s. In recent testing, PAH compounds were reduced by 75–85%, except for benz(a)anthracene, which was reduced by roughly 50%. Targeted nPAH compounds were also reduced dramatically with biodiesel fuel, with 2-nitrofluorene and 1-nitropyrene reduced by 90%, and the rest of the nPAH compounds reduced to only trace levels.


Hydrogenated oils and fats

This category of diesel fuels involves converting the triglycerides in vegetable oil and animal fats into alkanes by refining and
hydrogenation Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic c ...
, such as Neste Renewable Diesel or
H-Bio H-Bio is an oil-refining processes which involves converting vegetable oil into high-quality diesel via hydrogenation. Hydrogenation is a chemical reaction, in which a substance is treated with Hydrogen, thus resulting in a new product. In H-Bio, ...
. The produced fuel has many properties that are similar to synthetic diesel, and are free from the many disadvantages of FAME.


DME

Dimethyl ether, DME, is a synthetic, gaseous diesel fuel that results in clean combustion with very little soot and reduced emissions.


Storage

In the US, diesel is recommended to be stored in a yellow container to differentiate it from kerosene, which is typically kept in blue containers, and gasoline (petrol), which is typically kept in red containers. In the UK, diesel is normally stored in a black container to differentiate it from unleaded or leaded petrol, which are stored in green and red containers, respectively.


Standards

The diesel engine is a multifuel engine and can run on a huge variety of fuels. However, development of high-performance, high-speed diesel engines for cars and lorries in the 1930s meant that a proper fuel specifically designed for such engines was needed: diesel fuel. In order to ensure consistent quality, diesel fuel is standardised; the first standards were introduced after World War II. Typically, a standard defines certain properties of the fuel, such as
cetane number Cetane number (cetane rating) is an indicator of the combustion speed of diesel fuel and compression needed for ignition. It plays a similar role for diesel as octane rating does for gasoline. The CN is an important factor in determining the qua ...
, density, flash point,
sulphur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...
content, or biodiesel content. Diesel fuel standards include: Diesel fuel *
EN 590 EN 590 is a standard published by the European Committee for Standardization that describes the physical properties that all automotive diesel fuel must meet if it is to be sold in the European Union and several other European countries. Based on ...
(European Union) *ASTM D975 (United States) *GOST R 52368 (Russia; equivalent to EN 590) *NATO F 54 (NATO; equivalent to EN 590) *DIN 51601 (West Germany; obsolete) Biodiesel fuel * EN 14214 (European Union) *ASTM D6751 (United States) *CAN/CGSB-3.524 (Canada)


Measurements and pricing


Cetane number

The principal measure of diesel fuel quality is its
cetane number Cetane number (cetane rating) is an indicator of the combustion speed of diesel fuel and compression needed for ignition. It plays a similar role for diesel as octane rating does for gasoline. The CN is an important factor in determining the qua ...
. A cetane number is a measure of the delay of ignition of a diesel fuel. A higher cetane number indicates that the fuel ignites more readily when sprayed into hot compressed air. European (EN 590 standard) road diesel has a minimum cetane number of 51. Fuels with higher cetane numbers, normally "premium" diesel fuels with additional cleaning agents and some synthetic content, are available in some markets.


Fuel value and price

About 86.1% of diesel fuel mass is carbon, and when burned, it offers a net heating value of 43.1 MJ/kg as opposed to 43.2 MJ/kg for gasoline. Due to the higher density, diesel fuel offers a higher volumetric energy density: the density of EN 590 diesel fuel is defined as at , about 9.0-13.9% more than EN 228 gasoline (petrol)'s at 15 °C, which should be put into consideration when comparing volumetric fuel prices. The emissions from diesel are 73.25 g/MJ, just slightly lower than for gasoline at 73.38 g/MJ. Diesel fuel is generally simpler to refine from petroleum than gasoline, and contains hydrocarbons having a boiling point in the range of . Additional refining is required to remove sulfur, which contributes to a sometimes higher cost. In many parts of the United States and throughout the United Kingdom and Australia, diesel fuel may be priced higher than petrol per
gallon The gallon is a unit of volume in imperial units and United States customary units. Three different versions are in current use: *the imperial gallon (imp gal), defined as , which is or was used in the United Kingdom, Ireland, Canada, Austra ...
or
litre The litre (international spelling) or liter (American English spelling) (SI symbols L and l, other symbol used: ℓ) is a metric unit of volume. It is equal to 1 cubic decimetre (dm3), 1000 cubic centimetres (cm3) or 0.001 cubic metre (m3) ...
. Reasons for higher-priced diesel include the shutdown of some refineries in the Gulf of Mexico, diversion of mass refining capacity to gasoline production, and a recent transfer to ultra-low-sulfur diesel (ULSD), which causes infrastructural complications. In Sweden, a diesel fuel designated as MK-1 (class 1 environmental diesel) is also being sold. This is a ULSD that also has a lower aromatics content, with a limit of 5%. This fuel is slightly more expensive to produce than regular ULSD. In Germany, the fuel tax on diesel fuel is about 28% lower than the petrol fuel tax.


Taxation

Diesel fuel is similar to heating oil, which is used in
central heating A central heating system provides warmth to a number of spaces within a building from one main source of heat. It is a component of heating, ventilation, and air conditioning (short: HVAC) systems, which can both cool and warm interior spaces. ...
. In Europe, the United States, and Canada, taxes on diesel fuel are higher than on heating oil due to the fuel tax, and in those areas, heating oil is marked with
fuel dyes Fuel dyes are dyes added to fuels, as in some countries it is required by law to dye a low-tax fuel to deter its use in applications intended for higher-taxed ones. Untaxed fuels are referred to as "dyed", while taxed ones are called "clear" or "wh ...
and trace chemicals to prevent and detect tax fraud. "Untaxed" diesel (sometimes called "off-road diesel" or "red diesel" due to its red dye) is available in some countries for use primarily in agricultural applications, such as fuel for tractors, recreational and utility vehicles or other
noncommercial A non-commercial (also spelled noncommercial) activity is an activity that does not, in some sense, involve commerce, at least relative to similar activities that do have a commercial objective or emphasis. For example, advertising-free community ...
vehicles that do not use public roads. This fuel may have sulfur levels that exceed the limits for road use in some countries (e.g. US). This untaxed diesel is dyed red for identification, Cited as 26 CFR 48.4082-1. This regulation implements . and using this untaxed diesel fuel for a typically taxed purpose (such as driving use), the user can be fined (e.g. US$10,000 in the US). In the United Kingdom, Belgium and the Netherlands, it is known as red diesel (or gas oil), and is also used in
agricultural Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people ...
vehicles, home heating tanks, refrigeration units on vans/trucks which contain perishable items such as food and medicine and for marine craft. Diesel fuel, or marked gas oil is dyed green in the Republic of Ireland and Norway. The term "diesel-engined road vehicle" (DERV) is used in the UK as a synonym for unmarked road diesel fuel. In India, taxes on diesel fuel are lower than on petrol, as the majority of the transportation for grain and other essential commodities across the country runs on diesel. Taxes on
biodiesel Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil wit ...
in the US vary between states. Some states (Texas, for example) have no tax on biodiesel and a reduced tax on biodiesel blends equivalent to the amount of biodiesel in the blend, so that B20 fuel is taxed 20% less than pure petrodiesel. Other states, such as North Carolina, tax biodiesel (in any blended configuration) the same as petrodiesel, although they have introduced new incentives to producers and users of all biofuels.


Uses

Diesel fuel is mostly used in high-speed diesel engines, especially motor-vehicle (e.g. car, lorry) diesel engines, but not all diesel engines run on diesel fuel. For example, large two-stroke watercraft engines typically use heavy fuel oils instead of diesel fuel, and certain types of diesel engines, such as MAN
M-System The MAN M-System, also referred to as M-Process and M combustion process, is a direct injection system for Diesel engines. In M-System engines, the fuel is injected ''onto'' the walls of the combustion chamber that is solely located inside the pi ...
engines, are designed to run on petrol with knock resistances of up to 86 RON. On the other hand, gas turbine and some other types of internal combustion engines, and external combustion engines, can also be designed to take diesel fuel. The viscosity requirement of diesel fuel is usually specified at 40 °C. A disadvantage of diesel fuel in cold climates is that its viscosity increases as the temperature decreases, changing it into a gel (see Compression Ignition – Gelling) that cannot flow in fuel systems. Special low-temperature diesel contains additives to keep it liquid at lower temperatures.


On-road vehicles

Trucks and
bus A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
es, which were often otto-powered in the 1920s through 1950s, are now almost exclusively diesel-powered. Due to its ignition characteristics, diesel fuel is thus widely used in these vehicles. Since diesel fuel is not well-suited for otto engines, passenger cars, which often use otto or otto-derived engines, typically run on petrol instead of diesel fuel. However, especially in Europe and India, many passenger cars have, due to better engine efficiency, diesel engines, and thus run on regular diesel fuel.


Railroad

Diesel displaced coal and fuel oil for steam-powered vehicles in the latter half of the 20th century, and is now used almost exclusively for the combustion engines of self-powered rail vehicles (locomotives and railcars).


Aircraft

Packard DR-980 9-cylinder diesel aircraft engine, used in the first diesel-engine airplane In general, diesel engines are not well-suited for planes and helicopters. This is because of the diesel engine's comparatively low power-to-mass ratio, meaning that diesel engines are typically rather heavy, which is a disadvantage in aircraft. Therefore, there is little need for using diesel fuel in aircraft, and diesel fuel is not commercially used as aviation fuel. Instead, petrol (
Avgas Avgas (aviation gasoline, also known as aviation spirit in the UK) is an aviation fuel used in aircraft with spark-ignited internal combustion engines. ''Avgas'' is distinguished from conventional gasoline (petrol) used in motor vehicles, wh ...
), and
jet fuel Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial a ...
(e. g. Jet A-1) are used. However, especially in the 1920s and 1930s, numerous series-production aircraft diesel engines that ran on fuel oils were made, because they had several advantages: their fuel consumption was low, they were reliable, not prone to catching fire, and required minimal maintenance. The introduction of petrol direct injection in the 1930s outweighed these advantages, and aircraft diesel engines quickly fell out of use. With improvements in power-to-mass ratios of diesel engines, several on-road diesel engines have been converted to and certified for aircraft use since the early 21st century. These engines typically run on
Jet A-1 Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial av ...
aircraft fuel (but can also run on diesel fuel). Jet A-1 has ignition characteristics similar to diesel fuel, and is thus suited for certain (but not all) diesel engines.


Military vehicles

Until World War II, several military vehicles, especially those that required high engine performance (
armored fighting vehicle An armoured fighting vehicle (AFV) is an armed combat vehicle protected by armour, generally combining operational mobility with offensive and defensive capabilities. AFVs can be wheeled or tracked. Examples of AFVs are tanks, armoured cars, ...
s, for example the M26 Pershing or Panther tanks), used conventional otto engines and ran on petrol. Ever since World War II, several military vehicles with diesel engines have been made, capable of running on diesel fuel. This is because diesel engines are more fuel efficient, and diesel fuel is less prone to catching fire. Some of these diesel-powered vehicles (such as the Leopard 1 or MAN 630) still ran on petrol, and some military vehicles were still made with otto engines (e. g.
Ural-375 The Ural-375 is a general purpose 4.5 ton 6×6 truck, which has been produced at the Ural Automotive Plant in the Russian SFSR since 1961. The Ural-375 replaced the ZIL-157 as the standard Soviet Army truck in 1979. It was itself replaced by the ...
or Unimog 404), incapable of running on diesel fuel.


Tractors and heavy equipment

Today's tractors and
heavy equipment Heavy equipment or heavy machinery refers to heavy-duty vehicles specially designed to execute construction tasks, most frequently involving earthwork operations or other large construction tasks. ''Heavy equipment'' usually comprises five e ...
are mostly diesel-powered. Among tractors, only the smaller classes may also offer gasoline-fuelled engines. The
dieselization Dieselisation (US: dieselization) is the process of equipping vehicles with a diesel engine or diesel engines. It can involve replacing an internal combustion engine powered by petrol (gasoline) fuel with an engine powered by diesel fuel, as o ...
of tractors and heavy equipment began in Germany before World War II but was unusual in the United States until after that war. During the 1950s and 1960s, it progressed in the US as well. Diesel fuel is commonly used in oil and gas extracting equipment, although some locales use electric or natural gas powered equipment. Tractors and heavy equipment were often
multifuel Multifuel, sometimes spelled multi-fuel, is any type of engine, boiler, or heater or other fuel-burning device which is designed to burn multiple types of fuels in its operation. One common application of multifuel technology is in military sett ...
in the 1920s through 1940s, running either spark-ignition and low-compression engines, akryod engines, or diesel engines. Thus many farm tractors of the era could burn gasoline,
alcohol Alcohol most commonly refers to: * Alcohol (chemistry), an organic compound in which a hydroxyl group is bound to a carbon atom * Alcohol (drug), an intoxicant found in alcoholic drinks Alcohol may also refer to: Chemicals * Ethanol, one of sev ...
, kerosene, and any light grade of
fuel oil Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
such as heating oil, or
tractor vaporising oil Tractor vaporising oil (TVO) is a fuel for petrol-paraffin engines. It is seldom made or used today. In the United Kingdom and Australia, after the Second World War, it was commonly used for tractors until diesel engines became commonplace, e ...
, according to whichever was most affordable in a region at any given time. On US farms during this era, the name "distillate" often referred to any of the aforementioned light fuel oils. Spark ignition engines did not start as well on distillate, so typically a small auxiliary gasoline tank was used for cold starting, and the fuel valves were adjusted several minutes later, after warm-up, to transition to distillate. Engine accessories such as vaporizers and radiator shrouds were also used, both with the aim of capturing heat, because when such an engine was run on distillate, it ran better when both it and the air it inhaled were warmer rather than at ambient temperature. Dieselization with dedicated diesel engines (high-compression with mechanical fuel injection and compression ignition) replaced such systems and made more efficient use of the diesel fuel being burned.


Other uses

Poor quality diesel fuel has been used as an extraction agent for liquid–liquid extraction of palladium from nitric acid mixtures. Such use has been proposed as a means of separating the fission product palladium from PUREX
raffinate In chemical separation terminology, the raffinate (from French ''raffiner'', to refine) is a product which has had a component or components removed. The product having the removed materials is referred to as the extract. For example, in solvent ext ...
which comes from used nuclear fuel. In this system of solvent extraction, the hydrocarbons of the diesel act as the diluent while the di
alkyl In organic chemistry, an alkyl group is an alkane missing one hydrogen. The term ''alkyl'' is intentionally unspecific to include many possible substitutions. An acyclic alkyl has the general formula of . A cycloalkyl is derived from a cycloal ...
sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds lar ...
s act as the extractant. This extraction operates by a solvation mechanism. So far, neither a
pilot plant A pilot plant is a pre-commercial production system that employs new production technology and/or produces small volumes of new technology-based products, mainly for the purpose of learning about the new technology. The knowledge obtained is then ...
nor full scale plant has been constructed to recover palladium, rhodium or
ruthenium Ruthenium is a chemical element with the symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals ...
from nuclear wastes created by the use of nuclear fuel. Diesel fuel is often used as the main ingredient in oil-base mud drilling fluid. The advantage of using diesel is its low cost and its ability to drill a wide variety of difficult strata, including shale, salt and gypsum formations. Diesel-oil mud is typically mixed with up to 40% brine water. Due to health, safety and environmental concerns, Diesel-oil mud is often replaced with vegetable, mineral, or synthetic food-grade oil-base drilling fluids, although diesel-oil mud is still in widespread use in certain regions. During development of rocket engines in Germany during World War II J-2 Diesel fuel was used as the fuel component in several engines including the
BMW 109-718 The BMW 109-718 was a liquid-fuelled rocket engine developed by BMW at their Bruckmühl facility, in Germany during the Second World War. Development The 109-718 (109 prefix number for the ''Reichsluftfahrtministerium'', or ''RLM'', desig ...
. J-2 diesel fuel was also used as a fuel for gas turbine engines.


Chemical analysis


Chemical composition

In the United States, petroleum-derived diesel is composed of about 75%
saturated hydrocarbon In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in whic ...
s (primarily
paraffins In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in whic ...
including ''n'', ''iso'', and cycloparaffins), and 25%
aromatic hydrocarbon Aromatic compounds, also known as "mono- and polycyclic aromatic hydrocarbons", are organic compounds containing one or more aromatic rings. The parent member of aromatic compounds is benzene. The word "aromatic" originates from the past groupin ...
s (including
naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08  ppm by mass. As an aromati ...
s and
alkylbenzenes The alkylbenzenes are derivatives of benzene, in which one or more hydrogen atoms are replaced by alkyl groups of different sizes. They are a subset of the aromatic hydrocarbons. The simplest member is toluene, in which a hydrogen atom of the benze ...
). The average chemical formula for common diesel fuel is C12H23, ranging approximately from C10H20 to C15H28.


Chemical properties

Most diesel fuels freeze at common winter temperatures, while the temperatures greatly vary. Petrodiesel typically freezes around temperatures of −8.1 °C (17.5 °F), whereas biodiesel freezes between temperatures of 2° to 15 °C (35° to 60 °F). The viscosity of diesel noticeably increases as the temperature decreases, changing it into a gel at temperatures of −19 °C (−2.2 °F) to −15 °C (5 °F), that cannot flow in fuel systems. Conventional diesel fuels vaporise at temperatures between 149 °C and 371 °C. Conventional diesel flash points vary between 52 and 96 °C, which makes it safer than petrol and unsuitable for spark-ignition engines. Unlike petrol, the flash point of a diesel fuel has no relation to its performance in an engine nor to its auto ignition qualities.


Carbon dioxide formation

As a good approximation the chemical formula of diesel is . Note that diesel is a mixture of different molecules. As carbon has a molar mass of 12 g/mol and hydrogen has a molar mass of about 1 g/mol, so the fraction by weight of carbon in EN 590 diesel fuel is roughly 12/14. The reaction of diesel combustion is given by: 2 + 3n 2n + 2n Carbon dioxide has a molar mass of 44g/mol as it consists of 2 atoms of oxygen (16 g/mol) and 1 atom of carbon (12 g/mol). So 12 g of carbon yield 44 g of Carbon dioxide. Diesel has a density of 0.838 kg per liter. Putting everything together the mass of carbon dioxide that is produced by burning 1 liter of diesel fuel can be calculated as: 0.838 kg/L \cdot \cdot = 2.63 kg/L The figure obtained with this estimation is close to the values found in the literature. For gasoline, with a density of 0.75 kg/L and a ratio of carbon to hydrogen atoms of about 6 to 14, the estimated value of carbon emission if 1 liter of gasoline is burnt gives: 0.75 kg/L \cdot \cdot = 2.3 kg/L Source


Hazards


Environment hazards of sulfur

In the past, diesel fuel contained higher quantities of sulfur. European emission standards and preferential taxation have forced oil refineries to dramatically reduce the level of sulfur in diesel fuels. In the European Union, the sulfur content has dramatically reduced during the last 20 years. Automotive diesel fuel is covered in the European Union by standard
EN 590 EN 590 is a standard published by the European Committee for Standardization that describes the physical properties that all automotive diesel fuel must meet if it is to be sold in the European Union and several other European countries. Based on ...
. In the 1990s specifications allowed a content of 2000 ppm max of sulfur, reduced to a limit of 350 ppm by the beginning of the 21st century with the introduction of Euro 3 specifications. The limit was lowered with the introduction of Euro 4 by 2006 to 50 ppm ( ULSD, Ultra Low Sulfur Diesel). The standard for diesel fuel in force in Europe as of 2009 is the Euro 5, with a maximum content of 10 ppm. In the United States, more stringent emission standards have been adopted with the transition to ULSD starting in 2006, and becoming mandatory on June 1, 2010 (see also
diesel exhaust Diesel exhaust is the gaseous exhaust produced by a diesel type of internal combustion engine, plus any contained particulates. Its composition may vary with the fuel type or rate of consumption, or speed of engine operation (e.g., idling or at ...
).


Algae, microbes, and water contamination

There has been much discussion and misunderstanding of
algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthesis, photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from u ...
in diesel fuel. Algae need light to live and grow. As there is no sunlight in a closed fuel tank, no algae can survive, but some microbes can survive and feed on the diesel fuel. These microbes form a colony that lives at the interface of fuel and water. They grow quite fast in warmer temperatures. They can even grow in cold weather when fuel tank heaters are installed. Parts of the colony can break off and clog the fuel lines and fuel filters. Water in fuel can damage a fuel injection pump. Some diesel fuel filters also trap water. Water contamination in diesel fuel can lead to freezing while in the fuel tank. The freezing water that saturates the fuel will sometimes clog the fuel injector pump. Once the water inside the fuel tank has started to freeze, gelling is more likely to occur. When the fuel is gelled it is not effective until the temperature is raised and the fuel returns to a liquid state.


Road hazard

Diesel is less flammable than gasoline / petrol. However, because it evaporates slowly, any spills on a roadway can pose a slip hazard to vehicles. After the light fractions have evaporated, a greasy slick is left on the road which reduces
tire A tire (American English) or tyre (British English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which t ...
grip and traction, and can cause vehicles to skid. The loss of traction is similar to that encountered on
black ice Black ice, sometimes called clear ice, is a thin coating of glaze ice on a surface, especially on streets. The ice itself is not black, but visually transparent, allowing the often black road below to be seen through it. The typically low level ...
, resulting in especially dangerous situations for two-wheeled vehicles, such as motorcycles and
bicycle A bicycle, also called a pedal cycle, bike or cycle, is a human-powered or motor-powered assisted, pedal-driven, single-track vehicle, having two wheels attached to a frame, one behind the other. A is called a cyclist, or bicyclist. Bic ...
s, in roundabouts.


See also

*
Common ethanol fuel mixtures Several common ethanol fuel mixtures are in use around the world. The use of pure hydrous or anhydrous ethanol in internal combustion engines (ICEs) is only possible if the engines are designed or modified for that purpose, and used only in autom ...
*
Biodiesel Biodiesel is a form of diesel fuel derived from plants or animals and consisting of long-chain fatty acid esters. It is typically made by chemically reacting lipids such as animal fat (tallow), soybean oil, or some other vegetable oil wit ...
* Diesel automobile racing * Dieselisation * Gasoline *
Gasoline gallon equivalent Gasoline gallon equivalent (GGE) or gasoline-equivalent gallon (GEG) is the amount of an alternative fuel it takes to equal the energy content of one liquid gallon of gasoline. GGE allows consumers to compare the energy content of competing fue ...
* Hybrid vehicle * Liquid fuel *
List of diesel automobiles The following is a list of automobiles (including pickup trucks, SUVs, and vans) made with diesel engines. Alfa Romeo Former * 145 * 146 * 147 * 155 * 156 * 159 * 164 * 166 * 33 * 75 * 90 * Alfa 6 * Alfetta * Brera * GT Current * Giuli ...
* Turbo-diesel * '' United States vs. Imperial Petroleum'' *
Winter diesel fuel Winter diesel fuel (also known as ''winter diesel'', alpine diesel, or winterised diesel) refers to diesel fuel enhanced to prevent it from gelling in cold weather conditions. In general it is achieved by treatment with additives that change the ...


References


Further reading

* L. D. Danny Harvey, 2010, "Energy and the New Reality 1: Energy Efficiency and the Demand for Energy Services," London:Routledge-Earthscan, , 672 pp.; se

accessed 28 September 2014.


External links


U.S. Department of Labor Occupational Safety & Health Administration: Safety and Health Topics: Diesel Exhaust
{{Authority control Diesel fuel, Diesel engines Hydrocarbon solvents IARC Group 2B carcinogens Liquid fuels Petroleum products