Japanese classification society ClassNK has called for common CO2 quality specifications, shared reception hubs and verified data across the carbon-capture chain to support wider use of onboard carbon capture and storage, according to a company statement.
Tatsuya Hayashi, general manager of ClassNK’s Technical Solution Department, set out the requirements at the Japan CCUS Summit 2026 in Tokyo on 19 October.
His presentation covered shipping’s role in the carbon capture and storage chain and safety challenges in transporting liquefied CO2, including operation near CO2’s triple point and corrosion caused by impurities.
Hayashi also addressed the status of onboard carbon capture and storage, or OCCS, ClassNK’s existing guidelines and regulatory developments at the International Maritime Organization and in the European Union.
ClassNK’s current Guidelines for Onboard CO2 Capture and Storage Systems are Edition 2.1, released on 29 May 2026. The revision allows OCCS-ready vessel concepts to be assessed at the concept stage and assigned relevant class notations.
Edition 2.0, issued in October 2025, expanded the rules to membrane-separation capture systems. The original guidelines were issued in 2023.
The IMO is developing rules covering testing, surveys and certification, emissions measurement and verification, and the treatment of captured carbon. Its Sub-Committee on Carriage of Cargoes and Containers began work in September 2026 on interim safety guidelines covering the capture, conditioning, storage, handling and transfer of carbon onboard ships.
ClassNK was involved in a 2024 onboard carbon-capture operation with the Panama Maritime Authority, Taiwanese container shipping company Evergreen Marine and China’s Shanghai Marine Diesel Engine Research Institute.
CO2 captured from a Panama-flagged Neopanamax containership was offloaded ashore for recycling, with ClassNK verifying the quantity.
Under the flag administration’s direction, the verified amount was deducted from the ship’s annual CO2 emissions for its Carbon Intensity Indicator assessment.
ClassNK is an independent, non-profit Japanese ship classification society. At the end of August 2026, it had 9,835 ships totalling more than 285m gross tonnes under class, equivalent to about 20% of the world merchant fleet under classification.
