Joint Plant Ownership (Tables)

12 Months Ended

Dec. 31, 2022

Regulated Operations [Abstract]

Schedule of Joint Plant Ownership

The following table shows MGE's interest in utility plant in service, and the related accumulated depreciation reserves and other information related to MGE's jointly owned facilities:

(In thousands, except for percentages and MW)	Columbia(a)			Elm Road(b)			West Campus(c)			Forward Wind(d)			Two Creeks(e)			Badger Hollow I & II(f)
Ownership interest		19	%		8.33	%		55	%		12.8	%		33	%		33	%
Share of generation (MW)		211	MW		106	MW		157	MW		18	MW		50	MW		100	MW
For the year ended December 31,
Operating expense - 2022	$	26,141		$	18,613		$	(g)		$	662		$	1,032		$	787
Operating expense - 2021		33,284			18,478			(g)			669			953			140
Operating expense - 2020		27,127			17,259			(g)			664			118			—
As of December 31, 2022
Utility plant	$	—		$	202,118		$	115,137		$	34,117		$	67,890		$	74,941
Accumulated depreciation		—			(40,951)			(37,857)			(15,952)			(5,145)			(2,566)
Plant anticipated to be retired early, net		147,659			—			—			—			—			—
Construction work in progress		4,805			3,410			809			68			—			52,187
As of December 31, 2021
Utility plant	$	—		$	202,604		$	114,090		$	34,084		$	67,814		$	69,178
Accumulated depreciation		—			(39,279)			(34,907)			(14,945)			(2,932)			(227)
Plant anticipated to be retired early, net		158,983			—			—			—			—			—
Construction work in progress		2,388			898			493			21			—			19,748

(a)MGE and the other co-owners announced plans to retire Columbia, a two unit coal-fired generation facility located in Portage, Wisconsin. The co-owners intend to retire Unit 1 and Unit 2 by June 2026. Final timing and retirement dates are subject to change depending on operational, regulatory, and other factors. As of December 31, 2022 and 2021, early retirement of Columbia was probable. See Footnote 4 for further information.

(b)Two coal-fired generating units in Oak Creek, Wisconsin. In November 2021, MGE announced plans to end the use of coal as a primary fuel at the Elm Road Units and transition the plant to natural gas. By the end of 2030, MGE expects coal to be used only as a backup fuel at the Elm Road Units. This transition will help MGE meet its 2030 carbon reduction goals. By 2035, MGE expects that the Elm Road Units will be fully transitioned away from coal, which will eliminate coal as an internal generation source for MGE.

(c)MGE Power West Campus and the UW jointly own the West Campus Cogeneration Facility (WCCF) located on the UW campus in Madison, Wisconsin. The UW owns a controlling interest in the chilled-water and steam plants, which are used to meet the

needs for air-conditioning and steam-heat capacity for the UW campus. MGE Power West Campus owns a controlling interest in the electric generation plant, which is leased and operated by MGE.

(d)The Forward Wind Energy Center (Forward Wind) consists of 86 wind turbines located near Brownsville, Wisconsin.

(e)The Two Creeks solar generation array is located in the Town of Two Creeks and the City of Two Rivers in Manitowoc and Kewaunee Counties, Wisconsin. Date of commercial operation of the solar array was November 2020.

(f)The Badger Hollow I and II solar farm is located in southwestern Wisconsin in Iowa County, near the villages of Montfort and Cobb. Date of commercial operation of Badger Hollow I was November 2021. Construction of Badger Hollow II is expected to be completed in the second half of 2023.

(g)Operating charges are allocated to the UW based on formulas contained in the operating agreement. Under the provisions of this arrangement, the UW is required to reimburse MGE for their allocated portion of fuel and operating expenses. For the years ended December 31, 2022, 2021, and 2020, the UW's allocated share of fuel and operating costs was $8.7 million, $6.2 million, and $5.2 million, respectively.