Discribe how an internal combustion engine works. What is drawback to the type of power?

An internal combustion engine is a heat engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. The force of combustion is converted into mechanical energy through the use of levers and gears. The by products of combustion include energy, water vapor, carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), and carbon monoxide (CO). The two primary drawbacks to the internal combustion engine are the primary energy source is non-renewable (fossil fuels) and the by products can have damaging effects on the environment.