Guidelines on life cycle GHG intensity of marine fuels (LCA Guidelines)


Shipping will need new  zero or near-zero GHG emission fuels to achieve the levels of ambition of the 2023 IMO Strategy on Reduction of GHG Emissions from Ships. This includes ensuring achieving a reduction in the carbon intensity of international shipping by at least 40% by 2030 and a significant further reduction in carbon intensity to achieve the 2050 level of ambition – to reach net-zero GHG emissions by or around, i.e. close to, 2050, taking into account different national circumstances. 

To help ensure the pathway to net-zero shipping by 2050 the 2023 IMO GHG Strategy also includes indicative checkpoints aimed at reducing total GHG emissions from international shipping by “20% striving for 30% by 2030”, and “70%  striving for 80% by 2040”, compared to 2008 levels. 

The 2023 IMO Strategy states that  'the levels of ambition and indicative checkpoints should take into account the well-to-wake GHG emissions of marine fuels as addressed in the Guidelines on lifecycle GHG intensity of marine fuels (LCA guidelines) developed by the Organization with the overall objective of reducing GHG emissions within the boundaries of the energy system of international shipping and preventing a shift of emissions to other sectors'

According to projections in the Fourth IMO GHG Study 2020, about 64% of the total amount of CO2 reduction from shipping in 2050 will be achieved using alternative low/zero-carbon fuels.

The life cycle assessment (LCA) methodology

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).

Generic well-to-wake supply chain

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.

Development of Guidelines on life cycle GHG intensity of marine fuels (LCA Guidelines)

A candidate short-term measure in the Initial IMO GHG Strategy refers to developing "robust lifecycle GHG/carbon intensity guidelines for all types of fuels, in order to prepare for an implementation programme for effective uptake of alternative low-carbon and zero-carbon fuels". In accordance with the Initial Strategy, short-term measures are to be finalized by 2023.

ISWG-GHG 9, which took place from 15-17 September 2021, initiated concrete work on the development of Guidelines on life cycle GHG intensity of marine fuels (LCA Guidelines), and agreed that there was a need to develop a procedure with clear and objective criteria to be used to determine default emission values, or actual values under certain circumstances, including documentation, verification, and certification.

Following consideration of concrete proposals by IMO Member States, MEPC 78 (June 2022) established a Correspondence Group on marine fuel life cycle GHG analysis with the mandate to develop the draft LCA guidelines. The main tasks of the Group were:

  1. identify main initial fuel production pathways and feedstocks

  2. further consider sustainability criteria issues and further develop the Fuel Lifecycle Label (FLL)

  3. develop methodologies that allow for the calculation of Well-to-Tank, Tank-to-Wake and entire Well-to-Wake GHG emissions default values

  4. develop procedures that allow for the continuous review of emissions default values

  5. develop guidance for third-party verification and certification schemes (e.g.: scope of third-party verification, criteria for recognizing certification schemes)

ISWG-GHG 15 (26 to 30 June 2023) considered the final report of the Correspondence Group with a view to finalizing the draft LCA guidelines for adoption by MEPC 80 (3 to 7 July 2023).  

MEPC 80 adopted Guidelines on life cycle GHG intensity of marine fuels (LCA guidelines) RESOLUTION MEPC.376(80). The LCA guidelines 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.  

MEPC 80 also requested the Secretariat to undertake a review of existing practices on sustainability aspects/certification and third-party verification issues and to organize an expert workshop on the life cycle GHG intensity of marine fuels.

After further work by ISWG-GHG 16 (11 to 15 March 2024), 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. 

Further development of the LCA framework will be discussed at ISWG-GHG 17 in September 2024.

Global Industry Alliance on Low Carbon Shipping

IMO's Global Industry Alliance on Low Carbon Shipping is also working on life cycle GHG assessments. 

More information on the Global Industry Alliance can be found here:

The Glossary developed by Global Industry Alliance for understanding Life cycle assessment and sustainability criteria terminology can be found here.

See also the GreenVoyage 2050 training package on alternative fuels and energy carriers for shipping: