TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Component: The system comprises gasification reactors (a-d), single catalyst loading unit, catalyst loading units (c1 and c2, c1, c2 and c3, or c1, c2, c3 and c4), single carbonaceous material processing unit, or carbonaceous material processing units (m1 and m2, m1, m2 and m3, or m1, m2, m3 and m4), single heat exchanger unit, or heat exchanger units (h1 and h2, or h1, h2, h3 and h4), single acid gas remover unit, single methane removal unit and single steam source, or steam sources (s1 and s2), preferably gasification reactors (a-d), single catalyst loading unit or catalyst loading units (c1 and c2), single carbonaceous material processing unit or carbonaceous material processing units (m1 and m2), heat exchanger units (h1 and h2), single acid gas remover unit, single methane removal unit and single steam source, or steam sources (s1 and s2). The system further comprises a trace contaminant removal unit between a heat exchanger unit and an acid gas remover unit, to remove a substantial portion(s) of trace contaminants from the single cooled gas stream (b1) or cooled gas streams (g1, g2, g3 and g4) further containing trace contaminants of carbonyl sulfide, mercury and hydrogen cyanide, a reformer unit to convert a portion of single methane product stream into syngas, a methane compressor unit to compress a portion(s) of the single methane product stream, a carbon dioxide recovery unit to separate and recover methane carbon dioxide removed by single acid gas remover unit, a sulfur recovery unit to extract and recover sulfur from hydrogen sulfide removed by single acid gas remover unit, a catalyst recovery unit to extract and recover a portion(s) of the entrained catalyst from a portion(s) of the solid char product, and recycle a portion(s) of the recovered catalyst to the single catalyst loading unit, or catalyst loading units (c1, c2, c3 and c4), a gas recycle loop to recycle a portion(s) of the single methane-depleted gas stream to gasification reactors (a-d), a waste water treatment unit to treat waste water generated by the system, a super-heater to superheat the steam in or from the single steam source, or steam source (s1 and/or s2), a steam turbine to generate electricity from a portion(s) of the steam supplied by the single steam source, or steam source (s1 and/or s2) and/or a sour shift unit provided between heat exchanger and acid gas remover unit, and to contact a cooled gas stream (g1) with an aqueous medium and to convert a portion(s) of carbon monoxide in the cooled gas stream (g1) to carbon dioxide, preferably carbon dioxide recovery unit, sulfur recovery unit and catalyst recovery unit, carbon dioxide recovery unit and a carbon dioxide compressor unit to compress recovered carbon dioxide, sour shift unit and a trim methanator between an acid gas remover unit and a methane removal unit.