CHEYENNE, Wyo. (AP) — A utility company is considering early retirement for one Wyoming coal-fired power plant and part of another to keep down costs.

Portland, Oregon-based PacifiCorp is studying the potential savings of retiring coal-fired generating units as early as 2022.

The company said Thursday that four coal-fired units in Wyoming are leading early-retirement candidates, two at the Naughton plant outside Kemmerer and two at the Jim Bridger plant outside Rock Springs.

Coal-fired power has become less economical compared to low-priced natural gas generation and increasingly inexpensive wind and solar power.

PacifiCorp shut down one of Naughton's three units in January. Shutting down all three could mean the plant's closure, though PacifiCorp may convert one unit to burn natural gas.

PacifiCorp has 1.9 million customers in California, Idaho, Oregon, Utah, Washington and Wyoming.