Vegetable oil refining
Vegetable oil refining is a process to transform vegetable oil into fuel by hydrocracking or hydrogenation. Hydrocracking breaks big molecules into smaller ones using hydrogen while hydrogenation adds hydrogen to molecules. These methods can be used for production of gasoline, diesel, propane, and other chemical feedstock. Diesel fuel produced from these sources is known as green diesel or renewable diesel.
The majority of plant and animal oils are vegetable oils which are triglycerides—suitable for refining. Refinery feedstock includes canola, algae, jatropha, salicornia, palm oil, and tallow. 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.
Comparison to biodiesel
Based on its feedstock green diesel could be classified as biodiesel; however, based on the processing technology and chemical formula green diesel and biodiesel are different products. The chemical reaction commonly used to produce biodiesel is known as transesterification. Vegetable oil and alcohol are reacted, producing esters, or biodiesel, and the coproduct, glycerol.
When refining vegetable oil, no glycerol is produced, only fuels.
Various stages of converting renewable hydrocarbon fuels produced by hydrotreating is done throughout energy industry. Some commercial examples of vegetable oil refining are NExBTL, H-Bio, the ConocoPhilips process, and the UOP/Eni Ecofining process. Neste Oil is the largest manufacturer, producing 2 million tons annually (2013). Neste Oil 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.In practice, these renewable diesels lower greenhouse gas emissions by 40-90%, have higher energy per content yields than petroleum-based diesels, and better cold-flow properties to work in colder climates. In addition, all of these green diesels can be introduced into any diesel engine or infrastructure without many mechanical modifications at any ratio with petroleum-based diesels.
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