High-Temperature Combustion
Plastics are a hydrocarbon compound, similar to fuel oil, kerosene, or natural gas for example. Hydrocarbons burn well and cleanly when combined with sufficient air. As a general rule, the higher the temperature of combustion, the lower the products of incomplete combustion (PIC) escaping in the form of air emissions, or simply put, air pollution. As an example, plastics burned in a burn barrel generate flame temperatures in the 400-700oF range, and the intense smoke coming from the barrel is indicative of poor combustion, with many harmful PICs given off. In contrast, in controlled combustion devices, temperatures in the 2000oF range emit very few PICs, and hence this rather complete combustion is relatively free of harmful emissions.
Shown in the table below are various heats of combustion of materials when they are burned in a test device called a bomb calorimeter. Values shown are what are termed high heat values (HHV), which includes heat absorbed by the calorimeter when the products of combustion are cooled to ambient temperature.
| Material | Btu / lb. |
| Fuel oil | 20,900 |
| Polyethylene plastic (pots, mulch) | 19,900 |
| Polypropylene plastic (twine, lids) | 19,850 |
| Gasoline | 19,200 |
| Polystyrene plastic (inserts, Styrofoam) | 17,800 |
| PA Kittanning coal | 13,900 |
| Wyoming coal | 9,000 |
| Newspaper | 8,000 |
| Textiles | 6,900 |
| Wood | 6,700 |
| Avg. Municipal waste | 6,500 |
| Yard waste | 3,000 |
| Food waste | 2,600 |