•CTI-Maritec has been offering full range of biodiesel blends testing for bunker fuels since early 2022

• CTI-Maritec has tested quite a number of biodiesel blends in residual marine fuel, typically the biodiesel blends are ranged from B20 to B30.

CTI-MARITEC successfully tests biodiesel blends in bunker fuel says an article published in MARITEC.

Fame Content

Keeping in mind the ISO 8217 parameters, it is highly recommended that biodiesel blends shall also be measured for FAME content and lower calorific value (or net heat of combustion).

Biodiesel blends has lower energy content when compared to conventional fossil fuels and the calculated net specific energy commonly used for fossil fuels may not apply to biodiesel blends.

In order to plan for the consumption of biodiesel blend for a voyage and to determine the engine’s performance accurately, lower calorific value (or net heat of combustion) shall be measured.

When ordering biodiesel blends, the FAME content is agreed between buyer and seller, therefore it is important to measure the FAME content in order to ensure that the correct FAME content is received as per the biodiesel blend transaction.

Critical Parameters

Use of marine fuel containing FAME onboard ship may potentially pose some operation issues such as microbial growth; oxidative stability & long-term storage stability; low temperature operation & corrosion.

In view of the potential operation issues mentioned above, it is advised that vessel owners shall pre-emptively order optional analysis when routine ISO 8217 analysis indicates elevated values for some critical parameters as summarised below:

No Potential operation issues Routine ISO 8217


Recommended Analysis to further Evaluate the Biodiesel Blend
1 Corrosion issue If acid number is ≥ 1.5mgKOH/g 1)    Copper Corrosion – ASTM D130
2)    Rust Prevention Characteristic – ASTM D665a
3)    Fatty acids; monoglycerides; glycerine & other partial glycerides – by GC/MS technique such as Solid Phase Extraction (SPE) GCMS
2 Storage Stability If total sediment potential (TSP) is ≥ 0.07%m/m 1)    Total sediment accelerated (TSA)
2)    P-value by SMS 1600
Note: To determined fuel stability reserve
3 Oxidative Stability If total sediment potential (TSP) is ≥ 0.07%m/m 1)    Oxidation stability – EN 15751
Note: To determine fuel oxidative stability
4 Low temperature operation issue If pour point is ≥ 21oC 1)    Wax appearance temperature (WAT) and wax disappearance temperature (WDT) – ASTM D8420 or ASTM D 5773 equivalent
5 Potential microbial growth issue If water content is off-spec and biodiesel diesel blend is meant for long term storage before use 1)    Total Bacteria Count & Total Yeast & Mould – IP 385



Regulation 18.3 of MARPOL Annex VI – Use of Biofuels 

The approval of Unified Interpretation of regulation 18.3 of MARPOL Annex VI, with regard to the use of biofuels, by Marine Environmental Protection Committee (MEPC) as summarised below:

•a fuel oil which is a blend of not more than 30% by volume of biofuel should meet the requirements of regulation 18.3.1 of MARPOL Annex VI. It is therefore considered to be fuel oil of blends of hydrocarbons derived from petroleum refining and verification of the NOx impacts is not required;

•and a fuel oil which is a blend of more than 30% by volume of biofuel should meet the requirements of regulation 18.3.2 of MARPOL Annex VI. It may also be used without verification of the NOx impacts where the engine is already certified to Annex VI regulation 13 on a DM or RM grade fuel, and biofuels can be burnt without changes to the NOx critical components or settings/operating values outside those as given by that engine’s approved NOx Technical File.

Future Promises

In the near future, CTI-Maritec will expect to receive more biodiesel blends for analysis as more vessel owners will switch to biodiesel blends in order to comply with the regulatory requirements on reduction of GHG emissions especially reduction of carbon intensity from international shipping.

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