Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

Schedule of Property, Plant, and Equipment

Property, plant, and equipment consisted of the following as of December 31:

	MGE Energy				MGE
(In thousands)	2023		2022		2023		2022
Utility:
Electric(a)	$	1,769,559	$	1,585,847	$	1,769,576	$	1,585,864
Plant anticipated to be retired early(b)		133,268		147,659		133,268		147,659
Gas		603,502		566,551		603,513		566,562
Utility property, plant, and equipment, gross		2,506,329		2,300,057		2,506,357		2,300,085
Less: Accumulated depreciation and amortization		726,289		673,669		726,289		673,669
Utility property, plant, and equipment, net		1,780,040		1,626,388		1,780,068		1,626,416
Nonregulated:
Nonregulated		321,951		318,443		321,951		318,443
Less: Accumulated depreciation and amortization		83,870		79,479		83,870		79,479
Nonregulated property, plant, and equipment, net		238,081		238,964		238,081		238,964
Construction work in progress:
Utility construction work in progress(c)		107,724		101,529		107,724		101,529
Nonregulated construction work in progress		2,367		4,219		2,367		4,219
Total property, plant, and equipment	$	2,128,212	$	1,971,100	$	2,128,240	$	1,971,128

(a)Includes Badger Hollow II placed in service in December 2023. See Footnote 6 for further information on Badger Hollow II.

(b)An asset that will be retired in the near future and substantially in advance of its previously expected retirement date is subject to abandonment accounting. In the second quarter of 2021, the operator of Columbia received approval from MISO to retire Columbia Units 1 and 2. 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, 2023, early retirement of Columbia was probable. "Plant anticipated to be retired early" in table above is the net book value of these generating units. Assets for Columbia Unit 1 and Unit 2 are currently included in rate base, and MGE continues to depreciate them on a straight-line basis using the composite depreciation rates approved by the PSCW that included retirement dates of 2029 for Unit 1 and Unit 2. If it becomes probable that regulators will disallow full recovery or a return on the remaining net book value of a generating unit that is either abandoned or probable of being abandoned, an impairment loss would be required. An impairment

loss would be recorded to the extent that the remaining net book value of the generating unit exceeds the present value of the amount expected to be recovered from ratepayers. No impairment was recorded as of December 31, 2023.

(c)Includes Paris and Darien solar projects. See Footnote 6 for further information on renewable projects.