UPDATE 1-SWEPCO seeks Ark Supreme Court review of coal plant

HOUSTON, June 29 (Reuters) - A unit of American Electric Power Co Inc (AEP.N) has asked the Arkansas Supreme Court to review a lower-court ruling overturning the approval to build a 600-megawatt, coal-fired power that is already under construction.

In its petition, officials with AEP's Southwestern Electric Power Co (SWEPCO) said there were errors in a June 24 ruling from the Arkansas Court of Appeals regarding the 2007 approval of the $1.6 billion coal plant by the Arkansas Public Service Commission.

In the meantime, construction will continue at the John W. Turk Jr. plant site near Texarkana, Arkansas, SWEPCO said.

"This appellate court decision now seeks to reverse 30 years of practice and procedure and changes the rules without warning," said SWEPCO President Paul Chodak.

Interest in coal-fired power plants, which produce about half the electricity consumed in the United States, surged when natural gas prices rose earlier in the decade, but coal's resurgence led to widespread opposition from environmental groups.

Coal emits more carbon dioxide than any other fuel. Public concern about greenhouse gas emissions and climate change has resulted in cancellations of dozens of coal plants in the past two years as prospects for carbon regulation increase, making coal plants costlier.

Even so, more new coal plants are under construction in the United States than in the previous two decades, according to government data.

The Turk plant is being opposed by the Sierra Club, Audubon Arkansas and a coalition of "elite hunting clubs," Chodak said.

Utility regulators in Arkansas, Louisiana and Texas approved SWEPCO's need for additional power to meet future power needs of its 473,500 customers.

"When completed the Turk plant will be among the cleanest, most efficient coal plants in the United States," Chodak said.

SWEPCO said about $713 million has been spent so far on the Turk plant and $1.3 billion in contracts have been signed.

About 90 percent of the major equipment has been purchased. (Reporting by Eileen O'Grady; Editing by Gary Hill)