Liquefied petroleum gas

Source: Wikipedia, the free encyclopedia.

LPG storage spheres
Two 45 kg (99 lb) LPG gas cylinders in New Zealand used for domestic supply
LPG minibuses in Hong Kong
A dual fuel LPG-powered Ford Falcon taxicab in Perth
Tank cars in a Canadian train for carrying liquid petroleum gas by rail

Liquefied petroleum gas, also referred to as liquid petroleum gas (LPG or LP gas), is a

butylene, and isobutene.[1][2][3]

LPG is used as a

aerosol propellant[4] and a refrigerant,[5] replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer. When specifically used as a vehicle fuel, it is often referred to as autogas or even just as gas
.

Varieties of LPG that are bought and sold include mixes that are mostly propane (C
3
H
8
), mostly butane (C
4
H
10
), and, most commonly, mixes including both propane and butane. In the northern hemisphere winter, the mixes contain more propane, while in summer, they contain more butane.
[6][7] In the United States, mainly two grades of LPG are sold: commercial propane and HD-5. These specifications are published by the Gas Processors Association (GPA)[8] and the American Society of Testing and Materials.[9] Propane/butane blends are also listed in these specifications.

odorant, ethanethiol, is added so that leaks can be detected easily. The internationally recognized European Standard is EN 589. In the United States, tetrahydrothiophene (thiophane) or amyl mercaptan are also approved odorants,[10]
although neither is currently being utilized.

LPG is prepared by

petrol (gasoline).[11] However, its energy density per volume unit of 26 MJ/L is lower than either that of petrol or fuel oil, as its relative density is lower (about 0.5–0.58 kg/L, compared to 0.71–0.77 kg/L for gasoline). As the density and vapor pressure of LPG (or its components) change significantly with temperature, this fact must be considered every time when the application is connected with safety or custody transfer operations,[12]
e.g. typical cuttoff level option for LPG reservoir is 85%.

Besides its use as an energy carrier, LPG is also a promising feedstock in the chemical industry for the synthesis of olefins such as ethylene, propylene,[13][14]

As its boiling point is below room

explosive limits
and there is an ignition source. The second is suffocation due to LPG displacing air, causing a decrease in oxygen concentration.

A full LPG gas cylinder contains 86% liquid; the ullage volume will contain vapour at a pressure that varies with temperature.[15]

LPG prices around the world

Country/Territory US$/L
(95
RON
)
US$/US gallon
(95 RON)
Date of price Sources
Algeria 0.0661 0.25 9 Mar 2023 [16]
Angola 0.1991 0.75 9 Mar 2023 [17]
Saudi Arabia 0.2401 0.91 9 Mar 2023 [18]
Russia 0.2561 0.97 9 Mar 2023 [19]
Kyrgyzstan 0.3371 1.28 9 Mar 2023 [20]
Azerbaijan 0.3821 1.45 9 Mar 2023 [21]
Taiwan 0.4751 1.80 9 Mar 2023 [22]
Australia 0.4981 1.89 9 Mar 2023 [23]
Honduras 0.5071 1.92 9 Mar 2023 [24]
Peru 0.5071 1.92 9 Mar 2023 [25]
Belarus 0.5191 1.97 9 Mar 2023 [26]
Cambodia 0.5671 2.15 9 Mar 2023 [27]
Paraguay 0.5831 2.21 9 Mar 2023 [28]
Lithuania 0.6171 2.34 9 Mar 2023 [29]
Bulgaria 0.6271 2.37 9 Mar 2023 [30]
Turkey 0.6281 2.38 9 Mar 2023 [31]
Ukraine 0.6511 2.46 9 Mar 2023 [32]
Mongolia 0.6801 2.57 9 Mar 2023 [33]
Georgia 0.6851 2.59 9 Mar 2023 [34]
Albania 0.6921 2.62 9 Mar 2023 [35]
South Korea 0.6941 2.63 9 Mar 2023 [36]
Dominican Republic 0.7021 2.66 9 Mar 2023 [37]
Poland 0.7191 2.72 9 Mar 2023 [38]
Chile 0.7331 2.78 9 Mar 2023 [39]
Philippines 0.7701 2.92 9 Mar 2023 [40]
Estonia 0.7721 2.92 9 Mar 2023 [41]
Czech Republic 0.7921 3.00 9 Mar 2023 [42]
Bosnia And Herzegovina
0.8061 3.05 9 Mar 2023 [43]
India 0.8191 3.10 9 Mar 2023 [44]
Slovakia 0.8361 3.16 9 Mar 2023 [45]
San Marino 0.8381 3.17 9 Mar 2023 [46]
Latvia 0.8411 3.18 9 Mar 2023 [47]
Romania 0.8571 3.24 9 Mar 2023 [48]
Italy 0.8591 3.25 9 Mar 2023 [49]
Macedonia 0.8611 3.26 9 Mar 2023 [50]
Moldova 0.8611 3.26 9 Mar 2023 [51]
Belgium 0.8681 3.29 9 Mar 2023 [52]
Luxembourg 0.8701 3.29 9 Mar 2023 [53]
Netherlands 0.8891 3.37 9 Mar 2023 [54]
Lebanon 0.9031 3.42 9 Mar 2023 [55]
Serbia 0.9101 3.45 9 Mar 2023 [56]
Portugal 0.9151 3.46 9 Mar 2023 [57]
United Kingdom 0.9171 3.47 9 Mar 2023 [58]
Canada 0.9281 3.51 9 Mar 2023 [59]
Slovenia 0.9931 3.76 9 Mar 2023 [60]
Croatia 1.0261 3.88 9 Mar 2023 [61]
Israel 1.0341 3.91 9 Mar 2023 [62]
Hungary 1.0431 3.95 9 Mar 2023 [63]
Spain 1.0491 3.97 9 Mar 2023 [64]
France 1.0531 3.99 9 Mar 2023 [65]
Greece 1.0571 4.00 9 Mar 2023 [66]
Fiji 1.0601 4.01 9 Mar 2023 [67]
Switzerland 1.1411 4.32 9 Mar 2023 [68]
Germany 1.1531 4.36 9 Mar 2023 [69]
Sweden 1.3451 5.09 9 Mar 2023 [70]

Uses

LPG has a wide variety of uses in many different markets as an efficient fuel container in the agricultural, recreation, hospitality, industrial, construction, sailing and fishing sectors. It can serve as fuel for cooking, central heating and water heating and is a particularly cost-effective and efficient way to heat off-grid homes.

Cooking

LPG is used for cooking in many countries for economic reasons, for convenience or because it is the preferred fuel source.

In India, nearly 8.9 million tons of LPG were consumed in the six months between April and September 2016 in the domestic sector, mainly for cooking. The number of domestic connections are 215 million (i.e., one connection for every six people) with a circulation of more than 350 million LPG cylinders.[71] Most of the LPG requirement is imported. Piped city gas supply in India is not yet developed on a major scale. LPG is subsidised by the Indian government for domestic users. An increase in LPG prices has been a politically sensitive matter in India as it potentially affects the middle class voting pattern.

LPG was once a standard cooking fuel in Hong Kong; however, the continued expansion of town gas to newer buildings has reduced LPG usage to less than 24% of residential units. However, other than electric, induction, or infrared stoves, LPG-fueled stoves are the only type available in most suburban villages and many public housing estates.

LPG is the most common cooking fuel in Brazilian urban areas, being used in virtually all households, with the exception of the cities of Rio de Janeiro and São Paulo, which have a natural gas pipeline infrastructure. Since 2001, poor families receive a government grant ("Vale Gás") used exclusively for the acquisition of LPG. Since 2003, this grant is part of the government's main social welfare program ("Bolsa Família"). Also, since 2005, the national oil company Petrobras differentiates between LPG destined for cooking and LPG destined for other uses, establishing a lower price for the former. This is a result of a directive from the Brazilian federal government, but its discontinuation is currently being debated.[72]

LPG is commonly used in North America for domestic cooking and outdoor grilling.

Rural heating

LPG cylinders in India
Liquefied petroleum gas tank on a rural farm

Predominantly in Europe and rural parts of many countries, LPG can provide an alternative to electric heating, heating oil, or kerosene. LPG is most often used in areas that do not have direct access to piped natural gas. In the UK about 200,000 households use LPG for heating.

LPG can be used as a power source for

combined heat and power
technologies (CHP). CHP is the process of generating both electrical power and useful heat from a single fuel source. This technology has allowed LPG to be used not just as fuel for heating and cooking, but also for decentralized generation of electricity.

Bottling LPG in the Marshall Islands for storage

LPG can be stored in a variety of manners. LPG, as with other

fossil fuels, can be combined with renewable power sources to provide greater reliability while still achieving some reduction in CO2 emissions. However, as opposed to wind and solar renewable energy sources, LPG can be used as a standalone energy source without the prohibitive expense of electrical energy storage. In many climates renewable sources such as solar and wind power would still require the construction, installation and maintenance of reliable baseload power sources such as LPG fueled generation to provide electrical power during the entire year. 100% wind/solar is possible, the caveat being that the expense of the additional generation capacity necessary to charge batteries plus the cost of battery electrical storage makes this option economically feasible in only a minority of situations.[citation needed
]

Motor fuel

Skoda 120
White-bordered green diamond symbol used on LPG-powered vehicles in China

When LPG is used to fuel

particulates
present in the latter.

LPG has a lower energy density per liter than either petrol or fuel-oil, so the equivalent

fuel consumption
is higher. Many governments impose less tax on LPG than on petrol or fuel-oil, which helps offset the greater consumption of LPG than of petrol or fuel-oil. However, in many European countries, this tax break is often compensated by a much higher annual tax on cars using LPG than on cars using petrol or fuel-oil. Propane is the third most widely used motor fuel in the world. 2013 estimates are that over 24.9 million vehicles are fueled by propane gas worldwide. Over 25 million tonnes (over 9 billion US gallons) are used annually as a vehicle fuel.

Not all automobile engines are suitable for use with LPG as a fuel. LPG provides less upper cylinder lubrication than petrol or diesel, so LPG-fueled engines are more prone to valve wear if they are not suitably modified. Many modern common rail diesel engines respond well to LPG use as a supplementary fuel. This is where LPG is used as fuel as well as diesel. Systems are now available that integrate with OEM engine management systems.

Conversion kits can switch a vehicle dedicated to gasoline to using a dual system, in which both gasoline and LPG are used in the same vehicle.

In 2020, BW LPG successfully retrofitted a Very Large Gas Carrier (VLGC) with LPG propulsion technology, pioneering LPG's application in large-scale maritime operations.[75] LPG’s lowers emissions of carbon dioxide, sulfur oxides, nitrogen oxides, and particulate matter[76] align with stricter standards set by the International Maritime Organization (IMO), making LPG a viable transition option as the maritime industry transitions towards net zero carbon emissions.[77]

Conversion to gasoline

LPG can be converted into

alkylate which is a premium gasoline
blending stock because it has exceptional anti-knock properties and gives clean burning.

Refrigeration

LPG is instrumental in providing

gas absorption refrigerator
.

Blended from pure, dry propane (refrigerant designator R-290) and isobutane (R-600a) the blend "R-290a" has negligible ozone depletion potential, very low global warming potential and can serve as a functional replacement for R-12, R-22, R-134a and other chlorofluorocarbon or hydrofluorocarbon refrigerants in conventional stationary refrigeration and air conditioning systems.[78]

Such substitution is widely prohibited or discouraged in motor vehicle air conditioning systems, on the grounds that using

flammable hydrocarbons in systems originally designed to carry non-flammable refrigerant presents a significant risk of fire or explosion.[79][80]

Vendors and advocates of hydrocarbon refrigerants argue against such bans on the grounds that there have been very few such incidents relative to the number of vehicle air conditioning systems filled with hydrocarbons.[81][82] One particular test, conducted by a professor at the University of New South Wales, unintentionally tested the worst-case scenario of a sudden and complete refrigerant expulsion into the passenger compartment followed by subsequent ignition. He and several others in the car sustained minor burns to their face, ears, and hands, and several observers received lacerations from the burst glass of the front passenger window. No one was seriously injured.[83]

Propellant

HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) or combinations of the two. More recently, liquid hydrofluoroolefin (HFO) propellants have become more widely adopted in aerosol systems due to their relatively low vapor pressure, low global warming potential (GWP), and nonflammability.[86]
Manual pump sprays can be used as an alternative to a stored propellant.

Global production

Global LPG production reached over 292 million metric tons per year (Mt/a) in 2015, while global LPG consumption to over 284 Mt/a.

crude oil.[88] 44% of global consumption is in the domestic sector. The U.S. is the leading producer and exporter of LPG.[89]

Security of supply

Because of the natural gas and the oil-refining industry, Europe is almost self-sufficient in LPG. Europe's security of supply is further safeguarded by:

  • a wide range of sources, both inside and outside Europe;
  • a flexible supply chain via water, rail and road with numerous routes and entry points into Europe.

According to 2010–12 estimates, proven world reserves of natural gas, from which most LPG is derived, stand at 300 trillion cubic meters (10,600 trillion cubic feet). Production continues to grow at an average annual rate of 2.2%.

Comparison with natural gas

LPG is composed mainly of propane and butane, while natural gas is composed of the lighter

calorific value (46 MJ/m3 equivalent to 12.8 kWh/m3) than natural gas (methane) (38 MJ/m3 equivalent to 10.6 kWh/m3), which means that LPG cannot simply be substituted for natural gas. In order to allow the use of the same burner controls and to provide for similar combustion characteristics, LPG can be mixed with air to produce a synthetic natural gas (SNG) that can be easily substituted. LPG/air mixing ratios average 60/40, though this is widely variable based on the gases making up the LPG. The method for determining the mixing ratios is by calculating the Wobbe index
of the mix. Gases having the same Wobbe index are held to be interchangeable.

LPG-based SNG is used in emergency backup systems for many public, industrial and military installations, and many utilities use LPG

peak shaving
plants in times of high demand to make up shortages in natural gas supplied to their distributions systems. LPG-SNG installations are also used during initial gas system introductions when the distribution infrastructure is in place before gas supplies can be connected. Developing markets in India and China (among others) use LPG-SNG systems to build up customer bases prior to expanding existing natural gas systems.

LPG-based SNG or natural gas with localized storage and piping distribution network to the households for catering to each cluster of 5000 domestic consumers can be planned under the initial phase of the city gas network system. This would eliminate the last mile LPG cylinders road transport which is a cause of traffic and safety hurdles in Indian cities. These localized natural gas networks are successfully operating in Japan with feasibility to get connected to wider networks in both villages and cities.

Environmental effects

Commercially available LPG is currently derived mainly from fossil fuels. Burning LPG releases

kWh produced by oil, 70% of that of coal, and less than 50% of that emitted by coal-generated electricity distributed via the grid.[90] Being a mix of propane and butane, LPG emits less carbon per joule
than butane but more carbon per joule than propane.

LPG burns more cleanly than higher molecular weight

As it is much less polluting than most traditional solid-fuel stoves, replacing cookstoves used in developing countries with LPG is one of the key strategies adopted to reduce household air pollution in the developing world.[92]

Fire/explosion risk and mitigation

LPG Horton sphere tanks at a Repsol Butano facility in Gijón, Spain

In a refinery or gas plant, LPG must be stored in

pressure vessels. These containers are either cylindrical and horizontal (sometimes referred to as bullet tanks) or spherical (of the Horton sphere type). Typically, these vessels are designed and manufactured according to some code. In the United States, this code is governed by the American Society of Mechanical Engineers
(ASME).

LPG containers have pressure relief valves, such that when subjected to exterior heating sources, they will vent LPGs to the atmosphere or a

flare stack
.

If a tank is subjected to a fire of sufficient duration and intensity, it can undergo a boiling liquid expanding vapor explosion (BLEVE). This is typically a concern for large refineries and petrochemical plants that maintain very large containers. In general, tanks are designed so that the product will vent faster than pressure can build to dangerous levels.

One remedy that is utilized in industrial settings is to equip such containers with a measure to provide a fire-resistance rating. Large, spherical LPG containers may have up to a 15 cm steel wall thickness. They are equipped with an approved pressure relief valve. A large fire in the vicinity of the vessel will increase its temperature and pressure. The relief valve on the top is designed to vent off excess pressure in order to prevent the rupture of the container itself. Given a fire of sufficient duration and intensity, the pressure being generated by the boiling and expanding gas can exceed the ability of the valve to vent the excess. Alternatively, if, due to continued venting, the liquid level drops below the area being heated, the tank structure can be overheated and subsequently weakened in that area. If either occurs, the container may rupture violently, launching pieces of the vessel at high velocity, while the released products can ignite as well, potentially causing catastrophic damage to anything nearby, including other containers.

People can be exposed to LPG in the workplace by breathing it in, skin contact, and eye contact. The

immediately dangerous to life and health (due solely to safety considerations pertaining to risk of explosion).[93]

See also

References

  1. ^ World Energy Prices: Database Documentation (PDF) (Report) (2020 ed.). International Energy Agency. Archived (PDF) from the original on 8 February 2024. Retrieved 8 February 2024.
  2. .
  3. .
  4. ^ Alvi, Moin ud-Din. "Aerosol Propellant | Aerosol Propellant Gas | Aerosol Supplies Dubai – Brothers Gas". www.brothersgas.com. Archived from the original on 30 December 2016. Retrieved 14 June 2016.
  5. ^ "Performance and Safety of LPG Refrigerants" (PDF). Archived from the original (PDF) on 10 March 2015.
  6. from the original on 4 June 2016.
  7. ^ Unipetrol. "Analysis of seasonal mixtures – Propane-butane Fuel Mixture (Summer, Winter)". Archived from the original on 9 August 2010. Retrieved 29 April 2013.
  8. ^ "Liquefied Petroleum Gas Specifications and Test Methods". Gas Processors Association. Archived from the original on 21 June 2013. Retrieved 18 May 2012.
  9. ^ "ASTM D1835 – 11 Standard Specification for Liquefied Petroleum (LP) Gases". American Society for Testing & Materials. Archived from the original on 22 May 2012.
  10. ^ 49 CFR 173.315
  11. .
  12. .
  13. ^ "High-purity propylene from refinery LPG".
  14. ^ Kinetic studies of propane oxidation on Mo and V based mixed oxide catalysts. 2011.
  15. ^ "LPG pdf" (PDF).
  16. ^ "Algeria Lpg Prices".
  17. ^ "Angola Lpg Prices".
  18. ^ "Saudi Arabia Lpg Prices".
  19. ^ "Russia Lpg Prices".
  20. ^ "Kyrgyzstan Lpg Prices".
  21. ^ "Azerbaijan Lpg Prices".
  22. ^ "Taiwan Lpg Prices".
  23. ^ "Australia Lpg Prices".
  24. ^ "Honduras Lpg Prices".
  25. ^ "Peru Lpg Prices".
  26. ^ "Belarus Lpg Prices".
  27. ^ "Cambodia Lpg Prices".
  28. ^ "Paraguay Lpg Prices".
  29. ^ "Lithuania Lpg Prices".
  30. ^ "Bulgaria Lpg Prices".
  31. ^ "Turkey Lpg Prices".
  32. ^ "Ukraine Lpg Prices".
  33. ^ "Mongolia Lpg Prices".
  34. ^ "Georgia Lpg Prices".
  35. ^ "Albania Lpg Prices".
  36. ^ "South Korea Lpg Prices".
  37. ^ "Dominican Republic Lpg Prices".
  38. ^ "Poland Lpg Prices".
  39. ^ "Chile Lpg Prices".
  40. ^ "Philippines Lpg Prices".
  41. ^ "Estonia Lpg Prices".
  42. ^ "Czech Republic Lpg Prices".
  43. ^ "Bosnia And Herzegovina Lpg Prices".
  44. ^ "India Lpg Prices".
  45. ^ "Slovakia Lpg Prices".
  46. ^ "San Marino Lpg Prices".
  47. ^ "Latvia Lpg Prices".
  48. ^ "Romania Lpg Prices".
  49. ^ "Italy Lpg Prices".
  50. ^ "Macedonia Lpg Prices".
  51. ^ "Moldova Lpg Prices".
  52. ^ "Belgium Lpg Prices".
  53. ^ "Luxembourg Lpg Prices".
  54. ^ "Netherlands Lpg Prices".
  55. ^ "Lebanon Lpg Prices".
  56. ^ "Serbia Lpg Prices".
  57. ^ "Portugal Lpg Prices".
  58. ^ "United Kingdom Lpg Prices".
  59. ^ "Canada Lpg Prices".
  60. ^ "Slovenia Lpg Prices".
  61. ^ "Croatia Lpg Prices".
  62. ^ "Israel Lpg Prices".
  63. ^ "Hungary Lpg Prices".
  64. ^ "Spain Lpg Prices".
  65. ^ "France Lpg Prices".
  66. ^ "Greece Lpg Prices".
  67. ^ "Fiji Lpg Prices".
  68. ^ "Switzerland Lpg Prices".
  69. ^ "Germany Lpg Prices".
  70. ^ "Sweden Lpg Prices".
  71. ^ "LPG Profile" (PDF). Archived (PDF) from the original on 8 April 2017. Retrieved 30 March 2017.
  72. ^ "ANP quer fim de diferença entre preços do gás de botijão – 17/08/2017 – Mercado". Folha de S.Paulo. Retrieved 25 January 2019.
  73. ^
    S2CID 109657186
    .
  74. ^ .
  75. ^ "World's first VLGC to be retrofitted with pioneering LPG propulsion technology achieves historic milestone; successfully runs on LPG fuel". BW Group. 21 October 2020. Retrieved 21 February 2024.
  76. ^ "Benefits of LPG Propulsion". BW LPG. Retrieved 21 February 2024.
  77. ^ "Net-zero by 2050: Achieving shipping decarbonization through industry momentum and the new ambition at IMO | UNCTAD". unctad.org. 22 September 2023. Retrieved 21 February 2024.
  78. ^ "*overview of advantages and disadvantages of alternatives*" (PDF). Technical Meeting on HCFC Phase-Out. European Commission. 5–6 April 2008. Archived from the original (PDF) on 5 August 2009. Retrieved 30 July 2009.
  79. ^ "Detailed Questions About HC-12a ®, OZ-12 ®, DURACOOL 12a ®, EC-12a, and other Flammable Hydrocarbon Refrigerants". Ozone Layer Depletion - Alternatives / SNAP. United States Environmental Protection Agency. Archived from the original on 7 August 2009. Retrieved 30 July 2009.
  80. ^ "A Warm Weather Warning: Stay Away from Flammable Hydrocarbon Refrigerants". Society of Automotive Engineers. 27 April 2005. Archived from the original on 5 May 2005. Retrieved 30 July 2009.
  81. ^ Iemma, Morris; Lo Po', Faye (16 October 1997). "Motor Vehicle Hydrocarbons". Parliament of New South Wales. Archived from the original on 1 July 2009. Retrieved 30 July 2009.
  82. ^ Ryan, J. F. (29 June 2000). "Hydrocarbon Refrigerants". Parliament of New South Wales. Archived from the original on 22 May 2005. Retrieved 30 July 2009.
  83. ^ "Car explosion leads to prosecution against leading hydrocarbon promoter" (PDF). VASA. 7 April 2005. Archived from the original (PDF) on 19 July 2008. Retrieved 24 May 2012.
  84. ^ "Fires Halted Quickly by "Lazy" Freon Gas". Popular Mechanics. Vol. 87. Hearst Magazines. April 1947. p. 115. Retrieved 7 June 2019. Freon chemical compounds in household refrigerators, air-cooling systems and as a DDT carrier in aerosol insect bombs have been found to be more effective in extinguishing fires than carbon dioxide.
  85. ISSN 2325-1026
    .
  86. ^ "Solstice® Propellant Technical Bulletin" (PDF). Honeywell. 2017.
  87. ^ "Statistical Review of Global LPG 2016" (PDF). Argus Media. Archived from the original (PDF) on 10 April 2017. Retrieved 13 January 2017.
  88. ^ "WLPGA Annual Report 2015" (PDF). World LPG Association. Archived (PDF) from the original on 10 April 2017. Retrieved 13 January 2017.
  89. ^ Needham, John (7 April 2016). "U.S. Is World's Largest LPG Exporter, But When Will Market Balance?". Butane Propane News. Archived from the original on 30 December 2017. Retrieved 10 April 2017.
  90. .
  91. .
  92. ^ World Health Organization (2016). Burning opportunity : clean household energy for health, sustainable development, and wellbeing of women and children. Geneva, Switzerland: WHO. Archived from the original on 24 November 2017.
  93. ^ "CDC – NIOSH Pocket Guide to Chemical Hazards – L.P.G." www.cdc.gov. Archived from the original on 8 December 2015. Retrieved 28 November 2015.

"Calorific value of Different Fuels". Centre for Ecological Sciences. IISc. Archived from the original on 19 February 2020.

External links