UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows used in operating activities:
Net loss	$ (13,909)	$ (22,060)
Adjustments to reconcile net loss for the period to net cash used in operating activities:
Non-cash portion of interest expense – Note 8	2,963	3,835
(Gain) loss on fair value adjustment for warrant liabilities – Note 11	(122)	5,321
Depreciation and amortization – Note 5	718	920
Stock-based compensation	608	401
Accretion – Note 10	186	102
Gain on sale of equipment	0	(625)
Changes in operating assets and liabilities:
Accounts receivable	2,771	0
Interest receivable	(53)	0
Production-related inventories	0	6,137
Materials and supplies inventories, net	62	166
Prepaids and deposits	792	1,161
Accounts payable and accrued expenses	(1,082)	(2,848)
Other liabilities	(1,752)	574
Net cash used in operating activities	(8,818)	(6,916)
Cash flows (used in) provided by investing activities:
Additions to property, plant and equipment	(271)	(351)
Proceeds from sale of equipment	0	711
Proceeds from assets held for sale	0	1,250
Net cash (used in) provided by investing activities	(271)	1,610
Cash flows (used in) provided by financing activities:
Principal payments on debt	(550)	(24,406)
Principal payments on notes payable	(32)	(31)
Proceeds from issuance of common stock and warrants, net of issuance costs - Note 12	0	190,179
Net cash (used in) provided by financing activities	(582)	165,742
Net (decrease) increase in cash, cash equivalents, and restricted cash	(9,671)	160,436
Cash, cash equivalents, and restricted cash, beginning of period	175,966	46,635
Cash, cash equivalents, and restricted cash, end of period	166,295	207,071
Reconciliation of cash, cash equivalents, and restricted cash:
Cash and cash equivalents	131,987	172,778
Restricted cash	34,308	34,293
Total cash, cash equivalents, and restricted cash	$ 166,295	$ 207,071