Property, Plant and Equipment

12 Months Ended

Dec. 31, 2023

Property, Plant and Equipment [Abstract]

PROPERTY, PLANT AND EQUIPMENT


Property, Plant and Equipment
As of December 31	2023	2022
Millions
Regulated Operations
Property, Plant and Equipment in Service	$5,167.2	$5,198.6

Construction Work in Progress	146.7	74.0
Accumulated Depreciation	(1,969.4)	(1,972.3)
Regulated Operations – Net	3,344.5	3,300.3
ALLETE Clean Energy
Property, Plant and Equipment in Service	1,612.8	1,619.4
Construction Work in Progress	48.9	51.1
Accumulated Depreciation	(229.1)	(176.8)
ALLETE Clean Energy – Net	1,432.6	1,493.7






Corporate and Other (a)
Property, Plant and Equipment in Service	355.8	295.2
Construction Work in Progress	27.5	50.9
Accumulated Depreciation	(147.0)	(136.1)
Corporate and Other – Net	236.3	210.0
Property, Plant and Equipment – Net	$5,013.4	$5,004.0

(a)Primarily includes BNI Energy and a small amount of non-rate base generation.

NOTE 2. PROPERTY, PLANT AND EQUIPMENT (Continued)

Depreciation is computed using the straight-line method over the estimated useful lives of the various classes of assets.

Estimated Useful Lives of Property, Plant and Equipment (Years)

Regulated Operations

Generation

4 to 50

ALLETE Clean Energy

5 to 35

Transmission

50 to 75

Corporate and Other

3 to 50

Distribution

18 to 70

Asset Retirement Obligations. We recognize, at fair value, obligations associated with the retirement of certain tangible, long lived assets that result from the acquisition, construction, development or normal operation of the asset. Asset retirement obligations (AROs) relate primarily to the decommissioning of our coal-fired and wind energy facilities, and land reclamation at BNI Energy. AROs are included in Other Non-Current Liabilities on the Consolidated Balance Sheet. The associated retirement costs are capitalized as part of the related long-lived asset and depreciated over the useful life of the asset. Removal costs associated with certain distribution and transmission assets have not been recognized, as these facilities have indeterminate useful lives.

Conditional asset retirement obligations have been identified for treated wood poles and remaining polychlorinated biphenyl and asbestos-containing assets; however, the period of remediation is indeterminable and removal liabilities have not been recognized.

Long-standing ratemaking practices approved by applicable state and federal regulatory authorities have allowed provisions for future plant removal costs in depreciation rates. These plant removal cost recoveries are classified either as AROs or as a regulatory liability for non-AROs. To the extent annual accruals for plant removal costs differ from accruals under approved depreciation rates, a regulatory asset has been established in accordance with GAAP for AROs. (See Note 4. Regulatory Matters.)


Asset Retirement Obligations
Millions
Obligation as of December 31, 2021						$184.5
Accretion						9.5
Liabilities Recognized						7.8
Liabilities Settled						(4.4)
Revisions in Estimated Cash Flows						3.0
Obligation as of December 31, 2022						200.4
Accretion						10.3

Liabilities Settled						(10.2)
Revisions in Estimated Cash Flows						2.4
Obligation as of December 31, 2023						$202.9