Electric ferry between Sweden and Denmark will make nearly 20,000 crossings a year
By: +David Herron; Date: May 14, 2019Ferry boats run every day many times a day carrying passengers, and their cars and trucks, and by switching to electric ferry systems can prevent a tremendous amount of diesel fuel from being burned. Such ships typically burn low grade "bunker fuel" but an electric ferry of course burns nothing. These ships are also so massive to make it seem an impossibility, but here is what is called an "existence proof".
According to this video, a traditional Ferry boat was converted to an electric drive system.
They replaced a traditional diesel engine with four electric motors that together run a peak power of around 20 megaWatts. Obviously that peak would be hit during maneuvers, and during normal cruising the power draw would be quite a bit less.
The route is a 4 kilometer crossing between Helsingør-Helsingborg. The company, ForSea, operating on this route says:
In 2017, ForSea transported 7.1 million passengers and 1.3 million cars, 428,000 trucks and 18,000 buses, corresponding to around 20% of the vehicles crossing Öresund. Passengers can shop onboard at attractive prices, dine at the ferries’ restaurants and cafés or enjoy activities such as jazz concerts among other things.
The ship does over 40 trips a day, every day of the week, for over 17,000 trips per year. So the number of crossings are double that.
Each trip consumes approximately 1,175 kWh. From the video the ship contains a 4.1 megaWatt-hour battery pack, but they've designed the system to keep State of Charge between 40% and 65%. That is done for battery longevity, since it is understood that keeping a battery from going too low and from going to high a state of charge increases its longevity.
In other words, despite doing well over 30,000 charging sessions a year, the company expects the battery pack to last for over 5 years.
In each port is a tower with a robot arm that connects the charging cable automatically every time the ship comes to the dock. The system charges 10.5 kV, 600Amp and 10.5MW. Charging time is 6 minutes on one side, and 9 minutes on the other side.