Airships were once considered the future of flight. Now, they are being touted as a greener method of transport.

A solar-powered airship being built by UK-based firm Varialift Airships could eventually be used as a low-emissions way to freight cargo internationally. On a transatlantic flight between the UK and the US, the airship would use 8 percent of the fuel of a conventional jet aeroplane, says Varialift CEO Alan Handley.