The term fuel oil generally includes any liquid fuel that is burned in a furnace or boiler to generate heat (heating oils), or used in an engine to generate power (as motor fuels). However, it does not usually include other liquid oils, such as those with a flash point of approximately 42°C (108°F), 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 naphtha.
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 (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.
Fuel oil truck making a delivery in North Carolina, 1945
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 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 impractical on small, fast moving vehicles. However, power plants and large ships are able to use residual fuel oil.
Use of residual fuel oil was more common in the past. It powered boilers, railroadsteam locomotives, and steamships. 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 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. 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,[1] and all buildings using fuel oil No. 6 had been converted to less polluting fuel by the end of 2015.[2]
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[update], electricity production from all forms of petroleum, including diesel and residual fuel, is only 3% of total production.[citation needed] 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.[3]
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 38°C (100°F) heated to 65–120°C (149–248°F) 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 65°C (149°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 40°C (104°F), pumping at around 50°C (122°F) and finalizing for burning at around 90–120°C (194–248°F).
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.[4]
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.[5]
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%.[5]
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.[6]
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 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.[7]
Number 1 fuel oil is a volatile distillate oil intended for vaporizing pot-type burners and high-performance/clean diesel engines.[8] 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 no. 1, kerosene, and jet fuel. Former names include: coal oil, stove oil, and range oil.[7]
Number 2 fuel oil is a distillate home heating oil.[8] Trucks and some cars use similar 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 manufacture.[7]
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.[8]
Number 4 fuel oil is a commercial heating oil for burner installations not equipped with preheaters.[8] It may be obtained from the heavy gas oil cut.[7] 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 77–104°C (171–219°F) for proper atomization at the burners.[8] It may be obtained from the heavy gas oil cut,[7] or it may be a blend of residual oil with enough number 2 oil to adjust viscosity until it can be pumped without preheating.[8] 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 104–127°C (219–261°F). 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.[8]
United Kingdom
The British Standard BS 2869, Fuel Oils for Agricultural, Domestic and Industrial Engines, specifies the following fuel oil classes:
Class C1 and C2 fuels are kerosene-type fuels. C1 is for use in flue less appliances (e.g. lamps). C2 is for vaporizing or atomizing burners in appliances connected to flues.
Class A2 fuel is suitable for mobile, off-road applications that are required to use a 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 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
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.[9] 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 991kg/m3; with modern purifiers it is also possible to purify oil with a density of 1010kg/m3.
The first British standard for fuel oil came in 1982. The latest standard is ISO 8217 issued in 2017.[10] 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):
Maximum sulfur content in the open ocean is 0.5% since January 2020.[11] 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°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 or bunker crude is technically any type of fuel oil used aboard 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.[12] 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.[13] 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 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.[14] This is where Marine Distillate Fuels and other alternatives[15] 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.[16]Greenhouse gas emissions resulting from the use of international bunker fuels are currently included in national inventories.[17][18]
Heavy fuel oil is still the primary fuel for cruise ships, 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.[19][20][21]
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.[22]
Alternatively "bunkering" may apply to the shipboard logistics of loading fuel and distributing it among available bunkers (on-board fuel tanks).[23]
Finally, in the context of the oil industry in Nigeria, bunkering[24] has come to refer to the 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 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 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.[25] Further removal of sulfur translates to additional energy and capital costs[26] 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 .[27]
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 SO2 and PM. CO2 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.[18] At the 1997 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.[28]
See also
Coconut oil– Edible oil derived from coconut: an important fuel for ships in regions such as the Philippines, Papua New Guinea, and Vanuatu[29]
Kerosene, or paraffin, 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 Greek: κηρός (kērós) meaning "wax", and was registered as a trademark by Nova Scotia geologist and inventor Abraham Gesner in 1854 before evolving into a generic trademark. It is sometimes spelled kerosine in scientific and industrial usage.
Diesel fuel, also called diesel oil or historically heavy 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.
Biodiesel is a renewable biofuel, a form of diesel fuel, derived from biological sources like vegetable oils, animal fats, or recycled greases, and consisting of long-chain fatty acid esters. It is typically made from fats.
An oil refinery or petroleum refinery is an industrial process plant where petroleum is transformed and refined into products such as gasoline (petrol), diesel fuel, asphalt base, fuel oils, heating oil, kerosene, liquefied petroleum gas and petroleum naphtha. Petrochemical feedstock like ethylene and propylene can also be produced directly by cracking crude oil without the need of using refined products of crude oil such as naphtha. The crude oil feedstock has typically been processed by an oil production plant. There is usually an oil depot at or near an oil refinery for the storage of incoming crude oil feedstock as well as bulk liquid products. In 2020, the total capacity of global refineries for crude oil was about 101.2 million barrels per day.
A visbreaker is a processing unit in an oil refinery whose purpose is to reduce the quantity of residual oil produced in the distillation of crude oil and to increase the yield of more valuable middle distillates by the refinery. A visbreaker thermally cracks large hydrocarbon molecules in the oil by heating in a furnace to reduce its viscosity and to produce small quantities of light hydrocarbons.. The process name of "visbreaker" refers to the fact that the process reduces the viscosity of the residual oil. The process is non-catalytic.
Petroleum products are materials derived from crude oil (petroleum) as it is processed in oil refineries. Unlike petrochemicals, which are a collection of well-defined usually pure organic compounds, petroleum products are complex mixtures. Most petroleum is converted into petroleum products, which include several classes of fuels.
Singapore Petroleum Company Limited, in short SPC, is a Singaporean multinational oil and gas company. It is involved in the exploration and production of petroleum, refining, trading and petroleum product distribution.
Petroleum coke, abbreviated coke, pet coke or petcoke, is a final carbon-rich solid material that derives from oil refining, and is one type of the group of fuels referred to as cokes. Petcoke is the coke that, in particular, derives from a final cracking process—a thermo-based chemical engineering process that splits long chain hydrocarbons of petroleum into shorter chains—that takes place in units termed coker units. Stated succinctly, coke is the "carbonization product of high-boiling hydrocarbon fractions obtained in petroleum processing ". Petcoke is also produced in the production of synthetic crude oil (syncrude) from bitumen extracted from Canada's tar sands and from Venezuela's Orinoco oil sands.
The Calculated Ignition Index (CII) is an index of the ignition quality of residual fuel oil. It is used to determine the suitability of heavy fuel oil for (marine) engines.
Mazut is a low-quality heavy fuel oil, used in power plants and similar applications in the countries of the former Soviet Union. In the West, through Fluid catalytic cracking, mazut is distilled into diesel and other light distillates. Mazut may be used for heating houses in the former USSR and in countries of the Far East that do not have the facilities to blend or break it down into more conventional petro-chemicals.
Gdańsk oil refinery is a 10.5 million tonne per year refinery located near the Polish city of Gdańsk on the Baltic Sea. The refinery was established in 1975 to supply fuels and lubricants, and has undergone several upgrades and expansions to increase its capacity and the range of products available. It now has a Nelson complexity index of 11.1. It is one of two oil refineries in Poland, the other is Plock refinery.
Marine diesel oil (MDO) is a type of distillate diesel oil. Marine diesel oil is also called distillate marine diesel. MDO is widely used by medium speed and medium/high speed marine diesel engines. It is also used in the larger low speed and medium speed propulsion engine which normally burn residual fuel. Those fuels result from a catalytic cracking and visbreaking refinery. Marine diesel oil has been condemned for its nimiety of sulfur, so many countries and organizations established regulations and laws on MDO use. Due to its lower price compared to more refined fuel, MDO is favored particularly by the shipping industry.
Automotive oil recycling involves the recycling of used oils and the creation of new products from the recycled oils, and includes the recycling of motor oil and hydraulic oil. Oil recycling also benefits the environment: increased opportunities for consumers to recycle oil lessens the likelihood of used oil being dumped on lands and in waterways. For example, one gallon of motor oil dumped into waterways has the potential to pollute one million gallons of water.
The environmental effects of shipping include air pollution, water pollution, acoustic, and oil pollution. Ships are responsible for more than 18% of nitrogen oxides pollution, and 3% of greenhouse gas emissions.
Petroleum refining processes are the chemical engineering processes and other facilities used in petroleum refineries to transform crude oil into useful products such as liquefied petroleum gas (LPG), gasoline or petrol, kerosene, jet fuel, diesel oil and fuel oils.
Emulsified Fuels are emulsions composed of water and a combustible liquid, either oil or a fuel. Emulsions are a particular example of a dispersion comprising a continuous and a dispersed phase. The most commonly used emulsion fuel is water-in-diesel emulsion. In the case of emulsions, both phases are the immiscible liquids, oil and water. Emulsion fuels can be either a microemulsion or an ordinary emulsion. The essential differences between the two are stability and particle size distribution. Microemulsions are isotropic whereas macroemulsions are prone to settling and changes in particle size over time. Both use surfactants and can be either water-in-oil, or oil-in-water or bicontinuous.
Emission control areas (ECAs), or sulfur emission control areas (SECAs), are sea areas in which stricter controls were established to minimize airborne emissions from ships as defined by Annex VI of the 1997 MARPOL Protocol.
A marine LNG engine is a dual fuel engine that uses natural gas and bunker fuel to convert chemical energy in to mechanical energy. Due to natural gas' cleaner burning properties, the use of natural gas in merchant ship propulsion plants is becoming an option for companies in order to comply with IMO and MARPOL environmental regulations. The natural gas is stored in liquid state (LNG) and the boil-off gas is routed to and burned in dual fuel engines. Shipping companies have been cautious when choosing a propulsion system for their fleets. The steam turbine system has been the main choice as the prime mover on LNG carriers over the last several decades. The decades-old system on steam propelled LNG carriers uses BOG. LNG carriers are heavily insulated to keep the LNG at around -160 °C – to keep it liquefied. Despite insulation, the LNG containment area is penetrated by heat which allows for naturally generated boil-off gas (BOG).
Base oils are used to manufacture products including lubricating greases, motor oil and metal processing fluids. Different products require different compositions and properties in the oil. One of the most important factors is the liquid’s viscosity at various temperatures. Whether or not a crude oil is suitable to be made into a base oil is determined by the concentration of base oil molecules as well as how easily these can be extracted.
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 contaminated with several different compounds including aromatics, sulfur, and nitrogen, making emissions upon combustion more polluting compared to other fuel oils. HFO is predominantly used as a fuel source for marine vessel propulsion using marine diesel engines due to its relatively low cost compared to cleaner fuel sources such as distillates. The use and carriage of HFO on-board vessels presents several environmental concerns, namely the risk of oil spill and the emission of toxic compounds and particulates including black carbon. The use of HFOs is banned as a fuel source for ships travelling in the Antarctic as part of the International Maritime Organization's (IMO) International Code for Ships Operating in Polar Waters (Polar Code). For similar reasons, an HFO ban in Arctic waters is currently being considered.
↑ "Sulfur oxides (SOx) – Regulation 14". International Maritime Organization. Archived from the original on 23 December 2014. Retrieved 11 July 2013. SOx and particulate matter emission controls apply to all fuel oil
1 2 Schrooten, L; De Vlieger, Ina; Int Panis, Luc; Styns, R. Torfs, K; Torfs, R (2008). "Inventory and forecasting of maritime emissions in the Belgian sea territory, an activity based emission model". Atmospheric Environment. 42 (4): 667–676. Bibcode:2008AtmEn..42..667S. doi:10.1016/j.atmosenv.2007.09.071. S2CID93958844.
↑ Vidal, John (21 May 2016). "The world's largest cruise ship and its supersized pollution problem". the Guardian. Archived from the original on 9 February 2019. Retrieved 21 August 2018. 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
↑ "bunker fuel". Cruise Law News. 31 March 2017. Archived from the original on 21 August 2018. Retrieved 21 August 2018.
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