Pilot Project Achieves Better Than Projected 98% Reduction in Methane Slip

 

A multi-year Japanese project sponsored by the government is reporting that it has achieved much higher than anticipated reductions in unburnt methane emissions (methane slip) during demonstrations on an in-service bulker operated by Japan’s Mitsui O.S.K. Lines. They are testing methane oxidation catalysts, noting that it is a first for the technology, and confirms very promising results in tackling a key environmental concern.

The project began in 2021 as part of efforts sponsored by Japan’s New Energy and Industrial Technology Development Organization (NEDO) with the goal of reducing methane emissions by at least 70 percent. Unburnt methane scientists report has a higher greenhouse effect than CO2 and takes far longer to break down, making it is high priority in the efforts to reduce GHG emissions.

Hitachi Zosen and Yanmar Power Technology developed the methane oxidation catalyst system. It is placed on the exhaust pipe, similar to the application of emissions SOx scrubbers, and the methane is oxidized to reduce methane slip.

The companies undertook land-based tests in December 2023 and reported achieving a reduction rate of 93.8 percent at 100 percent load. The system combines with an exhaust gas recirculation technology that recirculates engine exhaust gases to reduce unburnt methane slip and NOx. The results were independently verified by ClassNK and reviewed with NEDO for continued support.

 

Methane slip reduction system on board (Left: EGR system, Right: Methane oxidation catalyst layer) (Yanmar)

 

Japan’s industrial and engineering corporation Kanadevia Corporation (formerly Hitachi Zosen) continues to lead the project. Working with Yanmar and MOL, the goal was to modify the land-based test equipment for onboard use on a large, LNG-fueled coal carrier.

MOL’s vessel Reimei was fitted for the tests, which began in May 2025. Delivered in November 2023 from Japan’s Namura Shipbuilding Co., the 95,792 dwt bulker is a Panamax coal carrier. It operates for Japan’s Kyushu Electric Power Co., transporting coal to Japan for thermal power plants.

Test results during the demonstration reported a 98 percent reduction in methane slip, far exceeding the 70 percent goal of the project and the earlier 93.8 percent reduction in the land-based trials. They highlight that the vessel was operating under normal conditions, including a fluctuation in load rate due to weather conditions, and was at a practical operating load (75 percent) while achieving the 98 percent reduction. 

Onboard trials are continuing into FY 2026 to evaluate overall system performance and catalyst durability. The aim is to commercialize the system starting in FY 2027.