Fuel

A fuel is a chemical substance whose stored energy can be converted into usable energy by combustion.

There are various types of fuels like solid, liquid and gaseous. The category of solid fuels includes wood and coal. Heating oil and alcohols belong to liquid and natural gas, biogas and liquid gas to gaseous fuels. Depending on the fuel type, different requirements of the exhaust system must be met.

In addition there are fossil fuels and renewable fuels. Although renewable materials grow again and are infinite (e.g. wood / biogas), fossil fuels were created tens of thousands of years ago and today they are only mined, e.g. coal. So fossil fuels are finite and cannot be replicated.