Annual report pursuant to Section 13 and 15(d)

Related party transactions (Details)

v3.8.0.1
Related party transactions (Details)
1 Months Ended 9 Months Ended 12 Months Ended
Aug. 02, 2016
$ / shares
shares
Jan. 31, 2017
USD ($)
Jul. 31, 2016
USD ($)
$ / shares
shares
Sep. 30, 2017
USD ($)
company
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
$ / shares
May 19, 2016
Dec. 28, 2015
USD ($)
Related Party Transaction [Line Items]                
Number of affiliated companies | company       2        
Equity interest in joint venture (percent)       43.00%        
Warrant exercise price per share (in dollars per share) | $ / shares     $ 4.00     $ 4.00    
Proceeds from exercise of warrants     $ 2,700,000   $ 0 $ 2,700,000    
Investments in joint venture       $ 13,500,000        
Return of investment in Ultra Emissions Technologies Ltd         2,000,000 0    
Purchase of remaining assets of Ultratek         580,044 139,725    
Office space and warehouse facilities                
Related Party Transaction [Line Items]                
Sublease rental         34,995 63,842    
Affiliated companies                
Related Party Transaction [Line Items]                
Payments to acquire used equipment   $ 985,000            
Affiliated companies | Sublease under operating leased assets | Office space and warehouse facilities                
Related Party Transaction [Line Items]                
Sublease rental         48,092 34,995    
Affiliated companies | TTcogen, LLC                
Related Party Transaction [Line Items]                
Due from related party         585,492 107,377    
Revenue from related parties         347,275 93,143    
Affiliated companies | Tedom USA                
Related Party Transaction [Line Items]                
Due from related party         10,259 692    
Affiliated companies | Ultratek                
Related Party Transaction [Line Items]                
Return of investment in Ultra Emissions Technologies Ltd         2,000,000      
Purchase of remaining assets of Ultratek         400,000      
Due from related party         0 $ 65,631    
Co-venturer                
Related Party Transaction [Line Items]                
Investments in joint venture       8,500,000        
Chief Executive Officer (John N. Hatsopoulos)                
Related Party Transaction [Line Items]                
Officers' compensation         $ 1      
Percentage of time spent on company affairs         50.00%      
Ultra Emissions Technology Ltd.                
Related Party Transaction [Line Items]                
Equity interest in joint venture (percent)               50.00%
TTcogen, LLC                
Related Party Transaction [Line Items]                
Equity interest in joint venture (percent)             50.00%  
Offshore Investors                
Related Party Transaction [Line Items]                
Investment by other party to joint venture               $ 3,000,000
Tedom a.s.                
Related Party Transaction [Line Items]                
Equity interest in joint venture (percent)             50.00%  
Warrant                
Related Party Transaction [Line Items]                
Warrants exercised (shares) | shares     675,000          
Warrant | Ultra Emissions Technology Ltd.                
Related Party Transaction [Line Items]                
Warrants exercised (shares) | shares 2,000,000              
Warrant exercise price per share (in dollars per share) | $ / shares $ 1.00              
Chief Executive Officer (John N. Hatsopoulos)                
Related Party Transaction [Line Items]                
Loan from related party       $ 850,000 $ 850,000      
Chief Executive Officer (John N. Hatsopoulos) | Demand notes                
Related Party Transaction [Line Items]                
Stated interest rate (percent)       6.00% 6.00%