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Note 1 - Nature of Activities and Summary of Significant Accounting Policies (Details Textual) MMBTU in Thousands, gal in Millions	1 Months Ended			3 Months Ended		12 Months Ended
	Apr. 30, 2023 USD ($)	May 31, 2022 USD ($)	Oct. 31, 2020 USD ($)	Mar. 31, 2023 USD ($) MMBTU gal	Dec. 31, 2022 USD ($)	Dec. 31, 2022 USD ($)
Renewable Natural Gas in Storage (Millions of British Thermal Unit) | MMBTU				31
Low Carbon Fuel Standard Credits, Per Metric Ton				$ 70
Low Carbon Fuel Standard Credits, Per D3 Cellulosic RIN				1.96
Low Carbon Fuel Standard Credits, Estimated Market Value Per MMBtu				53.37
Awarded Grants				8,000,000.0
Proceeds from Grantors				4,200,000
Matching Contribution				1,600,000
U.S. Department of Food And Agriculture Forest Service [Member]
Awarded Grants				245,000
Proceeds from Grantors				216,000
LCFPP [Member]
Awarded Grants				4,200,000
Proceeds from Grantors				3,800,000
CDFAs[Member]
Awarded Grants			$ 7,800,000
Proceeds from Grantors				3,900,000
CEC [Member]
Matching Contribution				7,900,000
Actual Expenses Incurred				5,000,000.0
Unearned Grant Proceeds				1,700,000		$ 1,700,000
CEC [Member] | Maximum [Member]
Awarded Grants				5,000,000.0
CAL FIRE Business and Workforce Development Grant Program [Member]
Awarded Grants		$ 2,000,000
Proceeds from Grantors						0
Matching Contribution		5,800,000
CAL Fire [Member]
Awarded Grants		500,000
Proceeds from Grantors						$ 0
US Forest Service [Member]
Awarded Grants		642,000
Matching Contribution		$ 2,400,000
AAFK Plan [Member]
Awarded Grants				6,000,000.0
Matching Contribution				5,300,000
PG&E SEM Incentive Program [Member]
Proceeds from Grantors					$ 374,000
CEC PG&E Pipeline Interconnect [Member]
Proceeds from Grantors				$ 5,000,000
Kakinada Plant [Member]
GallonPerYear (Gallon) | gal				50
Kakinada Plant [Member] | Subsequent Event [Member]
Amount of Biodiesel, Offer To Ship	$ 34,000,000.0

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-25

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