23 October 2026 – ClassNK has released a new handbook entitled ‘Onboard Carbon Capture Systems Implementation Framework’ as part of its Handbook on Ship GHG Emissions Evaluation series.
The handbook provides practical guidance for shipowners, operators and other stakeholders considering the introduction of onboard carbon capture systems (OCCS). It is intended to help them understand the considerations involved across an entire OCCS project and to facilitate discussions among relevant parties and consideration of OCCS implementation.
The introduction of OCCS requires consideration not only of the value chain from onboard CO₂ capture through to storage and other forms of final treatment, but also of mechanisms for quantifying and verifying emissions reductions.
These include MRV*1and CoC*2 systems for managing captured CO₂ and its associated attribute information.
The handbook brings together these considerations from technical, infrastructure, regulatory and emissions-reduction assessment perspectives, and can be used to support discussions among relevant stakeholders and the consideration of specific OCCS projects.
Background
The maritime industry is pursuing various measures to reduce GHG emissions, including operational improvements, the introduction of energy-efficiency technologies and the transition to alternative fuels.
Among these options, onboard CO₂ capture, in which CO₂ is captured from ships’ exhaust gas, processed and temporarily stored on board, has attracted attention as a means of supporting GHG emissions reduction, with demonstration projects and discussions on relevant regulatory frameworks progressing internationally.
However, translating the use of OCCS into actual emissions reductions requires more than the onboard system itself. Routes must be secured for the unloading, transportation, storage, sequestration or utilisation of captured CO₂, together with mechanisms for quantifying and verifying emissions reductions.
As these considerations span technology, infrastructure, regulation and emissions-reduction assessment, a project-wide perspective is essential.
Through the development of its “Guidelines for Onboard CO₂ Capture and Storage Systems”*3, ClassNK has worked to establish safety and technical requirements for such systems, while accumulating knowledge through demonstration projects and experience through various GHG certification services.
Drawing on this knowledge and experience, the handbook has been prepared to help stakeholders considering the introduction of OCCS gain a project-wide understanding of the relevant considerations.
ClassNK will continue to support the maritime industry’s decarbonisation efforts through the provision of relevant information.
How to access the handbook
The handbook is available on the following page of ClassNK’s website. (URL: www.classnk.or.jp).
Home > Information Services > ClassNK Transition Support Services
Please click here to access the handbook.
The handbook is also available under ‘Technical Publication’ on ClassNK MyPage. MyPage can be accessed here.
*1 Monitoring, Reporting and Verification (MRV): A framework for the continuous monitoring, reporting, and verification of emissions or emission reductions.
*2 Chain of Custody (CoC): A framework for transferring, tracking, and managing captured CO₂ and its associated attributes throughout each stage of the supply chain.
*3 Related Press Release: ClassNK releases ‘Guidelines for Onboard CO2 Capture and Storage Systems (Edition 2.0)’ – World-first requirements for onboard CO2 capture systems using membrane separation method
https://www.classnk.or.jp/hp/en/hp_pressrelease.aspx?id=14242&layout=1
