Mechanical and electrical power are produced along with synthesis or fuel gas by the partial oxidation process with integrated combustion and steam turbines. By-product vaporized liquefied natural gas for feed to a pipeline for gas consumers is obtained by heat exchange with heat containing streams from the partial oxidation gasification and gas cleaning and purification zone; and optionally from heat containing streams from combustion and/or steam turbine zones which are integrated with the partial oxidation process. Heat from the combustion turbine exhaust gas is used as follows: (1) superheat steam for use in a steam turbine; (2) preheat water saturated clean sulfur-free synthesis or fuel gas with or without supplemental methane enrichment; (3) preheat oxygen gas for the partial oxidation zone; and (4) vaporize LNG. Pre, inter, and after stages of an air compressor are cooled by indirect heat exchange with LNG which is thereby warmed or vaporized.