Sizing and Management of Fuel Cell Based Powertrains for City Ferry Applications

Fuel cell powered ferries with fast refueling time and high energy density are of great interest as they help reduce carbon emissions. This paper considers the sizing and management of fuel cell based powertrains and performs a case study using the real-world data of a city ferry, i.e., Älvsnabben 4. An optimization problem is formulated to minimize the sum of the hydrogen cost and the component costs. Various components of the powertrain are examined: electric machine, fuel cell, and energy buffer. In particular, the fuel cell degradation and the cycle life characteristics of different energy buffer technologies including lithium-ion battery, supercapacitor, and lithium-ion capacitor are taken into account. Results show that the total cost of the hybrid system composed of fuel cell and supercapacitor is the lowest due to the long cycle life and high power density of the supercapacitor technology. Moreover, since the hydrogen cost is the major contributor to the total cost, the variation of the hydrogen unit price can significantly impact the total cost.