Lifecycle GHG - carbon intensity guidelines

Shipping will need new low/zero-carbon fuels to achieve the levels of ambition of the IMO's Initial GHG Strategy. 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 – cutting GHG emissions by 50%, in line with IMO's vision to ultimately phase out GHG emissions as soon as possible in this century.

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.

A candidate short-term measure in the IMO Initial 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.

Carbon intensity refers to CO2 emissions per transport work and therefore links carbon emissions to the amount of cargo transported and the distance sailed for a specific ship.

The lifecycle assessment (LCA) method 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 (or Tank-to Propeller) part (from the ship's fuel tank to the exhaust, also known as downstream emissions).

MEPC 76 instructed the Intersessional Working Group on reduction of GHG emissions from ships (ISWG-GHG) to further consider concrete proposals to encourage the uptake of alternative low-carbon and zero-carbon fuels, including the development of lifecycle assessment GHG/carbon intensity guidelines (LCA Guidelines) for all relevant types of fuels.

Candidate future 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 determination of lifecycle GHG intensity values for a wide range of fuels requires assessments using a scientific and holistic approach. 

ISWG-GHG 9, which took place from 15-17 September 2021, initiated concrete work on the development of 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.

Other elements and general principles of the LCA guidelines relate to emissions scope, global warming potential time horizon, accounting principles and identified priority areas for further work to advance the development of the guidelines. It also includes identification of sustainability criteria, of appropriate fuel certification schemes, and of approaches for regular review by IMO of both upstream and downstream (default) emission values. 

The development of draft lifecycle assessment GHG/carbon intensity guidelines for maritime fuels will be further considered by ISWG-GHG. 
 Well-to-wake (3).png
Overview of a basic “well-to-tank” and “tank-to wake” life-cycle GHG emissions approach, Source:  GV2050 Alternative Fuels and Energy Carriers for Shipping Training Package

Global Industry Alliance on Low Carbon Shipping

In the context of IMO’s Global Industry Alliance on Low Carbon Shipping, there is also a work-stream on lifecycle GHG assessments. 

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

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