Syngas (from synthesis gas) is the name given to gasses of varying composition that are generated in coal gasification and some types of waste-to-energy facilities. The name comes from their use in creating synthetic petroleum for use as a fuel or lubricant via Fischer-Tropsch synthesis.

Syngas consists primarily of carbon monoxide and hydrogen, and has less than half the energy density of natural gas. It also contains some sulfur compounds, a safety feature since this allows for its detection in the case of leakage. Syngas can be produced from natural gas as follows:

CH₄ + H₂O → CO + 3 H₂

These gasses are combustible, and are often stored to be burned as a fuel source.

For the most part, the amount of synthetic gas produced in a waste to energy facility is only enough to keep the plant operating.

Coal gasification processes[1] (e.g., the water gas process) are reasonably efficient and were used for many years to manufacture illuminating gas (coal gas) for gas lighting, before electric lighting became widely available.