Hybrid Propulsion

Hybrid propulsion combines two or more energy sources or conversion paths in one ship’s drivetrain, typically a combustion engine plus a battery and an electric machine on the shaft, so each runs near its best point. The control system shifts between diesel-mechanical drive for transit, battery-electric for low-load or harbor operation, and load-leveling that lets the engine avoid inefficient part-load running. Documented fuel and emission cuts run 10 to 35 percent on duty cycles with wide load swings, such as ferries, tugs, and offshore vessels. The battery also provides spinning reserve, so a generator can be taken offline rather than idled.