Since 1958, the shortest ferry route in Denmark has been the lifeline of ven0 island in the north of Jutland. The scenery of this route is very charming. Now it only takes two minutes to cross the narrow canyon 17 meters deep. The ven ø ferry ferries shuttle back and forth at 30 minute intervals, 36000 times a year since 2010. For six years, it used diesel for power generation and propulsion, and needed 90000 liters of fuel every year.

In order to cut costs and achieve more sustainable operation, the ferry needs solutions that can reduce the fuel consumption of auxiliary generators. Danfoss drives, eptechnologies, Super B, Hvide Sande shipyard and the contractor vest El worked together to comprehensively evaluate the ferry and conduct extensive tests on battery power supply and power conversion. Finally, a customized hybrid power generation system was installed for the ferry.

Diesel power runs for 19 hours a day from before

Reduced to 20 minutes

Before the transformation, two diesel auxiliary generators were used to provide power for payloads, bridge equipment, engine room pumps and fire-fighting equipment. In order to meet the power demand in the worst case (such as when the ship is on fire), the rated capacity of these generators is 2 x 86 kW, while the typical load is 12 kW, and the fuel consumption is very large (up to 300g/ KWH). In order to meet the demand, these generators need to operate for 19 hours a day.

Now, when crossing the shortest route of 200 meters between Struer and ven0 Island, the power consumption of the ferry is provided by the battery pack. In order to prolong the charging time as much as possible, the crew will connect the battery to the shore power system as soon as the ferry pulls in. When the next passenger gets on board, the battery charging process can be completed.

The capacity of the battery pack installed on the ship is 88 kwh. Only when the battery power decreases, the auxiliary generator will automatically start to charge the battery. The fuel consumption has been reduced to 209 g/kwh, and the daily running time of the generator has been significantly reduced to only 20 minutes!

Schematic diagram of hybrid power generation system

Before the real renovation of the ferry, Danfoss transmission used the test bench to simulate the generator, so as to conduct a comprehensive test of the system. The actual battery and micro grid system are used in the test, and the ship load is simulated by Danfoss inverter with load resistance and motor. Danfoss and eptechnologies calculated the economic benefits and obtained the expected fuel consumption reduction effect when the battery hybrid is running.

The electric equipment of ferries is now mainly powered by batteries, and the batteries are charged through the shore power system between round trips, which is the first time in Denmark. After the transformation from pure diesel to hybrid in 2016, the annual diesel consumption has been reduced by 20000l (from 90000 l to 70000 L)—— S ø Ren adsersen, Operations Manager

Redundant propulsion system

This same type of ferry is driven by two identical Volvo penta marine diesel engines, and there is a schottel rotary propeller at both ends (located in their respective engine rooms). The diesel propulsion system has complete redundancy.

The core of hybrid power scheme

Fireproof battery pack and reliable Danfoss frequency converter Vacon ®  Nxc can ensure reliable operation when the battery is powered.

The previous two diesel propulsion systems on board remain in place, while the battery system, transformer and Danfoss Vacon ®  Nxc frequency converter is installed in the free position below the deck.

The Super B battery pack provided by eptechnologies meets strict fire safety standards and adopts LiFePO4 battery with the highest safety performance, so it becomes the first choice of this scheme. These batteries are designed to ensure that the fire in one battery cell will not spread to other cells.

In addition, these batteries can also guarantee a long service life (more than 10 years) under high charging cycle conditions (1 cycle = battery from full charge to full discharge and then to full recovery).

Turn losses into profits

The ferry operator Struer municipality has been losing money for many years, and now it can save 20000 liters of diesel every year. They finally see a healthy economic prospect. The battery powered system can realize the return on investment within eight years. The subsequent fuel savings will directly improve the revenue of the ferry, and the profit is expected to reach more than 40000 euros in the battery life cycle.

There is another direct benefit of less diesel consumption, which is conducive to reducing emissions.

Another added benefit of hybrid power generation systems is that the engine room can usually be unattended. Since there are no crew members in the engine room most of the time, the cabin door connecting the noisy engine room with the outside world can always be opened. In this way, without additional heating system, the heat generated by the engine can heat the entire lower deck area, thus greatly saving heating consumption under the low-temperature weather conditions of six months a year.

It was cold and windy on the deck in winter, but s ø Ren adsersen, the ferry operation manager, was always enthusiastic: "this is a great success for us. We are very satisfied that we can do it without any cost increase in eight years." He said with a smile.