ClassNK Calls for Shared CO2 Reception Hubs to Scale Up Onboard Carbon Capture

Japanese classification society ClassNK called for common CO2 quality specifications, shared reception hubs and verified data across the entire carbon capture chain, with the aim of supporting wider adoption of onboard carbon capture and storage, known as OCCS. The call was made by Tatsuya Hayashi, General Manager of ClassNK's Technical Solutions Department, during the Japan CCUS Summit 2026 held in Tokyo on October 19.

In his presentation, Hayashi addressed the role of shipping in the carbon capture and storage chain, as well as the safety challenges of transporting liquefied CO2, including operation near the gas's triple point and corrosion caused by impurities. He also reviewed the current status of OCCS technology, ClassNK's existing guidelines, and ongoing regulatory developments at both the International Maritime Organization (IMO) and the European Union.

ClassNK's Guidelines for Onboard CO2 Capture and Storage Systems are currently in their 2.1 edition, published on May 29, 2026, which allows for the assessment of OCCS-ready ship concepts from the design stage and the assignment of corresponding class notations. The 2.0 edition, from October 2025, had extended the rules to membrane separation-based capture systems, while the original guidelines date back to 2023. In parallel, IMO's Sub-Committee on Carriage of Cargoes and Containers began work in September 2026 on interim safety guidelines covering the onboard capture, conditioning, storage, handling and transfer of carbon.

In 2024, ClassNK took part in an onboard carbon capture operation together with the Panama Maritime Authority, Taiwanese shipping line Evergreen Marine and China's Shanghai Marine Diesel Engine Research Institute. In that trial, CO2 captured aboard a Panamanian-flagged Neopanamax container ship was offloaded ashore for recycling, with ClassNK verifying the quantity. Under the flag administration's direction, that verified volume was deducted from the ship's annual CO2 emissions for its Carbon Intensity Indicator (CII) assessment.

In parallel, ClassNK unveiled a new handbook titled 'Onboard Carbon Capture Systems Implementation Framework,' part of its Handbook on Ship GHG Emissions Evaluation series. The document aims to provide practical guidance for shipowners, operators and other stakeholders considering the adoption of onboard carbon capture systems (OCCS), helping them understand the full implications of such a project.

The handbook brings together technical, infrastructure, regulatory and emissions-reduction assessment considerations, including MRV systems and chain of custody (CoC) frameworks for managing captured CO2 and its associated data. According to the source, adopting OCCS requires not only the onboard system itself but also pathways for the offloading, transport, storage, sequestration or use of the captured CO2, which is why ClassNK drew on the knowledge gained through its guidelines and demonstration projects to develop the document, reaffirming its commitment to continue supporting the decarbonization of the maritime sector.