View source for Fuel oil

{{Short description|Petroleum product burned to generate motive power or heat}}
{{Use dmy dates|date=October 2019}}
[[File:Bunkering-or-taking-fuel.jpg|thumb|An [[oil tanker]] taking on fuel, or "[[bunkering]]"]]'''Fuel oil''' is any of various [[fractional distillation|fractions]] obtained from the [[distillation]] of [[petroleum]] (crude oil). Such oils include [[distillate]]s (the lighter fractions) and [[residue (chemistry)|residues]] (the heavier fractions). Fuel oils include [[heavy fuel oil]] (bunker fuel), [[marine fuel oil]] (MFO), '''furnace oil''' (FO), [[gas oil]] (gasoil), [[heating oil]]s (such as home heating oil), [[diesel fuel]], and others.
The term ''fuel oil'' generally includes any [[liquid fuel]] that is burned in a furnace or [[boiler]] to generate heat ([[heating oil]]s), or used in an [[engine]] to generate power (as [[motor fuel]]s). However, it does not usually include other liquid oils, such as those with a [[flash point]] of approximately {{convert|42|°C}}, or oils burned in cotton- or wool-wick burners. In a stricter sense, ''fuel oil'' refers only to the heaviest commercial fuels that crude oil can yield, that is, those fuels heavier than [[gasoline]] (petrol) and [[petroleum naphtha|naphtha]].
Fuel oil consists of long-chain [[hydrocarbon]]s, particularly [[alkane]]s, [[cycloalkane]]s, and [[aromatic]]s. Small molecules, such as those in [[propane]], naphtha, gasoline, and [[kerosene]], have relatively low [[boiling point]]s, and are removed at the start of the [[fractional distillation]] process. Heavier petroleum-derived oils like [[diesel fuel]] and [[lubricant|lubricating oil]] are much less volatile and distill out more slowly.
==Uses==
[[File:Zigui-Sinopec-boat-fuel-station-4959.jpg|thumb|A fuel station in [[Zigui County]] on the [[Yangtze]] River]] [[File:DOT hazmat class 3 (alt 2).svg|thumb|HAZMAT class 3 fuel oil]] Oil has many uses; it heats homes and businesses and fuels [[truck]]s, [[ship]]s, and some [[car]]s. A small amount of [[electricity]] is produced by diesel, but it is more [[pollution|polluting]] and more expensive than [[natural gas]]. It is often used as a backup fuel for [[peaking power plant]]s in case the supply of natural gas is interrupted or as the main fuel for small [[electrical generator]]s. In Europe, the use of diesel is generally restricted to cars (about 40%), SUVs (about 90%), and trucks and buses (over 99%). The market for home heating using fuel oil has decreased due to the widespread penetration of [[natural gas]] as well as [[heat pumps]]. However, it is very common in some areas, such as the [[Northeastern United States]].
[[File:Fuel Oil Truck 1945.jpg|left|thumb|Fuel oil truck making a delivery in North Carolina, 1945]]
[[Heavy fuel oil|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 may contain relatively high amounts of [[pollutant]]s, 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, [[boat]]s 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 impractical on small, fast moving vehicles. However, [[power plant]]s and large ships are able to use residual fuel oil.
Use of residual fuel oil was more common in the past. It powered [[boiler]]s, [[railroad]] [[steam locomotive]]s, and [[steamship]]s. Locomotives, however, have become powered by diesel or electric power; steamships are not as common as they were previously due to their higher operating costs (most [[LNG carrier]]s 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. Some industrial boilers still use it and so do some old buildings, including in [[New York City]]. In 2011 New York City estimated that the 1% of its buildings that burned fuel oils No. 4 and No. 6 were responsible for 86% of the [[soot]] pollution generated by all buildings in the city. New York 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,<ref>{{cite web|title=Mayor Bloomberg Presents an Update to PlaNYC: a Greener, Greater New York|url=https://www1.nyc.gov/office-of-the-mayor/news/129-10/mayor-bloomberg-presents-update-planyc-a-greener-greater-new-york#/9|publisher=NYC.gov|access-date=22 April 2011|date=2010-03-22|archive-url=https://web.archive.org/web/20170202061223/http://www1.nyc.gov/office-of-the-mayor/news/129-10/mayor-bloomberg-presents-update-planyc-a-greener-greater-new-york#/9|archive-date=2 February 2017|url-status=live}}</ref> and all buildings using fuel oil No. 6 had been converted to less polluting fuel by the end of 2015.<ref>{{cite web|last1=Office of the Mayor|title=Mayor de Blasio and DEP Announce That All 5,300 Buildings Have Discontinued Use of Most Polluting Heating Oil, Leading to Significantly Cleaner Air|url=https://www1.nyc.gov/office-of-the-mayor/news/152-16/mayor-de-blasio-dep-that-all-5-300-buildings-have-discontinued-use-most-polluting|publisher=City of New York|access-date=14 September 2017|date=2016-02-09|archive-url=https://web.archive.org/web/20170914125417/http://www1.nyc.gov/office-of-the-mayor/news/152-16/mayor-de-blasio-dep-that-all-5-300-buildings-have-discontinued-use-most-polluting|archive-date=14 September 2017|url-status=live}}</ref>
Residual fuel's use in electrical generation has also decreased. In 1973, residual fuel oil produced 16.8% of the electricity in the US. By 1983, it had fallen to 6.2%, and {{As of|2005|lc=on}}, electricity production from all forms of petroleum, including diesel and residual fuel, is only 3% of total production.{{Citation needed|reason=can this final figure be cited and/or broken down to give a % for residual oil?|date=June 2018}} 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, produces uniformly higher [[carbon dioxide]] emissions than natural gas.<ref>{{cite web |url=http://www.eia.doe.gov/oiaf/1605/coefficients.html |title=U.S. Energy Information Administration (EIA) |access-date=2009-08-21 |url-status=dead |archive-url=https://web.archive.org/web/20041101051713/http://eia.doe.gov/oiaf/1605/coefficients.html |archive-date=1 November 2004 |df=dmy-all}}</ref>
Heavy fuel oils continue to be used in the boiler "lighting up" facility in many coal-fired power plants. This use is approximately analogous to using kindling to start a fire. Without performing this act 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 {{convert|38|°C}} heated to {{convert|65|-|120|°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 {{convert|65|°C|°F}}. 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 for lighter fuels.
For comparison, [[BS 2869]] Class G heavy fuel oil behaves in similar fashion, requiring storage at {{convert|40|°C}}, pumping at around {{convert|50|°C}} and finalizing for burning at around {{convert|90|-|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. 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, because 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 these properties reduce 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.
== Health impacts ==
Because of the low quality of bunker fuel, when burnt it is especially harmful to the health of humans, causing serious illnesses and deaths. Prior to the IMO's 2020 sulfur cap, shipping industry air pollution was estimated to cause around 400,000 premature deaths each year, from lung cancer and cardiovascular disease, as well as 14 million childhood asthma cases each year.<ref>{{Cite journal|last1=Sofiev|first1=Mikhail|last2=Winebrake|first2=James J.|last3=Johansson|first3=Lasse|last4=Carr|first4=Edward W.|last5=Prank|first5=Marje|last6=Soares|first6=Joana|last7=Vira|first7=Julius|last8=Kouznetsov|first8=Rostislav|last9=Jalkanen|first9=Jukka-Pekka|last10=Corbett|first10=James J.|date=2018-02-06|title=Cleaner fuels for ships provide public health benefits with climate tradeoffs|journal=Nature Communications|language=en|volume=9|issue=1|page=406|doi=10.1038/s41467-017-02774-9|pmid=29410475|pmc=5802819|bibcode=2018NatCo...9..406S|issn=2041-1723|doi-access=free}}</ref>
Even after the introduction of cleaner fuel rules in 2020, shipping air pollution is still estimated to account for around 250,000 deaths each year, and around 6.4 million childhood asthma cases each year.
The hardest hit countries by air pollution from ships are China, Japan, the UK, Indonesia, and Germany. In 2015, shipping air pollution killed an estimated 20,520 people in China, 4,019 people in Japan, and 3,192 people in the UK.<ref name="theicct.org">{{Cite web|title=A global snapshot of the air pollution-related health impacts of transportation sector emissions in 2010 and 2015 {{!}} International Council on Clean Transportation|url=https://theicct.org/publications/health-impacts-transport-emissions-2010-2015|website=theicct.org|access-date=2020-04-30}}</ref>
According to an ICCT study, countries located on major shipping lanes are particularly exposed, and can see shipping account for a high percentage of overall deaths from transport sector air pollution. In Taiwan, shipping accounts for 70% of all transport-attributable air pollution deaths in 2015, followed by Morocco at 51%, Malaysia and Japan both at 41%, Vietnam at 39%, and the UK at 38%.<ref name="theicct.org"/>
As well as commercial shipping, cruise ships also emit large amounts of air pollution, damaging people's health. Up to 2019, it was reported that the ships of the single largest cruise company, [[Carnival Corporation & plc]], emitted ten times more sulfur dioxide than all of Europe's cars combined.<ref>{{Cite news |last=Abbasov |first=Faig |date=June 4, 2019 |title=Luxury cruise giant emits 10 times more air pollution (SOx) than all of Europe’s cars – study |url=https://www.transportenvironment.org/articles/luxury-cruise-giant-emits-10-times-more-air-pollution-sox-all-europes-cars-study |url-status=live |work=T&E (European Federation for Transport and Environment)}}</ref>
==General classification==
===United States===
Although the following trends generally hold true, different organizations may have different numerical specifications for the six fuel grades. The boiling point and [[catenation|carbon chain]] length of the fuel increases with fuel oil number. [[Viscosity]] also increases with number, and the heaviest oil must be heated for it to flow. Price usually decreases as the fuel number increases.<ref name="riegel">Kent, James A. ''Riegel's Handbook of Industrial Chemistry'' (1983) Van Nostrand Reinhold Company {{ISBN|0-442-20164-8}} pp.492-493</ref>
'''Number 1 fuel oil''' is a volatile distillate oil intended for vaporizing pot-type burners and high-performance/clean diesel engines.<ref name="perry">Perry, Robert H., Chilton, Cecil H. and Kirkpatrick, Sidney D. ''Perry's Chemical Engineers' Handbook'' 4th edition (1963) McGraw Hill p.9-6</ref> It is the [[kerosene]] refinery cut that boils off immediately after the heavy naphtha cut used for [[gasoline]]. This fuel is commonly known as [[diesel fuel|diesel no. 1]], [[kerosene]], and [[jet fuel]]. Former names include: coal oil, stove oil, and range oil.<ref name="riegel" />
'''Number 2 fuel oil''' is a distillate home [[heating oil]].<ref name="perry"/> Trucks and some cars use similar [[diesel fuel|diesel no. 2]] with a [[cetane number]] limit describing the ignition quality of the fuel. Both are typically obtained from the light gas oil cut. The name ''gasoil'' 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 carbureted water gas [[manufactured gas|manufacture]].<ref name="riegel"/>
'''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.<ref name="perry"/>
'''Number 4 fuel oil''' is a commercial heating oil for burner installations not equipped with preheaters.<ref name="perry"/> It may be obtained from the heavy gas oil cut.<ref name="riegel"/> This fuel is sometimes known by the Navy specification of '''Bunker A'''.
'''Number 5 fuel oil''' is a residual-type industrial heating oil requiring preheating to {{convert|77|–|104|C|0}} for proper atomization at the burners.<ref name="perry"/> It may be obtained from the heavy gas oil cut,<ref name="riegel" /> or it may be a blend of residual oil with enough number 2 oil to adjust viscosity until it can be pumped without preheating.<ref name="perry" /> This fuel is sometimes known by the Navy specification of '''Bunker B'''.
'''Number 6 fuel oil''' is a high-viscosity residual oil requiring preheating to {{convert|104|–|127|C|0}}. 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% water and 0.5% [[mineral oil]]. 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.<ref name="perry"/>
===United Kingdom===
The British Standard BS 2869, ''Fuel Oils for Agricultural, Domestic and Industrial Engines'', specifies the following fuel oil classes:
{| class="wikitable" style="margin:auto;"
|+ Fuel oil classes per BS 2869
|-
! Class !! Type !! Min. kinematic viscosity !! Max. kinematic viscosity !! Min. flash point !! Max. sulfur content !! Alias
|-
|C1
|Distillate
|—
|—
|43&nbsp;°C
|0.040 % (m/m)
|Paraffin
|-
|C2
|Distillate
|1.000&nbsp;mm<sup>2</sup>/s at 40&nbsp;°C
|2.000&nbsp;mm<sup>2</sup>/s at 40&nbsp;°C
|38&nbsp;°C
|0.100 % (m/m)
|[[Kerosene]], 28-second oil
|-
|A2
|Distillate
|2.000&nbsp;mm<sup>2</sup>/s at 40&nbsp;°C
|5.000&nbsp;mm<sup>2</sup>/s at 40&nbsp;°C
|> 55&nbsp;°C
|0.001 % (m/m)
|low-sulfur gas oil, [[Ultra-low-sulfur diesel|ULSD]]
|-
|D
|Distillate
|2.000&nbsp;mm<sup>2</sup>/s at 40&nbsp;°C
|5.000&nbsp;mm<sup>2</sup>/s at 40&nbsp;°C
|> 55&nbsp;°C
|0.100 % (m/m)
|Gas oil, [[red diesel]], 35-second oil
|-
|E
|Residual
|—
|8.200&nbsp;mm<sup>2</sup>/s at 100&nbsp;°C
|66&nbsp;°C
|1.000 % (m/m)
|Light fuel oil, LFO, 250-second oil
|-
|F
|Residual
|8.201&nbsp;mm<sup>2</sup>/s at 100&nbsp;°C
|20.000&nbsp;mm<sup>2</sup>/s at 100&nbsp;°C
|66&nbsp;°C
|1.000 % (m/m)
|Medium fuel oil, MFO, 1000-second oil
|-
|G
|Residual
|20.010&nbsp;mm<sup>2</sup>/s at 100&nbsp;°C
|40.000&nbsp;mm<sup>2</sup>/s at 100&nbsp;°C
|66&nbsp;°C
|1.000 % (m/m)
|Heavy fuel oil, HFO, 3500-second oil
|-
|H
|Residual
|40.010&nbsp;mm<sup>2</sup>/s at 100&nbsp;°C
|56.000&nbsp;mm<sup>2</sup>/s at 100&nbsp;°C
|66&nbsp;°C
|1.000 % (m/m)
|—
|}
Class C1 and C2 fuels are kerosene-type fuels. C1 is for use in flueless appliances (e.g. [[kerosene lamp|lamps]]). C2 is for vaporizing or atomizing burners in appliances connected to flues.
Class A2 fuel is suitable for mobile, [[non-road engine|off-road applications]] that are required to use a [[Ultra-low-sulfur diesel|sulfur-free fuel]]. Class D fuel is similar to Class A2 and is suitable for use in stationary applications, such as domestic, commercial, and industrial heating. The BS 2869 standard permits Class A2 and Class D fuel to contain up to 7% (V/V) [[biodiesel]] ([[fatty acid methyl ester]], FAME), provided the FAME content meets the requirements of the BS EN 14214 standard.
Classes E to H are residual oils for atomizing burners serving boilers or, with the exception of Class H, certain types of larger combustion engines. Classes F to H invariably require heating prior to use; Class E fuel may require preheating, depending on ambient conditions.
===Russia===
[[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. In the Russian practice, though, "mazut" is an umbrella term roughly synonymous with the fuel oil in general, that covers most of the types mentioned above, except US grades 1 and 2/3, for which separate terms exist ([[kerosene]] and [[diesel fuel]]/solar oil respectively — Russian practice doesn't differentiate between diesel fuel and heating oil). This is further separated in two grades, "naval mazut" being analogous to US grades 4 and 5, and "furnace mazut", a heaviest residual fraction of the crude, almost exactly corresponding to US Number 6 fuel oil and further graded by viscosity and sulfur content.
==Maritime fuel classification==
In the [[Shipping|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]])''' - Roughly equivalent to no. 3 fuel 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)''' - Roughly equivalent no. 4 fuel oil, a blend of gasoil and heavy fuel oil, with less gasoil than marine diesel oil
*'''HFO (Heavy fuel oil)''' - Pure or nearly pure residual oil, roughly equivalent to no. 5 and no. 6 fuel oil
*'''NSFO (Navy special fuel oil)''' - Another name for no. 5 HFO
*'''MFO (Marine fuel oil)''' - Another name for no. 6 HFO
Marine diesel oil contains some heavy fuel oil, unlike regular diesels.
===Standards and classification===
[[Calculated Carbon Aromaticity Index|CCAI]] and [[Calculated Ignition Index|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.<ref>{{cite web|url=http://www.bunkerworld.com/markets/prices/nl/rtm/|title=Bunkerworld Account - Login|website=www.bunkerworld.com|access-date=18 February 2009|archive-url=https://web.archive.org/web/20090303174917/http://www.bunkerworld.com/markets/prices/nl/rtm/|archive-date=3 March 2009|url-status=live}}</ref> The unit of viscosity used is the [[centistoke]] (cSt) 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% sulfur)
*'''IFO 180''' - Intermediate fuel oil with a maximum viscosity of 180 centistokes (<3.5% sulfur)
*'''LS 380''' - Low-sulfur (<1.0%) intermediate fuel oil with a maximum viscosity of 380 centistokes
*'''LS 180''' - Low-sulfur (<1.0%) intermediate fuel oil with a maximum viscosity of 180 centistokes
*'''MDO''' - Marine diesel oil
*'''MGO''' - Marine gasoil
*'''LSMGO''' - Low-sulfur (<0.1%) Marine Gas Oil - The fuel is to be used in EU Ports and Anchorages. [[EU Sulfur directive 2005/33/EC]]
*'''ULSMGO''' - Ultra-Low-Sulfur Marine Gas Oil - referred to as Ultra-Low-Sulfur Diesel (sulfur 0.0015% max) in the US and Auto Gas Oil (sulfur 0.001% max) in the EU. Maximum sulfur allowable in US territories and territorial waters (inland, marine, and automotive) and in the EU for inland use.
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 work with a fuel having a maximum of 991&nbsp;kg/m3; with modern purifiers it is also possible to purify oil with a density of 1010&nbsp;kg/m3.
The first British standard for fuel oil came in 1982. The latest standard is ISO 8217 issued in 2017.<ref>https://www.iso.org/standard/64247.html {{Webarchive|url=https://web.archive.org/web/20171201034243/https://www.iso.org/standard/64247.html |date=1 December 2017 }} ISO8217:2017</ref> 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):
{| class="wikitable"
|-
!colspan=7|Marine distillate fuels
|- align=center
! Parameter || Unit || Limit || DMX || DMA || DMB || DMC
|-
|Density at 15&nbsp;°C
|kg/m<sup>3</sup>
|Max
| -
|890.0
|900.0
|920.0
|-
|Viscosity at 40&nbsp;°C
|mm<sup>2</sup>/s
|Max
|5.5
|6.0
|11.0
|14.0
|-
|
|mm<sup>2</sup>/s
|Min
|1.4
|1.5
| -
| -
|-
|Water
|% V/V
|Max
| -
| -
|0.3
|0.3
|-
|Sulfur<sup>1</sup>
|% (m/m)
|Max
|1.0
|1.5
|2.0
|2.0
|-
|Aluminium + Silicon<sup>2</sup>
|mg/kg
|Max
| -
| -
| -
|25
|-
|[[Flash point]]<sup>3</sup>
|°C
|Min
|43
|60
|60
|60
|-
|[[Pour point]], Summer
|°C
|Max
| -
|0
|6
|6
|-
|Pour point, Winter
|°C
|Max
| -
| -6
|0
|0
|-
|[[Cloud point]]
|°C
|Max
| -16
| -
| -
| -
|-
|Calculated Cetane Index
|
|Min
|45
|40
|35
| -
|}
{| class="wikitable"
|-
!colspan=13|Marine residual fuels
|- align=center
! Parameter || Unit || Limit || RMA 30 || RMB 30 || RMD 80 || RME 180 || RMF 180|| RMG 380 || RMH 380 || RMK 380 || RMH 700 || RMK 700
|-
|Density at 15&nbsp;°C
|kg/m<sup>3</sup>
|Max
|960.0
|975.0
|980.0
|991.0
|991.0
|991.0
|991.0
|1010.0
|991.0
|1010.0
|-
|Viscosity at 50&nbsp;°C
|mm<sup>2</sup>/s
|Max
|30.0
|30.0
|80.0
|180.0
|180.0
|380.0
|380.0
|380.0
|700.0
|700.0
|-
|Water
|% V/V
|Max
|0.5
|0.5
|0.5
|0.5
|0.5
|0.5
|0.5
|0.5
|0.5
|0.5
|-
|Sulfur<sup>1</sup>
|% (m/m)
|Max
|3.5
|3.5
|3.5
|3.5
|3.5
|3.5
|3.5
|3.5
|3.5
|3.5
|-
|Aluminium + Silicon<sup>2</sup>
|mg/kg
|Max
|80
|80
|80
|80
|80
|80
|80
|80
|80
|80
|-
|[[Flash point]]<sup>3</sup>
|°C
|Min
|60
|60
|60
|60
|60
|60
|60
|60
|60
|60
|-
|[[Pour point]], Summer
|°C
|Max
|6
|24
|30
|30
|30
|30
|30
|30
|30
|30
|-
|Pour point, Winter
|°C
|Max
|0
|24
|30
|30
|30
|30
|30
|30
|30
|30
|}
# Maximum sulfur content in the open ocean is 0.5% since January 2020.<ref>{{Cite web |title=IMO 2020 – cutting sulphur oxide emissions |url=https://www.imo.org/en/MediaCentre/HotTopics/Pages/Sulphur-2020.aspx |access-date=2022-08-03 |website=www.imo.org}}</ref> Maximum sulfur content in designated areas is 0.1% since 1 January 2015. Before then it was 1.00%.
# The content of aluminum and silicon is limited because those metals are dangerous for the engine. Those elements are present because some components of the fuel are manufactured with Fluid Catalytic Cracking process, which makes use of catalyst containing aluminum and silicon.
# The flash point of all fuels used in the engine room should be at least 60&nbsp;°C. (DMX is used for things like emergency generators and not normally used in the engine room. Gaseous fuels such as LPG/LNG have special class rules applied to the fuel systems.)
===Bunker fuel===
{{Main|Heavy fuel oil}}
[[File:residual fuel oil.JPG|thumb|upright|A sample of residual fuel oil]]
'''Bunker fuel''' or '''bunker crude''' is technically any type of fuel oil used aboard [[watercraft|water vessels]]. Its name is derived from coal bunkers, where the fuel was originally stored. In 2019, large ships consumed 213 million metric tons of bunker fuel.<ref>{{cite web |first1=Adrian  |last1=Tolson |title=Welcome to the 229 Million Metric Ton Global Bunker Market! |url=https://shipandbunker.com/news/world/375323-welcome-to-the-229-million-metric-ton-global-bunker-market |website=Ship & Bunker |archive-url= https://web.archive.org/web/20210724213558/https://shipandbunker.com/news/world/375323-welcome-to-the-229-million-metric-ton-global-bunker-market |archive-date=24 July 2021 |date=25 March 2021 |url-status=live}}</ref> The Australian Customs and the Australian Tax Office defines a bunker fuel as the fuel that powers the engine of a ship or aircraft. Bunker A is No. 4 fuel oil, bunker B is 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''' ('''NSFO''') or just '''navy special'''; No. 5 or 6 are also commonly called '''heavy fuel oil''' ('''HFO''') or '''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. Bunkers are rarely labeled this way in modern maritime 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 2010 and 2017. The latest edition of bunker fuel specification is ISO 8217: 2017. The standard divides fuels into residual and distillate fuels. The most common residual fuels in the shipping industry are RMG and RMK.<ref>{{cite web|url=https://www.chevronmarineproducts.com/docs/Requirements_for_Residual_Fuel_2010.pdf|title=RMG and RMK|url-status=dead|archive-url=https://web.archive.org/web/20120126135721/http://www.chevronmarineproducts.com/docs/Requirements_for_Residual_Fuel_2010.pdf|archive-date=26 January 2012|df=dmy-all}}</ref> The differences between the two are mainly the density and viscosity, with RMG generally being delivered at 380 [[Viscosity#Units|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 around the world, ''e.g.'', California, European Union, have established Emission Control Areas (ECA) that limit the maximum sulfur of fuels burned in their ports to limit pollution, reducing the percentage of sulfur and other particulates from 4.5% m/m to as little as 0.10% as of 2015 inside an ECA. As of 2013 3.5% continued to be permitted outside an ECA, but the International Maritime Organization has planned to lower the sulfur content requirement outside the ECAs to 0.5% m/m by 2020.<ref name=IMO14>{{cite web|title=Sulfur oxides (SOx) – Regulation 14|url=http://www.imo.org/en/OurWork/environment/pollutionprevention/airpollution/pages/sulphur-oxides-(sox)-%E2%80%93-regulation-14.aspx|publisher=International Maritime Organization|access-date=11 July 2013|quote=SOx and particulate matter emission controls apply to all fuel oil|url-status=dead|archive-url=http://arquivo.pt/wayback/20141223211746/http://www.imo.org/OurWork/Environment/PollutionPrevention/AirPollution/Pages/Sulphur-oxides-%28SOx%29-%e2%80%93-Regulation-14.aspx|archive-date=23 December 2014|df=dmy-all}}</ref> This is where Marine Distillate Fuels and other alternatives<ref name=Bloomberg71013>{{cite news|title=Rolls-Royce Revives Age of Sail to Beat Fuel-Cost Surge: Freight|url=https://www.bloomberg.com/news/2013-07-10/rolls-royce-revives-age-of-sail-to-beat-fuel-cost-surge-freight.html|access-date=11 July 2013|newspaper=Bloomberg|date=10 July 2013|author=Robert Wall|quote=a development which will prompt a switch to "a much more diverse fuel pallet"|archive-url=https://web.archive.org/web/20130715031020/http://www.bloomberg.com/news/2013-07-10/rolls-royce-revives-age-of-sail-to-beat-fuel-cost-surge-freight.html|archive-date=15 July 2013|url-status=live}}</ref> to use of heavy bunker fuel 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.<ref>{{cite web|url=https://www.chevronmarineproducts.com/docs/Requirements_for_Distillate_Fuel_2010.pdf|title=DMA and DMB|url-status=dead|archive-url=https://web.archive.org/web/20120126122253/http://www.chevronmarineproducts.com/docs/Requirements_for_Distillate_Fuel_2010.pdf|archive-date=26 January 2012|df=dmy-all}}</ref> [[Greenhouse gas]] emissions resulting from the use of international bunker fuels are currently included in national inventories.<ref name="Schrooten1">
{{cite journal
| last1= Schrooten
| first1= L
| title= Emissions of maritime transport: a reference system
| journal= Science of the Total Environment
| volume= 408
| issue= 2
| pages= 318–323
| year= 2009
| doi= 10.1016/j.scitotenv.2009.07.037
| pmid=19840885
| last2= De Vlieger
| first2= Ina
| last3= Int Panis
| first3= Luc
| last4= Chiffi
| first4= Cosimo
| last5= Pastori
| first5= Enrico
| bibcode= 2009ScTEn.408..318S| s2cid= 8271813
}}</ref><ref name="Schrooten2">{{cite journal
| last1= Schrooten
| first1= L
| title= Inventory and forecasting of maritime emissions in the Belgian sea territory, an activity based emission model
| journal= Atmospheric Environment
| volume= 42
| issue= 4
| pages= 667–676
| year= 2008
| doi= 10.1016/j.atmosenv.2007.09.071
| last2= De Vlieger
| first2= Ina
| last3= Int Panis
| first3= Luc
| last4= Styns, R. Torfs
| first4= K
| last5= Torfs
| first5= R
| bibcode= 2008AtmEn..42..667S
| s2cid= 93958844
}}</ref>
{| class="wikitable" style="margin:auto;"
|+ Table of fuel oils
|-
! Name !! Alias !! Alias !! Alias !! Alias !! Alias !! Type !! Chain length
|-
| No. 1 fuel oil
| No. 1 distillate
| No. 1 diesel fuel
| [[Kerosene]]
| [[Jet fuel]]
|
| Distillate
| 9-16
|-
| No. 2 fuel oil
| No. 2 distillate
| No. 2 [[diesel fuel]]
| Road diesel
| Rail diesel
| Marine gas oil
| Distillate
| 10-20
|-
| No. 3 fuel oil
| No. 3 distillate
| No. 3 diesel fuel
| Marine diesel oil
|
|
| Distillate
|
|-
| No. 4 fuel oil
| No. 4 distillate
| No. 4 residual fuel oil
| Bunker A
| Intermediate fuel oil
|
| Distillate/Residual
| 12-70
|-
| No. 5 fuel oil
| No. 5 residual fuel oil
| Heavy fuel oil
| Bunker B
| Navy special fuel oil
| Furnace fuel oil
| Residual
| 12-70
|-
| No. 6 fuel oil
| No. 6 residual fuel oil
| Heavy fuel oil
| Bunker C
| Marine fuel oil
| Furnace fuel oil
| Residual
| 20-70
|}
Heavy fuel oil is still the primary fuel for [[cruise ship]]s, a tourism sector that is associated with a clean and friendly image. In stark contrast, the [[exhaust gas]] emissions - due to HFO's high sulfur content - result in an eco balance significantly worse than that for individual mobility.<ref name="Vidal 2016">{{cite web |last=Vidal |first=John |title=The world's largest cruise ship and its supersized pollution problem |website=the Guardian |date=2016-05-21 |url=https://www.theguardian.com/environment/2016/may/21/the-worlds-largest-cruise-ship-and-its-supersized-pollution-problem |access-date=2018-08-21 |quote="Cruise companies create a picture of being a bright, clean and environmentally friendly tourism sector. But the opposite is true. One cruise ship emits as many air pollutants as five million cars going the same distance because these ships use heavy fuel that on land would have to be disposed of as hazardous waste."... "Heavy fuel oil can contain 3,500 times more sulfur than diesel that is used for land traffic vehicles. Ships do not have exhaust abatement technologies like particulate filters that are standard on passenger cars and lorries" |archive-url=https://web.archive.org/web/20190209105703/https://www.theguardian.com/environment/2016/may/21/the-worlds-largest-cruise-ship-and-its-supersized-pollution-problem |archive-date=9 February 2019 |url-status=live }}</ref><ref name="Cruise Law News 2017">{{cite web |title=bunker fuel |website=Cruise Law News |date=2017-03-31 |url=https://www.cruiselawnews.com/tags/bunker-fuel/ |access-date=2018-08-21 |archive-url=https://web.archive.org/web/20180821223209/https://www.cruiselawnews.com/tags/bunker-fuel/ |archive-date=21 August 2018 |url-status=live }}</ref><ref name="Stand.earth 2016">{{cite web |title=Clean up the Shipping Industry |website=Stand.earth |date=2016-12-14 |url=https://www.stand.earth/campaigns/clean-shipping-industry |access-date=2018-08-21 |archive-url=https://web.archive.org/web/20180821223138/https://www.stand.earth/campaigns/clean-shipping-industry |archive-date=21 August 2018 |url-status=dead }}</ref>
{{See also|#Environmental issues}}
==Bunkering==
The term "[[bunkering]]" broadly relates to storage of petroleum products in tanks (among other, disparate meanings). The precise meaning can be further specialized depending on context. Perhaps the most common, more specialized usage refers to the practice and business of refueling ships. Bunkering operations are located at seaports, and they include the storage of bunker (ship) fuels and the provision of the fuel to vessels.<ref>{{cite web|title=Bunkering|url=http://www.mpa.gov.sg/sites/port_and_shipping/port/bunkering/bunkering.page|publisher=Maritime and Port Authority of Singapore (MPA)|access-date=16 January 2015|url-status=dead|archive-url=https://web.archive.org/web/20150107064443/http://www.mpa.gov.sg/sites/port_and_shipping/port/bunkering/bunkering.page|archive-date=7 January 2015|df=dmy-all}}</ref>
Alternatively "bunkering" may apply to the shipboard logistics of loading fuel and distributing it among available bunkers (on-board fuel tanks).<ref>{{cite web|author=MOHIT|title=Bunkering is Dangerous: Procedure for Bunkering Operation on a Ship|url=https://www.marineinsight.com/guidelines/bunkering-is-dangerous-procedure-for-bunkering-operation-on-a-ship/|publisher=Marine Insight|date=19 October 2010|access-date=16 January 2015|postscript=. Site seems to require enabling of [[HTTP cookie|cookies]].|archive-url=https://web.archive.org/web/20151231131601/http://www.marineinsight.com/guidelines/bunkering-is-dangerous-procedure-for-bunkering-operation-on-a-ship/|archive-date=31 December 2015|url-status=live}}</ref>
Finally, in the context of the [[Petroleum industry in Nigeria|oil industry]] in [[Nigeria]], bunkering<ref>{{cite news|author=Jon Gambrell and Associated Press|title=Oil bunkering threatens Nigeria's economy, environment|url=https://www.washingtonpost.com/national/oil-bunkering-threatens-nigerias-economy-environment/2013/07/18/e38cb4a0-e273-11e2-aef3-339619eab080_story.html|newspaper=[[The Washington Post]]|date=20 July 2013|access-date=16 January 2015|archive-url=https://web.archive.org/web/20160309163038/https://www.washingtonpost.com/national/oil-bunkering-threatens-nigerias-economy-environment/2013/07/18/e38cb4a0-e273-11e2-aef3-339619eab080_story.html|archive-date=9 March 2016|url-status=live}}</ref> has come to refer to the [[oil theft in Nigeria|illegal diversion of crude oil]] (often subsequently refined in makeshift facilities into lighter transportation fuels) by the unauthorized cutting of holes into transport pipelines, often by very crude and hazardous means and causing [[Petroleum industry in Nigeria#Oil spills and water contamination|spills]].
As of 2018, some 300 million metric tons of fuel oil is used for ship bunkering. On January 1, 2020, regulations set by the International Marine Organization (IMO) all marine shipping vessels will require the use of [[very low sulfur fuel oil]] (0.5% Sulfur) or to install [[Flue-gas desulfurization|exhaust gas scrubber]] systems to remove the excess sulfur dioxide. The emissions from ships have generally been controlled by the following sulfur caps on any fuel oil used on board: 3.50% on and after 1 January 2012 and 0.50% on and after 1 January 2020.<ref>{{cite web|url=https://dan-bunkering.com/Admin/Public/DWSDownload.aspx?File=%2fFiles%2fFiler%2fDB%2fPdf%2fEmission_control_Regulations.pdf|title=Regulations for the prevention of air pollution from ships|website=www.dan-bunkering.com|access-date=4 October 2020}}</ref>
Further removal of sulfur translates to additional energy and capital costs<ref>{{Cite journal|last1=Chu Van|first1=Thuy|last2=Ramirez|first2=Jerome|last3=Rainey|first3=Thomas|last4=Ristovski|first4=Zoran|last5=Brown|first5=Richard J.|date=2019-05-01|title=Global impacts of recent IMO regulations on marine fuel oil refining processes and ship emissions|url=https://eprints.qut.edu.au/128190/2/128190.pdf|journal=Transportation Research Part D: Transport and Environment|language=en|volume=70|pages=123–134|doi=10.1016/j.trd.2019.04.001|s2cid=133571823|issn=1361-9209}}</ref> and can impact fuel price and availability. If priced correctly the excess cheap yet dirty fuel would find its way into other markets, including displacing some onshore energy production in nations with low environmental protection .<ref>{{cite web|url=https://www.hellenicshippingnews.com/power-sectors-thirst-for-fuel-oil-after-imo-low-sulfur-cap-shifts-bunker-demand/|title=Power sector's thirst for fuel oil after IMO low sulfur cap shifts bunker demand - Hellenic Shipping News Worldwide|website=www.hellenicshippingnews.com|access-date=16 May 2018|archive-url=https://web.archive.org/web/20180516175327/https://www.hellenicshippingnews.com/power-sectors-thirst-for-fuel-oil-after-imo-low-sulfur-cap-shifts-bunker-demand/|archive-date=16 May 2018|url-status=dead}}</ref>
==Transportation==
Fuel oil is transported worldwide by fleets of [[oil tanker]]s making deliveries to suitably sized strategic ports such as [[Houston]], US; [[Singapore]]; [[Fujairah]], [[United Arab Emirates]]; [[Balboa, Panama]], [[Cristóbal, Colón|Cristobal]], Panama; Sakha, [[Egypt]]; [[Algeciras]], Spain and [[Rotterdam]], Netherlands. Where a convenient seaport does not exist, inland transport may be achieved with the use of [[barge]]s. Lighter fuel oils can also be transported through [[pipeline transport|pipelines]]. The major physical supply chains of Europe are along the [[Rhine River]].
==Environmental issues==
{{Further|Environmental impact of shipping}}
Emissions from bunker fuel burning in ships contribute to climate change and to [[air pollution]] levels in many port cities, especially where the emissions from industry and [[road traffic]] have been controlled. The switch of auxiliary engines from heavy fuel oil to diesel oil at berth can result in large emission reductions, especially for [[sulfur dioxide|SO<sub>2</sub>]] and [[particulates|PM]]. [[Carbon dioxide|CO<sub>2</sub>]] emissions from bunker fuels sold are not added to national GHG emissions. For small countries with large international ports, there is an important difference between the emissions in territorial waters and the total emissions of the fuel sold.<ref name="Schrooten2"/> At the 1997 [[United Nations Climate Change conference#1997: COP 3, Kyoto, Japan|Third Conference of the Parties]] in Kyoto, Japan, countries agreed to exempt bunker fuels, and multilateral military operations, from national emissions totals after insistence from the U.S. climate change delegation for such exemptions.<ref>{{cite news|last1=Hermann|first1=Burkely|date=January 20, 2022|title=National Security and Climate Change: Behind the U.S. Pursuit of Military Exemptions to the Kyoto Protocol|language=en|publisher=[[National Security Archive]]|url=https://nsarchive.gwu.edu/briefing-book/environmental-diplomacy/2022-01-20/national-security-and-climate-change-behind-us|url-status=live|access-date=February 9, 2022|archive-url=https://web.archive.org/web/20220123162738/https://nsarchive.gwu.edu/briefing-book/environmental-diplomacy/2022-01-20/national-security-and-climate-change-behind-us|archive-date=January 23, 2022|series=[[National Security Archive#Publications|Briefing Book]] # 784}}</ref>
==See also==<!-- New links in alphabeteical order please -->
{{Div col}}
*{{annotated link|Coconut oil}}: an important fuel for ships in regions such as the Philippines, Papua New Guinea, and Vanuatu<ref>National Geographic magazine, April 2012</ref>
*{{annotated link|Diesel fuel}}
*{{annotated link|Fuel-management systems}}
*{{annotated link|Fuel price risk management}}
*{{annotated link|Gas oil separation plant}}
*{{annotated link|Gasoline}}
*{{annotated link|Heating oil}}
*{{annotated link|Hot-bulb engine}}
*{{annotated link|Jet fuel}}
*{{annotated link|Kerosene}}
*{{annotated link|Lubricant}}
*{{annotated link|Marine fuel management}}
*{{annotated link|Petroleum naphtha}}
*{{annotated link|OW Bunker|OW Bunker test case}}
*{{annotated link|Pyrolysis oil}}
{{Div col end}}
==References==
{{Reflist}}
==External links==
*[http://www.nature.nps.gov/hazardssafety/toxic/fueloil.pdf National Park Service - Fuel Oil] {{Webarchive|url=https://web.archive.org/web/20070610035043/http://www.nature.nps.gov/hazardssafety/toxic/fueloil.pdf |date=10 June 2007 }}
*[https://science.howstuffworks.com/environmental/energy/oil-refining.htm How Oil Refining Works – HowStuffWorks]
*[https://ibia.net/ International Bunker Industry Association]
*[https://response.restoration.noaa.gov/oil-and-chemical-spills/oil-spills/oil-types.html NOAA Oil Types]
{{ISO standards}}
{{Authority control}}
[[Category:IARC Group 2B carcinogens]]
[[Category:Liquid fuels]]
[[Category:Petroleum products]]