Feasibility analysis of the drive train electrification for a rescue boat

Progressing constraints on greenhouse gas emissions are favouring a sustainability trend, that is affecting greatly the transport sector. Nowadays, companies show increasing interest in developing sustainable solutions. This thesis has been started thanks to a project given by Sjöräddningssällskapet, the

most relevant association that performs sea rescue operations in Swedish waters. Sjöräddningssällskapet would like to explore the possibility of making their rescue boat fleet entirely carbon-free, hence more sustainable. What may provide a suitable solution is an electric drive train with hybrid energy storage,

composed by a battery pack and a fuel cell stack. The research question is whether it would be feasible to combine fuel cell stacks and battery packs to provide power to a fast small boat. From a sketch of a rescue boat, the drive train design for such boat is studied in its integrity, from the water jet pump to the battery and fuel cell systems. The required power has been calculated empirically, using data from online tests on water jet boats. Different tests have been considered, resulting in a mean power curve and a mean consumption curve and allowing comparison between the hybrid electric drive train with

an internal combustion engine drive train. Three profiles of speed, power and consumption have been assumed for the calculation of the required energy and hence rate the energy storage system. A design has been proposed in terms of fuel cell capacity and battery capacity. The propulsion unit, composed by the electric machine and water jet, has been studied, focusing on different electric drive technologies. Few conclusions on both the weight and sustainability requirements are discussed. A sustainability analysis is carried out in terms of CO 2 emissions, through a life cycle assessment accounting for the environmental impact of the system during the whole life cycle, from cradle to grave. Keywords: electric boat, rescue sector, boating, drive train modelling, water jet, fuel cells, batteries, hybrid electric storage, sustainability, CO 2 emissions, life cycle assessment.