NEW YORK - TransAlta Corp's 406-megawatt Unit 4 at the Sundance coal-fired power plant in Alberta shut on Tuesday, the Alberta Electric System Operator said in a report.

The 2,071 MW Sundance station is located about 40 miles (70 km) west of Edmonton, Alberta, on the south shore of Wabamun Lake. There are six units at the station, including two 280 MW units, 1 (which entered service in 1970) and 2 (1973), two 353 MW units, 3 (1976) and 5 (1978), the 406 MW Unit 4 (1977) and the 399 MW Unit 6 (1980).

The plant consumes about 9 million tonnes of coal each year from TransAlta's Highvale Mine.

The company said on its website the power from the plant is governed by a power purchase agreement from Jan. 1, 2001 until Dec. 31, 2017, for Units 1 and 2, and Dec. 31, 2020, for Units 3, 4, 5 and 6. Additionally, 53 MW of power from Unit 4 and 44 MW of power from Unit 6 are sold through the PPA Buyers to the Alberta Power Pool.

Unit 5 shut by Aug. 14 and will likely return during the fourth quarter of 2009.

All of the other units were also available for service.

One MW powers about 1,000 homes in Alberta.

TransAlta, of Calgary, Alberta, owns and operates some 9,000 MW of generating capacity and markets energy commodities in Canada, the United States, Mexico and Australia. (Reporting by Scott DiSavino; Editing by John Picinich)