Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating Activities
Net loss	$ (25,090)	$ (21,713)
Adjustments to reconcile net loss to net cash used in operating activities:
Loss/(Gain) from change in fair value of derivative warrant liability	5,325	7,080
Loss/(Gain) from change in fair value of the 2017 Notes	1,775	(3,425)
Loss/(Gain) on conversion of debt		(285)
Loss/(Gain) on extinguishment of warrant liability	923	(1,775)
Loss/(Gain) on issuance of equity	1,519
Stock-based compensation	542	698
Depreciation and amortization	3,282	3,281
Non-cash interest expense	2,130	1,767
Changes in operating assets and liabilities:
Accounts receivable	(283)	42
Inventories	602	1,389
Prepaid expenses and other current assets	(153)	160
Accounts payable, accrued expenses, and long-term liabilities	(1,937)	(2,104)
Net cash used in operating activities	(11,365)	(14,885)
Investing Activities
Acquisitions of property, plant and equipment	(4,847)	(175)
Proceeds from sales tax refund for property, plant and equipment		144
Net cash used in investing activities	(4,847)	(31)
Financing Activities
Payments on secured debt	(84)	(131)
Debt and equity offering costs	(1,997)	(2,785)
Proceeds from issuance of common stock and common stock units	13,023	23,850
Proceeds from the exercise of warrants	10,856	10,151
Net cash provided by financing activities	21,798	31,085
Net increase in cash and cash equivalents	5,586	16,169
Cash and cash equivalents
Beginning of period	17,031	6,359
End of period	22,617	22,528
Supplemental disclosures of cash and non-cash investing and financing transactions
Cash paid for interest, net of interest capitalized	2,165	2,297
Non-cash purchase of property, plant and equipment		15
Conversion of convertible debt to common stock		2,000
2015 Warrants | Series A Warrant
Supplemental disclosures of cash and non-cash investing and financing transactions
Warrant issuance		1,437
2015 Warrants | Series B Warrant
Supplemental disclosures of cash and non-cash investing and financing transactions
Warrant issuance		2,528
2015 Warrants | Series C Warrant
Supplemental disclosures of cash and non-cash investing and financing transactions
Warrant issuance		$ 1,299
2016 Warrants | Series F Warrant
Supplemental disclosures of cash and non-cash investing and financing transactions
Warrant issuance	2,162
2016 Warrants | Series G Warrant
Supplemental disclosures of cash and non-cash investing and financing transactions
Warrant issuance	1,577
2016 Warrants | Series H Warrant
Supplemental disclosures of cash and non-cash investing and financing transactions
Warrant issuance	$ 1,060