Here is another example innovation through combination of existing concepts: Cargo ships equipped sails in the form of kites.
Arguably, all they have done at German Skysails is reinventing the sailing ship. But the important - and innovative - thing is that they have actually done it. Wind is free and oil is not and they claim that the can reduce oil consumption by 10 – 35% on annual average depending on wind conditions. The concept is still being developed and ships with bigger sails are under construction. This video explains it better than text.