Spanning the Champs Elysees this weekend were a row of green squares: energy harvesting tiles made by Pavegen systems, which can generate as much as 8 watts of electricity from each footfall that can be used to charge batteries. Inhabitat reports that the 40,000 runners of the Paris Marathon generated about 7 kWh of electricity, (about 35 cents worth) from 176 tiles. Whether this is a good return on investment is one question, but the other one is, what did it do to the marathoners times?
These things work by converting the kinetic energy of the footfall to electrical energy via some form of piezoelectric action. 8 watts of energy output means 8 watts of energy were taken from the runner instead of being returned in the bounce off the pavement. That means time, probably too small to be meaningful, but it exists.
I have always had a thing about these energy harvesting devices; when you drive over them, they are stealing your gas. When you walk over them, they are stealing your food, which most of us have enough of. But in a marathon, they are stealing your time.
They seem like the ultimate green gizmo, a feel-good thing that takes a lot of energy to make, makes you feel good, but doesn't do very much at all. What do you think?