Concept design for a hydrogen or an ammonia driven ship

Abstract

The world is facing environmental challenges and shipping industry has to adapt and be a part of the solution rather than staying a contributor of CO2 emissions. To reduce the CO2 emissions new fuels with low or zero emissions and propulsion systems with higher efficiencies are needed. Two potentially low climate impact options are hydrogen and ammonia. The aim of this thesis is to assess the possibility to use hydrogen and ammonia on a case study ship and to develop conceptual ship designs. The case study ship is a work boat operated by the Swedish Maritime Administration. The project starts with research on possibility of using hydrogen and ammonia as alternative fuels. The method contains several parts with the main challenge of the investigation of the operational profile of the vessel. Based on this operational profile, fuel consumption was estimated for both hydrogen and ammonia. The next part is related to the sizing of all the different tanks inside the hull to estimate the space available for new fuel tanks. This is followed by sizing of the new tanks to determine the exact amount of hydrogen and ammonia that can be stored for two different cases. Component selection for the new propulsion system was carried out to present a concept design of the two propulsion systems. Lastly, stability calculations are performed for the hydrogen propulsion system to make sure that the work boat M/S Scandica can withstand the change in the weight distribution inside the hull and that the impact on its stability is within the limits. Part of the results is the daily operational profile of the vessel and the endurance and range that it can cover with the hydrogen and ammonia propulsion system. The operational profile is investigated for fairway maintenance, ice breaking and transport operations for the case study ship. The days of operation depends on the type of operation that the ship is performing and the space available for fuel storage. For case 1, it resulted in approximately 13 days for fairway maintenance, 13 days for ice breaking and 12 days for transport operation for hydrogen as fuel, and 20 days for fairway maintenance, 19 days for ice breaking and 18 days for transport operation for ammonia as fuel. For case 2, it resulted in 5 days for fairway maintenance and 5 days for ice breaking and 4 days for transport operation for hydrogen as fuel and 7 days for fairway maintenance and 7 days for ice breaking and 7 days for transport operation for ammonia as fuel. It can be seen that it is feasible to operate the ship using hydrogen or ammonia as main fuels. Using ammonia as the main fuel gives an advantage in terms of the days for which the ship can operate before refilling but ammonia propulsion system is less developed as a concept compared to hydrogen. However, to use any of these propulsion systems, changes will be required in how the ship is operated.