Syngas consists primarily of carbon monoxide and hydrogen, and has less than half the energy density of natural gas. Syngas can be produced from natural gas as follows:
CH4 + H2O ==> CO + 3 H2These gasses are combustible, and are often stored to be burned as a fuel source.
For the most part, the ammount 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 for gas lighting, before electric lighting became widely available.