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The use of residual fuels in the shipping industry since the 1960s has presented a concern due to the emissions of harmful particulate matter (PM), sulfur oxides (SOx), nitrogen oxides (NOx), and carbon dioxide (CO2). Therefore, there is a push for alternative fuels that can meet the emission standards and regulations set by the IMO (International Maritime Organization) as well as meet the market demands for energy-efficient and lower-cost fuels within the shipping industry. Biofuels, such as Biodiesel, Ethanol and Renewable Diesel are a viable option towards decarbonization and rapid rollout.

The initial strategy for reducing greenhouse gases (GHG) aims to reduce the average CO2 emissions across international shipping by at least 40% by 2030, with a goal of 70% by 2050, as compared to 2008. Additionally, it aims to reduce the total annual GHG emissions from international shipping by at least 50% by 2050, also as compared to 2008. There are several potential alternative fuels for the shipping sector, including liquefied natural gas, biodiesel, methanol, hydrogen, and ammonia. Among these options, biodiesel/Hydrotreated vegetable oils (renewable diesel) are attractive since they can be blended with the current marine fuels and used with and without modifications to engine infrastructure.

There is also a strong push across many other industries such as rail, trucking, municipal fleets and aviation to reduce their carbon footprint.


Biodiesel, also known as Fatty Acid Methyl Ester (FAME) when produced via the transesterification of various oils such as plant and animal oils. Transesterification is the process by which the triglycerides or the fatty components of the feedstock are converted to methyl esters and the byproducts of glycerol and water are removed as undesirable side products. It is the preferred method when the feedstock contains less than 0.5% free fatty acids, however, higher contents of free fatty acids require esterification in the presence of a catalyst for conversion to FAME. Although various catalysts can be used during the conversion process, sodium hydroxide, potassium hydroxide, and sodium methylate are commonly used.

Hydrotreated vegetable oil (HVO) is an advanced biofuel produced from plant oils or animal fat through hydrodeoxygenation and refining, typically in the presence of a catalyst. Hydrotreated renewable diesel can be used as a drop-in marine fuel, either neat or as a blend, with no engine or system modifications.

Fuel typeVery low sulfur fuel oil (VLSFOs)Heavy fuel oil (HFOs)Biodiesel (FAME)Hydrotreated vegetable oil (HVO)Diesel
Density @ 15 C936.0979888780829
Viscosity @ 50C106.4278.73.72.5152.7
Cetane number5680-9940-50
Est Cetane number32.218.8
Carbon content (%)86867786
Oxygen content (%)1100
Heating value (MJ/Kg)41.740.438 (has 7-8% lower heating value than HFO)44.143.1
Characteristics of FAME and HVO in comparison to diesel and VLSFOs.


There may be three major issues related to blending biodiesel with residual fuels/VLSFOs: (i) compatibility and stability properties of the blend, (ii) oxidation stability (storage stability properties), and (iii) acidity.

  • Stability/compatibility is one of the major, yet crucial issues related to the VLSFOs. Stability is determined by checking for sedimentation, which could be due to asphaltene agglomeration or oxidation of unsaturated components.
  • The presence of oxygen in biodiesel fuel can cause fuel degradation over time and the formation of peroxides, acids, and other insoluble compounds. Not only does this affect the long-term storability of the fuel, but it can result in fuel filter clogging due to the oxidation by-products.
  • The increase in oxidation and thermal stresses correspondingly increases the acid number of biodiesel, which is attributed to the formation of fatty acid chains when FAME is decomposed. Oxidation will increase corrosion within the fuel system, leading to engine damage.


The focus of V-TIC Services research is on biodiesel & renewable diesel, and their usage in newer applications and new blends. In addition to providing the regular Biodiesel and blend testing, finished product quality checks, we also offer troubleshooting and contamination identification services. Our experienced team provides the expertise and resources you need to ensure a quality deliverable.

There is very little published in the industry about blending biodiesel/hydrotreated vegetable oil with residual fuel. No specification standards nor test methods are available. Currently, when biodiesel blended fuel oils are supplied, they are generally checked against the existing ISO 8217 grades & specification limits. Recently, the ASTM released draft standards that approve blends of 100 percent biodiesel in addition to 6-20 percent, which will result in additional changes to fuels in circulation.

Our analyses show that significant improvement was noted in the blended fuels in the following properties:

  1. The ignition combustion properties (ECN) improved with increasing the Biodiesel content in final blends.
  2. The sediment values reduced with the increased addition of Biodiesel/Hydrotreated vegetable oils.
  3. Addition of Biodiesel always improves the lubricity properties.
  4. The long-term stability properties were significantly improved with the addition of Biodiesel/Hydrotreated vegetable oil.

However, please note that the characteristics of the blended biodiesel/HVO with VLSFOs are dependent on the type of biodiesel/HVO feedstock since the fatty acid profiles of each feedstock vary significantly. Since these fuels are new to the market, we recommend a detailed characterization of the final blends and their components at the desired ratio. Talk to us for more details.


Formerly known as the National Biodiesel Board


ASTM D445Kinematic Viscosity @ 40 C
ASTM D5453Sulfur by UVF
ASTM D130Copper Strip Corrosion
ASTM D613Cetane Number
ASTM D4530Micro Carbon Residue
ASTM D189Conradson Carbon Residue
ASTM D524Ramsbottom Carbon Residue
ASTM D664Total Acid Number
ASTM D2500Cloud Point
ASTM D93Flash Point
EN 14538Calcium & Magnesium
EN 14538Sodium & Potassium
ASTM D4951Phosphorus
ASTM D874Sulfated Ash
ASTM D6584Total & Free Glycerin
EN 14112Oxidation Stability
ASTM D2709Water & Sediment
ASTM D1160Distillation in Vacuum
ASTM D7501Cold Soak Filtration for Biodiesel
EN 14110Methanol in Biodiesel


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