Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets, Current [Abstract]
Cash and cash equivalents	$ 20,892	$ 22,793
Accounts receivable	725	882
Inventory	765	1,239
Prepaid expenses and other current assets	370	770
Total current assets	22,752	25,684
Non-current assets
Property and equipment, net	45,548	45,733
Intellectual property, net	1,271	1,461
Other assets	1,800	1,564
Total non-current assets	48,619	48,758
Total assets	71,371	74,442
Current liabilities
Accounts payable	2,088	1,436
Accrued expenses	5,196	1,801
Deferred rent, current portion	8	192
Lease liability, current portion	121	0
Notes payable, current portion	311	405
Convertible note payable, current portion	4,075	0
Total current liabilities	11,799	3,834
Deferred rent, non-current portion	27	771
Lease liability, non-current portion	110	0
Asset retirement obligation	745	701
Notes payable, non-current portion	8,600	8,839
Convertible note payable, non-current portion	0	1,332
Total liabilities	21,281	15,477
Commitments and contingencies
Stockholders’ equity
Common stock; $0.001 par value; 50,000,000 shares authorized; 38,932,437 and 27,554,076 shares issued and outstanding as of December 31, 2018 and December 31, 2017, respectively	39	27
Additional paid-in capital	145,147	113,780
Accumulated deficit	(95,096)	(54,842)
Total stockholders’ equity	50,090	58,965
Total liabilities and stockholders’ equity	$ 71,371	$ 74,442