Five years ago, Sam Elsom shocked his friends and family when he quit his job as a fashion designer to set up a seaweed farm in Tasmania, inspired by the potential of a special strain to radically reduce methane emissions in livestock. Two weeks ago his company was named as a finalist in one of the world’s most prestigious environmental prizes, Earthshot, founded by Prince William and Sir David Attenborough. The dividend, a year’s mentoring by billionaire Michael Bloomberg and the chance to compete for the big prize in November. And the global recognition has come at just the right time. Having built a state-of-the-art lab, trialled his special seaweed-based feed and had it adopted by a national burger chain, Sam has now reached a crunch point. With a million doses on the shelf, can he generate enough interest to get farmers and government on board?