Property, Plant and Equipment

12 Months Ended

Dec. 31, 2022

Property, Plant and Equipment

Property, Plant and Equipment

8.  Property, Plant and Equipment

Property, plant and equipment at December 31, 2022 and 2021 consists of the following (in thousands):

	December 31, 2022		December 31, 2021
Land	$	1,772	$	1,165
Construction in progress		575,141		169,415
Leasehold improvements		21,363		2,099
Software, machinery, and equipment		169,633		112,068
Property, plant and equipment		767,909		284,747
Less: accumulated depreciation		(48,116)		(29,124)
Property, plant and equipment, net	$	719,793	$	255,623

Construction in progress is primarily comprised of construction of five hydrogen production plants, the Gigafactory in Rochester, NY, and our facility in the Slingerlands, NY. Completed assets are transferred to their respective asset classes, and depreciation begins when an asset is ready for its intended use. Interest on outstanding debt is capitalized during periods of capital asset construction and amortized over the useful lives of the related assets. For the years ended December 31, 2022 and 2021, we capitalized $13.1 million and $5.5 million of interest.

Depreciation expense related to property, plant and equipment was $19.0 million, $6.9 million, and $4.8 million for the years ended December 31, 2022, 2021, and 2020, respectively.