* To buy two plants of combined capacity 931 mw
* Says plants can power 700,000 Colorado households
The plants are the 621-megawatt Rocky Mountain Energy Center and the 310-megawatt Blue Spruce Energy Center. They currently provide power to PSCo under power purchase agreements.
The plants can collectively power about 700,000 Colorado households, the companies said in a statement.
Shares of both Minneapolis-based Xcel and Houston based-Calpine were up marginally at $21.47 and $12.07 respectively in Monday morning trade on the New York Stock Exchange. (Reporting by Krishna N. Das in Bangalore; Editing by Unnikrishnan Nair)