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



	September 30, 2017
			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)	$	5,337	$	1,916	$	3,235	$	2,536	$	699	$	—	$	—	$	—
Closure of Ash Impoundments	4,594		1,650		2,124		2,105		19		42		777		—
Other	274		35		80		35		45		39		16		15
Total ARO	$	10,205	$	3,601	$	5,439	$	4,676	$	763	$	81	$	793	$	15
Less: current portion	619		304		250		250		—		6		58		—
Total noncurrent ARO	$	9,586	$	3,297	$	5,189	$	4,426	$	763	$	75	$	735	$	15

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

ARO Liability Rollforward

Actual closure costs incurred could be materially different from current estimates that form the basis of the recorded AROs. 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, 2016^(a)	$	10,611		$	3,895		$	5,475		$	4,697		$	778		$	77		$	866		$	14
Accretion expense^(b)	329			140			172			147			25			3			25			1
Liabilities settled^(c)	(430		)	(201		)	(193		)	(152		)	(41		)	(4		)	(26		)	(7		)
Liabilities incurred in the current year	48			5			—			—			—			7			27			7
Revisions in estimates of cash flows^(d)	(353		)	(238		)	(15		)	(16		)	1			(2		)	(99		)	—
Balance at September 30, 2017	$	10,205		$	3,601		$	5,439		$	4,676		$	763		$	81		$	793		$	15


(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 nine months ended September 30, 2017, substantially all accretion expense relates to Duke Energy's regulated electric operations and has been deferred in accordance with regulatory accounting treatment.


(c)	Primarily relates to ash impoundment closures and nuclear decommissioning of Crystal River Unit 3.


(d)	Primarily relates to favorable contract prices for closure of ash impoundments compared to original estimates.

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.