Andy Pag, from Croydon, south London, came up with the idea of converting the bus, rescued from a scrap heap, into a "biotruck", using reclaimed materials to turn it into a comfortable eco-home, the Telegraph reported.
He converted the bus to run on waste cooking oil and installed a filtering system and a 1,200-litre tank under the bed before setting off in September 2009 determined to prove what can be achieved with people's rubbish.
After a year of travelling he met American freelance journalist Christina Ammon while he was passing through Indonesia, and she joined him on the journey, as she wanted to write about his trip.
Their friendship soon blossomed into love and they became a couple, and Ammon joked that her friends thought she was "crazy" to be taking to the road in a beaten-up old bus.
And despite being arrested and facing jail time in India, Pag and Ammon say they had a fantastic time travelling around the globe.
After travelling through Europe and Africa, the couple plan to tour schools and businesses across Britain early next year to give talks about the lessons they have learned about climate change and carbon reduction efforts.