NYK Line reveals plans for main engine upgrade on Moss-type LNG carriers

Japanese shipping major NYK Line has teamed up with compatriot shipbuilders Namura Shipbuilding Co. and Sasebo Heavy Industries Co. to replace the main propulsion on steam turbine–driven Moss-type LNG carriers.

In October 2023, NYK was granted Approval in Principle (AiP) from the Japanese classification society Class NK for converting the steam turbine of an LNG carrier to a dual-fuel diesel engine. This is the first AiP granted by Class NK for main engine conversion on LNG carriers.

The three companies plan to proceed with a detailed design of steam turbine conversion, aiming to improve environmental performance, make efficient use of existing vessels, and contribute to stable LNG transportation.

“LNG is promising as an essential transition energy for realizing a decarbonized society, and LNG transportation demand is expected to grow steadily. On the other hand, the shortage of LNG carriers is a concern due to the limited number of new LNG carriers that can be ordered and the retirement of steam turbine–driven LNG carriers due to their inferior fuel economic performance compared to diesel engine LNG carriers,” NYK said.

The trio aims to replace the main propulsion of steam turbine–driven LNG carriers with dual-fuel, low-speed diesel engines called X-DF engines. The Moss-type LNG tanks installed on steam turbine–driven LNG carriers are durable and can withstand long-term use, NYK explained.

Therefore, in addition to improving fuel economic performance, the engine replacement is expected to contribute to an efficient use of the ship’s resources.

By harnessing the technical prowess inherent in Japan’s maritime cluster, the three industry majors want to support stable LNG transport by converting main engines and contribute to the efficient use of ship resources.