The purchase of SCE’s 48% interest in 4 and 5 units increases APS’s total Four Corners capacity from 791MW to 970MW, and its ownership to 63%.

APS has also permanently closed the plant’s older, less efficient units 1, 2 and 3, during a ceremony on January 1, 2013, as part of a plan announced in November 2010, thereby reducing the capacity from 2,100MW to 1,540MW.

APS chairman, president and chief executive officer Don Brandt said, ”We have completed a transaction that will benefit the environment, allow us to continue to support the economy of the Navajo Nation and surrounding community, and help electric users in the Southwest with an important, low-cost generating resource.”

APS Operations executive vice president Mark Schiavoni said, ”Our plan for the plant moving forward saves APS customers nearly a half-billion dollars over other energy sources and maintains a highly reliable, cost-effective source of electricity generation for APS and other users in the Southwest.”

Comprising complete dismantling and removal of the older units and any associated structures, the decommissioning work will begin immediately and is expected to last about three years.

The company is also planning to install selective catalytic reduction equipment on Units 4 and 5 by July 2018, to meet best available retrofit technology (BART) requirements for the plant issued by the US Environmental Protection Agency in August 2012.