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


	March 31, 2026			December 31, 2025
Land	$	1,568		$	1,568
Buildings and improvements		38,914			38,914
Machinery and equipment		324,311			321,834
Gas mineral rights		35,526			35,526
Construction work in progress		198,087			163,277
Total	$	598,406		$	561,119
Less: Accumulated depreciation and amortization		(226,916	)		(219,724	)
Property, plant & equipment, net	$	371,490		$	341,395

Depreciation expense for Property, plant and equipment was $7,969 and $5,908 for the three months ended March 31, 2026 and 2025, respectively. Depletion expense for gas mineral rights was $91 and $90 for the three months ended March 31, 2026 and 2025, respectively.

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.