With such a focus on alternative propulsion for cars, it's easy for forget that every day, millions of other vehicles are used around the world.

Bikes, for example, or scooters and motorcycles - we've seen those going electric recently. Fork-lift trucks have been electric for years. But what about farm equipment? How about a hydrogen tractor?

Believe it or not, New Holland Agriculture has just revealed details of its second-generation hydrogen fuel cell tractor (via SAE International)...

A prototype was demonstrated at our engineering school in the 1960s. It was hooked back-to-back with a conventional tractor of equal size and not only stalled it's engine, but pulled it backwards. The only sound it made was the faint whine of the electric motor.