ASSET RETIREMENT OBLIGATIONS

The Duke Energy Registrants record AROs when there is a legal obligation to incur retirement costs associated with the retirement of a long-lived asset and the obligation can be reasonably estimated. Actual closure costs incurred could be materially different from current estimates that form the basis of the recorded AROs.

The following table presents the AROs recorded on the Condensed Consolidated Balance Sheets.



	March 31, 2019
			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^(a)	$	5,753	$	2,368	$	3,239	$	2,709	$	530	$	—	$	—	$	—
Closure of ash impoundments	6,961		3,013		3,197		3,177		20		52		699		—
Other	321		47		70		37		33		41		20		19
Total ARO	$	13,035	$	5,428	$	6,506	$	5,923	$	583	$	93	$	719	$	19
Less: current portion	779		209		456		452		4		6		108		—
Total noncurrent ARO	$	12,256	$	5,219	$	6,050	$	5,471	$	579	$	87	$	611	$	19

(a) Duke Energy amount includes purchase accounting adjustments related to the merger with Progress Energy.

ARO Liability Rollforward

The following table presents the change in liability associated with AROs for the Duke Energy Registrants.



				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, 2018^(a)	$	10,467		$	3,949		$	5,411		$	4,820		$	591		$	93		$	722		$	19
Accretion expense^(b)	110			48			57			50			7			1			7			—
Liabilities settled^(c)	(184		)	(76		)	(97		)	(82		)	(15		)	(1		)	(10		)	—
Revisions in estimates of cash flows^(d)	2,642			1,507			1,135			1,135			—			—			—			—
Balance at March 31, 2019	$	13,035		$	5,428		$	6,506		$	5,923		$	583		$	93		$	719		$	19


(a)	Primarily relates to decommissioning nuclear power facilities, closure of ash impoundments, asbestos removal, closure of landfills at fossil generation facilities, retirement of natural gas mains and removal of renewable energy generation assets.


(b)	For the three months ended March 31, 2019, substantially all accretion expense relates to Duke Energy's regulated operations and has been deferred in accordance with regulatory accounting treatment.


(c)	Primarily relates to ash impoundment closures.


(d)	Relates to increases in closure estimates for certain ash impoundments as a result of the NCDEQ's determination that all ash basins must be excavated. See Note 4 for more information. The incremental amount recorded represents the discounted cash flows for estimated closure costs based upon the probability weightings of the potential closure methods as evaluated on a site-by-site basis.

Asset retirement costs associated with the AROs for operating plants and retired plants are included in Net property, plant and equipment and Regulatory assets within Other Noncurrent Assets, respectively, on the Condensed Consolidated Balance Sheets.

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 following table presents the fair value of NDTF assets legally restricted for purposes of settling AROs associated with nuclear decommissioning. Duke Energy Florida is actively decommissioning 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 12 for additional information related to the fair value of the Duke Energy Registrants' NDTFs.



(in millions)	March 31, 2019		December 31, 2018
Duke Energy	$	6,102	$	5,579
Duke Energy Carolinas	3,443		3,133
Duke Energy Progress	2,659		2,446