Onboard carbon capture has quietly shifted from PowerPoint to real hardware. By mid-2025, full-scale systems were running on ships like Solvang’s Clipper Eris and pilot units from Wärtsilä, Seabound, Langh Tech and others were capturing 50–70% of CO₂ from exhaust streams at sea. Class rules and IMO discussions are catching up fast, so 2026–2030 is shaping up as the proving decade for whether OCCS can extend the life of conventional fuels without blowing up costs or complexity.
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Onboard Carbon Capture Systems: Advantages and Disadvantages
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| Category |
Advantages |
Disadvantages |
Notes / Considerations |
| Emissions & compliance |
✅ Can cut CO₂ emissions from the treated exhaust stream by roughly 50–70% on current pilots and full-scale systems.
✅ Lets ships keep existing engines and fuels while still reducing calculated emissions under schemes like EU ETS, FuelEU and CII, if the captured CO₂ is permanently stored or properly accounted for.
✅ Can be combined with scrubbers and NOₓ solutions for a single “stack treatment” package.
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❌ Regulatory treatment is still evolving; rules on how captured and stored CO₂ counts in different schemes are not yet fully harmonised.
❌ Leakage or incomplete storage may reduce the claimed climate benefit.
❌ Does not address upstream fuel emissions unless well-to-wake rules are in place.
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Ask explicitly how captured CO₂ will be reported in EU ETS, FuelEU and charterer reporting, and who is responsible for proof of storage or utilisation.
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| Technology status |
✅ Several real ships now run OCCS at sea, including full-scale installations on gas carriers, bulkers and cement or container ships, with measured capture rates typically in the 50–70% range for treated streams.
✅ Commercial solutions are being marketed by exhaust treatment specialists and start-ups, not just in lab or demo phase.
✅ Leverages industrial CO₂ capture tech that is already proven on land (amine absorption, advanced solvents, sorbents).
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❌ Overall technology readiness for large deep-sea fleets is still below mature fuels like LNG or scrubbers; most deployments through 2026 are pilots or first-of-kind projects.
❌ Long-term reliability, solvent degradation and maintenance needs in harsh marine conditions are still being mapped.
❌ Designs are not yet standardised; integration looks different between vendors and ship types.
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Treat early projects as learning assets with strong monitoring and data sharing, not just as hardware purchases.
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| Space, weight & integration |
✅ Can be added as a retrofit module near the funnel, sometimes combined with new scrubbers or exhaust towers.
✅ Modular concepts (especially from newer vendors) aim to fit smaller carriers and feederships with limited deck area.
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❌ Capture units, piping and CO₂ tanks take significant volume and weight, which can affect cargo capacity, stability and trim on some vessels.
❌ Extra topside weight and tank placement must satisfy class, damage stability and structural rules.
❌ Retrofitting on compact container or RoPax layouts can be especially challenging.
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Run early 3D layout and stability checks; space for CO₂ tanks and offloading gear can be a bigger constraint than the capture skid itself.
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| Energy & fuel impact |
✅ Enables large CO₂ cuts without fully switching fuels, which can buy time while green fuel supply ramps up.
✅ Some designs integrate heat recovery from engines or scrubbers to lower additional fuel demand for capture.
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❌ Capture, compression and liquefaction consume extra power; studies show several percentage points of added energy demand, which means more fuel burned to run the capture system.
❌ If not carefully optimised, the extra fuel and methane slip (for gas engines) can claw back part of the climate benefit.
❌ For some routes, the marginal CO₂ cost per tonne avoided can be higher than switching to certain low-carbon fuels.
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Always evaluate OCCS on a well-to-wake basis: extra fuel in versus CO₂ actually stored, not just stack concentration.
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| Safety & operations |
✅ Class guidelines from DNV and others now cover key safety aspects for OCCS, including hazardous area zoning, CO₂ handling and offloading.
✅ High-concentration CO₂ systems are familiar in some gas and offshore contexts, giving a base of experience for training and procedures.
✅ Automated monitoring and shutdown functions can isolate faults and protect crew from CO₂ exposure.
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❌ CO₂ is an asphyxiant; leaks in enclosed or low-lying spaces pose real hazards without strong ventilation and detection.
❌ Operators must manage new chemicals (solvents or sorbents), high-pressure systems and cold CO₂ handling routines.
❌ Adds to crew workload and skills requirements unless supported by robust remote monitoring and vendor service.
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Integrate OCCS into the Safety Management System like any other high-energy, high-pressure system: drills, permits, maintenance routines and clear emergency playbooks.
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| CO₂ logistics & value chain |
✅ Links shipping into emerging CO₂ transport and storage chains such as Northern Lights and other hub projects, creating a tangible pathway from ship funnel to permanent storage.
✅ Potential for future CO₂ utilisation markets (e-fuels, materials) if quality and impurity specs are managed.
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❌ Very few ports can presently receive captured CO₂ directly; offloading infrastructure is a critical missing piece for large-scale adoption.
❌ Contracts for transport, storage and liability over decades are complex and largely untested for shipping.
❌ CO₂ purity and impurities from exhaust can affect where and how the CO₂ can be stored or used.
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Design OCCS projects together with storage and offloading partners; “capture on ship, figure out storage later” is not a workable plan.
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| Commercial & fleet strategy |
✅ Offers a transitional option for large, hard-to-electrify ships and trades where alternative fuels are scarce or expensive.
✅ Can be positioned as a compliance tool for tightening CII, ETS and fuel standards, especially for high-emitting legacy tonnage.
✅ May unlock green premiums from cargo owners that value immediate CO₂ cuts while long-term fuel strategy evolves.
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❌ High CAPEX and OPEX relative to simple exhaust cleaning, with payback heavily dependent on future carbon prices and fuel spreads.
❌ Unclear second-hand market value: buyers may worry about long-term OCCS maintenance, solvent supply and storage contracts.
❌ Risk that policy moves strongly toward fuel mandates or well-to-wake metrics that favour direct use of green fuels instead.
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Model OCCS against alternative decarbonisation paths (speed, routing, new fuels, newbuilds) route by route; it will make sense on some ships but not as a universal, one-size retrofit.
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Summary: Onboard carbon capture systems are moving from trial to early commercial use, with credible 50–70% capture rates on treated exhaust streams and growing class and IMO attention. The upside is a way to de-risk near-term CO₂ exposure on existing fuels and hulls; the downside is added energy use, space, cost and a heavy dependency on still-forming CO₂ storage and policy frameworks. For most owners, OCCS is a targeted tool for specific trades and vessels, not yet a blanket answer for the whole fleet.
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Onboard carbon capture will not suit every hull or route, but it is no longer a science project. A handful of real ships are now proving what capture rates, fuel penalties and operational burdens actually look like at sea, while regulators and storage projects figure out how to credit and handle the CO₂ that comes off the funnel. For owners, the next step is to treat OCCS like any other major retrofit option: run the numbers against your own fuel use, carbon exposure and port pattern, compare it with alternative decarbonisation paths, and decide where a capture module genuinely extends the life and value of high-consumption vessels rather than simply adding another complex box on deck.
