In this prototype carbon capture apparatus, a solution of potassium hydroxide is wicked up into polypropylene fibres; circulating air evaporates the water in the solution, concentrating it to very high levels. The white crystals are nearly pure potassium carbonate, formed from carbon removed directly from air. 

University of Toronto engineers have unveiled a “rock candy” style method of capturing carbon dioxide directly from the air that could cut the cost of building carbon capture plants by up to 40 per cent.