Major classes of property, plant and equipment
(Millions of Dollars)Dec. 31, 2024Dec. 31, 2023
Property, plant and equipment, net
Electric plant$56,791 $52,494 
Natural gas plant9,834 9,080 
Common and other property3,515 3,190 
Plant to be retired (a)
1,793 2,055 
CWIP4,720 2,873 
Total property, plant and equipment76,653 69,692 
Less accumulated depreciation(19,852)(18,399)
Nuclear fuel3,491 3,337 
Less accumulated amortization(3,094)(2,988)
Property, plant and equipment, net$57,198 $51,642 
(a)Amounts include Sherco 1 and 3 and A.S. King for NSP-Minnesota; Comanche Units 2 and 3, Craig Units 1 and 2, Hayden Units 1 and 2 and coal generation assets at Pawnee pending facility gas conversion for PSCo; and Tolk Unit 1 and 2 for SPS. The Dec. 31, 2023 amounts also include coal generation assets at Harrington, which were retired in 2024 and the conversion to natural gas is in process. Amounts are presented net of accumulated depreciation.

Joint Ownership of Generation, Transmission and Gas Facilities
The utility subsidiaries’ jointly owned assets as of Dec. 31, 2024:
(Millions of Dollars, Except Percent Owned)Plant in ServiceAccumulated DepreciationPercent Owned
NSP-Minnesota
Electric generation:
Sherco Unit 3$636 $499 59 %
Sherco common facilities189 128 80 
Sherco substation59 
Electric transmission:
Grand Meadow11 50 
Huntley Wilmarth49 50 
CapX2020855 160 51 
Total NSP-Minnesota (a)
$1,745 $798 
(a)Projects additionally include $10 million in CWIP.
(Millions of Dollars, Except Percent Owned)Plant in ServiceAccumulated DepreciationPercent Owned
NSP-Wisconsin
Electric transmission:
La Crosse, WI to Madison, WI$179 $30 37 %
CapX2020169 44 80 
Total NSP-Wisconsin (a)
$348 $74 
(a)Projects additionally include $1 million in CWIP.
(Millions of Dollars, Except Percent Owned)Plant in ServiceAccumulated DepreciationPercent Owned
PSCo
Electric generation:
Hayden Unit 1$158 $117 76 %
Hayden Unit 2152 93 37 
Hayden common facilities45 33 53 
Craig Units 1 and 282 58 10 
Craig common facilities40 27 
Comanche Unit 3933 212 67 
Comanche common facilities29 77 
Electric transmission:
Transmission and other facilities190 75 Various
Gas transmission:
Rifle, CO to Avon, CO28 10 60 
Gas transmission compressor50 
Total PSCo (a)
$1,665 $633 
(a)Projects additionally include $28 million in CWIP.
Each company separately records its share of operating expenses and construction expenditures. Respective owners are responsible for providing their own financing.

Historical Timeline

Fiscal YearFiled
2024Feb 27, 2025Showing above
2023Feb 21, 2024
2022Feb 23, 2023
2021Feb 23, 2022
2020Feb 17, 2021
2019Feb 21, 2020
2018Feb 22, 2019

About PP&E Disclosures

The PP&E disclosure details a company's physical asset base — land, buildings, machinery, and equipment — along with the depreciation methods and useful life assumptions that determine how these costs flow through the income statement. Capitalization policy thresholds reveal management's judgment on the boundary between expense and asset, directly affecting both reported earnings and asset values.

Key signals: changes in estimated useful lives or depreciation methods can materially shift reported earnings without any operational change. Compare capital expenditures against depreciation expense — when capex consistently trails depreciation, the asset base may be aging and underinvested. Watch for large asset impairments or write-downs that signal overvalued carrying amounts. Asset retirement obligations reveal future environmental or decommissioning costs that are often underappreciated. Compare PP&E intensity (PP&E-to-revenue) against industry peers to assess capital efficiency and competitive positioning.