Where 600 flights used to take off and land every day here at Pittsburgh International Airport, there are now about 300. Partway down Terminal B, the moving sidewalk that used to lead to a dozen gates now stops abruptly at a plain gray wall.

The airport is oversized for its current business. A relic of USAir (US Airways) expansion. It is down from 21 million passenger (at peak) to around 8 million.

Salvation?

The quiet runways, it turns out, are sitting on enough natural gas to run the whole state of Pennsylvania for a year and a half