From Official Factorio Wiki
Fuel is every item that can be burned to provide energy to the structure. The Items differ in fuel value which is the provided energy portion.
A list of all items usable as fuel in burner devices ordered by fuel value.
|Wooden chest||6 kJ|
|Raw wood||4 kJ|
Burner devices to be fueled directly
|Burner inserter||Boiler||Stone furnace |-||Steel furnace||Diesel locomotive||Car |-||Burner mining drill|