Optimization and design of shore to ship charging Systems for all-electric and plug-in hybrid ferries
Electrification of marine vessels has become an important and efficient solution for moving toward the zero-emission sea transportation. Existing technologies for reducing emissions include diesel-electric, hybrid and fully battery-electric propulsion systems. While hybrid or plug-in hybrid propulsion systems can reduce the consumption of fossil fuels, fully battery-electric solutions can eliminate all emissions from regular operation. Indeed, hybrid propulsion systems allows for onboard batteries to be recharged by diesel generators or discharged to supply loads . Furthermore, another way to recharge the onboard batteries is shore charging which can allow for sustainable energies, such as wind, solar and hydropower energies available in onshore power systems to be utilized for propulsion in the onboard power system. In many countries the electricity generated on land is also cheaper and more sustainable than the electricity generated by onboard diesel engines. For instance, in Norway, more than 90 percent of national electricity demand is produced by renewable energy such as hydropower energy.
The main challenge of using batteries in maritime vessels is their low energy density. In other words, a marine battery pack which weighs about tens of tones and spaces hundreds of square meters cannot guarantee sailing for long distances. Thus, due to the current range limitations for fully electric ships, all-electric ships are not suitable for long distance transportation. With tight schedules for short-distanced ferries, it is important to take advantage of docking time efficiently, explaining the need for fast charging. Further, another challenge of shore-charging system for motor/car ferries is that usually the ports are located in remote areas with limited capacity in the local power grid. This means that the local grid may not be able to provide high power for fast charging loads, so using stationary energy storage systems, which act as energy buffers, is a proper solution for supporting the weak grid. However, using stationary battery introduces internal energy loss in the energy flow from shore to ship.
- A mathematical model for charging and discharging of onboard batteries which is required for energy efficiency, reliability and stability studies.
- A design Platform for charging infrastructures at ports concerning the power system architecture.
- An onshore power and energy management system compatible for generating an optimal charging regime with the highest energy efficiency, sharing the power between the onshore batteries and the grid.
- For charging all-electric and hybrid ferries
- Smart ports facilitating shore charging
Shore-to-ship charging for all-electric or hybrid ships
A technology and methodology survey has been carried out to fully understand the current unsolved challenges of shore to ship charging systems. Then an evaluation of energy efficiency for different charging topologies, wired and wireless solutions has been accomplished.