As part of the cultural Olympiad, Stewart came up with the idea of a Tree of Light, a performance piece which involves an enormous structure like a tree, which will be lit by the power of human-generated electricity. In other words, guys and gals on bikes, pedalling away like mad to provide enough energy to light up what sounds like an extraordinary piece of living, moving art.
Lighting a tree is one thing - energising a humble kettle is quite another. Stewart reckons a great many household things should be so powered. It would give us a whole new appreciation of the wonder that is electricity. He said it took him plus three other adults, all on bikes, a full five minutes to pedal enough energy to heat up a small travel kettle.
Every home should have a human dynamo. It'd solve the obesity crisis and save the planet at the same time.