Property, Plant and Equipment, Net

As of December 31, 2019 and 2018, the components of property, plant and equipment are stated at cost less accumulated depreciation as follows (in millions):



	2019		2018		Depreciable Lives
Buildings, machinery and equipment	$	16,510	$	16,400	1.5 – 50 Years
Geothermal properties	1,553		1,501		13 – 58 Years
Other	291		286		3 – 50 Years
	18,354		18,187
Less: Accumulated depreciation	6,851		6,832
	11,503		11,355
Land	128		121
Construction in progress	332		966
Property, plant and equipment, net	$	11,963	$	12,442

Total depreciation expense, including amortization of finance lease assets, recorded for the years ended December 31, 2019, 2018 and 2017, was $627 million, $684 million and $638 million, respectively.

We have various debt instruments that are collateralized by our property, plant and equipment. See Note 8 for a discussion of such instruments.

Buildings, Machinery and Equipment

This component primarily includes power plants and related equipment. Included in buildings, machinery and equipment are assets under finance leases. See Note 4 for further information regarding these assets under finance leases.

Geothermal Properties

This component primarily includes power plants and related equipment associated with our Geysers Assets.

Other

This component primarily includes software and hardware as well as emission reduction credits that are power plant specific and not available to be sold.

Capitalized Interest

The total amount of interest capitalized was $12 million, $29 million and $26 million for the years ended December 31, 2019, 2018 and 2017, respectively.