Note 3 - Revenues From Contracts With Customers and Other Revenues - Disaggregated Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues from contracts with customers	$ 120	$ 192	$ 479	$ 5,005
Other revenues	22	0	178	0
Total revenues	142	192	657	5,005
Transferred at Point in Time [Member]
Revenues from contracts with customers	120	122	479	4,889
Other revenues	(3)	0	0	0
Total revenues	117	122	479	4,889
Transferred over Time [Member]
Revenues from contracts with customers	0	70	0	116
Other revenues	25	0	178	0
Total revenues	25	70	178	116
Ethanol Sales and Related Products [Member]
Revenues from contracts with customers	16	21	16	3,804
Other revenues	0	0	0	0
Total revenues	16	21	16	3,804
Hydrocarbon [Member]
Revenues from contracts with customers	104	101	463	1,085
Other revenues	0	0	0	0
Total revenues	104	101	463	1,085
Grant and Other [Member]
Revenues from contracts with customers	0	70	0	116
Other revenues	22	0	178	0
Total revenues	$ 22	$ 70	$ 178	$ 116