Pedal-powered yule trees are nothing new. London did it last year, but now Copenhagen's tree on the City Hall Square is pedal-powered this year.
I suppose when the whole world is coming in a week for the Climate Conference, stuff like this is important symbolism. The 700 lights on the 17 metre high tree are kept glowing by 15 stationary bicycles. Each bicycle is rigged to a section of the tree.
Haven't tried it yet.
Here's my shot of the tree a couple of years ago.