Property, plant and equipment and construction in progress (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 136,109,235	$ 135,071,263
Less accumulated depreciation	83,162,696	77,383,279
Property, Plant and Equipment, Net, Total	52,946,539	57,687,984
Construction in progress	710,863	440,384
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,316,537	3,566,537
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	23,255,925	23,250,843
Plant And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	64,324,377	63,734,860
Distribution Systems [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	39,780,272	39,149,063
Office furniture, fixtures and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	3,051,814	3,083,811
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	2,079,874	1,999,463
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	287,980	274,230
Lab equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 12,456	$ 12,456