The contaminated sites would often cost too much to clean up for other reuse, so more and more cities are opting to allow solar power installations.
"In Chicago, Dave Graham, who works on the city's brownfield program, said the City Solar project just "fell into our laps." He was called into a meeting in the mayor's office with representatives from Exelon and SunPower, and found they wanted to create a massive solar farm on a derelict brownfield site. Actually, massive is an understatement for this project: it's the largest urban solar plant in the U.S. Its 32,000 photo voltaic (PV) panels provide 10 MW of energy, enough for 1,500 local homes. In addition, GPS tracking systems help tilt the panels, ensuring the most efficient use of solar energy.
Heavily contaminated sites can cost up to $150,000 per acre to clean up. The West Pullman site for City Solar, which 'has a variety of issues,' would have cost $20 million alone to clean up, 'something no one in the city wanted to invest in.'"