This seesaw was built for a non-profit called Global Inheritance as a part of their energy playground. It uses bicycle parts to spin a permanent magnet alternator, which generates electricity. This electricity is then used to charge festival goers' cell phones, among other small electrics.
You can see photos of the proof of concept, the early prototype and production version. This is currently being used at various music festivals across the US.
You can see photos of the proof of concept, the early prototype and production version. This is currently being used at various music festivals across the US.