I found a couple of links about converting brownfields to sites for renewable energy via an article on Slashdot. The first is an article about the idea from The Daily Climate and the second is a list of brownfield sites from the EPA.
Despite the fact that we have thousands of these contaminated sites this sounds look a good idea. It puts recycling to work in a whole new way. It looks like Detroit could become the green capital of the U.S.A. the way it was the automotive capital since it has lots of industrial sites that could be repurposed. It is such a simple idea that makes so much sense I'm surprised it hasn't already been going on. I look forward to seeing how this develops.