Tugboat featuring the hybrid propulsion system for the first time in Japan in service
-Reducing fuel consumption and CO2 emissions about 20% in comparison with a similar conventional system-

Recently, the environment-conscious tugboat that features the hybrid propulsion system developed by NIIGATA Power Systems Co., Ltd., (hereinafter referred to as “Niigata”) for the first time in Japan (hereinafter referred to as the “hybrid tugboat”) was put into service in the Port of Yokohama. The tugboats are small ships that mainly support the arrival and departure of large ships from the harbor area, and the load factor significantly differs between normal movement and actual service operations. With the hybrid propulsion system, the operation mode can be chosen according to the operation conditions of the tugboat so that the overall output of the drive source (diesel engine for propulsion, motor) and the power supply source (diesel engine for power generation, high-performance lithium-ion battery) can be optimum. As a result, the fuel consumption and the CO2 emissions can be reduced by about 20%, in comparison with a tugboat that does not feature the hybrid propulsion system, thereby contributing to a reduction in the environmental load.

The special features of the hybrid system can be summarized as follows:

1. The compactness of the system has been attempted by installing the motor on Z-Peller as a solid structure, which is the strong point of Niigata.
2. The system excels in redundancy, as the system is provided with two kinds of drive power sources (diesel engine for propulsion, motor) and two kinds of power supply sources (diesel engine for power generation, high-performance lithium-ion battery), and the combined use of such power sources enables efficient operations according to the conditions.
3. The tugboat is navigated with the motor by mainly using the lithium ion battery or the diesel engine for power generation during low-speed navigation, and fuel consumption is reduced by keeping the diesel engine for propulsion at a stop.
4. While the tugboat is navigated with the motor, while shutting down the diesel engine for propulsion, outstanding quietness is ensured compared to conventional tugboats, thereby contributing to consideration of the peripheral environment and the onboard environment.

The applied research and development work of the system was implemented as subsidized by the Ocean Policy Research Foundation (Ship & Ocean Foundation). In addition, studies were executed through a joint research system with Nippon Kaiji Kyokai (Class NK) in the practical application stage, and studies were supported by a scheme of Joint R&D with Industries and Academic Partners of Class NK. The demonstration boat was constructed through joint research with Nippon Yusen Kabushiki Kaisha, the ship owner Wing Maritime Service Corporation, and the shipbuilding yard Keihin Dock Co., Ltd. The hybrid tugboat was named Tsubasa (Wing), and a commissioning reception party was held on March 27.

NPS will proactively continue sales activities of the hybrid propulsion system in the future and contribute to a reduction in the environmental loads of ships.



Photo:Hybrid tugboat “Tsubasa”