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DNV: New requirement for Selective Catalytic Reduction Systems enters into force on 1 May

New requirement is applicable for marine diesel engines installed on ships with keel laid on or after 1 November 2025 or with a delivery date on or after 1 May 2026.

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Classification society DNV on Tuesday (3 March) released a statutory news on a new requirement for Selective Catalytic Reduction (SCR) Systems, which will enter into force on 1 May 2026. 

The new requirement is applicable for marine diesel engines installed on ships with keel laid on or after 1 November 2025 or with a delivery date on or after 1 May 2026:

Recent changes to the SCR Guidelines have altered how NOx measurement accuracy is assessed for catalyst monitoring. The former ±5% accuracy requirement has been replaced by a more flexible but less clearly defined concept of “sufficient accuracy”. This update places greater responsibility on applicants to justify the performance and monitoring of the lifetime of NOx catalysts.

Key changes to the requirements for NOx measurements

The requirements for NOx measurement devices used to monitor catalyst condition and potential degradation have been amended. Under the previous guidance, such devices were required to achieve an accuracy of ±5% relative to a reference NOx analyser (chemiluminescence detector, or CLD) compliant with the NTC 2008 standard. This explicit accuracy requirement has now been removed.

Under the 2025 SCR Guidelines, the NOx measurement method must instead be “sufficiently accurate” to enable the reliable monitoring of catalyst condition and degradation. However, the guidelines do not provide a specific definition or quantitative criterion for what constitutes “sufficiently accurate”.

Implications

Consequently, it is the responsibility of the applicant to demonstrate that the deviation between the on-board NOx measurement device and an NTC 2008‑compliant reference analyser remains within an appropriate range to support a dependable assessment of catalyst condition and degradation. In doing so, consideration may be given to factors such as the inherent measurement accuracy of the device, its expected measurement drift over time, and the margin to the applicable NOx limit value.

In addition, the assessment may need to address not only the raw NOx measurement results (e.g. concentrations expressed in parts per million), but also the evaluation process used to interpret these results and to determine whether the catalyst remains in an acceptable condition.

It should also be noted that NOx measurement accuracy is influenced not only by the performance device itself, but also by the exhaust gas sampling location and the degree of exhaust gas mixing at the sampling point. These aspects should therefore be duly addressed during testing and verification.

A proposal outlining recommended actions to support the implementation of the requirements under the 2025 Guidelines on SCR systems is provided in the Appendix to this news.

Recommendations

To ensure compliance with the 2025 SCR Guideline, it may be necessary to update the documentation, including the Technical Files, for individual engines or for existing engine groups or families.

In addition, the requirements of the 2025 SCR Guideline should be considered when planning and conducting parent engine emission tests and when preparing the associated documentation for new engine groups or families.

References

IMO resolution MEPC 399(83), 2025 Guidelines on SCR

 

Photo credit: william william on Unsplash
Published: 23 April, 2026

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Ammonia

Mitsui E&S commercialises ammonia dual-fuel engines and fuel supply systems

Company says it has established a supply framework for marine propulsion systems aimed at the practical implementation of ammonia-fuelled vessels.

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Mitsui E&S commercialises ammonia dual-fuel engines and fuel supply systems

Mitsui E&S on Thursday (20 August) said it has completed the commercialisation of large ammonia dual-fuel marine engines and ammonia fuel supply systems (AFSS).

As the only company in Japan manufacturing both ammonia dual fuel engines and AFSS, the company said it has established a supply framework for marine propulsion systems aimed at the practical implementation of ammonia-fuelled vessels.

“While ammonia holds promise as a next-generation fuel that emits no carbon dioxide during combustion, it is difficult to ignite and poses risks related to toxicity and corrosiveness; therefore, ensuring safety, reliability, and environmental performance is crucial for its practical implementation in society,” it said. 

In February, Mitsui E&S conducted land-based tests involving the integrated operation of the Ammonia dual fuel engine MITSUI-Everllence B&W 7S60ME-C10.5-LGIA-HPSCR and the AFSS, witnessed by ClassNK (Nippon Kaiji Kyokai), and verified their performance. 

Following the completion of the tests and the subsequent review, Mitsui E&S confirmed the completion of onshore testing in accordance with classification society rules and verified compliance with International Maritime Organization (IMO) NOx regulations through NOx certification. 

“Consequently, we have finalised the commercialisation of the ammonia dual fuel engines and the AFSS and are now able to supply it for actual vessels,” it added. 

Mitsui E&S said it has already decided to expand its land-based testing facilities for AFSS compatible with both Everllence and WinGD licensed engines. 

“In conjunction with this, we will establish a mass-production system for both the engines and the AFSS to meet the anticipated rise in demand,” it said. 

Mitsui E&S added the company is expanding its engine lineup to accommodate a diverse range of next-generation marine fuels, including ammonia, by offering ammonia-fuelled engines and AFSS as an integrated package.

 

Photo credit: Mitsui E&S
Published: 24 August, 2026

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Events

London forum to address critical bottlenecks holding back maritime decarbonisation

Marine Energy Transition Forum 2026 will be held on 11 November to address bunker fuel, technology and infrastructure barriers that continue to slow the industry’s transition to net-zero emissions.

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London forum to address critical bottlenecks holding back maritime decarbonisation

The Marine Energy Transition Forum (METF) 2026 will bring together leading voices from across the global maritime sector on 11 November 2026 at Norton Rose Fulbright, London.

The forum will tackle one of shipping’s most pressing challenges: how to overcome the fuel, technology and infrastructure barriers that continue to slow the industry’s transition to net-zero emissions.

Under the theme “Reframing the maritime decarbonisation roadmap: addressing fuel, technology and infrastructure bottlenecks,” the one-day forum will provide a platform for shipowners, fuel suppliers, technology developers, ports, policymakers and financiers to examine the practical steps needed to accelerate progress while maintaining commercial competitiveness.

As the maritime industry navigates an increasingly complex regulatory and commercial landscape, METF 2026 will focus on delivering practical insight into the challenges—and opportunities—shaping the next phase of the energy transition.

The conference programme will explore five key themes:

  • The effectiveness of current regulatory frameworks and policy measures, including regional and international initiatives driving maritime decarbonisation.
  • Progress in developing a resilient multi-fuel future, examining investment, fuel availability, supply chains and infrastructure.
  • The commercial readiness of emerging technologies, including alternative propulsion systems, vessel optimisation, batteries, carbon capture, wind propulsion and digital solutions.
  • Building a supportive business environment for energy transition companies, with discussions covering finance, innovation, scaling businesses and market development.
  • The evolving role of ports as critical enablers of shipping’s energy transition through new fuel infrastructure, shore power and energy cluster development.

METF 2026 is designed to encourage open discussion between every part of the maritime value chain, recognising that collaboration across fuel producers, shipowners, ports, technology providers, investors and policymakers will be essential if global decarbonisation ambitions are to be achieved.

The event will feature expert speakers, panel discussions and extensive networking opportunities, enabling delegates to exchange ideas, develop partnerships and gain practical insight into the strategies shaping the future of maritime energy.

Registration for METF 2026 is now open. Further information and registration can be found here

 

Photo credit: ship.energy
Published: 13 August, 2026

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Engine

Japan’s first WinGD methanol dual-fuel marine engine passes FAT at MITSUI E&S

Company successfully completed the Factory Acceptance Test of the DU-WinGD 6X82DF-M-1.0 LP-SCR, the first methanol dual-fuel WinGD large marine engine built in Japan.

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MITSUI E&S completes FAT of Japan's first WinGD methanol dual-fuel engine

MITSUI E&S on Monday (3 August) announced that Mitsui E&S DU, a group company of MITSUI E&S, has successfully completed the Factory Acceptance Test (FAT) of the DU-WinGD 6X82DF-M-1.0 LP-SCR, the first methanol dual-fuel WinGD large marine engine built in Japan.

The engine is also the first WinGD large marine engine manufactured at MITSUI E&S Tamano Works.

“The engine is scheduled to be installed on the first vessel in a series of four vessels being built for a domestic shipowner,” the company said on its website. 

By utilising green methanol as fuel, it will contribute to a substantial reduction in greenhouse gas (GHG) emissions from shipping operations.

“To meet the expected increase in marine engine demand under the Japanese government’s Shipbuilding Industry Revitalisation Roadmap, the MITSUI E&S Group is working to enhance production efficiency for large marine engines through integrated operation at MITSUI E&S Tamano and Mitsui E&S DU Aioi,” the company added.

 

Photo credit: MITSUI E&S
Published: 4 August, 2026

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