Controversial path to possible glut of natural gas

Shale gas reserves have a powerful economic lure. Companies, states, and landowners could all reap a windfall in the tens of billions. Some also predict lower heating costs for residential gas users as production increases.

Now, scores of natural gas companies are fanning out from Fort Worth, Texas, where hydraulic fracturing of shale has been done for at least five years, to lease shale lands in 19 states, including Pennsylvania and New York.

But some warn that by expanding