I think I see where he's coming from.
In the UK we have a proliferation of "Speed Bumps" on the roads.
Now if those speed bumps were connected to an energy conversion/collection system, then not only will they be doing their job of slowing traffic down, they will be doing something useful as well
The biggest problem that I see is converting lots of small energy impulses into a large energy store that will generate a constant power source.
I am sure that there are lots of different systems that you could use. Air, hydraulic or micro generators.
I, personally would go for a hydraulic system to avoid unnecessary losses.
Anyway, let us know what you decide, and how you get on.