NOVELTY - Preparation of gaseous effluent (I) rich in hydrogen, carbon monoxide and other fuel gases of composition (A1) from a feed of heterogeneous organic material comprised of e.g. municipal trash and refuse, comprises anaerobic gasification and pyrolysis (in a reactor) that is caused by a hot driver gas devoid of free oxygen and of sufficient heat and water content to effect the conversion reactions and produced externally to the reactor chamber.    USE - (I) is useful: as fuel to gas turbine; for generating electricity; and useful in petroleum refining industry to convert and to treat refinery streams, for making cleaner and more valuable products.    ADVANTAGE - (I) has maximum energy conversion from the organic material, high volume consumption of the organic feed material, less pollution of gaseous products than prior art systems and solid residuals for disposal are minimal and non-hazardous. The process is simple, convenient and cost effective. The process: handles a higher amount of wet feeds than other types of gasifiers because of the very effective drying zone; avoids the potential of explosive mixtures of oxidant and fuel; maximizes the oxidation rate for heat and oxygen control by putting it completely into the gas phase; provides either a mode of recycling organic liquid or removing a liquid oil/tar phase product as the economics of recovery dictate; and provides a high enough gas flow to reduce pyrolysis section residence time below that required for secondary (reaction with solid matrix material) formation of dioxins and furans.    DETAILED DESCRIPTION - Preparation of gaseous effluent (I) rich in hydrogen, carbon monoxide and other fuel gases of composition (A1) of formula (CxHy) from a feed of heterogeneous organic material comprised of municipal trash, refuse, garbage or other post-consumer wastes, comprises anaerobic gasification and pyrolysis (in a reactor) that is caused by a hot driver gas devoid of free oxygen and of sufficient heat and water content to effect the conversion reactions and produced externally to the reactor chamber.    An INDEPENDENT CLAIM is also included for a preparation of hydrocarbon gases (II) from a feed of heterogeneous organic material (where the heat source comprises a hot driver gas that performs: gasifying the carbon in the pyrolytic residual char/slag to less than 0.1 wt.% of the final solid effluent via the reaction of carbon with water to give carbon monoxide and hydrogen, making a syngas product that adds to the total driver gas stream; liquefying the pyrolytic slag material to allow for its ultimate removal from the reactor; providing complete or nearly complete pyrolytic decomposition of the organic feed material; providing all the sensible heat necessary to raise the feed material to the appropriate decomposition temperatures; and drying and removing water entrained by surface adsorption or other physico-chemical attraction to the feed material charged into the reactor).