Note 3 - Revenues From Contracts With Customers; Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 6,104	$ 8,575	$ 17,565	$ 26,238
Other revenues	6		34
Total revenues	6,110	8,575	17,599	26,238
Transferred at Point in Time [Member]
Revenue from Contract with Customer, Including Assessed Tax	6,104	8,575	17,565	26,213
Other revenues
Total revenues	6,104	8,575	17,565	26,213
Transferred over Time [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Other revenues	6		34
Total revenues	6		34	25
Ethanol Sales and Related Products [Member]
Revenue from Contract with Customer, Including Assessed Tax	5,554	8,071	16,184	25,102
Other revenues
Total revenues	5,554	8,071	16,184	25,102
Hydrocarbon [Member]
Revenue from Contract with Customer, Including Assessed Tax	550	504	1,381	1,111
Other revenues
Total revenues	550	504	1,381	1,111
Grant and Other [Member]
Revenue from Contract with Customer, Including Assessed Tax				25
Other revenues	6		34
Total revenues	$ 6		$ 34	$ 25