Together with the Norwegian shipyard Fjellstrand, Siemens has developed the world's first electrically powered car ferry.

The 80m long vessel, with a capacity for 120 cars and 360 passengers, will serve the route between Lavik and Oppedal, across the Sognefjord, from 2015. The ship's batteries will be recharged in the breaks between crossings, a procedure which only takes 10 minutes.

The vessel currently serving this route uses on average 1M litres of diesel/year and emits 570 tonnes of CO2 and 15 tonnes of NOx. The electrically powered ferry was developed for submission to a competition organised by Norway's Ministry of Transport.

As a reward for winning the competition, shipping company Norled has been granted the license to operate the route until 2025.

The ferry has been specially designed to accommodate the requirements of an electric drive system. As a catamaran with two slim hulls, it offers less resistance in the water than a conventional vessel. Furthermore, the hulls are made of aluminum instead of steel.

In place of a diesel engine, the ferry is equipped with electric motors to drive the ship’s two screws. These motors are powered by a Li-ion battery weighing 10 tonnes.

All in all, the new vessel weighs only half as much as a ferry of conventional design.

This saving has a direct impact on the specifications of the drive system.

Whereas the ferry currently serving the route has an engine with an output of 1500 kW, the battery in the new vessel will have an output of 800 kW. In normal conditions, operating at a speed of 10 knots, battery power of 400 kW will suffice. According to Fjellstrand, the energy required for crossing the route at 11 knots is 155 kWh, and at 13 knots, 201 kWh. A full day’s operation would consume 6300 kWh. It takes only 10 minutes to recharge the 1000 kWh lithium-polymer battery pack, using a 1000 kW charger.

In the two small villages linked by the ferry, the local grid is not equipped to deliver such a large amount of power in such a short space of time. To deal with this problem, batteries have been installed at each port. These serve to recharge the ferry’s battery during turnaround and are then themselves slowly recharged from the local grid.

Hundreds of ferries link Norway’s mainland to the islands off its coast and provide routes across its many fjords. Using today’s battery and recharging technology, all crossings of up to 30 minutes in duration could be served by electrically powered vessels.

(www.worldcargonews.com 14 January 2013)