CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows used in operating activities:
Net loss	$ (55,024)	$ (60,828)
Adjustments to reconcile net loss for the period to net cash used in operating activities:
Non-cash portion of interest expense – Note 9	12,255	13,149
Depreciation and amortization – Notes 2 and 5	2,814	3,356
Stock-based compensation – Note 17	2,920	2,469
Accretion – Note 8	1,087	408
Impairment charges and write-downs – Notes 4, 5, and 7	495	1,051
Non-cash (gain) loss on fair value adjustment for warrant liabilities – Notes 14 and 21	(175)	159
Gain on sale of assets, net of commissions	(544)	(3,948)
Gain on settlement of accrued liability	(1,151)	0
Asset retirement obligation adjustments – Note 8	(3,416)	4,701
Gain on extinguishment of debt – Note 9	0	(5,041)
Changes in operating assets and liabilities:
Accounts receivable	2,774	(2,774)
Contract liabilities – Note 11	500	1,050
Supplies inventories – Note 4	479	1,464
Interest receivable	(208)	(459)
Prepaids and deposits – Note 3	(1,991)	(498)
Accounts payable and accrued expenses – Note 10	(2,330)	(3,786)
Production-related inventories	0	15,808
Other liabilities – Note 12	67	(1,136)
Net cash used in operating activities	(41,448)	(34,855)
Cash flows (used in) provided by investing activities:
Additions to property, plant, and equipment	(1,070)	(951)
Proceeds from sale of assets – Note 5	563	2,714
Proceeds from assets held for sale, net of commissions expense – Note 7	0	6,574
Net cash (used in) provided by investing activities	(507)	8,337
Cash flows (used in) provided by financing activities:
Proceeds from issuance of common stock and warrants, net of issuance expenses – Note 15	867	188,859
Principal payments on debt and finance leases – Note 15	(2,328)	(33,010)
Net cash (used in) provided by financing activities	(1,461)	155,849
Net (decrease) increase in cash, cash equivalents, and restricted cash	(43,416)	129,331
Cash, cash equivalents, and restricted cash, beginning of period	175,966	46,635
Cash, cash equivalents, and restricted cash, end of period	132,550	175,966
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	106,210	141,984
Restricted cash	26,340	33,982
Total cash, cash equivalents, and restricted cash	$ 132,550	$ 175,966