INSIGHT: Bunker Fuel GHG Carbon Footprint Reduction by Blending

By Ara Barsamian and Daniel Byeong C. Son, Refinery Automation Institute, LLC
Tuesday July 19, 2022

Great efforts are undertaken to develop alternative fuels to traditional hydrocarbon bunker. IBIA has started a working group to evaluate the potential and practicality of alternative fuels, encompassing among others, hydrogen, ammonia, methanol, and biofuels. It is an admirable effort bringing all suppliers, engine manufacturers, shipowners, and users together.

But there is a straightforward practical alternative right now which does not require modifying ship engines, storage tanks, or other safety engineering related mods: GHC CI blending.

Dilution of Green House Gas (GHG) Carbon Intensity (CI)

Dilution of CI is done by blending two or more fuel blend components with different CI's.
Each fuel material has a CI number, expressed in gCO2e/MJ. The CI number depends on the "pathway" used to determine the fuel life cycle, from its "birth to death"; that's the reason two similar fuels, e.g., FAME, have different CI's depending on their individual pathways.

CI data bases are available from US EPA and other organizations (see references 1 through 4).

The CI "blending method" and achieve substantial reduction in carbon intensity

  • Without new alternative or experimental fuels
  • Mostly without modifications to existing engines or fuel infrastructure

To put the theory to test, we calculated a blend of RMG 380 with FAME biodiesel [1] using the EPA CI database numbers; the results show a potential reduction of 21% in the CI of the 70/30% blend:

Of course, you can also use Renewable Diesel (RD), or "Green" middle distillates, such as green diesel, green jet, etc.

Applicability of Blending Method to Dilute Carbon Intensity (CI)

The GHG CI dilution by blending applies equally to alternative fuels, e.g., blending "Green" hydrogen with "Brown" hydrogen, or Ammonia or Methanol, etc.

If you are interested in getting a copy of the Excel-based GHG CI dilution blending spreadsheet, send us a request to or

The calculator covers GHG CI dilution for bunkers, diesel, and gasoline. You can modify it to suit your needs, and it can be used with any fuels, as long as the fuels are compatible and approved for use with a particular engine.

[2] IBIA's Future Fuels Working Group