4. INVESTMENT IN SALES-TYPE LEASES, NET

Under sales-type leases, Xi’an TCH leases the following systems: (i) BMPG systems to Pucheng Phase I and II (15 and 11 year terms, respectively); (ii) BMPG systems to Shenqiu Phase I (11-year term); and (iii) Shenqiu Phase II (9.5-year term). In addition, as of June 30, 2016, Erdos TCH leased power and steam generating systems from waste heat from metal refining to Erdos (five systems) for a term of twenty years. The components of the net investment in sales-type leases as of June 30, 2016 and December 31, 2015 are as follows:

	2016			2015
Total future minimum lease payments receivable	$	251,758,685		$	387,612,418
Less: executory cost		(71,723,294	)		(93,054,738	)
Less: unearned interest income		(62,545,595	)		(154,799,027	)
Investment in sales-type leases, net		117,489,796			139,758,653
Current portion		5,629,204			6,679,019
Noncurrent portion	$	111,860,592		$	133,079,634

As of June 30, 2016, the future minimum rentals to be received on non-cancelable sales-type leases by years are as follows:

2017	$	22,839,682
2018		20,098,462
2019		20,214,464
2020		21,413,149
2021		23,056,507
Thereafter		144,136,421
Total	$	251,758,68