Veteran Alpine lake ferry set for battery repower

Written by Nick Blenkey
Heimat is to be repowered with batteries

Heimat's next repower will be with batteries

An historic Swiss passenger ferry built in 1933 and now on its third diesel engine is to be repowered again, but this time with batteries. Carrying up to 60 passengers, the ferry, the Heimat, operates year round, making up to 12 daily trips between Maur and Uster on the Greifensee lake near Zurich.

Its electrification is being carried out by Norwegian battery and electric driveline specialist ZEM (Zero Emissions Marine) in partnership with Lake Lucerne shipyard Shiptech AG which carried out a feasibility study for the project evaluating proposals from several suppliers.

Towing tests and dynamic power measurements of propulsion and hotel loads gave Shiptec AG the information needed to assess the most suitable dimensions and placement of motor and batteries, likely service life, and an estimate of the likely investment and operating costs.

The results confirmed the viability of the conversion and vessel owner SSG gave the go ahead, with ZEM, which is owned by Volvo Penta, being selected based on its experience with these vessel types.

To power its typical 20 kilometers or so of daily operation, ZEM and Shiptec will retrofit the Heimat with a 99 kWh AKAZEM lithium-ion battery system. Already proven in a variety of smaller ships and ferries, this solution will provide more than enough power for a normal day’s work.

SGG and Shiptec required robust components with a high safety integrity level. “This aligns perfectly with ZEM’s values and our system design,” said Sebastian Wang-Hansen, the project leader at ZEM. “Together with Shiptec, we suggested therefore to retrofit the Heimat with a 99 kWh AKAZEM lithium-ion battery system and a 40-kW electric propulsion motor from Danfoss Editron. The permanent magnet motor from Danfoss provides high torque and is, therefore, able to drive the propeller shaft without the need for a reduction gear. This results in a lighter, more efficient, and less maintenance-intensive driveline.”

The vessel has an unladen weight of 10.2 tonnes and a transport capacity of 60 people, including 20 passengers in its cabin. The speed required must be maintained at the same 15 km/h as before conversion, and the emergency stop must not exceed three and a half ship lengths of 14.9 meters. The system, requires 84 kWh of energy per day, including a 10-kWh reserve, this includes 14 round trips over the lake and back, two transfer trips from Maur to Greifensee and back, as well an extra trip in the evening at a lower speed. The vessel needs 1.6 kWh of power to travel one kilometer.

THREE-BATTERY SOLUTION

Three batteries of 33 kWh each were selected, giving a total capacity of 99 kWh. This requires recharging during the day. There is a good 30 minutes of reloading time between the hourly round trips. With a charge power of 30 kW, an energy charge of 15 kWh or 15% SOC is possible.

“It would be possible to equip a system with two batteries of 33 kWh each. The choice of three batteries enables a higher level of redundancy since if one battery fails, it is still possible to continue driving with two batteries without any limitations. We also expect the batteries to have a longer service life and allow greater flexibility in use on ships. The variant with three batteries appears as an optimization between redundancy, costs and weight,” said Martin Einsiedler of Shiptec.

“The MS Heimat already provided a relatively sustainable public transport solution by removing the need for people to drive all the way, around the southern or the northern edge of the lake to visit either town,” said former SGG chairman Dr. Allen Fuchs, who is leading the project. “But once the project is complete, it will provide a quieter, more environmentally friendly solution in harmony with the Greifensee nature reserve, while preserving the boat’s outward appearance as a historically relevant example of the motorization in the region.”

The Heimat project will be the first joint effort between ZEM and Shiptec, and the partners expect that more projects will develop out of this cooperation. There is a rising concern about polluting ship traffic on many alpine lakes in Switzerland, Germany, and Austria.

“ZEM can contribute its Nordic maritime expertise to solve these challenges, by making new and modern tourist vessels electric, and by converting the traditional ferries that make the Swiss lakes so unique,” says Jan-Olaf Willums, the Norwegian founder of ZEM, who grew up in Switzerland.

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