Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2021

Property, plant and equipment at December 31, 2021 and 2020 consisted of the following:


	Estimated Useful Life (in Years)	2021		2020
Energy systems	10 - 15 years	$	3,556,488	$	3,526,514
Machinery and equipment	5 - 7 years	1,463,153		1,448,024
Furniture and fixtures	5 years	193,698		193,698
Computer software	3 - 5 years	192,865		192,865
Leasehold improvements	*	466,789		450,792
		5,872,993		5,811,893
Less - accumulated depreciation and amortization		(4,090,049)		(3,528,047)
Net property, plant and equipment		$	1,782,944	$	2,283,846

* Lesser of estimated useful life of asset or lease term