Tech File: Battery-buffered Diesel-electric Hybrid Drive Proves Value on German FiFi Boats

Hamburg Fire Fighting Vessels Dresden and Prag sport diesel-electric hybrid propulsion and battery systems from EST-Floattech.

After the first 100 days of operation, operator Flotte Hamburg is reports it is satisfied with the two new firefighting ships Dresden and Prague: "Due to the full approval for the use of the EST battery system 'Green Orca 1050' on inland waterway vessels, which was already available at the start of the project, the first hybrid ships of the Hamburg fleet were successfully put into operation in close cooperation with Damen Shipyards and the electrical and automation project partner Royal Van der Leun," said Christof Sacher, the responsible project manager at Flotte Hamburg, a subsidiary of the Hamburg Port Authority (HPA).

Flotte Hamburg, fleet manager for the more than 50 ships of the ‘Free and Hanseatic City of Hamburg’ since 2017, is implementing its environmental strategy for both fire-fighting boats. The concept includes:

• the switch to low-emission fuels
• exhaust after treatment for new purchases 
• retrofitting existing ships 
• innovative drive technologies, and
• efficient ship operation.

An example of Pillar IV – innovative drive technologies – is the battery-buffered diesel-electric hybrid drive. The battery system for the two 35.5 x 7.8 m, 12-knot vessels was supplied by Dutch energy technology company EST-Floattech, which has a decade of experience in developing and installing lithium batteries on ships. 

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Photo courtesy EST Floattech

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The Green Orca 1050 modules, certified by DNV, each have a total battery capacity of 315 kWh. The plug-in hybrid allows up to four hours of fully electric and therefore emission-free travel through the port at an average speed.

Lithium-Ion Batteries: Safety is Job One

An important aspect in selecting the battery systems was the safety of using the lithium-ion batteries. "We apply high-quality pouch battery cells that ensure high-energy density, good heat dissipation and high-energy efficiency," said Marc Mühlenbeck, Sales Account Manager at EST-Floattech Hamburg, the company's German subsidiary, founded in 2021. “In addition, two independent battery management systems monitor and control safe charging and discharging. Other safety features include a fireproof housing and a venting system in the event of a thermal runaway.”

This system has proven itself in practice. "Due to the user-friendly implementation of the on-board power management and the smooth integration of the batteries as a reliable backbone of the on-board energy supply, the hybrid drive has enjoyed full acceptance among the crews since the first day of operation, contrary to initial reservations," said Sacher. "In particular, the almost noiseless propulsion system when sailing electrically and the fact that a classic blackout of the ship is virtually impossible, from the basis for this popularity. In the project phase, the compact structure of the batteries as an encapsulated system and the high safety standard in terms of design and monitoring by the integrated Battery Management System (BMS) were decisive."

The new propulsion technology has also been well received by the crews: "I'm delighted with the handling of the two fire-fighting vessels in hybrid mode," says Melvin Siebold, Captain at Flotte Hamburg. "As captain, I can not only carry out extremely precise maneuvers, but also navigate large parts of the port of Hamburg in battery mode in an anticipatory sailing style. In addition to pleasant, noiseless sailing, I also observe that my colleagues are not exposed to exhaust fumes when working on deck.”

Both the Prag, which is on full-time charter for the Hamburg Fire Brigade, and the Dresden, used multifunctionally by the HPA (e.g. for building inspections) and the fire brigade, were built at Damen Shipyards Hardinxveld.

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Josefin Klindt & Marc Mühlenbeck, EST Floattech Hamburg.Photo courtesy EST Floattech