Fruit-powered batteries are the ultimate school science experiment, but they’re normally used to power a pocket calculator. This week’s listener wants to know if they could do more, and sends the team on a quest to discover whether they could used to send a rocket into space?Professor Saiful Islam is the Guinness World Record holder for the highest voltage from a fruit-based battery, but disappoints the team when he reveals they produce very little power. He used 3,000 of them and only managed a measly 2 Watts. Given that spaceships are famously difficult to get off the ground, it seems a lemon battery might just fail the acid test. Author Randall Munroe is undeterred and suggests alternative ways to get energy from citrus, including burying them to make oil. Then the team discuss the pros and cons of switching to a lemon-based diet. For battery expert Paul Shearing, all this raises a serious question, about how we will power the planes of the future. He suggests solar power could play a part in short-haul flights and discusses some of the exciting battery materials being tested today.Contributors:Randall Munroe, author Professor Paul Shearing, Oxford University Professor Saiful Islam, Oxford University Producer: Marijke Peters Executive Producer: Alexandra Feachem A BBC Studios Audio Production