Difference between HVO and Biodiesel production

How are HVO and Biodiesel different? The production processes for Hydrotreated Vegetable Oil (HVO) and Fatty Acid Methyl Esters (FAME), commonly known as biodiesel, are quite different, leading to distinct properties and performance characteristics for each fuel type. Here’s a closer look at how they differ:

Production Process

1. HVO (Hydrotreated Vegetable Oil)

   • Hydroprocessing: HVO is produced through a process called hydroprocessing or hydrotreatment, where vegetable oils or animal fats are treated with hydrogen at high temperatures and pressures in the presence of a catalyst. This process removes oxygen, nitrogen, and sulfur impurities and breaks down the triglycerides into straight-chain hydrocarbons.
   • Outcome: The result is a paraffinic hydrocarbon that is very similar in chemical structure to petroleum diesel, making it a high-quality diesel fuel that can be used in existing diesel engines without any modifications.
     
     

2. FAME (Fatty Acid Methyl Esters)

   • Transesterification: FAME is produced through transesterification, where vegetable oils or animal fats are reacted with an alcohol (usually methanol) in the presence of a catalyst (such as sodium hydroxide or potassium hydroxide) to produce methyl esters and glycerol. This mixture is also called Methoxide. 
   • Outcome: The resulting biodiesel (FAME) still retains some oxygen, which makes it less chemically stable than HVO. This can affect its performance, especially in terms of oxidation stability and cold flow properties.

Performance and Stability

• Cold Weather Performance: HVO generally performs better in cold conditions when compared to FAME. HVO does not contain esters that can crystallize in cold weather, hence it has superior cold flow properties.
• Oxidation Stability: HVO is more stable over time and resistant to oxidation because it does not contain double bonds or ester groups that are prone to degradation.
• Storage and Handling: HVO is less hygroscopic (less likely to absorb water from the atmosphere) and less susceptible to microbial growth compared to FAME.
  
  

Environmental Impact and Use

• Emissions: Both HVO and FAME significantly reduce greenhouse gas emissions compared to conventional diesel. However, HVO typically offers a greater reduction in NOx and particulate matter due to its cleaner combustion.
• Application: HVO can be used directly in any proportion in diesel engines without modification, while FAME usually needs to be blended with conventional diesel and might require modifications to engine systems at higher blend levels to avoid issues like material compatibility or gumming.
  
  

Overall, HVO is often considered superior to FAME in terms of performance and stability, and whilst HVO may often be perceived as costing more than both petroleum diesel or FAME blends, the reduced operational costs associated with HVO can be advantageous in many applications.