Chimney Safety Institute of America (CSIA) Certification Practice Test

What does pyrolysis refer to?

1. The combustion of wood

2. The chemical alteration of wood as a result of heat application

3. The process of wood decay

4. The creation of ash from burning wood

The correct answer is: The chemical alteration of wood as a result of heat application

Pyrolysis refers to the chemical alteration of wood as a result of heat application without the presence of oxygen. During pyrolysis, organic materials decompose thermally at elevated temperatures, leading to the breakdown of complex molecules into simpler substances. This process produces char, bio-oil, and syngas, which can be utilized for various energy and material applications. In contrast, other terms describe distinct processes. Combustion of wood involves burning it in the presence of oxygen, which leads to energy release and ash production. The term "wood decay" typically refers to biological decomposition, primarily driven by fungi and bacteria, which is a separate natural process. Finally, the creation of ash is specifically a byproduct of wood combustion, rather than a transformation like pyrolysis. Thus, the definition around chemical alteration through heat application accurately captures the essence of pyrolysis within the broader context of thermal processes.