TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Components: The syngas generation unit comprises a steam methane reformer or a pre-former. The unreacted dimethyl ether in the plant is separated from the shift effluent and recycled to the pre-former or to the WGS reactor. The hydrogen purification unit is a pressure swing adsorption unit.Preferred Plant: The plant further comprises either at least two separate process lines (L2) and L2 for production of at least two hydrogen gas streams.(L1) contains:(i) a hydrocarbon source;(ii) a syngas generation unit (a) for producing syngas stream(iii) a WGS reactor (b) for producing a hydrogen-enriched gas stream; and(iv) a purification unit for producing a purified hydrogen stream;(L2) contains:(a) a hydrocarbon source;(b) a syngas generation unit (c) for producing syngas stream;(c) a WGS reactor (d) capable of implementing endothermic overall dimethyl ether reaction to hydrogen enriched gas for producing hydrogen-enriched gas stream(d) a dimethyl ether source with its associated system for supplying the reactor with dimethyl ether; and(e) a purification unit for producing a purified hydrogen stream;At least one process line (L3), for producing at least one hydrogen gas stream, contains:(i) a hydrocarbon source;(ii) a syngas generation unit (e) for producing syngas stream;(iii) a WGS reactor (f) capable of implementing endothermic overall dimethyl ether reaction to hydrogen enriched gas for producing hydrogen-enriched gas stream;(iv) a dimethyl ether source with its associated system for supplying the reactor with dimethyl ether, and a purification unit for producing a purified hydrogen stream;At least one process line (L6) for producing at least one hydrogen gas stream, contains:(i) a hydrocarbon source;(ii) a syngas generation unit (g) for producing syngas stream;(iii) a WGS reactor (h) capable of implementing endothermic overall dimethyl ether reaction to hydrogen enriched gas for producing hydrogen-enriched gas stream;(iv) a dimethyl ether source with its associated system for supplying the reactor with dimethyl ether; and(v) a purification unit for producing a purified hydrogen stream.The lines (L1) and (L2) are connected together after the reactors (a) and (c) and before the reactors (b) and (d) by a pipe capable of tapping off a fraction of the syngas stream to (d) in the event of failure of (c).The plant containing line (L3) further comprises at least one carbon monoxide production unit for producing a carbon monoxide stream; at least one pipe connecting the line (L3) after the reactor (e) and before the reactor (f) to the supply for the carbon monoxide production unit; and at least one pipe connecting the unit to the line (L3), after the reactor (f) and before the purification unit, for supplying the unit with a hydrogen-enriched stream in such a way as to produce carbon monoxide from the hydrocarbon stream that comes from the hydrogen source while at the same time maintaining the nominal purified-hydrogen production of the plant. The WSG reactor, the purification unit and the fluid transport pipes associated with them allows production of larger amounts of H2 than the nominal amount corresponding to the initial stream of hydrocarbons coming from the source and feeding (e). The plant containing (L6) further comprises at least one carbon monoxide source on the site of the plant or in its immediate vicinity; and a pipe connecting the carbon monoxide source to the line (L6) after (g) and before (h) in such a way as to substituted carbon monoxide coming from the carbon monoxide source with all or part of the syngas that supplies (h) in the event of failure of (g) that is producing the syngas.