Ammonia is suitable to be used as a marine fuel depending on a number of safety measures that are to be included in the design. This was the conclusion of new research by C-Job's Lead Naval Architect Niels de Vries. He has used a new concept design, an ammonia carrier fueled by its own cargo, to study the subject.
The research is the culmination of De Vries' Master’s Thesis "Safe and Effective Application of Ammonia as a Marine Fuel". Using ammonia as a marine fuel would result in a significant reduction of greenhouse gas (GHG) emissions from shipping activities.
The main risks of ammonia are the toxicity and environmental impact. Therefore, the likelihood and effect of exposure are to be limited. The flammability risks of ammonia are relatively low compared to the toxicity risks.
Safety measures should include ammonia (and hydrogen) detection as well as extra ventilation in the spaces containing fuel lines. Remote operated shut-off valves should be installed to isolate a leakage and limit its impact. Redundancy in the fuel supply line is to ensure sufficient fuel supply for continuous operation in case of a shut-off. In addition, fuel lines should be routed with a sufficient distance from the shell and be located in unmanned spaces where possible or make use of double-walled piping.
De Vries studied the following options for ammonia fuel power generation: a steam and gas turbine, an internal combustion engine (ICE) and fuel cells (proton exchange membrane (PEMFC), alkaline (AFC) and solid oxide fuel cells (SOFC)). Only the internal combustion engine (using ammonia hydrogen mixtures) and all three fuel cells were considered feasible for marine applications.
'Reviewing all ammonia power generation options, the Solid Oxide Fuel Cell is clearly the most efficient,' De Vries says. Yet, this type of fuel cell needs to be developed further and is still too expensive. Therefore, the ICE currently is the best solution. It is more efficient than the PEMFC and the AFC, less expensive and more robust with acceptable power density and load response.
Further Research Being Conducted
'While this research is unique in its scope and provides a valuable first step towards the application of ammonia as a marine fuel, additional research is still required to explore its full potential and feasibility,' De Vries explains. The next phases will include lab testing, a pilot project and evaluation.
As an ammonia carrier was used for the ammonia fuel system in this research, ammonia fuel storage was not addressed as it was covered by existing regulations for transporting ammonia as cargo. Therefore, ammonia fuel storage is also to be investigated further so that it can be applied on other ship types as well.
Renewable Fuel Partnerships
C-Job has increased its R&D investment into renewable fuels considerably in recent years. In addition to ammonia, methanol is also being investigated. The company does this in partnerships with other organisations such as the Ammonia Energy Association and a consortium that was established with Proton Ventures and Enviu in 2017. The completion of De Vries’ theoretical research marks a crucial contribution to the first phase of this consortium.