How do you clean the world's oceans of plastic? 10 years ago, when he was just 18, Dutchman Boyan Slat thought he knew how to do it, and set out his vision at TED talk.

The journey from theory to reality has proved difficult, but he is now extracting plastic from the Pacific and a number of rivers around the world. We speak to Boyan about the scale of the task at hand. Is it even an achievable goal? How is he raising enough money? What does he make of the accusation he’s helping multi-nationals ‘greenwash’ their reputations by taking sponsorship cash?

Presenter/producer: James Graham