IVL Swedish Environmental Research Institute

Electrification of ships offers zero-emission travel and is spreading rapidly, and more and more ships are operating on liquid natural gas, LNG, or other alternative fuels. However, the relation between these modern forms of ship propulsion and noise pollution is not generally understood.

The Silent@Sea project has investigated this through four case studies, where modern vessels have been measured in different propulsion modes and compared to sister vessels.

This has mainly been done in route, which permitted us to gather unique data on the noise radiation of large ships in commercial operation. The project has investigated radiated airborne and underwater noise as well as onboard noise and its impact on work environment and passenger comfort.

The results show that the modern forms of propulsion lead to lower noise levels onboard, which are coupled to a better work environment and greater passenger comfort.

The radiated airborne noise of electrical hybrid vessels is reduced in battery powered operation at certain low frequencies associated with the diesel engine. The same holds for the radiated underwater noise, but the differences are smaller there, indeed smaller than differences between sister vessels.

Finally, a new generation of LNG-powered vessels are found to be quieter than an older generation with similar specifications.