Compost Lab - Heat generation

Scott Holloway


Can a compost pile generate enough heat to combust?

California Standards


3. Energy cannot be created or destroyed, although in many processes energy is transferred to the environment as heat. As a basis for understanding this concept:

a. Students know heat flow and work are two forms of energy transfer between systems. 

c. Students know the internal energy of an object includes the energy of random motion of the object’s atoms and molecules, often referred to as thermal energy. The greater the temperature of the object, the greater the energy of motion of the atoms and molecules that make up the object.

d. Students know that most processes tend to decrease the order of a system over time and that energy levels are eventually distributed uniformly. 

Chemical Thermodynamics 

7.  Energy is exchanged or transformed in all chemical reactions and physical changes of matter. As a basis for understanding this concept: 

a. Students know how to describe temperature and heat flow in terms of the motion

b. Students know chemical processes can either release (exothermic) or absorb (endothermic) thermal energy.


Composting is the recycling of matter, typically vegetative, by the use of natural decomposition.  

Compost fires require oxygen and fuel, which is provided by the organic materials typically composted. Compost fires can be caused by spontaneous combustion, lightning strikes, heat from equipment or vehicles, sparks from welding activities, wildfires and arson. Spontaneous combustion is the most common cause.

Compost a suspect in the Sept. 20, 2009 fire in Southern California.  (mp3)