ONBOARD carbon capture, if it lives up to the hype, could be an important part of the solution to cutting shipping’s greenhouse gas emissions. But a simple, cheap and elegant solution it is not.

The Global Centre for Maritime Decarbonisation’s impressive work testing the technology shows it is technically possible.

Last year, researchers trapped CO2 from a tanker, offloaded it at Shanghai, then trucked it 2,200 km to Inner Mongolia, where it was turned into materials used in steel and cement making.

Broadly speaking, scrubbing CO2 from ship exhaust isn’t a million miles off what ships already do with sulphur.

The trouble is finding the space for the stored CO2 on board, and the extra fuel needed to run the system. At 10.7% carbon capture, this amounted to just over half a tonne of CO2 emitted for every tonne captured (though using waste heat recovery would help reduce this).

Another 375 kg per tonne was emitted by trucking the stuff all those 2,200 km, leading to just 0.3% of the lifecycle emissions saved. Not a great result in planetary terms.

The forecasts look better once start-up costs are taken out, and the process made more efficient. As always, the less you have to move captured CO2 around, the better the business case.

Using the CO2 to make carbon-intensive products is better than burying it underground, because doing so avoids emissions from making such products the normal way.

But the International Maritime Organization’s carbon accounting doesn’t recognise these gains as yet. That will need to change if the rules are to send the right signals to shipowners.

The technology will improve, and scrubbers have shown us that it is sometimes cheaper to turn a ship into a chemical plant than to switch to costlier fuel.

But will it work at scale? And will it be cheap enough? These questions still require answers.    

Declan Bush
Senior reporter, Lloyd’s List

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