Onboard Carbon Capture and Storage (OCCS)
Onboard carbon capture already exists technically, but still counts for nothing toward EEXI or CII: the full regulatory framework is not expected before 2028, a gap holding back large-scale adoption.
Operational Explanation
Onboard Carbon Capture and Storage (OCCS) captures CO2 from engine exhaust gas, compressing and storing it on board for offloading ashore at a dedicated facility. The technology is now "ship-ready" for some applications, but faces a significant regulatory gap: IMO's short-term measures (EEDI, EEXI, CII) currently give no credit for CO2 captured on board, a gap identified as a major brake on its commercial-scale adoption.
The MEPC has adopted a work plan to develop a complete OCCS regulatory framework, with finalization expected by 2028; meanwhile, guidelines for testing, surveying, certifying and approving OCCS systems are under discussion at a correspondence group, and OCCS is in any case listed among the potentially relevant lower-intensity energy sources under the greenhouse gas fuel intensity targets envisaged by the IMO Net-Zero Framework.
Regulatory Reference
No complete IMO OCCS framework yet: the MEPC is developing guidelines for testing, surveying, certifying and approving OCCS systems, with finalization of the overall regulatory framework expected by 2028; OCCS is mentioned as a potentially relevant energy option under the IMO Net-Zero Framework, without yet receiving credit under the EEDI/EEXI/CII measures.
Scope of Application
Ships installing CO2 capture systems from exhaust gas, with onboard storage pending offloading ashore; the technology is currently more mature for retrofit applications on large ships with available storage space.
Procedure / How to Complete It
- Assess the technical feasibility of an OCCS installation in relation to the space available on board for storing captured CO2 and the existing exhaust gas configuration.
- Do not rely on an EEXI/CII regulatory credit for captured CO2, since IMO's short-term measures do not yet recognize it in their current form.
- Monitor the development of IMO guidelines for testing, surveying, certifying and approving OCCS systems at the dedicated correspondence group.
- Plan logistical arrangements for offloading stored CO2 ashore, verifying the availability of receiving facilities at usual ports of call.
- Consider OCCS as part of a multi-lever decarbonization strategy, not as an isolated substitute for other efficiency measures already required (SEEMP, CII).
Practical Example
Example: a large ship installs a retrofit OCCS system capturing a significant portion of CO2 from exhaust gas during voyages, storing it in dedicated tanks for offloading ashore at ports equipped with receiving facilities; the owner does not, however, count on a direct improvement in the CII rating, pending completion of the dedicated regulatory framework expected by 2028.
Real Cases
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| Investment in an OCCS system based on the expectation of an immediate EEXI or CII credit | Disappointed regulatory expectations, since the credit is not currently recognized by IMO's short-term measures | Assess the OCCS investment based on the overall decarbonization strategy, not on an immediate regulatory benefit that does not yet exist |
| OCCS installation planned without verifying the availability of CO2 receiving facilities at usual ports of call | Logistical difficulties offloading captured CO2 | Verify the availability of CO2 receiving infrastructure on planned operating routes before investing |
| No monitoring of the development of IMO OCCS guidelines under way | Installed systems that may not align with future certification requirements | Actively follow the development of the OCCS regulatory framework at the dedicated IMO correspondence group |
PSC Observations
Operational Tips
- Do not expect an immediate EEXI or CII regulatory credit for installing an OCCS system: the dedicated framework is still under development.
- Always verify the availability of onshore CO2 receiving facilities on planned operating routes before investing in an OCCS system.
- Follow the development of the dedicated IMO guidelines, since the complete regulatory framework is expected only by 2028.
Checklist
- Technical feasibility of onboard CO2 storage space verified
- Regulatory expectations aligned with the current absence of EEXI/CII credit for OCCS
- Development of IMO OCCS guidelines actively monitored
- Availability of CO2 receiving facilities verified at usual ports of call
- Overall decarbonization strategy integrating OCCS with other already-required measures (SEEMP, CII)