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Hydrotreated vegetable oil

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Not to be confused with Hydrogenated vegetable oil.

Hydrotreated vegetable oil (HVO) is a biofuel made by the hydrocracking or hydrogenation of vegetable oil. Hydrocracking breaks big molecules into smaller ones using hydrogen while hydrogenation adds hydrogen to molecules. These methods can be used to create substitutes for gasoline, diesel, propane, kerosene and other chemical feedstock. Diesel fuel produced from these sources is known as green diesel or renewable diesel.

Diesel fuel created by hydrotreating is distinct from the biodiesel made through esterification.

Feedstock

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The majority of plant and animal oils are triglycerides, suitable for refining. Refinery feedstock includes canola, algae, jatropha, salicornia, palm oil, tallow and soybeans. One type of algae, Botryococcus braunii produces a different type of oil, known as a triterpene, which is transformed into alkanes by a different process.[citation needed]

Chemical analysis

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Synthesis

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The production of hydrotreated vegetable oils is based on introducing hydrogen molecules into the raw fat or oil molecule. This process is associated with the reduction of the carbon compound. When hydrogen is used to react with triglycerides, different types of reactions can occur, and different resultant products are combined.[1] The second step of the process involves converting the triglycerides/fatty acids to hydrocarbons by hydrodeoxygenation (removing oxygen as water) and/or decarboxylation (removing oxygen as carbon dioxide).

A formulaic example of this is C
3H
5(RCOO)
3 + 12 H
2 ⟶ C
3H
8 + 3 RCH
3 + 6 H
2O

Chemical composition

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The chemical formula for HVO Diesel is CnH2n+2

Chemical properties

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Hydrotreated oils are characterized by very good low temperature properties. The cloud point also occurs below −40 °C. Therefore, these fuels are suitable for the preparation of premium fuel with a high cetane number and excellent low temperature properties. The cold filter plugging point (CFPP) virtually corresponds to the cloud point value, which is why the value of the cloud point is significant in the case of hydrotreated oils.[1]

Comparison to biodiesel

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Both HVO diesel (green diesel) and biodiesel are made from the same vegetable oil feedstock. However the processing technologies and chemical makeup of the two fuels differ. The chemical reaction commonly used to produce biodiesel is known as transesterification.[2]

The production of biodiesel also makes glycerol, but the production of HVO does not.

Neste has published the differences between biodiesel and renewable diesel (HVO) which are summarized in the table below.[3]

NESTE MY Renewable Diesel Conventional ULSD Biodiesel B20
GHG Emissions Reduction Up to 75% None 15%
Renewable Source 100% No Yes
Performance in Cold Weather Excellent Excellent Depends
Cetane Number 70+ 45-55 50
Fuel Stability High Average Low
OEM Approval Yes Yes Yes


Commercialization

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Various stages of converting renewable hydrocarbon fuels produced by hydrotreating is done throughout energy industry. Some commercial examples of vegetable oil refining are:

Neste is the largest manufacturer, producing ca. 3.3 million tonnes annually (2023).[8] Neste completed their first NExBTL plant in the summer 2007 and the second one in 2009. Petrobras planned to use 256 megalitres (1,610,000 bbl) of vegetable oils in the production of H-Bio fuel in 2007. ConocoPhilips is processing 42,000 US gallons per day (1,000 bbl/d) of vegetable oil. Other companies working on the commercialization and industrialization of renewable hydrocarbons and biofuels include Neste, REG Synthetic Fuels, LLC, ENI, UPM Biofuels, Diamond Green Diesel partnered with countries across the globe. Manufacturers of these renewable diesels report greenhouse gas emissions reductions of 40-90% compared to fossil diesel,[9][10][11] as well as better cold-flow properties to work in colder climates.[9] In addition, all of these green diesels can be introduced into any diesel engine or infrastructure without many mechanical modifications[12] at any ratio with petroleum-based diesels.[9]

Renewable diesel from vegetable oil is a growing substitute for petroleum.[13] California fleets used over 200 million US gallons (760,000 m3) of renewable diesel in 2017. The California Air Resources Board predicts that over 2 billion US gallons (7,600,000 m3) of fuel will be consumed in the state under its Low Carbon Fuel Standard requirements in the next ten years. Fleets operating on Renewable Diesel from various refiners and feedstocks are reported to see lower emissions, reduced maintenance costs, and nearly identical experience when driving with this fuel.[14]

Sustainability concerns

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A number of issues have been raised about the sustainability of HVO, primarily concerning the sourcing of its lipid feedstocks. Waste oils such as used cooking oil are a limited resource and their use cannot be scaled up beyond a certain point. Further demand for HVO would have to be met with crop-based virgin vegetable oils, but the diversion of vegetable oils from the food market into the biofuels sector has been linked to increased global food prices, and to global agricultural expansion and intensification. This is associated with a variety of ecological and environmental implications; moreover, greenhouse gas emissions from land use change may in some circumstances negate or exceed any benefit from the displacement of fossil fuels.[15]

A 2022 study published by the International Council on Clean Transportation found that the anticipated scale-up of renewable diesel capacity in the U.S. would quickly exhaust the available supply of waste and residual oils, and increasingly rely on domestic and imported soy oil.[16] The report also noted that increased U.S. renewable diesel production risked indirectly driving the expansion of palm oil cultivation in Southeast Asia, where the palm oil industry is still endemically associated with deforestation and peat destruction.

Challenges in Producing Fuels from Bio-Derived Feedstocks with HVO

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Refinery hydrotreaters are used for processing HVO. Introducing even minor amounts of biomaterial into a diesel hydrotreater has implications and potential risk factors.[17] The main issues are corrosion, high hydrogen consumption, and catalyst deactivation.[18]

According to Haldor Topsoe's experience with their licensed units, HVO production poses certain challenges for hydrotreaters including:

Corrosion - There are several corrosion mechanisms from hydrotreating vegetable oils and animal fats. Most are acidic though this is tempered by being bound into tri and di-glycerides. However, difficult feedstocks like Distillers Corn Oil can contain 10-15% free fatty acids.[19] These acids can attack non-stainless steels in the preheat train, fired heater, piping, valves and reactors. In addition, chlorides that contaminate feeds can be converted to hydrogen chloride in the reactor which can then cause accelerated corrosion in the effluent lines and for sour water. The presence of chlorides in a wet environment is also problematic for the common stainless steel grades 304 and 316 due to the potential of intergranular stress chloride cracking.[20] In addition, the formation of carbon dioxide from decarboxylation reactions during hydrotreating can form carbonic acid when contacted with water.[18]

Hydrogen Consumption - removing oxygen, cracking long-chain molecules, and saturating olefinic bonds will chemically consume two to four times the hydrogen of a conventional ULSD hydrotreater. ULSD hydrotreating chemical hydrogen consumption is typically 300-600 scf/bbl of feed depending on the aromatic saturation required for cycle oils and other cracked feedstocks.[21] Chemical consumption for HVO approaches 2,500 scf/bbl depending on the level of saturation of feedstock and the length of the carbon chains.[18] Delivering hydrogen for consumption, in addition to quench and additional excess circulating hydrogen can pose significant challenges to unit revamp design and operation with hydraulics, distribution, and compressor power being critical.[22]

Fouling - alkali metals and especially phosphorus must be kept low in HVO feedstocks in order to minimize pressure drop from fouling and general catalyst deactivation. Phosphatidic glassing is an aggressive catalyst poisoning mechanism that will not only plug off a reactor's pore spaces thus causing rapid pressure drop, but will also interfere with the catalysts acid sites by coating the outside of the catalyst and begin adhering to other catalyst particles.[18]

Operational history

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HVO processing is a young technology relative to most other refining processes. The first commercial scale unit started up in Louisiana in 2010 with a capacity of 100 million US gallons (380,000 m3) per year. [23]

A newbuild plant was constructed in 2010 Geismar, LA by the Syntroleum Corporation and its joint-venture partner Tyson Foods.[24] The plant initiated startup in the 3rd quarter with a target of 75 million US gallons (280,000 m3) per year. [25] Feedstock for the plant was vegetable oil and pretreated rendered poultry fat. The site achieved 87% of its design capacity in 2011.[26] Corrosion, including chloride-linked stress corrosion cracking shut the plant down in 2012 for more than a year.[27] Tyson sold its 50% ownership to Renewable Energy Group (now Chevron) and Syntroleum's stock was announced by the same buyer in 2013 with closing in 2014.[28] In 2015, two fires caused damage to the plant with major damage being incurred.[29]

Operable capacity

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United States[30]
Company City State Capacity in Million Gallons/yr 000s bpd equivalent
Diamond Green Diesel LLC Norco Louisiana 982 30.7
Diamond Green Diesel LLC Port Arthur Texas 470 12.5
Dakota Prairie Dickinson North Dakota 192 8.8
Calumet Calumet Montana 135 8.2
HollyFrontier Artesia New Mexico 125 7.8
Phillips 66 Rodeo Rodeo California 120 7.7
HollyFrontier Sinclair Wyoming 117 7.6
Chevron/REG Geismar Louisiana 100 6.5
CVR Wynnewood Oklahoma 100 6.5
HollyFrontier Cheyenne Wyoming 92 6.0
Seaboard Energy Hugoton Kansas 85 5.5

See also

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References

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  1. ^ a b Zeman, Petr; Hönig, Vladimír; Kotek, Martin; Táborský, Jan; Obergruber, Michal; Mařík, Jakub; Hartová, Veronika; Pechout, Martin (2019). "Hydrotreated Vegetable Oil as a Fuel from Waste Materials". Catalysts. 9 (4): 337. doi:10.3390/catal9040337. ISSN 2073-4344. This article incorporates text from this source, which is available under the CC BY 4.0 license.
  2. ^ "Hydrotreated Vegetable Oils (HVO) Archived 2021-05-31 at the Wayback Machine", European Alternative Fuels Observatory (retrieved 27 May 2021).
  3. ^ "Product information". Neste. Retrieved 2024-11-07.
  4. ^ "Green Car Congress: Preem selects Haldor Topsoe HydroFlex technology for renewable diesel and jet fuel production". greencarcongress.com. 2020. Retrieved April 2, 2020.
  5. ^ "Digital Refining: PKN ORLEN selects Vegan® technology and process book supply from Axens". digitalrefining.com. 2020. Retrieved April 2, 2020.
  6. ^ "Green Car Congress: ConocoPhillips Begins Production of Renewable Diesel Fuel at Whitegate Refinery". greencarcongress.com. 2012. Retrieved December 27, 2012.
  7. ^ "UOP and Italy's Eni S.p.A. announce plans for facility to produce diesel fuel from vegetable oil" (PDF) (Press release). UOP LLC. June 19, 2007. Archived from the original (PDF) on June 30, 2007. Retrieved January 1, 2010.
  8. ^ "Annual Report 2023 Neste". Retrieved 2024-03-11.
  9. ^ a b c "Products". May 9, 2015. Retrieved June 1, 2015.
  10. ^ Szeto, Wai; Leung, Dennis Y. C. (2022). "Is hydrotreated vegetable oil a superior substitute for fossil diesel? A comprehensive review on physicochemical properties, engine performance and emissions". Fuel. 327: 125065. Bibcode:2022Fuel..32725065S. doi:10.1016/j.fuel.2022.125065.
  11. ^ Di Blasio, Gabriele; Ianniello, Roberto; Beatrice, Carlo (2022). "Hydrotreated vegetable oil as enabler for high-efficient and ultra-low emission vehicles in the view of 2030 targets". Fuel. 310: 122206. Bibcode:2022Fuel..31022206D. doi:10.1016/j.fuel.2021.122206.
  12. ^ "Renewable Diesel". Neste.com. Retrieved July 8, 2024.
  13. ^ "Renewable Diesel as a major transportation fuel in California: Opportunities, Benefits, and Challenges". www.Gladstein.org/gna_whitepapers/. August 2017.
  14. ^ "Renewable Diesel as a Major Transportation Fuel in California". www.StarOilco.net. January 20, 2018.
  15. ^ Merfort, L.; Bauer, N.; et al. (June 2023). "State of global land regulation inadequate to control biofuel land-use-change emissions". Nature Climate Change. 13 (7): 610–612. Bibcode:2023NatCC..13..610M. doi:10.1038/s41558-023-01711-7.
  16. ^ Malins, Chris; Sandford, Cato (January 2022). "Animal, Vegetable or Mineral (Oil)? Exploring the Potential Impacts of New Renewable Diesel Capacity on Oil and Fat Markets in the United States" (PDF). International Council on Clean Transportation.
  17. ^ "Future fuel - the challenges associated with renewable diesel hydrotreating". www.digitalrefining.com. Retrieved 2024-10-28.
  18. ^ a b c d Verdier, Sylvain (2020). "Hydroprocessing of renewable feedstocks - challenges and solutions" (PDF). www.topsoe.com.
  19. ^ Winkler-Moser, Jill K.; Hwang, Hong-Sik; Byars, Jeffrey A.; Vaughn, Steven F.; Aurandt-Pilgrim, Jennifer; Kern, Olivia (2023-03-01). "Variations in phytochemical content and composition in distillers corn oil from 30 U.S. ethanol plants". Industrial Crops and Products. 193: 116108. doi:10.1016/j.indcrop.2022.116108. ISSN 0926-6690.
  20. ^ "Susceptibility of Type 304/304L and 316/316L austenitic stainless steels to chlorides in cooling water". www.digitalrefining.com. Retrieved 2024-10-30.
  21. ^ "Study identifies optimum operating conditions for ULSD hydrotreaters". Oil & Gas Journal. 2003-08-04. Retrieved 2024-10-29.
  22. ^ Green, Sara (October 13, 2021). "Key considerations for design and operation of a renewable diesel unit". Hydrocarbon Processing. Online.
  23. ^ Gerveni, Maria; Hubbs, Todd; Irwin, and Scott (2023-03-08). "Overview of the Production Capacity of U.S. Renewable Diesel Plants through December 2022". Farmdoc Daily. 13 (42).
  24. ^ Corporation, Syntroleum (2010-07-15). "Syntroleum Announces Geismar Plant Mechanical Completion". GlobeNewswire News Room (Press release). Retrieved 2024-10-28.
  25. ^ "Syntroleum announces Geismar plant completion". Hydrocarbon Processing. July 16, 2010.
  26. ^ "Syntroleum/Tyson JV synthetic fuel plant produced 5.4 million US gallons (20,000 m3) in July; 87% of design capacity". Green Car Congress.
  27. ^ AEDC (2013-12-18). "Renewable Energy Group to buy Syntroleum Corp". Ascension Economic Development Corporation. Retrieved 2024-10-28.
  28. ^ "Renewable Energy Group completes Dynamic Fuels acquisition | Biomass Magazine". biomassmagazine.com. Retrieved 2024-10-28.
  29. ^ "New fire erupts at Renewable Energy Group's Louisiana biorefinery". Renewables Now.
  30. ^ Gerveni, Maria; Hubbs, Todd; Irwin, and Scott (2023-03-08). "Overview of the Production Capacity of U.S. Renewable Diesel Plants through December 2022". Farmdoc Daily. 13 (42).
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