TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred components: In step (D), an absorbent and at least one selective membrane or film, are used for removing the hydrogen sulfide and carbon dioxide respectively; and at least one hydrogen-permeable membrane is used to remove hydrogen from the hydrogen-rich gas. The absorbent is activated charcoal and/or zinc oxide. The membrane or film is selected from cellulose acetate, polysulfone or polyimide membrane; and made up of fluorinated polymers. For producing the high purity hydrogen product steam, a steam reformer and a high temperature shift/membrane reactor are used. The high temperature shift/membrane reactor, in one unit comprises a reactor (R1) that generates hydrogen and at least one hydrogen-permeable membrane that extracts hydrogen. (R1) Comprises a chamber; an inlet port for introducing the compressed, mixed gas stream into the chamber; several of hydrogen-permeable membranes in the form of tubes having an outer and inner surface in fluid communication with the compressed gas stream and a hydrogen product stream respectively that passes through the tubes housed within the chamber; a catalyst located within the chamber for facilitating an exothermic water-gas shift reaction; a first and second outlet port for removing the hydrogen product stream and a waste gas stream respectively; and optionally, cooling device for withdrawing thermal energy from the chamber.Preferred Method: The hydrogen-rich gas is generated by reacting steam with the compressed, mixed gas stream in presence of a catalyst to form a gas containing hydrogen, carbon dioxide or carbon monoxide, as principle components; and reacting the carbon monoxide in the formed gas with steam to produce carbon dioxide and additional hydrogen. After step (B), optionally condensing the mixed gas stream and passing the condensed stream to at least one gas-driven engine for fueling. The engine powers a generator, at least one mixed gas-fired reforming furnace, at least one steam boiler and optionally a first and second compressor. The generator produces electrical energy for powering a hydrogen generation and removal system and/or a mixed gas purification device. In step (D), after removing hydrogen sulfide and/or carbon dioxide by using the purification device, the resulting purified, mixed gas stream passes into the second compressor for compressing and directing the resultant compressed gas stream into a natural gas pipeline and/or storage receptacles; and after generating hydrogen-rich gas by using the hydrogen generation and removal system, the resulting high purity hydrogen product stream passes to at least one hydrogen fueled device and/or to the second compressor.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred System: The compressor compresses the mixed gas stream from the digester to a pressure of at least 2.17 (preferably at least 2.86, especially at least 20.8) megapascals exceeding the operating pressure of the purification device or the hydrogen generation and removal system. The system optionally contains a condenser in fluid communication with the anaerobic digester. When the system is used for the production of high-purity hydrogen gas, it optionally contains a device for directing the high-purity hydrogen product stream exiting the hydrogen generation and removal system to low-pressure hydrogen fueled devices and a device for directing the hydrogen product stream exiting the second compressor to at least one high pressure storage receptacles.