Gasification is a thermo-chemical process that generates a fuel rich gas. Two processes take place in the Moss gasifier in order to produce a useable gas. In the first stage, pyrolysis releases the volatile components of the fuel at temperatures below 1100°F (593°C). The by-product of pyrolysis, which is not vaporized, is called char and consists mainly of fixed carbon and ash. In the second stage of gasification, the carbon remaining after pyrolysis is either reacted with steam or combusted with ambient air, mixture of ambient air with recirculation air (FGR) or pure oxygen. Gasification with air results in a nitrogen rich low BTU gas. Gasification utilizing pure oxygen results in a higher quality mixture of carbon monoxide and hydrogen with virtually no nitrogen. Gasification with steam produces a hydrogen and carbon dioxide rich synthetic gas called syngas. Usually the exothermic reaction between carbon and oxygen provides the heat energy required to drive the pyrolysis and char gasification reactions.