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Jointly-Owned Facilities and Assets | 12 Months Ended
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Dec. 31, 2023
Jointly-Owned Facilities and Assets [Abstract] |
Jointly-Owned Facilities and Assets | JOINTLY-OWNED FACILITIES AND ASSETS Boswell Unit 4. Minnesota Power owns 80 percent of the 585 MW Boswell Unit 4. While Minnesota Power operates the plant, certain decisions about the operations of Boswell Unit 4 are subject to the oversight of a committee on which it and WPPI Energy, the owner of the remaining 20 percent, have equal representation and voting rights. Each owner must provide its own financing and is obligated to its ownership share of operating costs. Minnesota Power’s share of operating expenses for Boswell Unit 4 is included in Operating Expenses on the Consolidated Statement of Income. NOTE 3. JOINTLY-OWNED FACILITIES AND ASSETS (Continued) Minnesota Power’s investments in jointly-owned facilities and assets and the related ownership percentages are as follows:
Regulated Utility Plant | Plant in Service | Accumulated Depreciation | Construction Work in Progress | % Ownership
Millions |  |  |  |
As of December 31, 2023 |  |  |  |
Boswell Unit 4 | $725.9 | $369.8 | $2.8 | 80
Transmission Assets | 101.0 | 23.6 | — | 9.3 - 14.7
Total | $826.9 | $393.4 | $2.8 |
As of December 31, 2022 |  |  |  |
Boswell Unit 4 | $712.0 | $340.1 | $3.3 | 80
Transmission Assets | 101.0 | 21.1 | — | 9.3 - 14.7
Total | $813.0 | $361.2 | $3.3 |
Nemadji Trail Energy Center. South Shore Energy, ALLETE’s non-rate regulated, Wisconsin subsidiary, is developing NTEC, an approximately 600 MW proposed combined-cycle natural gas-fired generating facility to be built in Superior, Wisconsin, which will be jointly owned by Dairyland Power Cooperative, Basin and South Shore Energy. Minnesota Power is expected to purchase approximately 20 percent of the facility's output starting in 2028 pursuant to a capacity dedication agreement. Construction of NTEC is subject to obtaining additional permits from local, state and federal authorities. The total project cost is estimated to be approximately $700 million, of which South Shore Energy will be responsible for approximately 20 percent. South Shore Energy’s portion of NTEC project costs incurred through December 31, 2023, is approximately $9 million.

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