For years, balsa wood has been a key component in the giant rotor blades on the top of wind turbines. Most of it comes from the rain forests of South America and, in particular, from Ecuador. As the world transitions to green energy, lots of countries – particularly China – have been looking for more balsa to make blades. That pushed up prices, raised questions over sustainability and prompted some companies to look for alternatives to balsa wood. One alternative is PET, a foam made from recycled plastic bottles.So what should we be using to make the wind turbine blades of the future – biodegradable balsa wood or plastic foam made from old bottles?We talk to people on both sides of the debate and visit a wind farm in rural England to see the blades in action.(Picture: Crook Hill wind farm in Rochdale, north of England.)Presented and produced by Gideon Long