Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Current assets
Cash and cash equivalents	$ 40,500	$ 25,552
Prepaid expenses and other current assets	1,001	835
Total current assets	41,501	26,387
Property, plant and equipment, net	177,420	173,816
Operating lease right-of-use assets, net	1,257	590
Other non-current assets, net	24,566	21,312
Total assets	244,744	222,105
Current liabilities
Accounts payable	1,456	281
Share-based compensation liability	182	182
Accrued liabilities and other current liabilities	5,315	5,791
Current common stock warrant liabilities	0	1,376
Current operating lease liabilities	963	596
Total current liabilities	7,916	8,226
Non-current common stock warrant liabilities	5,461	2,587
Non-current operating lease liabilities	364	0
Other non-current liabilities	23,000	23,000
Total liabilities	36,741	33,813
Commitments and contingencies (Note 13)
Stockholders’ equity
Common stock, $0.0001 par value Authorized: 480.0 million shares at June 30, 2022 and December 31, 2021; Issued and outstanding: 127.3 million shares and 120.8 million shares at June 30, 2022 and December 31, 2021, respectively	13	12
Treasury stock: 742,263 shares and 346,126 shares at June 30, 2022 and December 31, 2021, respectively, at cost	(3,067)	(1,315)
Preferred stock, $0.0001 par value Authorized: 0.5 million, after designation of the Convertible Preferred Stock Issued and outstanding: none at June 30, 2022 and December 31, 2021	0	0
Additional paid-in-capital	213,749	191,264
Accumulated deficit	(192,418)	(170,069)
Total stockholders’ equity	18,277	19,892
Total liabilities, convertible preferred stock and stockholders’ equity	244,744	222,105
Series A Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	68,259	63,791
Series B Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	68,863	64,602
Series C Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	$ 52,604	$ 40,007