Property, plant and equipment and construction in progress (Details) - USD ($)	Dec. 31, 2025	Dec. 31, 2024
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	$ 144,452,605	$ 141,260,376
Less accumulated depreciation	89,300,847	88,828,094
Property, plant and equipment, net	55,151,758	52,432,282
Construction in progress	6,695,656	5,143,717
Land
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	5,903,738	5,903,738
Land improvement
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	1,639,615	403,351
Buildings
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	27,552,216	26,033,866
Plant and equipment
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	59,933,437	61,089,877
Distribution system
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	40,639,053	40,402,691
Office furniture, fixtures and equipment
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	3,398,386	3,277,313
Vehicles
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	5,072,211	3,830,539
Leasehold improvements
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	306,545	306,545
Lab equipment
Property, plant and equipment and construction in progress
Property, plant and equipment, gross	$ 7,404	$ 12,456