A gasification process for making producer gas is disclosed. A consistent quality of raw carbon source material is supplied for gasification. The impurity content of the raw carbon source material is adjusted to within an acceptable consistent range of impurity content. The raw carbon source material is heated in a non-oxidizing environment to adjust the tar content and to remove volatile hydrocarbon constituents and to produce a devolatilized carbon source material. The devolatilized carbon source material is gasified by heating the carbon source material to a gasification temperature in a gasification generator, supplying steam, and supplying enhanced oxygen content air to react with the devolatilized carbon source material and to thereby form consistent, high energy value, low impurity producer gas.