Why use gas or electricity to heat your water when the power of the sun will do it for free? Faisal Ghani, a young Bangladeshi-Australian engineer, has invented a deceptively simple glass pyramid that takes cold water in at the bottom and supplies hot water from the top. He believes it can bring cheap, hot water to every home around the Equator. In the first of a new series packed with carbon-busting ideas Tom Heap visits Faisal at his Dundee production line to hear about his plans to bring hot showers to the world. Climate scientist, Dr Tamsin Edwards of King's College, London, helps Tom calculate just how much carbon hot water from the sun can save. Producer: Alasdair Cross Researcher: Sarah Goodman Produced in association with the Royal Geographical Society. Special thanks for this episode to Dr Nazmi Sellami of Robert Gordon University, Professor Chris Sansom of Cranfield University and Professor Henning Sirringhaus from the University of Cambridge.