Concept Design and Performance Evaluation of a Fossil-Free Operated Cargo Ship with Unlimited Range

To meet the IMO goals of emissions reduction in shipping, drastic actions must be taken. Wind-assisted propulsion and renewable energy sources are today discussed frequently as realistic alternatives for future ship propulsion and energy production. This study presents a new and innovative concept of a fossil-free operated cargo ship aiming to achieve an unlimited range. The purpose of the study is to present the feasibility but also the limitations of a ship propelled and operated purely on renewable energy harnessed at sea, independent from shore-based energy sources. Aside from Flettner rotors for propulsion, the ship concept incorporates photovoltaic generators, wind turbines, and a dual-mode propeller to produce energy for the auxiliary systems and for the Flettner rotors, as well as batteries to balance the energy production and consumption. The dual-mode propeller can be used for energy generation and propulsion, thus levelling out any speed drops or peaks and thereby ensuring more reliable operation. The whole system is modelled numerically, and full ship voyages are simulated using the ship performance model ShipCLEAN. Results show feasible achieved speeds on a route with realistic weather conditions. However, negative energy balances limit the pure renewable sailing conditions. Further logistic and technical challenges are discussed.