Seawater greenhouses; the “insect apocalypse”; and zero carbon flight

Imagine greenhouses that produce food using just sunshine and sea-water. In Australia and Africa they’re already a reality. We talk to one of the pioneers of the concept. Also, the latest research on the so-called “insect apocalypse”. And, the new aviation prize open to any enterprising spirit able to cross the Atlantic in a plane powered entirely by renewable energy.