Boston (Platts)--20Dec2012/419 pm EST/2119 GMT

Southwestern Electric Power Co. said Thursday that the new 600-MW Turk coal unit in Hempstead County, Arkansas, has begun commercial operation.

Swepco, a subsidiary of American Electric Power, said in a statement that the $1.8 billion Turk facility is the first ultra-supercritical pulverized coal unit to come online in the US.

An ultra-supercritical unit, it said, "generates electricity more efficiently at higher temperatures, requires less coal and produces fewer emissions to generate the same amount of power as existing coal units."

Swepco holds a 73%, or about440-MW, ownership interest in Turk, while Arkansas Electric Cooperative Corp. holds a 12% stake; East Texas Electric Cooperative, 8%; and Oklahoma Municipal Power Authority, 7%.

The Turk project was one of the most controversial in recent years. In December 2011, environmental groups that had opposed the project agreed to drop their last legal challenges to it in exchange for commitments by the project's co-owners to buy 400 MW of wind power and by Swepco to retire its 528-MW Welsh-2 coal unit in Texas -- both by the end of 2014.

--Housley Carr, newsdesk@platts.com --Edited by Carla Bass, carla_bass@platts.com