The Polish science-fiction writer Stanislav Lem once set a story in a world in which the energy of children running about and playing was harnessed for power production.

As I walk round in Rome in Summer, I think about that whenever I am  knocked off the pavement by blasts of hot air issuing from air-conditioned buildings. I suppose that super-heating pedestrians is good for the economy since it stimulates cold drink consumption, but it also seems obvious that there must be something more useful we can do with this hot air than pumping it out into the streets. Couldn’t we set up little welding shops or or have mini pineapple plantations there ?  And think of all the heat jet engines produce, we should at the very least be able to make use of that to iron everybody’s clothes before they land and dispel that jaded transcontinental look which makes baggage carousels so depressing even when you do get your baggage. Read more…