1.7 million tonnes: big boxships could become CO2 suppliers to Rotterdam

Large container ships calling at Rotterdam alone could land around 1.7 million tonnes of liquefied CO2 per year by 2050 — a cargo flow generated not by factories but by the ships' own exhaust pipes. That is the central finding of an analysis by Diederik Westerkamp and Johan-Paul Verschuure of the Rebel Group, who charted what onboard carbon capture and storage (OCCS) means for ports and carriers.

The mechanism is simple enough. A solvent absorbs CO2 from the exhaust stream, the gas is liquefied, and the ship carries it in tanks until it reaches a port with a route to permanent storage. By 2025, some 60 vessels carried OCCS systems, according to DNV. The 14,000 TEU container ship EVER TOP has already offloaded LCO2 in pilot schemes in Shanghai and Rotterdam.

How big is the flow, really?

The Rebel Group based its estimate on roughly 750 calls by ships over 12,000 TEU at Rotterdam in 2025, as reported by Alphaliner, and assumed 40 per cent of those calls will be made by retrofitted ships by 2050. The result: around 1.7 million tonnes per annum, requiring one hectare of buffer storage at the port.

The assumptions are conservative and specific:

• Ships run conventional fuel oil — HFO or VLSFO — since OCCS will mostly go in as retrofits on such vessels.
• The capture plant takes three quarters of the CO2 out of the exhaust.
• It also burns a quarter more fuel on top of propulsion, in line with the IMO's life cycle assessment guidelines, first adopted in 2023 and updated in 2024.
• Storage follows a published Mitsubishi Shipbuilding design of two 2,700 m3 tanks.

Upscaling the technology to large container ships is yet to be proven. The International Chamber of Shipping notes gas carriers and large tankers are also strong candidates, given their space and energy profiles. With faster uptake, or with tankers, bulk carriers and car carriers joining, volumes could triple.

What does OCCS change for ports?

Not every port wins. Only ports combining large throughput with carbon storage projects can generate enough demand to justify investment in the medium term. Most CO2 handled at LCO2 terminals such as CO2next will come from industrial emitters — OCCS adds upside, not base load.

There is also a logistics wrinkle. Container ships use their own terminals, so their LCO2 must be pumped into barges alongside — bunkering in reverse. That means squeezing transfers into tight terminal schedules, safety zones, enough barge and berth capacity, and coordination between terminal and barge operators. Discharging will concentrate in ports with large traffic plus a dedicated LCO2 terminal or CCS project: on the Asia–Europe route, that means Singapore and North Sea ports tied to storage projects such as Aramis, Northern Lights and the UK's Northern Endurance Partnership.

Lost boxes versus saved allowances

Here is the liner's dilemma, and it comes down to hard numbers. The two 2,700 m3 reference tanks occupy roughly the space of 80 FEU — worth some €250,000 in freight revenue per trip at today's Asia–Europe rates. Against that, CO2 kept on board needs no emission allowances. Under the EU-ETS, voyages between an EU and a non-EU port count for 50 per cent of their emissions, and at roughly €85 per tonne of carbon, OCCS saves a similar amount per trip in ETS costs. For now, the trade-off roughly cancels out.

One regulation still bites. FuelEU Maritime does not recognise OCCS, so a fuel-oil ship fitted with the system still pays FuelEU penalties because the fuel remains fossil. The European Commission will consider including OCCS in its review of the regulation, due by the end of 2027.

Is the regulation ready?

Partly. EU law exempts CO2 destined for geological storage from waste-shipment rules, including arrivals from outside the EU, as long as storage follows the EU CCS Directive. The ETS counts captured CO2 as not emitted once it reaches a permitted storage site. Offshore, the London Protocol allows export for sub-seabed storage only under bilateral arrangements, such as those between North Sea countries. Outside Europe, crediting remains unclear; Singapore is working on bilateral agreements with Indonesia and Australia to ship CO2 abroad. The IMO is developing a global OCCS framework, due by 2028.

The business will hinge on carbon prices, regulation, the pace of clean fuel availability and the number of ports able to take the CO2 — but for ports positioned to win, the message is to start planning the infrastructure now, because infrastructure planning takes longer than technology development.