New study finds blue ammonia unsuitable for decarbonization

IFPEN has released a report assessing the performance of methanol and ammonia in terms of decarbonization and compliance with regulatory frameworks.

The study “Evaluation of alternative marine fuels for the decarbonization of maritime transport” commissioned by CMA CGM and conducted by IFPEN, evaluates the greenhouse gas emissions of alternative marine fuels, focusing on methanol and ammonia.

The Life Cycle Assessment (LCA) study evaluated the greenhouse gas (GHG) emissions of methanol and ammonia from a well-to-wake (WtW) perspective, considering various production pathways. It analyzed 17 production regions, accounting for differences in electricity grid intensities and transport distances, with bunkering either in Rotterdam or Singapore.

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Key Findings of the study:

E-Methanol

Average fuel WtW emissions per MJ for e-methanol across 17 locations, assuming fully powered by renewable energy with cradle-to-grave emissions, carbon captured from flue gases in up to 2035 and from Direct Air Capture in 2050, are 16 ± 4 gCO₂eq/MJ (2025), 12 ± 3 gCO₂eq/MJ (2035) and 5 ± 1 (2050) [with ± values representing mean absolute deviation].
Average fuel WtW emissions per MJ for e-methanol across 17 locations, assuming carbon capture is powered by natural gas and auxiliary processes are powered by local electricity, are 26 ± 7 gCO₂eq/MJ (2025), 14 ± 4 gCO₂eq/MJ (2035) and 7 ± 1 (2050). Under this configuration, these emissions meet the 70% reduction threshold for RFNBO compliance under RED only from 2035 onwards.
In container unit transportation WtW GHG emissions (gCO₂eq/TEU.km), e-methanol is fit for decarbonisation, achieving an average 70% reduction (range 60-80%) compared to VLSFO. However, it relies on the availability of biogenic CO₂ and its capture, which may present logistical and scalability challenges.
Credit: IFPEN

Bio-Methanol

Supply chain for waste wood and gasification efficiency losses are the most important contributors.
RED compliance is met in all regions reaching (~95% GHG reduction)
In container unit transportation WtW GHG emissions (gCO₂eq/TEU.km), bio-methanol is fit for decarbonisation and offers the highest reduction potential. It achieves on average 80% lower WtW emissions (range 75-85%) compared to VLSFO, provided that sustainable biomass feedstocks are used. Transporting finished bio-methanol rather than raw biomass significantly reduces emissions.

E-Ammonia

Average WtW emissions per MJ for e-ammonia across 17 locations, assuming fully powered by renewable electricity with cradle-to-grave emissions, are 17 ± 4 gCO₂eq/MJ (2025), 12 ± 3 gCO₂eq/MJ (2035) and 5 ± 1 (2050). These emissions meet the 70% reduction threshold for RFNBO compliance under RED from 2025 onwards.
In container unit transportation WtW GHG emissions (gCO₂eq/TEU.km), e-ammonia achieves an average 50% reduction (range 35-85%) compared to VLSFO. While fit for decarbonization, its effectiveness is currently constrained by lower engine efficiency, high pilot fuel needs, and N₂O emissions. As this technology is still in its early stages and rapidly evolving, these findings are subject to significant uncertainties, therefore conclusions should be considered with caution and not considered as definitive. Further research and vessel design optimization are required to improve performance and reduce uncertainties.

Blue Ammonia

Average WtW emissions per MJ for blue-ammonia across 17 locations, assuming a natural gas-powered Steam Methane Reforming unit with MEA carbon capture and storage up to 2035, and a natural gas-powered Auto Thermal Reforming Unit with VPSA carbon capture and storage in 2050, are 83 ± 12 gCO₂eq/MJ (2025), 61 ± 6 gCO₂eq/MJ (2035) and 29 ± 4 (2050). These emission levels fail to meet the 70% reduction threshold for LCF (Low-Carbon Fuels) compliance under the Gas Directive in both 2025 and 2035, mainly due to due to methane and CO2 emissions associated with the natural gas supply chain and the process used to produce blue hydrogen. Even under optimistic scenarios with reduced upstream blue hydrogen emissions, it only meets the 70% reduction threshold in 6 out of 17 regions by 2050.
In container unit transportation WtW GHG emissions (gCO₂eq/TEU.km), blue ammonia achieves on average slightly higher emissions than those of VLSFO. Hence, blue ammonia is not currently a viable decarbonisation option. However, under specific conditions—such as optimized upstream blue hydrogen production using ATR technology—it may serve as a transitional solution until e-ammonia production scales up. However, such conditions were only considered to become widely adopted in 2050 for this study.

The report found that while e-methanol and bio-methanol offer the highest reduction potential, e-ammonia offers decarbonization benefits but requires further technological development to address efficiency, pilot fuel use, and N₂O emissions.

Blue ammonia remains unsuitable for deep decarbonization unless substantial improvements in methane emissions control and carbon capture technology are realized. Strategic decisions in the broader shipping industry must account not only for regulatory compliance but also for the full life-cycle emissions and the feasibility of adopting alternative fuels.

Impact of Production Region and Transport

The proximity of fuel production to the bunkering location significantly affects total emissions. Transporting fuels over long distances (e.g., from remote renewable energy hubs to Europe) adds substantial emissions that can impact RFNBO / LCF / biofuels compliance.

Electricity grid mix is a critical factor for both e-methanol and e-ammonia. Countries with high shares of renewables or low-carbon power (e.g., France, Canada) obtain significantly lower WtW emissions compared to regions reliant on fossil-fuel-based electricity (e.g., India, South Africa).

The use of e-ammonia and e- or bio-methanol as fuel for their own transport (expected by 2050) will reduce transport-related emissions, making geographical differences in emissions less pronounced over time.

Regulatory and Prospective Insights

Using the RED-compliant methodology, e-fuels derived from green hydrogen show a ~90% GHG reduction potential compared to the fossil reference. However, this approach does not account for emissions from renewable energy infrastructure, leading to over-optimistic estimates.

Under full cradle-to-gate accounting, including emissions from renewable energy infrastructure, e-fuels can still achieve ~80% reduction. While the 70% RFNBO threshold does not technically account for these emissions, the results demonstrate that the assessed e-fuels remain compliant even when they are considered.

GHG emissions are projected to decline further due to global grids decarbonization, improved electrolyser efficiency, and better transport logistics.