Power/Plant Arches: An idea

I was walking to the bank and hated that the sidewalks had no shade. In Florida, shade is a precious commodity. As an environmentalist I dislike that on either side of the sidewalk, grass had lazily been the decision as filler between the sidewalk and the road. So I came up with this:

http://brianstuckeyart.com/Blog/sidewalk.jpg

It would cost a lot to set up, but if you have one of these every six feet on the side of the road, you'd have a veritable power plant. They could each connect directly to the grid and reduce the strain on the existing power plants. And if each one was individually hooked up into the grid, a car crash would'nt interrupt anything. Having three levels of plant boxes is a much better use of space. you could double the amount of vegitation per square foot. Grass isn't the best thing for the environment. It creates very little oxygen, retains very little water, and isn't drought tolerant. If you plant native grasses, flowers, and bushes they would survive better, and require less maintenance. But I don't want to put lawn mowers out of a job. I think you could use the very same people to maintain and repair these arches.

anyway.... just had to get that out there.