Interactive Pavements for Interactive Playgrounds

As playgrounds like other architectural constructs move toward embedded interactivity, things like the ipavement will host the next generation of playground games.  The goal of its founders is to turn city streets into information platforms; and they sport Bluetooth and Wi-Fi along with their own operating system, apps, and sensors. 

"Each stone measures 40 x 40 x 7 centimeters (15.75 x 15.75 x 2.76 in), weighs approximately 24 kilograms (53 lbs), and contains a 5 GB microprocessor that communicates with nearby mobile devices via WiFi and Bluetooth. Power and internet access are supplied to each stone via a hard-wired 1,000-watt cable." [gizmag]

image from pavegen

which is cool but it seems obvious to try to combine the idea with that of the electricity generating tiles like those from pavegen rather than using a hard-wired cable.

And in fact the company Powerleap is currently developing just that, a tile that uses footfall energy to power embedded wireless transmitters. 

image from powerleap

These technologies are especially interesting for the playground because the power in a playground 'footfall', say at the bottom of a slide, is much greater than that of a mall-strolling 'footfall'' more like say, the heavy footfalls used to generate energy by sustainabledanceclub. 

image from sustainabledanceclub

I've felt a little uncomfortable with the playground devices that harvest the motion of a child on a teeter-totter or swing to produce electrical or mechanical power...since they are often advocated for impoverished areas I worry (no evidence of this, just wondering) whether their use could become coercive in some way.   What if a child had to keep swinging to ensure his family's water supply?

 So I like the idea of footfalls (a less controllable event) powering interactivity (a less imperative event) on the playground.  Interested in your thoughts.