58 Human-Powered Prototypes

Perhaps the world's energy problems cannot be solved through manning countless rows of giant hamster-wheels with marathon runners, but these Human-powered prototypes are a good start.

From pedal-powered submarines to human-run helicopters, these designs are not only environmentally friendly, they're also incredibly inventive. A human being -- no matter what shape their in -- cannot produce as much energy as their weight in a fuel source like petroleum or diesel could. This means that the vehicles and machines featured here need to be that much more energy efficient. To illustrate: if a human-powered submarine is not efficient enough to be propelled by the muscle power of its occupant, it could very well sink -- which is very bad for its occupant.