Note 6 - Property, Plant and Equipment (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

Property, Plant and Equipment [Table Text Block]

	Useful Life			March 31,			December 31,
	(in years)			2020			2019
Luverne retrofit asset		20		$	70,820		$	70,820
Plant machinery and equipment		10			17,424			17,413
Site improvements		10			7,054			7,054
Lab equipment, furniture and fixtures and vehicles		5			6,396			6,393
Demonstration plant		2			3,597			3,597
Buildings		10			2,543			2,543
Leasehold improvements, pilot plant, land and support equipment	2	to	5		2,523			2,523
Computer, office equipment and software	3	to	6		2,120			2,034
Construction in progress					8,412			7,710
Total property, plant and equipment					120,889			120,087
Less accumulated depreciation and amortization					(55,034	)		(53,391	)
Property, plant and equipment, net				$	65,855		$	66,696

Schedule of Depreciation and Amortization Expense [Table Text Block]

	Three Months Ended March 31,
	2020		2019
Cost of goods sold	$	1,587	$	1,560
Operating expenses		56		52
Total depreciation and amortization	$	1,643	$	1,612