ACQUISITIONS AND DISPOSITIONS (Tables)

12 Months Ended

Dec. 31, 2021

Business Combination and Asset Acquisition [Abstract]

Schedule of asset acquisition

Asset Acquisitions

Project Facility	Resource	Seller	Approximate Nameplate Capacity (MW)	Location	Southern Power Ownership Percentage	COD	PPA Contract Period
Asset Acquisitions During 2021
Deuel Harvest(a)	Wind	Invenergy Renewables LLC	300	Deuel County, SD	100% of Class B	February 2021	25 years and 15 years
Asset Acquisitions During 2020
Beech Ridge II	Wind	Invenergy Renewables LLC	56	Greenbrier County, WV	100% of Class A(b)	May 2020	12 years
Asset Acquisitions During 2019
DSGP(c)	Fuel Cell	Bloom Energy	28	Delaware	100% of Class B	N/A(d)	15 years(e)

(a)On March 26, 2021, Southern Power acquired a controlling interest in the project from Invenergy Renewables LLC and, on March 30, 2021, Southern Power completed a tax equity transaction whereby it sold the Class A membership interests in the project. Southern Power consolidates the project's operating results in its financial statements and the tax equity partner and Invenergy Renewables LLC each own a noncontrolling interest.

(b)In May 2020, Southern Power purchased a controlling interest and now consolidates the project's operating results in its financial statements. The Class B member owns the noncontrolling interest.

(c)During 2019, Southern Power purchased a controlling interest and now consolidates the project's operating results in its financial statements. The Class A and Class C members each own a noncontrolling interest. Southern Power records net income attributable to noncontrolling interests for approximately 10 MWs of the facility.

(d)Southern Power's 18-MW share of the facility was repowered between June and August 2019. In December 2019, a Class C member joined the existing partnership between the Class A member and Southern Power and made an investment to repower the remaining 10 MWs.

(e)Remaining PPA contract period at the time of acquisition.

Schedule of construction projects

Project Facility	Resource	Approximate Nameplate Capacity (MW)	Location	Actual/Expected COD	PPA Contract Period
Projects Under Construction at December 31, 2021
Tranquillity Solar Storage(a)	Battery energy storage system	72	Fresno County, CA	November 2021 and first quarter 2022(b)	20 years
Garland Solar Storage(a)	Battery energy storage system	88	Kern County, CA	September 2021, December 2021, and first quarter 2022(c)	20 years
Projects Completed During 2021
Glass Sands(d)	Wind	118	Murray County, OK	November 2021	12 years
Projects Completed During 2020
Skookumchuck(e)	Wind	136	Lewis and Thurston Counties, WA	November 2020	20 years
Reading(f)	Wind	200	Osage and Lyon Counties, KS	May 2020	12 years

(a)In December 2020, Southern Power restructured its ownership of the project, while retaining the controlling interests, by contributing the Class A membership interests to an existing partnership and selling 100% of the Class B membership interests. During the third quarter 2021, Southern Power further restructured its ownership in the battery energy storage projects and completed tax equity transactions whereby it sold the Class A membership interests in the projects. Southern Power consolidates each project's operating results in its financial statements and the tax equity partner and two other partners each own a noncontrolling interest.

(b)The facility has a total capacity of 72 MWs, of which 32 MWs were placed in service in November 2021 and the remaining MWs are expected to be placed in service later in the first quarter 2022.

(c)The facility has a total capacity of 88 MWs, of which 73 MWs were placed in service during 2021 and the remaining MWs are expected to be placed in service later in the first quarter 2022.

(d)In December 2020, Southern Power purchased 100% of the membership interests of the Glass Sands facility.

(e)In 2019, Southern Power purchased 100% of the membership interests of the Skookumchuck facility pursuant to a joint development arrangement. In November 2020, Southern Power completed a tax equity transaction whereby it received $121 million, resulting in 100% ownership of the Class B membership interests. Southern Power subsequently sold a noncontrolling interest in the Class B membership interests and now retains the controlling ownership interest in the facility.

(f)In 2018, Southern Power purchased 100% of the membership interests of the Reading facility pursuant to a joint development arrangement. In June 2020, Southern Power completed a tax equity transaction whereby it received $156 million and owns 100% of the Class B membership interests.

Schedule of pre-tax income

Plant Nacogdoches and Plant Mankato represented individually significant components of Southern Power. Pre-tax income for these components for the years ended December 31, 2020 and 2019 are presented below:

	2020		2019
	(in millions)
Earnings before income taxes:
Plant Nacogdoches(a)(b)	N/A		$	13
Plant Mankato(a)(c)	$	2	$	29

(a)Earnings before income taxes reflect the cessation of depreciation and amortization on the long-lived assets being sold upon classification as held for sale (November 2018 for Plant Mankato and April 2019 for Plant Nacogdoches).

(b)2019 amount represents the period from January 1, 2019 to June 13, 2019 (the divestiture date).

(c)2020 amount represents the period from January 1, 2020 to January 17, 2020 (the divestiture date).