Integration of industrial gas site with liquid hydrogen production

A method for liquefying a pressurized hydrogen gas originating from a pressure swing adsorber unit, the method comprising the steps of:

• withdrawing a hydrogen containing gas from a methanol production unit;
• introducing the hydrogen containing gas to a pressure swing adsorber (PSA) unit under conditions effective for purifying the hydrogen containing gas to produce a purified hydrogen stream;
• sending the purified hydrogen gas to a hydrogen liquefaction unit under conditions effective for the liquefaction of hydrogen thereby producing a liquefied hydrogen stream,
• wherein the hydrogen liquefaction unit is configured to provide a first refrigeration source and a second refrigeration source, wherein the first refrigeration source provides refrigeration using expansion of a high pressure nitrogen stream, wherein the second refrigeration source provides refrigeration using expansion of a high pressure hydrogen gas stream to produce a warm hydrogen gas stream,
• wherein the high pressure hydrogen gas stream is derived from a hydrogen stream selected from the group consisting of the purified hydrogen stream, a second purified hydrogen stream withdrawn from a second PSA unit, and combinations thereof.