Techno-economic assessment of advanced fuels and propulsion systems in future fossil-free ships

This paper analyses the potential of renewable fuels in different propulsion systems for the maritime sector that can replace fossil fuels by 2030. First, a fuel cost analysis is performed for a range of biofuels, bio-electrofuels, electrofuels plus liquid hydrogen and electricity in 18 fuel production pathways. Next, fuel production costs are combined with different utilisation rates, propulsion cost, on-board fuel storage cost and a cost for reduced cargo space to determine the total cost of ownership for four types of ships: large ferries, general cargo, bulk carriers and container vessels using internal combustion engines, fuel cells or battery-electric propulsion systems and travelling different distances. In large ferries, the battery-electric propulsion is found at a lower cost than all fuel options except biofuels. For the other ship types, cheaper fuels (as biofuels) benefit internal combustion engines, while expensive fuels (as electrofuels) increase the competitiveness of fuel cells due to their higher efficiency. Similarly, low utilisation rates benefit internal combustion engines, while higher utilisation rates tend to support fuel cells. General cargo vessels have a similar total cost of ownership for both four-stroke internal combustion engines and fuel cells. Bulk carriers and container ships use two-stroke engines, with efficiencies closer to fuel cells, but the lowest-cost solution remains internal combustion engines, except when increasing the efficiency or reducing the investment cost of fuel cells. In almost all fuel-propulsion combinations, methanol is the lowest-cost fuel, but dimethyl ether and ammonia show only marginally higher costs.