RICHMOND, Va. (AP) — Dominion Resources Inc. said Thursday that it is looking to sell two power plants in Illinois and another in Massachusetts because it can earn a better return elsewhere.

Three of four units of the Brayton Point plant in Somerset, Mass., and the Kincaid power station in Kincaid, Ill., run on coal. The Elwood plant outside Chicago, in which Dominion holds a 50 percent stake, is fired by natural gas.

Coal plants have become less economical because strong production of natural gas has made that fuel so much cheaper.

Richmond, Va.-based Dominion has owned the Illinois plants since the 1990s and the Massachusetts one since 2005.

The company, which hopes to sell the plants in the first half of next year, said the plants have or are getting new emissions-control systems and the coal-fired units meet federal clean-air standards.

But Dominion continually judges the return on investment from assets, said Chairman and CEO Thomas F. Farrell II. "

We believe the sale of these assets and the redeployment of capital to our regulated businesses is the best path forward for shareholders," he said.

Dominion shares rose $1.24, or 2.4 percent, to $53.74 in afternoon trading.