Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets
Cash and cash equivalents	$ 22,608	$ 15,736
Investment securities	0	62,207
Prepaid expenses and other current assets	670	859
Total current assets	23,278	78,802
Property, plant and equipment, net	161,662	134,591
Operating lease right-of-use assets, net	429	1,054
Other non current assets	16,299	6,748
Total assets	201,668	221,195
Current liabilities
Accounts payable	207	11,912
Share-based compensation liability	182	182
Accrued liabilities and other current liabilities	1,032	8,751
Current Common Stock Warrant liabilities	3,290	0
Current operating lease liabilities	432	698
Total current liabilities	5,143	21,543
Non-current Common Stock Warrant liabilities	874	12,034
Non-current operating lease liabilities	0	3
Other non-current liabilities	22,916	0
Total liabilities	28,933	33,580
Commitments and contingencies (Note 14)
Stockholders’ equity
Common stock, $0.0001 par value Authorized: 480.0 million shares at December 31, 2020 and December 31, 2019, Issued and outstanding: 117.8 million shares and 117.3 million shares at December 31, 2020 and December 31, 2019, respectively	12	12
Treasury stock: 249,742 shares and 137,860 shares at December 31, 2020 and December 31, 2019, respectively, at cost	(1,031)	(685)
Preferred stock, $0.0001 par value Authorized: 0.9 million, after designation of the Series A and Series B Convertible Preferred Stock, Issued and outstanding: none at December 31, 2020 and December 31, 2019	0	0
Additional paid-in-capital	209,481	224,091
Accumulated deficit	(148,030)	(133,701)
Total stockholders’ equity	60,432	89,717
Total liabilities, Series A and Series B Convertible Preferred Stock and stockholders’ equity	201,668	221,195
Series A Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	55,522	48,084
Series B Convertible Preferred Stock [Member]
Current liabilities
Convertible Preferred Stock	$ 56,781	$ 49,814