The Philadelphia Eagles' Lincoln Financial Field, built before the advent of seriously green construction, is soon to become the greenest stadium in the world. Next September, if all goes as planned, the stadium will have 100 wind turbines and 2,500 solar panels. The anticipated $60 million savings over 20 years may not sound like a lot. But it's nothing to be sniffed at, either. "It's not just do-good environmentalism," said Temple's Michael Leeds, who specializes in sports economics.