World’s first all-electric tug has impressive green and opex profile

Responsive and manoeuvrable

When compared to a diesel-mechanical tug, an all-electric tug offers the captain and crew better response and manoeuvrability. “Full power is right under your hand,” said Mr Acuner. “It is limited only by your mechanical systems.” Added benefits for the crew are that an all-electric tug is quiet, with minimal or no vibration.

A full charge for the tug can be accomplished in one hour by a quick-charging station specially designed by Navtek.

To optimise electric power consumption, analyse the operational profile and extend the range of the electric tug, Navtek designed the Smart Tug Energy Management System (STEMS). STEMS software monitors Zeetug’s performance via an onboard data acquisition system. It tracks tug speed, motor speed, power consumption, battery-motor temperature and battery state of charge, providing feedback and suggested actions to the captain.

As compared with similar-sized, diesel-mechanical tugs, Mr Acuner said the all-electric Zeetug30 is expected to save 210 tonnes in CO₂ emissions and 9 tonnes of NOx emissions in a year.

Just as impressive as the tug’s environmental credentials are its operational expenses. Navtek estimates the operational expenses for the Zeetug will be 15% of that of a similar-sized diesel tug. Mr Acuner said Navtek based its calculations on the studies of five similar-sized diesel-drive tugboats. Calling the Zeetug’s projected opex “amazing,” Mr Acuner said his team was in the process of verifying the figures based on Gisas Power’s first month of actual operations.

Remote monitoring and diagnostics allow technicians and engineers to resolve any issues in real-time. Additionally, any software system updates can be performed remotely.

For the design and construction of the Zeetug, Navtek collaborated with fellow Turkish power systems integrator BMA Technology, drive and converter supplier ABB and energy storage systems provide Corvus Energy.

Inevitably, when discussing all-electric vessels, questions about battery life are raised. Mr Acuner said the expectations are that the vessel’s batteries will have a life of 10 years. “By the 10th year we expect 87% capacity,” he said. “You can switch out for newer technology.” While a lithium-Ion battery might no longer be suitable for use on the vessel, the remaining capacity – 60 to 70% – can still find a ‘second life’ for other uses before it is recycled.

“Battery life and efficiency are the most crucial questions from owners,” said Mr Acuner, “but I think they have already been solved.”

Snapshot CV: Ferhat Acuner

• General manager of Navtek Naval Technologies since 1999
• Held senior positions at Powership, Karadeniz Holding AS
• 33 years of engineering experience
• Bachelor’s degree in Naval Architecture & Marine Engineering, Istanbul Technical University