With global shipping responsible for 3% of greenhouse gases, one startup’s quicklime-powered tech promises to make cargo ships more climate-friendly, by turning exhaust fumes into harmless limestone
Containers full of quicklime could help clean up one of the world’s filthiest industries.
Global shipping, which is fuelled predominantly by marine diesel, belches out around 3% of planetary greenhouse gas emissions, making the sector a bigger polluter than aviation.
Now, London-based startup Seabound has come up with a solution to help freighters chart a course for net zero, with a surprisingly simple carbon capture system. The lo-fi method involves funnelling ships’ exhaust fumes through calcium oxide pebbles, also known as quicklime. They soak up the CO2, which leads to a chemical reaction that turns them into harmless limestone, which can be safely stored or even sold for profit.
A three-week ocean-going trial showed that Seabound’s method can hoover up 78% of a ship’s carbon emissions and 90% of toxic sulphur exhaust fumes.
The company’s latest prototype packs into a standard shipping container, making it easy to install on cargo decks and swap out in port.
The big challenge now is scale: Seabound will need a steady supply of sustainably produced quicklime. Traditional production methods are energy-hungry, emitting significant emissions of their own.
While some critics claim that carbon capture systems are a distraction from the urgent task of weaning sectors off fossil fuels, others concede that they will be required to meet climate targets.
Seabound’s system comes at a time when efforts to reduce the shipping sector’s emissions are all at sea. Last month, a landmark deal to cut global shipping emissions was scuppered by the Trump administration, which threatened smaller countries with tariffs if they signed up.
Given the slow pace of change, some smaller players are taking matters into their own hands. British marine engineers BAR Technologies have been trialling modern-day sails, which look more like wind turbine blades, on cargo vessels. And in May, the world’s largest electric ferry, Incat Hull 096, took to the water for the first time. Capable of carrying 2,100 passengers and 225 vehicles, the Aussie-built vessel is due to enter service between Argentina and Uruguay.
Main image: Ian Taylor
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