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Diesel-electric and integrated electric propulsion feed propulsion motors, thrusters and hotel loads from one electrical bus, while DC grids let gensets run at variable speed and connect batteries directly. ABB, Siemens Energy and GE Vernova lead the segment, which now underpins hybrid ferries, offshore vessels, naval combatants and the first cruise-ship DC retrofit.
Hybrid marine propulsion pairs engines with a battery for peak shaving, spinning reserve, engine-off port operation and regeneration, and hybrids make up 68% of the Maritime Battery Forum register. Documented savings range from 4-5% on steady transit to 20-30% on tugs and DP vessels, so the value depends on load profile.
Battery-electric ships carry lithium-ion packs charged from shore and drive motors, pods or waterjets, and the Maritime Battery Forum register passed 2,000 vessels with about 2.4 GWh in October 2026. The 130 m China Zorrilla entered service with more than 40 MWh, while charging power has scaled from 1 MW to planned 55 MW.
Hydrogen reaches a propeller through PEM or solid-oxide fuel cells feeding electric drives, or through hydrogen combustion engines, and modules from Ballard, PowerCell, Yanmar and Hanwha now hold class approvals. Only about seven hydrogen-fuelled ships are in operation, and MF Hydra's trucked liquid hydrogen at EUR 13-14 per kg shows why.
A shaft generator lets the main engine supply hotel load in PTO mode and, as a permanent-magnet machine, motor the shaft from gensets or batteries in PTI mode. Wartsila puts the EEXI gain at 3-5%, and ABB booked 30 LNG carriers in one order, while superconducting motors remain in naval research.