Note 3 - Revenues From Contracts With Customers and Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Revenue from Contract with Customer, Including Assessed Tax	$ 5,463	$ 24,453
Other revenues	73	34
Total revenues	5,536	24,487
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	5,310	24,453
Other revenues
Total revenues	5,310	24,453
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	153
Other revenues	73	34
Total revenues	226	34
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	3,809	22,115
Other revenues
Total revenues	3,809	22,115
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	1,501	2,338
Other revenues
Total revenues	1,501	2,338
Grant and Other [Member]
Revenue from Contract with Customer, Including Assessed Tax	153
Other revenues	73	34
Total revenues	$ 226	$ 34