Simulations Used to Model Hybrid Battery Systems with Shaft Generators

modeling to develop hybrid battery with shaft generators
(Battery system file photo)

Published Dec 2, 2021 9:02 PM by The Maritime Executive

A group of companies from across the maritime industry is conducting a new research project designed to optimize ship design to incorporate battery hybrid systems into the main engines of large, ocean-going commercial vessels. In this joint research, which is being undertaken with NYK Line and MTI Co. of the NYK Group, along with ABS and engine manufacturer Winterthur Gas & Diesel (WinGD), they will seek to create an integrated simulation model for ships as a first step to the deployment of the battery technology on an NYK ship.

The companies believe that hybrid battery systems can help to reduce GHG emissions, but they point to challenges to making the system efficient on these classes of ships. To date, most of the battery installations have been for shortsea routes, ferries, or similar vessels that use the batteries for limited periods of propulsion or to eliminate emissions in environmentally sensitive areas. 

The partners highlighted several challenges to maximizing the efficiency of hybrid battery systems for long endurance operations. Among the issues they will be looking at is how to address load fluctuation while using battery systems. They note that vessels maintain their navigation speed even when encountering strong waves and winds in stormy weather, which may require significantly increasing the number of revolutions of the main engine and conversely lowering revolutions in good sea conditions. 

Using a shaft generator, which is connected to the propeller shaft of the ship to generate electric power, they are seeking to develop systems that can address this load fluctuation. The current systems generate power according to the rotation speed of the main engine and supply electric power to the ship.

The companies believe that introducing a battery hybrid system will provide an efficient means to address when the load of the main engine fluctuates and reduce the load on the shaft generator by supplying electric power from the battery to the ship. Providing an efficient, consistent source of electricity to the ship through the haft generator and the hybrid battery system makes it possible for ships even at sea to reduce or eliminate the use of diesel generators.

Working together, NYK and MTI's actual sea area performance along with WinGD's engine plant modeling technology including batteries will be combined to create an integrated model of the entire ship, with ABS providing the third party validation and giving advice on the evaluation of the GHG reduction effect. 

The four companies will jointly design a ship in digital space. Then, we will conduct a simulation scenario that assumes the meteorological and oceanographic conditions of the actual sea area. Seeking to improve the simulation model by reflecting the issues, they aim to optimize the ship design. In this joint research, they will take a new step in the use of model simulations, sharing a digital model to collaborate to build a ship. They will also utilize simulations to optimize the operation and control methods of battery hybrid systems.

In the future, NYK and MTI will collaborate with ABS, WinGD, and a shipyard to collate the simulation results obtained through joint research with the data from actual sea areas and operations to improve the accuracy of the simulation. 

NYK expects to incorporate the results of the simulations and core technologies developed into its future new shipbuilding plans. In a separate announcement, NYK also said that it has ordered to VLGCs from Kawasaki using dual-fuel LPG and hybrid battery systems with shaft generators similar to the hybrid systems being modeled in this project. NYK plans to take delivery of the new gas carriers in 2024.