Property, plant and equipment consist of the following as of June 30, 2026 and December 31, 2025:


	June 30, 2026			December 31, 2025
Land	$	1,568		$	1,568
Buildings and improvements		39,071			38,914
Machinery and equipment		326,315			321,834
Gas mineral rights		35,526			35,526
Construction work in progress		217,561			163,277
Total	$	620,041		$	561,119
Less: Accumulated depreciation and amortization		(234,417	)		(219,724	)
Property, plant & equipment, net	$	385,624		$	341,395

Depreciation expense for Property, plant and equipment was $7,507 and $6,640 for the three months ended June 30, 2026 and 2025, respectively, and $15,476 and $12,548 for the six months ended June 30, 2026 and 2025, respectively. Depletion expense for gas mineral rights was $91 for both the three months ended June 30, 2026 and 2025, and $182 for both the six months ended June 30, 2026 and 2025.

Construction work in progress consists of RNG and REG capital expenditures on developmental projects and improvements to existing sites. Development projects, on average, last between 18 to 36 months, and when completed for their intended use, costs are placed in service and begin depreciating.