Expanding the Toolkit
Classification society ClassNK has released Edition 2 of its Guidelines for Onboard CO2 Capture and Storage Systems, the first global rulebook to include membrane separation technology. The update builds on the 2023 edition, which covered amine absorption, and reflects growing industry interest in turning ships into mobile carbon capture units that complement fuel transitions such as methanol or ammonia.
Why Membranes Matter
Membrane systems filter exhaust gases through specialised polymer sheets that allow carbon dioxide to pass while blocking most other molecules. Compared with amine based scrubbers, membranes require less energy, occupy a smaller footprint, and do not rely on a steady supply of chemical solvent. These characteristics make them suitable for container feeders, bulk carriers, and even offshore support vessels where space and power are at a premium.
Unified Structure
The new edition reorganises requirements into generic foundations common to every capture method and specific chapters for each technology. Designers now have a single reference for safety, control logic, storage tank integrity, and crew training regardless of the chosen approach. This structure should accelerate approval timelines because naval architects can reuse compliance work from one project on another.
Non-Obvious Insight
A subtle benefit is that membrane systems can operate flexibly alongside variable engine loads typical in real world sailing. Their capture rate adjusts almost linearly with exhaust volume, avoiding the part load performance dips that challenge chemical absorbers. This dynamic responsiveness can improve overall voyage efficiency when weather or routing changes force throttle adjustments.
Path Forward
ClassNK offers free access to the guidelines, encouraging manufacturers and owners to experiment confidently. Early adopters may find value in retrofitting pilot scale units during routine dry docking to collect performance data before committing fleetwide.
Conclusion
By codifying membrane-based capture standards, ClassNK is lowering entry barriers for innovative solutions that keep maritime trade moving while steadily shrinking its emissions footprint.