An oil tanker taking on bunker fuel.

Fuel oil is a fraction obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash point of approximately 40 °C (104 °F) and oils burned in cotton or wool-wick burners. In this sense, diesel is a type of fuel oil. Fuel oil is made of long hydrocarbon chains, particularly alkanes, cycloalkanes and aromatics. The term fuel oil is also used in a stricter sense to refer only to the heaviest commercial fuel that can be obtained from crude oil, heavier than gasoline and naphtha.

Classes[link]

The American Society for Testing and Materials (ASTM) has published specifications for six grades of fuel oil, numbered 1 to 6. This classification system was originally based on early refining and combustion engineering practices and nomenclature. Some specifications have changed over the years to reflect new refining practices and refinery by-products. Other organizations have published modified versions of the original six fuel specifications to assist operators of older equipment find appropriate fuels from current refinery products.^[1]

Although the following trends generally hold true, different organizations may have different numerical specifications for the six fuel grades. The boiling point and carbon chain length of the fuel increases with fuel oil number. Viscosity also increases with number, and the heaviest oil has to be heated to get it to flow. Price usually decreases as the fuel number increases.^[2]

Number 1 fuel oil is a volatile distillate oil intended for vaporizing pot-type burners.^[1] It is the kerosene refinery cut that boils off right after the heavy naphtha cut used for gasoline. Older names include coal oil, stove oil and range oil.^[2]

Number 2 fuel oil is a distillate home heating oil.^[1] Trucks and some cars use similar diesel fuel with a cetane number limit describing the ignition quality of the fuel. Both are typically obtained from the light gas oil cut. Gas oil refers to the original use of this fraction in the late 19th and early 20th centuries - the gas oil cut was used as an enriching agent for carburetted water gas manufacture.^[2]

Number 3 fuel oil was a distillate oil for burners requiring low-viscosity fuel. ASTM merged this grade into the number 2 specification, and the term has been rarely used since the mid-20th century.^[1]

Number 4 fuel oil is a commercial heating oil for burner installations not equipped with preheaters.^[1] It may be obtained from the heavy gas oil cut.^[2]

Number 5 fuel oil is a residual-type industrial heating oil requiring preheating to 170 – 220 °F (77 – 104 °C) for proper atomization at the burners.^[1] This fuel is sometimes known as Bunker B. It may be obtained from the heavy gas oil cut,^[2] or it may be a blend of residual oil with enough number 2 oil to adjust viscosity until it can be pumped without preheating.^[1]

Number 6 fuel oil is a high-viscosity residual oil requiring preheating to 220 – 260 °F (104 – 127 °C). Residual means the material remaining after the more valuable cuts of crude oil have boiled off. The residue may contain various undesirable impurities including 2 percent water and one-half percent mineral soil. This fuel may be known as residual fuel oil (RFO), by the Navy specification of Bunker C, or by the Pacific Specification of PS-400.^[1]

Mazut is a residual fuel oil often derived from Russian petroleum sources and is either blended with lighter petroleum fractions or burned directly in specialized boilers and furnaces. It is also used as a petrochemical feedstock.

Bunker fuel[link]

A sample of residual fuel oil.

Small molecules like those in propane gas, naphtha, gasoline for cars, and jet fuel have relatively low boiling points, and they are removed at the start of the fractional distillation process. Heavier petroleum products like diesel and lubricating oil are much less volatile and distill out more slowly, while bunker oil is literally the bottom of the barrel; the only things more dense than bunker fuel are carbon black feedstock and bituminous residue which is used for paving roads (asphalt) and sealing roofs.

Bunker fuel is technically any type of fuel oil used aboard ships. It gets its name from the containers on ships and in ports that it is stored in; in the days of steam they were coal bunkers but now they are bunker fuel tanks. The Australian Customs and the Australian Tax Office define a bunker fuel as the fuel that powers the engine of a ship or aircraft. Bunker A is No. 2 fuel oil, bunker B is No. 4 or No. 5 and bunker C is No. 6. Since No. 6 is the most common, "bunker fuel" is often used as a synonym for No. 6. No. 5 fuel oil is also called navy special fuel oil or just navy special; No. 5 or 6 are also called furnace fuel oil (FFO); the high viscosity requires heating, usually by a recirculated low pressure steam system, before the oil can be pumped from a bunker tank. In the context of shipping, the labeling of bunkers as previously described is rarely used in modern practice.

Since the 1980s the International Organization for Standardization (ISO) has been the accepted standard for marine fuels (bunkers). The standard is listed under number 8217, with recent updates in 2005 and 2010. They have broken it down to Residual and Distillate fuels. The most common residual fuels in the shipping industry are RMG and RMK.^[3] The differences between the two are mainly the density and viscosity, with RMG generally being delivered at 380 centistokes or less, and RMK at 700 centistokes or less. Ships with more advanced engines can process heavier, more viscous, and thus cheaper, fuel. Governing bodies (i.e. California, European Union) around the world are starting to limit the maximum sulfur of fuels burned in their ports to limit pollution. This is where Marine Distillate Fuels come into play. They have similar properties to Diesel #2 which is used as road Diesel around the world. The most common grades used in shipping are DMA and DMB.^[4]

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Uses[link]

A fuel station in Zigui County on the Yangtze River

Oil has many uses; it heats homes and businesses and fuels trucks, ships and some cars. A small amount of electricity is produced by diesel, but it is more polluting and more expensive than natural gas. It is often used as a backup fuel for peaking power plants in case the supply of natural gas is interrupted or as the main fuel for small electrical generators. In Europe the use of diesel is generally restricted to cars (about 40%), SUVs (about 90%), and trucks and buses (virtually all). The market for home heating using fuel oil, called heating oil, has decreased due to the widespread penetration of natural gas. However, it is very common in some areas, such as the Northeastern United States.

Residual fuel oil is less useful because it is so viscous that it has to be heated with a special heating system before use and it contains relatively high amounts of pollutants, particularly sulfur, which forms sulfur dioxide upon combustion. However, its undesirable properties make it very cheap. In fact, it is the cheapest liquid fuel available. Since it requires heating before use, residual fuel oil cannot be used in road vehicles, boats or small ships, as the heating equipment takes up valuable space and makes the vehicle heavier. Heating the oil is also a delicate procedure, which is inappropriate to do on small, fast moving vehicles. However, power plants and large ships are able to use residual fuel oil.

Residual fuel oil was used more frequently in the past. It powered boilers, railroad steam locomotives and steamships. Locomotives now use diesel; steamships are not as common as they were previously due to their higher operating costs (most LNG carriers use steam plants, as "boil-off" gas emitted from the cargo can be used as a fuel source); and most boilers now use heating oil or natural gas. However, some industrial boilers still use it and so do a few old buildings, including in New York City. The city estimates that the 1% of its buildings that burn fuel oils No. 4 and No. 6 are responsible for 86% of the soot pollution generated by all buildings in the city. New York has made the phase out of these fuel grades part of its environmental plan, PlaNYC, because of concerns for the health effects caused by fine particulates.^[5]

Residual fuel's use in electricity generation has also decreased. In 1973, residual fuel oil produced 16.8% of the electricity in the United States. By 1983, it had fallen to 6.2%, and as of 2005^[update], electricity production from all forms of petroleum, including diesel and residual fuel, is only 3% of total production. The decline is the result of price competition with natural gas and environmental restrictions on emissions. For power plants, the costs of heating the oil, extra pollution control and additional maintenance required after burning it often outweigh the low cost of the fuel. Burning fuel oil, particularly residual fuel oil, also produces much darker smoke and uniformly higher Carbon Dioxide emissions than natural gas,^[6] which affects the community's perception.

Heavy fuel oils continue to be used in the boiler "lighting up" facility in many coal-fired power plants. Although on an enormous scale, this use is analogous to lighting kindling to start a fire; without performing this simple function it is difficult to begin the large-scale combustion process.

The chief drawback to residual fuel oil is its high initial viscosity, particularly in the case of No. 6 oil, which requires a correctly engineered system for storage, pumping, and burning. Though it is still usually lighter than water (with a specific gravity usually ranging from 0.95 to 1.03) it is much heavier and more viscous than No. 2 oil, kerosene, or gasoline. No. 6 oil must, in fact, be stored at around 100 °F (38 °C) heated to 150 °F (66 °C)–250 °F (121 °C) before it can be easily pumped, and in cooler temperatures it can congeal into a tarry semisolid. The flash point of most blends of No. 6 oil is, incidentally, about 150 °F (66 °C). Attempting to pump high-viscosity oil at low temperatures was a frequent cause of damage to fuel lines, furnaces, and related equipment which were often designed with lighter fuels in mind.

(For comparison, BS2869 Class G Heavy Fuel Oil behaves in similar fashion, requiring storage at 104 °F (40 °C), pumping at around 122 °F (50 °C) and finalising for burning at around 194 °F (90 °C) / 248 °F (120 °C).)

Most of the facilities which historically burned No. 6 or other residual oils were industrial plants and similar facilities constructed in the early or mid 20th century, or which had switched from coal to oil fuel during the same time period. In either case, residual oil was seen as a good prospect because it was cheap and readily available, even though it provided less energy per volume-unit than lighter fuels. Most of these facilities have subsequently been closed and demolished, or have replaced their fuel supplies with a simpler one such as gas or No. 2 oil. The high sulfur content of No. 6 oil—up to 3% by weight in some extreme cases—had a corrosive effect on many heating systems (which were usually designed without adequate corrosion protection in mind), shortening their lifespans and increasing the polluting effects. This was particularly the case in furnaces that were regularly shut down and allowed to go cold; the internal condensation produced sulfuric acid.

Environmental cleanups at such facilities are frequently complicated by the use of asbestos insulation on the fuel feed lines. No. 6 oil is very persistent, and does not degrade rapidly. Its viscosity and stickiness also make remediation of underground contamination very difficult, since it reduces the effectiveness of methods such as air stripping.

When released into water, such as a river or ocean, residual oil tends to break up into patches or tarballs—mixtures of oil and particulate matter such as silt and floating organic matter- rather than form a single slick. An average of about 5-10% of the material will evaporate within hours of the release, primarily the lighter hydrocarbon fractions. The remainder will then often sink to the bottom of the water column.

Maritime[link]

In the maritime field another type of classification is used for fuel oils:

• MGO (Marine gas oil) - roughly equivalent to No. 2 fuel oil, made from distillate only
• MDO (Marine diesel oil) - A blend of heavy gasoil that may contain very small amounts of black refinery feed stocks, but has a low viscosity up to 12 cSt so it need not be heated for use in internal combustion engines
• IFO (Intermediate fuel oil) A blend of gasoil and heavy fuel oil, with less gasoil than marine diesel oil
• MFO (Marine fuel oil) - same as HFO (just another "naming")
• HFO (Heavy fuel oil) - Pure or nearly pure residual oil, roughly equivalent to No. 6 fuel oil

Marine diesel oil contains some heavy fuel oil, unlike regular diesels. Also, marine fuel oils sometimes contain waste products such as used motor oil.

Standards and classification[link]

CCAI and CII are two indexes which describe the ignition quality of residual fuel oil, and CCAI is especially often calculated for marine fuels. Despite this marine fuels are still quoted on the international bunker markets with their maximum viscosity (which is set by the ISO 8217 standard - see below) due to the fact that marine engines are designed to use different viscosities of fuel.^[7] The unit of viscosity used is the Centistoke and the fuels most frequently quoted are listed below in order of cost, the least expensive first-

• IFO 380 - Intermediate fuel oil with a maximum viscosity of 380 Centistokes (<3.5% sulphur)
• IFO 180 - Intermediate fuel oil with a maximum viscosity of 180 Centistokes (<3.5% sulphur)
• LS 380 - Low-sulphur (<1.5%) intermediate fuel oil with a maximum viscosity of 380 Centistokes
• LS 180 - Low-sulphur (<1.5%) intermediate fuel oil with a maximum viscosity of 180 Centistokes
• MDO - Marine diesel oil.
• MGO - Marine gasoil.
• LSMGO - Marine gasoil.
• LSMGO - Low-sulphur (<0.1%) Marine Gas Oil - The fuel is to be used in EU community Ports and Anchorages. EU Sulphur directive 2005/33/EC

The density is also an important parameter for fuel oils since marine fuels are purified before use to remove water and dirt from the oil. Since the purifiers use centrifugal force, the oil must have a density which is sufficiently different from water. Older purifiers had a maximum of 991 kg/m3; with modern purifiers it is also possible to purify oil with a density of 1010 kg/m3.

The first British standard for fuel oil came in 1982. The latest standard is ISO 8217 from 2005. The ISO standard describe four qualities of distillate fuels and 10 qualities of residual fuels. Over the years the standards have become stricter on environmentally important parameters such as sulfur content. The latest standard also banned the adding of used lubricating oil (ULO).

Some parameters of marine fuel oils according to ISO 8217 (3. ed 2005):

1. Max sulfur content is 1.5% in designated areas. (since 1-07-2010 1% is max).
2. The aluminium+silicon value is used to check for remains of the catalyst after catalytic cracking. Most catalysts contains aluminium or silicon and remains of catalyst can cause damage to the engine.
3. The flash point of all fuels used in the engine room should be at least 60°C (DMX is used for things like emergency generators and not normally used in the engine room).

1. Max sulfur content is 1.5% in designated areas. (since 1-07-2010 1% is max).
2. The aluminium+silicon value is used to check for remains of the catalyst after catalytic cracking. Most catalysts contains aluminium or silicon and remains of catalyst can cause damage to the engine.
3. The flash point of all fuels used in the engine room should be at least 60°C.

Transportation[link]

Fuel oil is transported worldwide by fleets of supertankers making deliveries to suitably sized strategic ports such as Houston, Singapore, Fujairah, Balboa, Cristobal, Gibraltar and Rotterdam. Where a convenient seaport does not exist, inland transport may be achieved with the use of barges. The lighter fuel oils can also be transported through pipelines. The major physical supply chains of Europe are along the Rhine.

See also[link]

• Diesel fuel
• Gasoline
• Heating oil
• Jet fuel
• Kerosene
• Lubricant
• Naphtha
• Gas Oil Separation Plant
• Fuel management systems
• Fuel price risk management
• Marine fuel management
• Hot bulb engine

References[link]

1. Bunker Pricing Methodologies

External links[link]

• National Park Service - Fuel Oil
• World Bunker Prices
• How Stuff Works - Oil Refining
• Identity and Analysis of Total Petroleum Hydrocarbons
• The International Bunkering Industry Association

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Wood was one of the first fuels used by humans and is still the primary energy source in much of the world.^{[citation needed]}

Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air. Other processes used to convert fuel into energy include various other exothermic chemical reactions and nuclear reactions, such as nuclear fission or nuclear fusion. Fuels are also used in the cells of organisms in a process known as cellular respiration, where organic molecules are oxidized to release usable energy. Hydrocarbons are by far the most common source of fuel used by humans, but many other substances, such as radioactive metals, are currently used as well .

Chemical[link]

Chemical fuels are substances that release energy by reacting with substances around them, most notably by the process of oxidation.

Biofuels[link]

Biofuel can be broadly defined as solid, liquid, or gas fuel consisting of, or derived from biomass. Biomass can also be used directly for heating or power—known as biomass fuel. Biofuel can be produced from any carbon source that can be replenished rapidly e.g. plants. Many different plants and plant-derived materials are used for biofuel manufacture.

Perhaps the earliest fuel employed by humans is wood. Evidence shows controlled fire was used up to 1.5 million years ago at Swartkrans, South Africa. It is unknown which hominid species first used fire, as both Australopithecus and an early species of Homo were present at the sites.^[1] As a fuel, wood has remained in use up until the present day, although it has been superseded for many purposes by other sources. Wood has an energy density of 10–20 MJ/kg.^[2]

Recently biofuels have been developed for use in automotive transport (for example Bioethanol and Biodiesel), but there is widespread public debate about how carbon efficient these fuels are.

Fossil fuels[link]

Fossil fuels are hydrocarbons, primarily coal and petroleum (liquid petroleum or natural gas), formed from the fossilized remains of ancient plants and animals^[3] by exposure to high heat and pressure in the absence of oxygen in the Earth's crust over hundreds of millions of years.^[4] Commonly, the term fossil fuel also includes hydrocarbon-containing natural resources that are not derived entirely from biological sources, such as tar sands. These latter sources are properly known as mineral fuels.

Nuclear[link]

Nuclear fuel is any material that is consumed to derive nuclear energy. Technically speaking this definition includes all matter because any element will under the right conditions release nuclear energy, the only materials that are commonly referred to as nuclear fuels though are those that will produce energy without being placed under extreme duress.

Fission[link]

Nuclear fuel pellets are used to create nuclear energy.

The most common type of nuclear fuel used by humans is heavy fissile elements that can be made to undergo nuclear fission chain reactions in a nuclear fission reactor; nuclear fuel can refer to the material or to physical objects (for example fuel bundles composed of fuel rods) composed of the fuel material, perhaps mixed with structural, neutron moderating, or neutron reflecting materials. The most common fissile nuclear fuels are ²³⁵U and ²³⁹Pu, and the actions of mining, refining, purifying, using, and ultimately disposing of these elements together make up the nuclear fuel cycle, which is important for its relevance to nuclear power generation and nuclear weapons. In addition there are various types of fuels.

Fusion[link]

Fuels that produce energy by the process of nuclear fusion are currently not utilized by man but are the main source of fuel for stars, the most powerful energy sources in nature. Fusion fuels tend to be light elements such as hydrogen which will combine easily.

In stars that undergo nuclear fusion, fuel consists of atomic nuclei that can release energy by the absorption of a proton or neutron. In most stars the fuel is provided by hydrogen, which can combine together to form helium through the proton-proton chain reaction or by the CNO cycle. When the hydrogen fuel is exhausted, nuclear fusion can continue with progressively heavier elements, although the net energy released is lower because of the smaller difference in nuclear binding energy. Once iron-56 or nickel-56 nuclei are produced, no further energy can be obtained by nuclear fusion as these have the highest nuclear binding energies.^[5]

World trade[link]

Fuel imports in 2005

World Bank reported that the USA was the top fuel importer in 2005 followed by the EU and Japan.^{[citation needed]}

Use over time[link]

The first use of fuel was the combustion of wood or sticks by Homo erectus near 2 million years ago.^{[6][page needed]} Throughout the majority of human history fuels derived from plants or animal fat were the only ones available for human use. Charcoal, a wood derivative, has been used since at least 6,000 BCE for smelting metals. It was only supplanted by coke, derived from coal, as the forests started to become depleted around the 18th century. Charcoal briquettes are now commonly used as a fuel for barbecue cooking.^[7]

Coal was first used as a fuel around 1000 BCE in China. With the development of the steam engine in 1769, coal came into more common use as a power source. Coal was later used to drive ships and locomotives. By the 19 th century, gas extracted from coal was being used for street lighting in London. In the 20th century, the primary use of coal is for the generation of electricity, providing 40% of the world's electrical power supply in 2005.^[8]

Fossil fuels were rapidly adopted during the industrial revolution, because they were more flexible than traditional energy sources, such as water power.

Currently the trend has been towards renewable fuels, such as biofuels like alcohols.

See also[link]

Energy portal

Footnotes[link]

References[link]

• Ratcliff, Brian et al. (2000). Chemistry 1. Cambridge University press. ISBN 0-521-78778-5. 

Further reading[link]

Wikimedia Commons has media related to: Fuels

• Directive 1999/94/EC of the European Parliament and of the council of 13 December 1999, relating to the availability of consumer information on fuel economy and CO2 emissions in respect of the marketing of new passenger carsPDF (140 KiB).
• Council Directive 80/1268/EEC Fuel consumption of motor vehicles.

v t e Firecraft Tinder Kindling Wood fuel/Firewood Ember/Spark Campfire Wood ash Topics Combustion Friction fire Autoignition temperature (kindling point) Smoulder Early starters Hand drill Bow drill (Pump drill) Fire saw Fire plough Burning glass (parabolic mirror) Flint & Fire striker Fire piston Modern starters Match (lucifer) (Black match) Lighter Electric match Flint spark lighter Ferro rod (Ferrocerium) Other equipment Tinderbox Char cloth Fire ring Fire pan Punk (fireworks) Related articles Control of fire by early humans Native American use of fire Pyrolysis Survival skills Portal:Fire

An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils.

Etymology[link]

First attested in English 1176, the word oil comes from Old French "oile", from Latin "oleum",^[1] which in turn comes from the Greek "ἔλαιον" (elaion), "olive oil, oil"^[2] and that from "ἐλαία" (elaia), "olive tree".^[3] The earliest attested form of the word is the Mycenaean Greek e-ra-wo, written in Linear B syllabic script.^[4]

Types[link]

This unreferenced section requires citations to ensure verifiability.

Organic oils[link]

Organic oils are produced in remarkable diversity by plants, animals, and other organisms through natural metabolic processes. Lipid is the scientific term for the fatty acids, steroids and similar chemicals often found in the oils produced by living things, while oil refers to an overall mixture of chemicals. Organic oils may also contain chemicals other than lipids, including proteins, waxes and alkaloids.

Lipids can be classified by the way that they are made by an organism, their chemical structure and their limited solubility in water compared to oils. They have a high carbon and hydrogen content and are considerably lacking in oxygen compared to other organic compounds and minerals; they tend to be relatively nonpolar molecules, but may include both polar and nonpolar regions as in the case of phospholipids and steroids.^[5]

Mineral oils[link]

Crude oil, or petroleum, and its refined components, collectively termed petrochemicals, are crucial resources in the modern economy. Crude oil originates from ancient fossilized organic materials, such as zooplankton and algae, which geochemical processes convert into oil.^[6] It is classified as a mineral oil because it does not have an organic origin on human timescales, but is instead obtained from rocks, underground traps, or sands. Mineral oil also refers to several specific distillates of crude oil.

Applications[link]

This unreferenced section requires citations to ensure verifiability.

A bottle of olive oil used in food

Cosmetics[link]

Oils are applied to hair to give it a lustrous look, to prevent tangles and roughness and to stabilize the hair to promote growth.^{[citation needed]} See Hair conditioner.

Religion[link]

Oils are commonly used in ritual anointments. As a particular example, holy anointing oil has been an important ritual liquid for Judaism and Christianity.

Painting[link]

Color pigments are easily suspended in oil, making it suitable as a supporting medium for paints. The oldest known extant oil paintings date from 650 AD.^[7]

Heat transfer[link]

Oils are used as coolants in oil cooling, for instance in electric transformers. Oils are also used to enhance heating in other applications, such as cooking (especially in frying).

Lubrication[link]

Oils are commonly used as lubricants. Mineral oils are more commonly used as machine lubricants than biological oils are.

Fuel[link]

Some oils burn in liquid or aerosol form, generating heat which can be used directly or converted into other forms of energy such as electricity or mechanical work. To obtain many fuel oils, crude oil is pumped from the ground and is shipped via oil tanker to an oil refinery. There, it is converted from crude oil to diesel fuel (petrodiesel), ethane (and other short-chain alkanes), fuel oils (heaviest of commercial fuels, used in ships/furnaces), gasoline (petrol), jet fuel, kerosene, benzene (historically), and liquefied petroleum gas. A 42 gallon barrel (U.S.) of crude oil produces approximately 10 gallons of diesel, 4 gallons of jet fuel, 19 gallons of gasoline, 7 gallons of other products, 3 gallons split between heavy fuel oil and liquified petroleum gases,^[8] and 2 gallons of heating oil. The total production of a barrel of crude into various products results in an increase to 45 gallons.^[8] Not all oils used as fuels are mineral oils, see biodiesel and vegetable oil fuel.

Chemical feedstock[link]

Crude oil can be refined into a wide variety of component hydrocarbons. Petrochemicals are the refined components of crude oil and the chemical products made from them. They are used as detergents, fertilizers, medicines, paints, plastics, synthetic fibers, and synthetic rubber. Organic oils are another important chemical feedstock, especially in green chemistry.

See also[link]

• Cooking oil
• Emulsifier, a chemical which allows oil and water to mix
• Lubrication
• Wax, a class of compounds with oil-like properties that are solid at common temperatures

References[link]

This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. (October 2009)

External links[link]

Wikimedia Commons has media related to: Oil

• Petroleum Online e-Learning resource from IHRDC