Note 3 - Revenues From Contracts With Customers; Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Revenue from Contract with Customer, Including Assessed Tax	$ 988	$ 5,058	$ 4,813	$ 11,461
Other revenues		28		28
Total revenues	988	5,086	4,813	11,489
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	942	5,058	4,767	11,461
Other revenues
Total revenues	942	5,058	4,767	11,461
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	46		46
Other revenues		28		28
Total revenues	46	28	46	28
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	83	4,966	3,783	10,630
Other revenues
Total revenues	83	4,996	3,783	10,630
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	859	92	984	831
Other revenues
Total revenues	859	92	984	831
Grant and Other [Member]
Revenue from Contract with Customer, Including Assessed Tax	46		46
Other revenues		28		28
Total revenues	$ 46	$ 28	$ 46	$ 28