Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2024

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)	2024		2023		2024		2023
Utility:
Electric(a)	$	1,945,748	$	1,769,559	$	1,945,764	$	1,769,576
Property, plant, and equipment to be retired(b)		121,576		133,268		121,576		133,268
Gas		634,819		603,502		634,830		603,513
Utility property, plant, and equipment, gross		2,702,143		2,506,329		2,702,170		2,506,357
Less: Accumulated depreciation and amortization		789,400		726,289		789,400		726,289
Utility property, plant, and equipment, net		1,912,743		1,780,040		1,912,770		1,780,068
Nonregulated:
Nonregulated		326,574		321,951		326,574		321,951
Less: Accumulated depreciation and amortization		90,179		83,870		90,179		83,870
Nonregulated property, plant, and equipment, net		236,395		238,081		236,395		238,081
Construction work in progress:
Utility construction work in progress(c)		134,642		107,724		134,642		107,724
Nonregulated construction work in progress		3,566		2,367		3,566		2,367
Total property, plant, and equipment	$	2,287,346	$	2,128,212	$	2,287,373	$	2,128,240

(a)Includes Paris Solar placed in service in December 2024. See Footnote 6 for further information on Paris Solar.

(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 the end of 2029. Final timing and retirement dates are subject to change depending on operational, regulatory, capacity needs, and other factors impacting one or more of the Columbia co-owners. As of December 31, 2024, 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, 2024.

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