The huge wing sitting in a corner of the Scottish port of Hunterston does not look like part of a ship — but the 20m-long device could be one of the shipping industry’s weapons to fight carbon emissions.

When bolted to a vessel’s decks and sitting upright, the wing, called FastRig, will act as a sail capturing the wind. Smart Green Shipping (SGS), the company that has developed the device, and some of the world’s leading shipowners are convinced it can provide clean power to supplement ships’ engines.