Duke Energy Corp. expects to close much of a coal-powered generating plant in western Indiana within the next few years.

The company is watching new federal environmental regulations that are due for release in November and considering shutting down several of the six units at Wabash River Station near Terre Haute as soon as 2014, Duke spokeswoman Angeline Protogere said.

"While we haven't made any final decisions, our units at Wabash River Station are likely to be retired earlier than expected," Protogere told the Tribune-Star of Terre Haute.

The power plant was completed in stages between 1953 and 1968. Duke owns five of its generating units, with the other owned by Wabash Valley Power Association and SG Solutions.

Duke has about 100 employees and 40 full-time contractors at the plant, but Protogere said the company didn't yet know how a shutdown would affect the work force.

The review of the Wabash plant's future comes as Duke is completing construction of a nearly $3 billion coal-gasification plant near Edwardsport in southwestern Indiana. Duke is the state's largest electric utility with about 780,000 customers covering much of the state's midsection.

Three units at the Wabash plant were shut down in 2009 as part of an order from a federal judge after a jury found the plant's previous owner, Cinergy, violated the Clean Air Act by making unauthorized changes that increased pollution. An appeals court overturned that order last year, allowing Duke Energy to restart the units.

Protogere said Duke intends to keep the Wabash River Station property.

"It's usually difficult to find locations for new power generation, so the site is an option we'll consider for future generation," she said.