Cargo sails.

The food and agriculture giant Cargill is testing out adding WindWings, 123-foot-tall sails made of steel and composite glass, to its cargo ships to reduce its fuel use, Bloomberg reports.

This is an interesting innovation in an otherwise hard to abate sector. While wind propulsion won't work for all trading routes, sails can be retrofitted on existing ships, a big advantage.

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Cat Clifford

Senior Science and Economics Correspondent