RINA Unveils 'Mermaid' Concept That Puts the Main Engine to Work Beyond Propulsion
Key Takeaways
- •RINA's Mermaid concept combines a shaft generator, shaft clutch, and battery storage with a two-stroke main engine to produce onboard electrical power.
- •The system allows the main engine to supply electricity or charge batteries while the ship is at berth, reducing the use of polluting auxiliary diesel generators.
- •RINA's analysis suggests the concept could save more than 1,000 metric tons of fuel per year in some applications.
- •The design is fuel agnostic and applicable to vessel types including tankers, bulk carriers, and container ships.
- •RINA is developing Mermaid into a detailed design after receiving feedback from shipowners and shipyards.
RINA has unveiled a new ship propulsion concept that enables a vessel's main engine to generate onboard electrical power, reducing the need to run auxiliary engines.
Named Mermaid, the concept combines a shaft generator, a propeller shaft clutch and battery storage with the vessel's two-stroke main engine, RINA said in a press release on Thursday.
When the ship is in port, the propeller can be disconnected while the main engine continues to run. The engine can then supply electricity to the vessel or charge the batteries, which in turn can provide power once the engine is shut down. This addresses a long-standing operational inefficiency in shipping: at berth, vessels typically run auxiliary diesel generators to power onboard systems, contributing to in-port emissions that regulators and port cities have increasingly sought to curb.
The setup is designed to cut bunker fuel consumption, emissions and operating costs while making better use of the main engine. According to RINA, its analysis shows the concept could save more than 1,000 mt of fuel per year in some applications. Shaft generator systems are an established technology in merchant shipping, but combining one with a shaft clutch and battery storage to let the main engine serve as a stationary power source in port extends the idea further than conventional installations.
The system can also help optimise propulsion during slow steaming by matching engine power more closely to actual operating conditions. Two-stroke main engines are generally most efficient near high loads, so the ability to use excess power for electrical generation or battery charging can help keep the engine operating closer to its optimal point.
Mermaid is fuel agnostic and can be applied across vessel types, including tankers, bulk carriers and container ships. Its fuel-agnostic design means the concept could remain relevant as owners adopt alternative fuels in line with tightening International Maritime Organization greenhouse gas regulations.
RINA is now developing the concept into a detailed design after receiving feedback from shipowners and shipyards.
