Note 11 - Property, Plant and Equipment

12 Months Ended

Dec. 31, 2021

Notes to Financial Statements

Property, Plant and Equipment Disclosure [Text Block]

11. Property, Plant and Equipment

The following table sets forth the Company’s property, plant and equipment by classification (in thousands):

	Useful Life			December 31,
	(in years)			2021			2020
Luverne Facility retrofit asset		20		$	70,820		$	70,820
Plant machinery and equipment		10			17,949			17,374
Site improvements		10			7,157			7,157
Lab equipment, furniture and fixtures and vehicles		5			6,811			6,396
Demonstration plant		2			3,597			3,597
Leasehold improvements, pilot plant, land and support equipment	2	to	7		2,802			2,523
Buildings		10			2,543			2,543
Computer, office equipment and software	3	to	6		2,332			1,983
Construction in progress		—			88,989			13,132
Total Property, plant and equipment					203,000			125,525
Less accumulated depreciation and amortization					(63,859	)		(59,117	)
Property, plant and equipment, net				$	139,141		$	66,408

The Company recorded depreciation and amortization expense related to property, plant and equipment as follows (in thousands):

	Year Ended December 31,
	2021		2020		2019
Cost of goods sold	$	4,457	$	5,669	$	6,282
Operating expenses
Research and development expense		250		160		152
Selling, general and administrative expense		75		54		57
		325		214		209
Total	$	4,782	$	5,883	$	6,491