Presenters Jem Stansfield, Liz Bonnin and Maggie Philbin investigate how close Britain might get to running out of electricity. We live in a world where the lights are always on, but will that be the case in 20 years time? Maggie Philbin spends a day in one of Britain's most secret locations, the control room of the National Grid where she monitors our demand for electricity with supply. Here she learns almost half our generating capacity will disappear in our lifetimes. Jem shows how and why most of our electricity now relies on gas and reveals a potential fuel of the future - liquid air. Liz investigates renewable energy and tackles what could really offer viable solutions to our energy needs going forward.