Note 12 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	Year Ended
	December 31,
	2019			2018
U.S. federal statutory rate, beginning of year		21	%		21	%
Officers' compensation		7			(5	)
Other		(2	)		(1	)
Valuation allowance		(26	)		(15	)
Effective tax rate as reported		—	%		—	%

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

	Year Ended
	December 31,
	2019			2018
Deferred tax assets
Net operating loss carryforwards and credits	$	15,064		$	5,302
Share-based compensation expense		3,441			3,548
Property, plant and equipment		1,025			1,399
Common stock warrant liabilities		524			—
Operating lease liabilities		147			—
Other		21			51
Less: valuation allowance		(19,802	)		(10,300	)
Total deferred tax assets		420			—
Deferred tax liabilities
Operating lease right-of-use assets		(420	)		—
Total deferred tax liabilities		(420	)		—
Net deferred tax assets (liabilities)	$	—		$	—