Combustion
Fuel reacts with oxygen and release energy. Complete combustion happens in a plentiful supply of air. Incomplete combustion occurs when the supply of air is limited. Complete combustion releases more energy than incomplete combustion. Incomplete combustion also creates carbon monoxide, and more soot. Several factors must be considered when choosing the best fuel for a particular purpose. Fuels are substances that react with oxygen to release useful energy. Most of the energy is released as heat, but light energy is also released. About 21 per cent of the air is oxygen.