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Asset Retirement Obligations | 12 Months Ended
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Dec. 31, 2023
Asset Retirement Obligation Disclosure [Abstract] |
Asset Retirement Obligations | ASSET RETIREMENT OBLIGATIONS Duke Energy records an ARO when it has a legal obligation to incur retirement costs associated with the retirement of a long-lived asset and the obligation can be reasonably estimated. Certain assets of the Duke Energy Registrants have an indeterminate life, such as transmission and distribution facilities, and thus the fair value of the retirement obligation is not reasonably estimable. A liability for these AROs will be recorded when a fair value is determinable. The Duke Energy Registrants’ regulated operations accrue costs of removal for property that does not have an associated legal retirement obligation based on regulatory orders from state commissions. These costs of removal are recorded as a regulatory liability in accordance with regulatory accounting treatment. The amount spent may be higher than the amount accrued and result in a net asset. See Note 4 for the estimated cost of removal for assets without an associated legal retirement obligation, which are included in Regulatory liabilities on the Consolidated Balance Sheets. The following table presents the AROs recorded on the Consolidated Balance Sheets.
| December 31, 2023
|  |  | Duke |  |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont
Decommissioning of nuclear power facilities | $ | 4,576 |  |  | $ | 1,949 |  |  | $ | 2,601 |  |  | $ | 2,410 |  |  | $ | 191 |  |  | $ | — |  |  | $ | — |  |  | $ | — |
Closure of ash impoundments | 4,313 |  |  | 2,010 |  |  | 1,449 |  |  | 1,427 |  |  | 21 |  |  | 73 |  |  | 781 |  |  | — |
Other | 267 |  |  | 54 |  |  | 95 |  |  | 33 |  |  | 63 |  |  | 63 |  |  | 28 |  |  | 26 |
Total asset retirement obligation | $ | 9,156 |  |  | $ | 4,013 |  |  | $ | 4,145 |  |  | $ | 3,870 |  |  | $ | 275 |  |  | $ | 136 |  |  | $ | 809 |  |  | $ | 26 |
Less: Current portion | 596 |  |  | 224 |  |  | 245 |  |  | 244 |  |  | 1 |  |  | 6 |  |  | 120 |  |  | — |
Total noncurrent asset retirement obligation | $ | 8,560 |  |  | $ | 3,789 |  |  | $ | 3,900 |  |  | $ | 3,626 |  |  | $ | 274 |  |  | $ | 130 |  |  | $ | 689 |  |  | $ | 26 |
Nuclear Decommissioning Liability AROs related to nuclear decommissioning are based on site-specific cost studies. The NCUC and the PSCSC require Duke Energy Carolinas and Duke Energy Progress update cost estimates for decommissioning their nuclear plants every five years. The nuclear decommissioning liabilities are assessed and updated based on changes in cash flows provided in new studies as well as annual assessments to evaluate whether any indicators suggest a change in the estimate of the ARO is necessary. The following table summarizes information about the most recent site-specific nuclear decommissioning cost studies. Decommissioning costs are stated in 2023 or 2019 dollars, depending on the year of the cost study, and include costs to decommission plant components not subject to radioactive contamination.
| Annual Funding |  | Decommissioning |  |
(in millions) | Requirement(a) |  | Costs(a) |  | Year of Cost Study
Duke Energy | $ | 4 |  |  | $ | 8,814 |  |  | 2023 or 2019
Duke Energy Carolinas(b)(c) | — |  |  | 4,439 |  |  | 2023
Duke Energy Progress(d) | 4 |  |  | 4,181 |  |  | 2019
Duke Energy Florida(e) | — |  |  | 194 |  |  | N/A
(a) Amount represents annual funding requirement for the current fiscal year. Amounts for Progress Energy equal the sum of Duke Energy Progress and Duke Energy Florida. (b) Decommissioning costs for Duke Energy Carolinas reflects its ownership interest in jointly owned reactors. Other joint owners are responsible for decommissioning costs related to their interest in the reactors. (c) Duke Energy Carolinas' site-specific nuclear decommissioning cost study completed in 2023 was filed with the NCUC and PSCSC in 2024. A funding study was last completed and filed in 2019. An updated funding study will be completed and filed with the NCUC and PSCSC in 2024. (d) Duke Energy Progress' site-specific nuclear decommissioning cost study completed in 2019 was filed with the NCUC and PSCSC in March 2020. Duke Energy Progress also completed a funding study, which was filed with the NCUC and PSCSC in July 2020. In October 2021, Duke Energy Progress filed the 2019 nuclear decommissioning cost study with the FERC, as well as a revised rate schedule for decommissioning expense to be collected from wholesale customers. The FERC accepted the filing, as filed on December 9, 2021. (e) During 2019, Duke Energy Florida reached an agreement to transfer decommissioning work for Crystal River Unit 3 to a third party and decommissioning costs are based on the agreement with this third party rather than a cost study. Regulatory approval was received from the NRC and the FPSC in April 2020 and August 2020, respectively. Duke Energy Florida provides the FPSC periodic reports on the status and progress of decommissioning activities. Nuclear Decommissioning Trust Funds Duke Energy Carolinas, Duke Energy Progress and Duke Energy Florida each maintain NDTFs that are intended to pay for the decommissioning costs of their respective nuclear power plants. The NDTF investments are managed and invested in accordance with applicable requirements of various regulatory bodies including the NRC, FERC, NCUC, PSCSC, FPSC and the IRS. Use of the NDTF investments is restricted to nuclear decommissioning activities including license termination, spent fuel and site restoration. The license termination and spent fuel obligations relate to contaminated decommissioning and are recorded as AROs. The site restoration obligation relates to non-contaminated decommissioning and is recorded to cost of removal within Regulatory liabilities on the Consolidated Balance Sheets. The following table presents the fair value of NDTF assets legally restricted for purposes of settling AROs associated with nuclear decommissioning. Duke Energy Florida entered into an agreement with a third party to decommission Crystal River Unit 3 and was granted an exemption from the NRC, which allows for use of the NDTF for all aspects of nuclear decommissioning. The entire balance of Duke Energy Florida's NDTF may be applied toward license termination, spent fuel and site restoration costs incurred to decommission Crystal River Unit 3 and is excluded from the table below. See Note 17 for additional information related to the fair value of the Duke Energy Registrants' NDTFs.
| December 31,
(in millions) | 2023 |  | 2022
Duke Energy | $ | 8,851 |  |  | $ | 7,466 |
Duke Energy Carolinas | 5,002 |  |  | 4,208 |
Duke Energy Progress | 3,849 |  |  | 3,258 |
Nuclear Operating Licenses As described in Note 4, Duke Energy Carolinas and Duke Energy Progress intend to seek renewal of operating licenses and 20-year license extensions for all of their nuclear stations. The following table includes the current expiration of nuclear operating licenses.
Unit | Year of Expiration
Duke Energy Carolinas |
Catawba Units 1 and 2 | 2043
McGuire Unit 1 | 2041
McGuire Unit 2 | 2043
Oconee Units 1 and 2 | 2033
Oconee Unit 3 | 2034
Duke Energy Progress |
Brunswick Unit 1 | 2036
Brunswick Unit 2 | 2034
Harris | 2046
Robinson | 2030
The NRC has acknowledged permanent cessation of operation and permanent removal of fuel from the reactor vessel at Crystal River Unit 3. Therefore, the license no longer authorizes operation of the reactor. During 2019, Duke Energy Florida entered into an agreement for the accelerated decommissioning of Crystal River Unit 3. Regulatory approval was received from the NRC and the FPSC in April 2020 and August 2020, respectively. See Note 4 for more information. Closure of Ash Impoundments The Duke Energy Registrants are subject to state and federal regulations covering the closure of coal ash impoundments, including the EPA CCR Rule and the Coal Ash Act, and other agreements. AROs recorded on the Duke Energy Registrants' Consolidated Balance Sheets include the legal obligation for closure of coal ash basins and the disposal of related ash as a result of these regulations and agreements. The ARO amount recorded on the Consolidated Balance Sheets is based upon estimated closure costs for impacted ash impoundments. The amount recorded represents the discounted cash flows for estimated closure costs based upon specific closure plans. Actual costs to be incurred will be dependent upon factors that vary from site to site. The most significant factors are the method and time frame of closure at the individual sites. Closure methods considered include removing the water from ash basins, consolidating material as necessary and capping the ash with a synthetic barrier, excavating and relocating the ash to a lined structural fill or lined landfill or recycling the ash for concrete or some other beneficial use. The ultimate method and timetable for closure will be in compliance with standards set by federal and state regulations and other agreements. The ARO amount will be adjusted as additional information is gained through the closure and post-closure process, including acceptance and approval of compliance approaches, which may change management assumptions, and may result in a material change to the balance. See ARO Liability Rollforward section below for information on revisions made to the coal ash liability during 2023 and 2022. Asset retirement costs associated with the AROs for operating plants and retired plants are included in Net property, plant and equipment and Regulatory assets, respectively, on the Consolidated Balance Sheets. See Note 4 for additional information on Regulatory assets related to AROs and Note 5 for additional information on commitments and contingencies. Cost recovery for future expenditures will be pursued through the normal ratemaking process with federal and state utility commissions, which permit recovery of necessary and prudently incurred costs associated with Duke Energy’s regulated operations. See Note 4 for additional information on recovery of coal ash costs. ARO Liability Rollforward The following tables present changes in the liability associated with AROs.
|  |  | Duke |  |  |  | Duke |  | Duke |  | Duke |  | Duke |  |
| Duke |  | Energy |  | Progress |  | Energy |  | Energy |  | Energy |  | Energy |  |
(in millions) | Energy |  | Carolinas |  | Energy |  | Progress |  | Florida |  | Ohio |  | Indiana |  | Piedmont
Balance at December 31, 2021 | $ | 12,600 |  |  | $ | 5,301 |  |  | $ | 6,112 |  |  | $ | 5,675 |  |  | $ | 437 |  |  | $ | 136 |  |  | $ | 987 |  |  | $ | 22 |
Accretion expense(a) | 501 |  |  | 242 |  |  | 229 |  |  | 215 |  |  | 14 |  |  | 6 |  |  | 30 |  |  | 1 |
Liabilities settled(b) | (680) |  |  | (234) |  |  | (334) |  |  | (228) |  |  | (106) |  |  | (13) |  |  | (98) |  |  | — |
Liabilities incurred in the current year | 22 |  |  | — |  |  | 18 |  |  | — |  |  | 18 |  |  | — |  |  | 5 |  |  | — |
Revisions in estimates of cash flows(c) | 285 |  |  | 73 |  |  | 156 |  |  | 161 |  |  | (5) |  |  | 25 |  |  | 27 |  |  | 3 |
Balance at December 31, 2022 | 12,728 |  |  | 5,382 |  |  | 6,181 |  |  | 5,823 |  |  | 358 |  |  | 154 |  |  | 951 |  |  | 26 |
Accretion expense(a) | 523 |  |  | 254 |  |  | 237 |  |  | 225 |  |  | 12 |  |  | 7 |  |  | 33 |  |  | 1 |
Liabilities settled(b) | (758) |  |  | (256) |  |  | (379) |  |  | (292) |  |  | (87) |  |  | (15) |  |  | (108) |  |  | — |
Liabilities incurred in the current year | 29 |  |  | 3 |  |  | 21 |  |  | 6 |  |  | 15 |  |  | 1 |  |  | 4 |  |  | — |
Revisions in estimates of cash flows(c) | (3,366) |  |  | (1,370) |  |  | (1,915) |  |  | (1,892) |  |  | (23) |  |  | (11) |  |  | (71) |  |  | (1) |
Balance at December 31, 2023 | $ | 9,156 |  |  | $ | 4,013 |  |  | $ | 4,145 |  |  | $ | 3,870 |  |  | $ | 275 |  |  | $ | 136 |  |  | $ | 809 |  |  | $ | 26 |
(a) Substantially all accretion expense for the years ended December 31, 2023, and 2022, relates to Duke Energy’s regulated operations and has been deferred in accordance with regulatory accounting treatment. (b) Amounts primarily relate to ash impoundment closures and nuclear decommissioning. (c) The amounts recorded represent the discounted cash flows for estimated closure costs as evaluated on a site-by-site basis. The increases in 2022 primarily relate to higher unit costs associated with basin closure and routine maintenance. The decreases in 2023 primarily relate to lower discounted cash flows for decommissioning the nuclear power facilities due to changes in estimates and economic assumptions including discount rates, cost escalation rates and cash flow timing, as well as lower unit costs associated with basin closure, routine maintenance and beneficiation activities, as well as reduction in monitoring wells needed.

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- Definition The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//410-20/tableOfContent Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 20 -Topic 410 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-2 + Details
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