Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net loss and comprehensive loss	$ (22,180)	$ (18,243)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	200	194
Amortization of debt discount and issuance costs	3,062	3,002
Interest expense added to loan principal	7,523	7,246
Interest expense added to lease liability	947	827
Loss on debt conversion	38	83
Debt conversion expense	197
Compensation charge for stock and share option awards	410	350
Unrealized gain on warrant derivative liabilities		(1,268)
Changes in operating assets and liabilities:
Accounts receivable	(55)	(70)
Prepaid expenses and other current assets	(115)	(124)
Other assets	(215)	45
Accounts payable	405	502
Accrued liabilities	(921)	(1,188)
Net cash used in operating activities	(10,704)	(8,644)
Cash flows from investing activities:
Additions to property, plant and equipment and water programs	(1,428)	(1,258)
Net cash used in investing activities	(1,428)	(1,258)
Cash flows from financing activities:
Net proceeds from issuance of stock	14,890	14,581
Principal payments on long-term debt	(44)	(42)
Net cash provided by financing activities	14,846	14,539
Net increase in cash, cash equivalents and restricted cash	2,714	4,637
Cash, cash equivalents and restricted cash, beginning of period	12,691	13,163
Cash, cash equivalents and restricted cash, end of period	$ 15,405	$ 17,800