| Schedule of Intangible Assets | 
As of March 31, 2019 and December 31, 2018 the Company had the following amounts related to intangible assets and liabilities other than goodwill:
 
|  |  
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  
|   |   | March 31, 2019 |   | December 31, 2018 |  
| Intangible assets |   | Cost |   | Accumulated Amortization |   | Total |   | Cost |   | Accumulated Amortization |   | Total |  
| Product certifications |   | $ | 726,159 | 
 |   | $ | (359,221 | ) |   | $ | 366,938 | 
 |   | $ | 726,159 | 
 |   | $ | (345,658 | ) |   | $ | 380,501 | 
 |  
| Patents |   | 923,849 | 
 |   | (193,524 | ) |   | 730,325 | 
 |   | 910,569 | 
 |   | (188,239 | ) |   | 722,330 | 
 |  
| Developed technology |   | 240,000 | 
 |   | (96,000 | ) |   | 144,000 | 
 |   | 240,000 | 
 |   | (92,000 | ) |   | 148,000 | 
 |  
| Trademarks |   | 25,252 | 
 |   | — | 
 |   | 25,252 | 
 |   | 22,752 | 
 |   | — | 
 |   | 22,752 | 
 |  
| In Process R&D |   | 263,936 | 
 |   | — | 
 |   | 263,936 | 
 |   | 263,936 | 
 |   | — | 
 |   | 263,936 | 
 |  
| Favorable contract asset |   | 274,858 | 
 |   | (257,817 | ) |   | 17,041 | 
 |   | 1,561,739 | 
 |   | (232,099 | ) |   | 1,329,640 | 
 |  
| TTcogen intangible assets |   | 29,607 | 
 |   | (925 | ) |   | 28,682 | 
 |   | — | 
 |   | — | 
 |   | — | 
 |  
|   |   | $ | 2,483,661 | 
 |   | $ | (910,262 | ) |   | $ | 1,573,399 | 
 |   | $ | 3,754,762 | 
 |   | $ | (860,772 | ) |   | $ | 2,893,990 | 
 |  
|   |   |   |   |   |   |   |   |   |   |   |   |   |  
| Intangible liability |   |   |   |   |   |   |   |   |   |   |   |   |  
| Unfavorable contract liability |   | $ | 4,689,025 | 
 |   | $ | (1,818,686 | ) |   | $ | 2,870,339 | 
 |   | $ | 8,341,922 | 
 |   | $ | (876,972 | ) |   | $ | 7,464,950 | 
 |  |