The ‘sun shines’ on first LNG tugboat with hybrid system

JMS Sunshine

A new ‘sustainable innovation’ has been in regular operation in the port of Singapore since the middle of last month. JMS Sunshine, the world’s first LNG tug powered by a hybrid system with mtu gas engines supplied by Rolls-Royce. Seatrium Ltd, a leading engineering solutions provider to the global offshore and marine industry is the designer, builder and operator of the new 29m, 65-tonne bollard pull tug. The Port of Singapore has committed to the Maritime R&D Roadmap 2030 with the aim of making it more environmentally friendly and reducing energy consumption.

With this goal in mind, Rolls-Royce has supplied two 16-cylinder mtu Series 4000M55RN gas engines and the gas regulating unit (GRU) for the new hybrid harbour tug. Chiam Toon Chong, technical superintendent, Seatrium Marine Services, said: “The handling of mtu engines is straightforward, and user-friendly. Additionally, spare part availability and service support is excellent for the operation of tugs.”

Chew Xiang Yu, head of Rolls-Royce Power Systems' civil marine business in Asia, said: “We are proud that we were able to contribute to Seatrium’s innovative project with our gas engines. Furthermore, the workboat market is one of our strategic business areas and the mtu engines were selected because they meet the demanding requirements of harbour tug operations — in terms of reliability, ease of operation, dynamic engine behaviour and low emissions.”

Strong bollard pull
The mtu gas engines are already well below the limit values of current emission guidelines (such as IMO III) without exhaust gas after-treatment. The particulate mass is below the detection limit and they emit only small quantities of nitrogen oxides. The hybrid system is considered to be particularly suitable for the load profile of the harbour tug as it enables very precise manoeuvring and a strong bollard pull when full power is required. To achieve maximum thrust, the total power of the two azimuth stern thrusters is 4,000kW.

This is achieved by adding to the 1,492kW each supplied by the mtu gas engines and 500kW of electric motor power on each shaft. The tug is equipped with a battery capacity of 904kW hours. 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.

Rolls-Royce’s Power Systems division has already received orders for mtu gas engines as propulsion systems and on-board gensets to power 11 ships worldwide. These include ferries, tugs and government vessels. Two catamarans belonging to the Doeksen shipping company have been operating reliably with mtu gas engines on the North Sea in the Wadden Sea nature reserve since 2021, and the Richmond ferry has been operating a commuter service on the Lake Constance drinking water reservoir in southern Germany since 2023. The engines are very quiet, produce no vibrations, no unpleasant odours and no black smoke.