After the boom in natural gas

The nation is awash in so much natural gas that electric utilities, which burn the fuel in many generating plants, have curbed rate increases and switched more capacity to gas from coal, a dirtier fossil fuel.

Companies and municipalities are deploying thousands of new gas-powered trucks and buses, curbing noxious diesel fumes and reducing the nation’s reliance on imported oil.

And companies like fertilizer and chemical makers, which use gas as a raw material, are suddenly finding that the United States is an attractive place to put new factories, compared with, say, Asia, where gas is four times the price.

But while the gas rush has benefited most Americans, it’s been a money loser so far for many of the gas exploration companies and their tens of thousands of investors.