BUSINESS SEGMENTS

3 Months Ended

Mar. 31, 2026

Segment Reporting [Abstract]

BUSINESS SEGMENTS

BUSINESS SEGMENTS

The Company has three reporting segments: the Electricity segment, the Product segment and the Energy Storage segment. These segments are managed and reported separately as each offers different products and serves different markets.

•Under the Electricity segment, the Company builds, owns and operates geothermal, solar PV and recovered energy-based power plants ("REG") in the United States and geothermal power plants in foreign countries, and sells the electricity generated by those power plants.

•Under the Product segment, the Company designs, manufactures and sells equipment for geothermal and recovered energy-based electricity generation and provide services relating to the engineering, procurement and construction ("EPC") of geothermal and recovered energy-based power plants.

•Under the Energy Storage segment, the Company owns and operates grid connected In-Front-of-the-Meter battery energy storage systems ("BESS"), which provide capacity, energy and/or ancillary services directly to the electric grid.

The accounting policies of the segments are the same as those described under Note 1 to the consolidated financial statements in the 2025 Annual Report. Transfer prices between the segments were determined on current market values or cost plus markup of the seller’s segment. The Company’s Chief Operating Decision Maker (“CODM”) is comprised of its CEO and CFO. To evaluate segment performance and allocate the Company’s resources, the CODM uses segment measures of gross profit and operating income. The CODM reviews budget-to-actual variances of both profit measures on a monthly basis when making decisions about allocation of the Company’s resources to the segments. 

Summarized financial information concerning the Company’s reportable segments is shown in the following tables, including the Company's disaggregated revenues from contracts with customers as required by ASC 606, Revenue from Contracts with Customers (“ASC 606”). Total consolidated revenues, gross profit (loss) and operating income (loss) of the Company’s business segments exclude intersegment revenues, gross profit (loss) and operating income (loss) as these activities are eliminated in consolidation and are not included in CODM’s evaluation of performance of each segment.

	Electricity		Product		Energy Storage		Consolidated
	(Dollars in thousands)
Three Months Ended March 31, 2026:
Revenues from external customers:
United States (1)	$	131,597	$	2,052	$	44,925	$	178,574
Foreign (2)	50,006		175,331		—		225,337
Net revenue from external customers	181,603		177,383		44,925		403,911
Less:
Depreciation and amortization expenses (3)	59,630		2,116		9,376		71,122
Other cost of revenues expenses (4)	66,114		137,293		9,013		212,420
Segment gross profit	55,859		37,974		26,536		120,369
Less:
Segment operating expenses (income) (5)	14,284		12,053		13,776		40,114
Segment operating income	$	41,575	$	25,921	$	12,760	$	80,255
Total depreciation and amortization expense (6)	$	65,577	$	2,658	$	8,129	$	76,364
Segment assets at period end (7) (*)	5,772,836		283,188		716,414		6,772,438
Expenditures for long-lived assets	60,613		1,367		51,807		113,787
* Including unconsolidated investments	200,901		—		—		200,901
Three Months Ended March 31, 2025:
Revenues from external customers:
United States (1)	$	134,213	$	3,239	$	17,752	$	155,204
Foreign (2)	46,028		28,530		—		74,558
Net revenue from external customers	180,241		31,769		17,752		229,762

Less:
Depreciation and amortization expenses (3)	56,870		2,571		6,851		66,293
Other cost of revenues expenses (4)	62,963		22,113		5,467		90,542
Segment gross profit	60,408		7,085		5,434		72,927
Less:
Segment operating expenses (income) (5)	19,565		3,449		(1,000)		22,014
Segment operating income	$	40,843	$	3,636	$	6,434	$	50,913
Total depreciation and amortization expense (6)	$	59,976	$	2,894	$	6,908	$	69,777
Segment assets at period end (7) (*)	5,124,073		244,796		470,078		5,838,947
Expenditures for long-lived assets	171,350		1,200		20,052		192,602
* Including unconsolidated investments	158,618		—		—		158,618

(1)Electricity segment revenues in the United States are all accounted for under lease accounting except for $48.2 million in the three months ended March 31, 2026 and $40.2 million in the three months ended March 31, 2025 that are accounted for under ASC 606. Product and Energy Storage segment revenues in the United States are accounted for under ASC 606, except for Energy Storage revenues of $7.5 million for the three months ended March 31, 2026 and $3.5 million for the three months ended March 31, 2025 that are accounted for under lease accounting.

(2)Electricity segment revenues in foreign countries are all accounted for under lease accounting. Product segment revenues in foreign countries are all accounted for under ASC 606.

(3)Depreciation and amortization expense amounts align with the segment-level information that is regularly provided to the CODM, and do not include intersegment transactions. Depreciation and amortization expenses included in the segment measure of gross profit are related to the specific tangible and intangible assets associated with each of the reportable segments.

(4)Other cost of revenues expenses for each reportable segment include:

Electricity: primarily cost of manpower, utilities, repair and maintenance, royalties, and property taxes.

Products: primarily cost of raw materials and finished goods used in manufacturing, manpower, transportation, and third-party subcontractors.

Energy Storage: primarily cost of manpower, utilities, and insurance.

(5)Segment operating expenses include research and development expenses, selling and marketing expenses, and general and administrative expenses such as manpower, depreciation and amortization, legal and professional services. Such expenses do not include intersegment transactions. Segment operating expenses related to the Energy Storage segment are directly related to this segment. Segment operating expenses related to the Electricity and Product segments are allocated between these two segments based on their weighted contribution to revenues, except for certain specific expenses or gains that are specifically allocated to one of these segments, as applicable, such as impairment of long-lived assets, write-off of unsuccessful exploration activities, and other operating income.

(6)Total depreciation and amortization expenses for each segment are related to the specific tangible and intangible assets associated with the respective reportable segment.

(7)Electricity segment assets include goodwill in the amount of $163.4 million, and 146.7 million as of March 31, 2026 and 2025, respectively. Energy Storage segment assets include goodwill in the amount of $4.6 million as of March 31, 2026 and 2025. No goodwill is included in the Product segment assets as of March 31, 2026 and 2025.

Reconciling information between reportable segments and the Company’s consolidated totals is shown in the following table:

	Three Months Ended March 31,
	2026		2025
	(Dollars in thousands)
Reconciliation of profit or loss (segment gross profit):
Total segment gross profit	$	120,369	$	72,927
Less operating expenses:
Research and development expenses	1,132		2,542
Selling and marketing expenses	5,577		4,172
General and administrative expenses	27,336		17,909
Other operating income	(4,125)		(3,125)
Impairment of long-lived assets	8,112		—
Write-off of unsuccessful exploration and storage activities	2,082		516
Operating income	$	80,255	$	50,913
Interest income	1,430		1,313
Interest expense, net	(44,993)		(34,473)
Derivatives and foreign currency transaction gains (losses)	(1,537)		2,060
Income attributable to sale of tax benefits	16,621		17,571
Other non-operating income (expense), net	(23,145)		222
Total consolidated income before income taxes and equity in income of investees	$	28,631	$	37,606
Reconciliation of profit or loss (segment operating income):
Total segment operating income	$	80,255	$	50,913
Interest income	1,430		1,313
Interest expenses, net	(44,993)		(34,473)
Derivatives and foreign currency transaction gains (losses)	(1,537)		2,060
Income attributable to sale of tax benefits	16,621		17,571
Other non-operating income (expense), net	(23,145)		222
Total consolidated income before income taxes and equity in income of investees	$	28,631	$	37,606