Note 9 - Property, Plant and Equipment and Construction-in-process (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

Property, Plant and Equipment [Table Text Block]

	December 31,
	2021			2020
	(Dollars in thousands)
Land owned by the Company where the geothermal resource is located	$	40,545		$	40,157
Leasehold improvements		9,105			8,477
Machinery and equipment		302,367			271,981
Land, buildings and office equipment		48,275			43,555
Vehicles		10,724			8,960
Energy storage equipment		79,805			63,562
Geothermal and recovered energy generation power plants, including geothermal wells and exploration and resource development costs:
United States of America, net of cash grants		2,511,027			2,296,414
Foreign countries		800,000			732,537
Asset retirement cost		41,157			28,946
		3,843,005			3,494,589
Less accumulated depreciation		(1,548,032	)		(1,395,543	)
Property, plant and equipment, net	$	2,294,973		$	2,099,046

Construction In Progress [Table Text Block]

	December 31,
	2021		2020
	(Dollars in thousands)
Projects under exploration and development:
Up-front bonus costs	$	5,335	$	5,347
Exploration and development costs		44,664		45,478
Interest capitalized		703		703
		50,702		51,528
Projects under construction:
Up-front bonus costs		39,156		39,144
Drilling and construction costs		611,553		379,117
Interest capitalized		20,072		9,526
		670,781		427,787
Total	$	721,483	$	479,315

Rollforward Of Construction In Process [Table Text Block]

	Projects under exploration and development
	Up-front Bonus Costs			Exploration and Development Costs			Interest Capitalized		Total
	(Dollars in thousands)
Balance at December 31, 2018	$	17,018		$	53,237		$	703	$	70,958
Cost incurred during the year		—			17,215			—		17,215
Transfer of projects under exploration and development to projects under construction		—			(3,536	)		—		(3,536	)
Balance at December 31, 2019		17,018			66,916			703		84,637
Cost incurred during the year		—			5,832			—		5,832
Transfer of projects under exploration and development to projects under construction		(11,671	)		(27,270	)		—		(38,941	)
Balance at December 31, 2020		5,347			45,478			703		51,528
Cost incurred during the year		—			2,680			—		2,680
Transfer of projects under exploration and development to projects under construction		(12	)		(3,494	)		—		(3,506	)
Balance at December 31, 2021	$	5,335		$	44,664		$	703	$	50,702

	Projects under construction
	Up-front Bonus Costs		Drilling and Construction Costs			Interest Capitalized		Total
	(Dollars in thousands)
Balance at December 31, 2018	$	27,473	$	160,398		$	2,861	$	190,732
Cost incurred during the year		—		264,137			3,100		267,237
Transfer of projects under exploration and development to projects under construction		—		3,536			—		3,536
Insurance recoveries		—		(35,435	)		—		(35,435	)
Transfer of completed projects to property, plant and equipment		—		(134,152	)		—		(134,152	)
Balance at December 31, 2019		27,473		258,484			5,961		291,918
Cost incurred during the year		—		298,215			3,565		301,780
Transfer of projects under exploration and development to projects under construction		11,671		27,270			—		38,941
Transfer of completed projects to property, plant and equipment		—		(204,852	)		—		(204,852	)
Balance at December 31, 2020		39,144		379,117			9,526		427,787
Cost incurred during the year		—		403,296			10,546		413,842
Transfer of projects under exploration and development to projects under construction		12		3,494			—		3,506
Transfer of completed projects to property, plant and equipment		—		(174,354	)		—		(174,354	)
Balance at December 31, 2021	$	39,156	$	611,553		$	20,072	$	670,781