This section relates to the relevant consideration for the early adaption of Blue ammonia as an alternative fuel.
Natural gas is the primary feedstock for blue ammonia, and it is produced large scale in almost all regions of the world. The production of natural gas includes risk of upstream emissions including fugitive methane emissions, and these must all be mitigated for blue ammonia to play a role in decarbonizing the maritime industry. Best practice must be established and enforced, and measurement is essential for credible certification.
Ammonia synthesis is a mature technology using fossil feedstock (natural gas) but to make it carbon neutral the CO2 from the fossil feedstock needs to be captured and stored as part of the production process. A relatively low-cost of CO2 capture may be achieved due to the high concentration (>90%) of CO2 from methane-based ammonia synthesis. Currently, a solution for permanent CO2 storage is not available at scale making the maturation of a global CO2 storage infrastructure a key enabler for the ammonia fuel pathway.
Production of ammonia would need significant scaling as well, and new large-capacity ammonia plants will need to be constructed at record pace if blue ammonia is to have a significant role in decarbonizing shipping.
Fuel storage, logistics & bunkering
Ammonia is transported globally as a commodity (~20 million ton/year), but port infrastructure such as terminals and bunkering facilities must be significantly expanded to handle potentially hundreds of millions of shipping tons per year. The new technologies and the new requirements create a need for standards around hardware, bunkering and safety procedures.
Onboard energy storage & fuel conversion
The development of tank storage solutions for larger ammonia volumes, engine, and fuel cell technologies are ongoing. Dual-fuel ammonia engines are being developed but are not finally proven or commercially available yet. It also means that the required post-combustion emission reduction technologies are currently unknown. Solid Oxide Fuel Cells (SOFC) may run on ammonia directly, but SOFCs are significantly less mature and cannot be considered an ammonia-enabler for first movers. Boilers using ammonia as a fuel are under development but not yet commercially available.
Onboard safety & operations
Ammonia is highly toxic which makes risk assessments and impact on vessel design and cost key areas of investigation.
Onboard safety and operations are crucial for safe operation of ammonia fueled vessels. Currently, LPG carriers handle the safety management of ammonia as a cargo, but a vessel fueled by ammonia will introduce different risk including crew exposure from ammonia leakages or emissions. Risk management incl. quantitative risk assessments and human factor are required to enable detailed design and requirement specification for materials, components, location of systems like storage tanks, fuel gas supply system, and safety management systems.
Combustion of ammonia does not produce CO2 emissions as no carbon is contained in the fuel – except from the quantity of needed pilot fuel if it is carbon-based. Knowledge of, and experience, with emissions from ammonia internal combustion engines is limited. However, the potential exists for emissions of both N2O (a potent GHG combustion byproduct) and NH3 slip (highly toxic). Until fully developed and validated ammonia engines are available, the requirements for emission reduction technologies onboard are unclear. Based on potential emission scenarios, there will be a need for a selective catalytic reduction (SCR) system to remove NOx, potentially an N2O catalyst, as well as an additional catalyst or technology to remove ammonia slip. Based on the uncertainty of actual emissions from the engines under development, there are currently major challenges that need to be overcome before this fuel pathway can be matured.
Regulation & certification
On the regulatory side, some key outstanding concerns are present for using ammonia as a fuel. There is no ammonia fuel standard (on e.g. purity) which is needed to allow the use of ammonia. There is also no well-to-wake greenhouse gas quantification for ammonia developed in appropriate regulatory bodies such as the International Maritime Organization (IMO) or European Union (EU). Detailed prescriptive rules for ammonia as a fuel are not incorporated into the IGF code, requiring an alternative design approved by the Flag State for current ammonia-fueled vessel design projects. Classification societies have released guidelines for ammonia-fueled vessels; however, they are not consistent or unified in their approaches or requirements
Life cycle assessment policy needs to be developed. Regulating the climate impact of fuel use from a life cycle perspective offers the industry the opportunity to establish sustainable fuel production and consumption patterns. By regulating the upstream (well-to-tank) climate impact, fuel users can select fuels with solid sustainability credentials. Regulation from a life cycle perspective also reduces the risk of burden shift of climate impact from the downstream (tank-to-wake) part of the value chain to the upstream. This is an important consideration for alternative marine fuels whereby much of the climate impact resides in well-to-tank activities.
Ammonia as a marine fuel: Prospects for the shipping industry - Documentation of assumptions for NavigaTE 1.0 (2021)