The life cycle assessment (LCA) methodology refers to the assessment of greenhouse gas emissions from the fuel production to the end-use by a ship ("Well-to-Wake"); it results from the combination of a "Well-to-Tank" part (from primary production to carriage of the fuel in a ship's tank, also known as upstream emissions) and a "Tank-to-Wake" (also called "Tank-to Propeller") part (from the ship's fuel tank to the exhaust, also known as downstream emissions).
Candidate low-carbon and zero-carbon fuels for shipping have diverse production pathways (for example, different generations of biofuels, hydrogen-based fuels, etc.) entailing significant differences in their overall environmental footprint.
The effective transition to alternative low- and zero-emission fuels requires the development of a robust international framework to assess the GHG intensity and sustainability of alternative low- and zero-emission fuels in a scientific and holistic manner.
In July 2023, the IMO Marine Environment Protection Committee at its 80th session (MEPC 80) adopted the first version of the Guidelines on life cycle GHG intensity of marine fuels (LCA guidelines) (resolution MEPC.376(80)), which allow for a Well-to-Wake calculation, including Well-to-Tank and Tank-to-Wake emission factors, of total GHG emissions related to the production and use of marine fuels. After further work, the IMO Marine Environment Protection Committee at its 81st session (MEPC 81) adopted revised Guidelines on life cycle GHG intensity of marine fuels (2024 LCA Guidelines) (resolution MEPC.391(81)). The updated guidelines include revised calculations for default emission factors; updated appendix 4 on template for well-to-tank default emission factor submission; and new appendix 5 template for Tank-to-Wake (TtW) emission factors.
The GESAMP – Working Group on Life Cycle GHG Intensity of Marine Fuels, GESAMP-LCA WG, or WG 46, was established in April 2024 at the request of MEPC 81 in order to provide scientific and technical advice on issues related to the implementation of the Life Cycle Assessment (LCA) Guidelines. The input will serve for the Committees' future consideration on the further development of the IMO LCA framework to make it scientifically and technically more robust and accurate.
More information about IMO’s work on the Guidelines on life cycle GHG intensity of marine fuels (LCA Guidelines) can be found on the IMO Website.