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 (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.