Sakigake completes three months of operational demonstrations in Tokyo Bay

Emissions reductions highest at high engine loads

Click to learn more. NYK’s Sakigake tugboat has completed three months of demonstration operations on Tokyo Bay, achieving highest GHG emission reductions under high engine loads and 95% ammonia fuel. Source: NYK Line.

NYK’s Sakigake tugboat (Japan’s first LNG-fueled vessel retrofitted to become Japan’s first ammonia-fueled vessel) has officially completed a three month “demonstration voyage” on Tokyo Bay, operating under a wide range of conditions. Over the course of the voyage, NYK has analyzed the GHG emission reductions achieved at certain ammonia “co-firing rates” (i.e. using heavy marine fuel oil as a pilot fuel) and engine loads.

A peak of 94.4% emission reduction was achieved using 94.8% ammonia fuel under 75% engine load, with similar results at 100% engine load (95.2% ammonia fuel, 94% emissions reduction). At lower engine loads, more pilot fuel is required for stable engine operations, and emissions reductions are lower (e.g. 91% co-firing, 90% emission reduction at 25% engine load).

The Sakigake will continue to operate in Tokyo Bay, allowing NYK to continue to accumulate valuable knowledge and experience with the operation of ammonia-fueled vessels. NYK, Japan Engine Corporation, and Nippon Shipyard Co., Ltd. are also working to develop an ammonia-fueled ammonia gas carrier, which is scheduled to be delivered in November 2026.