Nature of Business and Basis of Presentation - Additional Information (Details) $ in Thousands			1 Months Ended	9 Months Ended
	Jul. 19, 2019 MW	Dec. 13, 2018 MW	May 08, 2019 shares	Jul. 31, 2019 USD ($) shares	Sep. 30, 2019 USD ($)	Sep. 04, 2019 USD ($)	May 07, 2019 shares	Oct. 31, 2018 USD ($) shares
Nature Of Business And Basis Of Presentation [Line Items]
Reverse stock split			1-for-12 reverse stock split
Reverse stock split, conversion ratio			0.084
Common stock, shares outstanding | shares			15,284,269	118,387,637			183,411,230	7,972,686
Common stock, shares authorized | shares			225,000,000	225,000,000				225,000,000
Preferred stock, shares authorized | shares			250,000	250,000
Long-term Line of Credit				$ 1,800
Hercules Capital, Inc. [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Maturity date				Oct. 22, 2019
Long-term Line of Credit				$ 7,426				$ 25,343
Proceeds from common stock sales				30.00%
Original maturity date				Apr. 01, 2020
Hercules Capital, Inc. [Member] | Minimum [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Maturity date				Oct. 21, 2019
Amount letters of intent from tax equity investors				$ 18,000
Hercules Capital, Inc. [Member] | Subsequent Event [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Long-term Line of Credit						$ 5,600
Hercules Capital, Inc. [Member] | Subsequent Event [Member] | Maximum [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Long-term Line of Credit					$ 5,000
NRG Energy [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Long-term Line of Credit				$ 5,750
Maturity date description				The Maturity date of each note payable to NRG is now the date that is the earliest of (a) September 30, 2019, (b) the commercial operation date or substantial completion date, as applicable, with respect to the fuel cell project owned by the co-borrower under such note, and (c) the repayment in full or the closing of a refinancing of the Company’s indebtedness with Hercules. NRG may also accelerate the maturity dates if it determines, in its sole discretion, that the deems that the Company is not making sufficient progress towards the completion of the construction of the 2.8 MW Tulare BioMAT projet in California.
NRG Energy [Member] | Tulare BioMAT [Member] | California [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Capacity of plant | MW	2.8	2.8
Fifth Third Binding Loan Agreement [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Maturity date		Oct. 21, 2019
Fifth Third Binding Loan Agreement [Member] | Minimum [Member]
Nature Of Business And Basis Of Presentation [Line Items]
Amount letters of intent from tax equity investors				$ 18,000