How gas engines and batteries work together for high-power propulsion

Rolls-Royce Solutions application engineer for commercial vessels, Cyrill Halbauer describes engines and propulsion systems on the world’s first LNG-hybrid tugboat, JMS Sunshine, which started commercial operations in May 2024.

He spoke to Riviera during the 27th ITS Convention, held 23 May in Dubai, UAE, after his presentation covering propulsion on this unique shiphandling vessel operating in Singapore.

This tug has electric drives, batteries and clean-burning LNG in two mtu series 4000 M55RN engines all delivering up to 65 tonnes of bollard pull.

For maximum thrust, two azimuth stern thrusters generate 4,000 kW of power, achieved by adding to the 1,492 kW each supplied by the mtu gas engines and 500 kW of electric motor power on each shaft.

This 29-m tug has a bollard pull of 65 tonnes and is equipped with a battery capacity of 904 kWh. The battery power is used to absorb peak loads, for example during acceleration, to manoeuvre purely electrically in port and to supply the ship on board with electricity.

During his presentation, Mr Halbauer explained the benefits of gas engines and the challenges in deploying them in harbour tugs.

He anticipates mtu gas engines will be used on larger vessels where there are less space constraints for the LNG storage and processing, such as offshore tugs with large enginerooms and tanks.

Mr Halbauer also explains how mtu engines are being developed for tugs using methanol and diesel fuels in the future.