Feasibility Study of a Fast Electric Passenger Ferry

Abstract

The negative effects of global warming can already be noticed. The burning of fossil fuel not only contributes to global warming, but also to the reduction of air quality, especially in urban areas. In order to limit the climate change, as well as to improve the air quality, more and more vehicles are replaced by emission free versions. This thesis is a case study in which the feasibility of replacing a fast passenger ferry (300 passengers, 30 knots) by an emission free vessel was investigated. Two options remained after analysing different methods of emission free propulsion: battery powered and hydrogen fuel cell powered, both in combination with an electric motor. So in this report, the emission free ferry is an electric vessel. Without additional design changes, a battery powered version is not possible. So a reduction in energy consumption is required. A hydrogen powered ferry is feasible, but more expensive, thus a reduction in energy consumption is desirable as well. It must be mentioned that costs is not the most important aspect, because the reduction in emissions might be worth it. Furthermore, a lot of indirect costs are related to pollution. The effect on energy consumption was analysed for three design related changes: elongating the hull, using carbon composite instead of aluminium, and applying expected future battery and fuel cell systems. Currently, a battery powered ferry is only feasible with an elongated hull, but future technology significantly increases feasibility, also for the original hull length. A reduction of structural weight also increases feasibility, which effectively means a reduction in costs. The hydrogen powered ferry was already feasible, but the above mentioned changes in design improve feasibility, i.e. reduce the costs. Two operational changes were analysed as well: operating at a lower design speed and operating on a shorter crossing. The first has a limited effect on energy consumption, but the latter significantly increases feasibility of the battery powered ferry. Both changes do not have much effect on the feasibility of the hydrogen powered concept. The final concept that was analysed is the hydrofoil supported catamaran, because hydrofoils can significantly reduce resistance. Compared to existing hydrofoil vessels, there are two major differences: the electric concept has relatively more weight, and its design speed is significantly lower. Therefore, the hydrofoil must be relatively large to generate the required lift, and a larger hydrofoil suffers from larger 3D and interference effects. This drastically lowers the efficiency, and as a result, the hydrofoil concept is not a feasible solution. It can be concluded that an emission free fast ferry is feasible. A battery powered ferry is best suited for short crossings and the hydrogen fuel cell powered ferry can operate at longer crossings. The direct costs are likely to be higher, but this might be worth it, as it leads to a reduction of emissions, and thus to a reduction of indirect costs related to pollution. So the remaining question is: do we want to invest now, or pay for the damage afterwards?