Kawasaki Heavy unveils pioneering gas engine hybrid propulsion system

Japanese conglomerate Kawasaki Heavy Industries (KHI) achieved a major milestone with the recent delivery of what has been described as the world’s first gas engine hybrid propulsion system designed for a bulk carrier that utilizes a gas engine as the main means of propulsion.

The system combines a natural gas engine with large-capacity batteries, and it is intended for a vessel operated by NS United Naiko Kaiun Kaisha.

Scheduled to commence operations in February 2024, the vessel will feature Japan’s pioneering gas-only engine coupled with a 2,847 kWh lithium-ion battery.

“By using a pure gas engine fueled only by natural gas as the main propulsion, the system cuts down CO₂ emissions during operation by approximately 24 percent compared with a conventional heavy-fuel-oil engine used in the same vessel type. It also achieves significant reductions in sulfur oxide (SOx) and nitrogen oxide (NOx). In addition, the system can operate in electric propulsion mode using the batteries when entering and leaving port to achieve navigation with zero greenhouse gas emissions,” Kawasaki said.

The gas-only engine will exclusively utilize natural gas for high-powered, long-distance voyages. For zero-emission operation during port maneuvers, the battery will supply both propulsion and onboard power upon entering, leaving, and berthing.

Kawasaki estimates that the introduction of the propulsion system will yield a 23.56% reduction in CO2 emissions (approximately 30% during normal load operation) compared to conventional vessels of the same type. The gas-only engine ensures minimal SOx emissions, while NOx emissions remain significantly below the stringent Tier III standards, KHI claims.

The vessel was ordered back in September 2021 through a joint endeavor between Nippon Steel Corporation, Nippon Steel Cement, as the charterers of the vessel, and NS United Naiko Kaiun Kaisha acting as the owner and operator of the ship.

It has a deadweight tonnage (DWT) of approximately 5,560 tons, a total length of around 93.8 meters, a molded breadth of approximately 18.2 meters, and a molded depth of roughly 9.9 meters.

Tsuneishi Shipbuilding was entrusted with the construction of the new bulker while Kawasaki Heavy Industries was tasked with delivery of the propulsion system. Japan Petroleum Exploration Co. has been selected as the supplier of liquified natural gas.

The bulker is intended to replace the limestone carrier “Shimokita Maru” owned by NSU Naiko.

On its primary routes between the loading port, Shiriyamisaki (Aomori Prefecture), and the unloading port, Muroran (Hokkaido), the vessel is planned to operate with zero emissions.

The project has been recognized and 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. It has received fiscal year 2021 subsidies to suppress carbon dioxide emissions.