Note 13 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended
	December 31,
	2021			2020
U.S. federal statutory rate, beginning of year		21	%		21	%
Officers' compensation		—			2
Other		(4	)		(3	)
Valuation allowance		(17	)		(20	)
Effective tax rate as reported		—	%		—	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	Year Ended
	December 31,
	2021			2020
Deferred tax assets
Net operating loss carryforwards and credits	$	25,742		$	20,698
Employee compensation		570			—
Share-based compensation expense		2,053			3,813
Property, plant and equipment		753			725
Common stock warrant liabilities		83			—
Operating lease liabilities		125			91
Other		55			54
Less: valuation allowance		(26,461	)		(22,669	)
Total deferred tax assets		2,920			2,712
Deferred tax liabilities
Common stock warrant liabilities		—			(1,129	)
Operating lease Right-of-use assets		(2,920	)		(1,583	)
Total deferred tax liabilities		(2,920	)		(2,712	)
Net deferred tax assets (liabilities)	$	—		$	—