Note 3 - Revenues From Contracts With Customers and Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from Contract with Customer, Including Assessed Tax	$ 192	$ 6,104	$ 5,005	$ 17,565
Other revenues		6		34
Total revenues	192	6,110	5,005	17,599
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	122	6,104	4,889	17,565
Other revenues
Total revenues	122	6,104	4,889	17,565
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	70		116
Other revenues		6		34
Total revenues	70	6	116	34
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	21	5,554	3,804	16,184
Other revenues
Total revenues	21	5,554	3,804	16,184
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	101	550	1,085	1,381
Other revenues
Total revenues	101	550	1,085	1,381
Grant and Other [Member]
Revenue from Contract with Customer, Including Assessed Tax	70		116
Other revenues		6		34
Total revenues	$ 70	$ 6	$ 116	$ 34