A new wind-powered propulsion system, operating like a giant mechanical sail, is being tested at sea on a cargo ship sailing from England to Canada with the aim of using less fuel to help reduce emissions. Like several other wind propulsion systems, the AirWing works like a vertical aeroplane wing, harnessing wind that hits its surface to propel the ship but uses internal fans to accelerate the air passing through it. "We hope this will be a real game changer," says Simon Merritt, a fleet manager at the company which owns the ship carrying out the cross-continent maiden journey. IMAGES AND SOUNDBITES