A group of Japanese firms have collaborated to build a limestone carrier vessel with a hybrid propulsion system that combines a gas-only engine and battery.

NS United Naiko Kaiun Kaisha signed a shipbuilding contract with Tsuneishi Shipbuilding for the construction of the liquefied natural gas (LNG) fuelled coastal limestone carrier.

Ship charterer Nippon Steel Corporation and Nippon Steel Cement, propulsion system provider Kawasaki Heavy Industries (KHI), and LNG supplier Japan Petroleum Exploration are also involved in the project.

The ship, which will replace NSU Naiko-owned limestone carrier Shimokita Maru, is expected to commence operations in February 2024 on the Shiriyamisaki-Muroran route.

With a deadweight tonnage of around 5,560t, the 93.8m-long hybrid vessel will have a moulded breadth of approximately 18.2m and moulded depth of nearly 9.9m.

The new limestone carrier will be equipped with Japan’s first gas-only engine and a 2,847 kWh lithium-ion battery.

In addition, its LNG fuel tank will include a 7% nickel steel plate, developed by Nippon Steel Corporation.

The vessel will obtain propulsion power and on-board electric power during sailing from the KHI-developed gas-only engine. For long-duration navigation, it will solely utilise natural gas.

Furthermore, during entering, leaving and berthing at ports, the vessel will use the battery for propulsion power along with on-board power for zero-emission operation.

The propulsion system on board the vessel is expected to reduce carbon emissions by 23.56%, as against conventional vessels of the same category.

In addition, the exhaust gas of the gas-only engine encompasses ‘almost’ no SOx as well as NOx emissions far below the Tier III standards.

The construction of the ship is supported by the Global Environment Bureau of the Japanese Ministry of the Environment and the Maritime Bureau of the Japanese Ministry of Land, Infrastructure, Transport and Tourism to promote the introduction of advanced technologies.

Recently, KHI delivered a bulk carrier for SPDB Financial Leasing named BBG Baise.