The invention relates to a method for producing hydrogen, in which, in a non-electrolytic method, a carbonaceous feed material is converted into non-electrolytically produced hydrogen and one or more further non-electrolytically produced products, and furthermore excess steam is provided using the non-electrolytic process. According to the invention at least a part of the excess steam is used at least intermittently to provide feed steam, which is converted by means of steam electrolysis to electrolytic hydrogen and electrolytic oxygen. The present invention also relates to a corresponding plant.

An electrolysis system includes at least one H.sub.2O electrolysis apparatus that electrolyzes water to produce hydrogen; and at least one CO.sub.2 electrolysis apparatus that electrolyzes carbon dioxide to produce carbon monoxide. The electrolysis system includes a co-electrolysis apparatus that co-electrolyzes water and carbon dioxide to produce less hydrogen per unit time than produced by the at least one H.sub.2O electrolysis apparatus and less carbon monoxide per unit time than produced by the at least one CO.sub.2 electrolysis apparatus.

An electrolysis system includes at least one H.sub.2O electrolysis apparatus that electrolyzes water to produce hydrogen; and at least one CO.sub.2 electrolysis apparatus that electrolyzes carbon dioxide to produce carbon monoxide. The electrolysis system includes a co-electrolysis apparatus that co-electrolyzes water and carbon dioxide to produce less hydrogen per unit time than produced by the at least one H.sub.2O electrolysis apparatus and less carbon monoxide per unit time than produced by the at least one CO.sub.2 electrolysis apparatus.

A carbon dioxide gas phase reduction device includes an oxidation tank including an oxidation electrode, a reduction tank to which carbon dioxide is supplied, an intermediate tank that is disposed between the oxidation tank and the reduction tank and capable of pouring and discharging an electrolytic solution, an ion exchange membrane disposed between the oxidation tank and the intermediate tank, a gas reduction sheet in which an ion exchange membrane and a reduction electrode are laminated and which is disposed between the reduction tank and the intermediate tank with the ion exchange membrane facing the intermediate tank and the reduction electrode facing the reduction tank, and a conducting wire connecting the oxidation electrode to the reduction electrode.

A carbon dioxide gas phase reduction device includes an oxidation tank including an oxidation electrode, a reduction tank to which carbon dioxide is supplied, an intermediate tank that is disposed between the oxidation tank and the reduction tank and capable of pouring and discharging an electrolytic solution, an ion exchange membrane disposed between the oxidation tank and the intermediate tank, a gas reduction sheet in which an ion exchange membrane and a reduction electrode are laminated and which is disposed between the reduction tank and the intermediate tank with the ion exchange membrane facing the intermediate tank and the reduction electrode facing the reduction tank, and a conducting wire connecting the oxidation electrode to the reduction electrode.

Methods and systems related to the field of electrolyzers are disclosed. An electrolyzer assembly is disclosed which includes a stack of cells, a plurality of polar plates in the stack of cells, a plurality of flow fields between the plurality of polar plates, a conduit fluidly connecting flow fields in the plurality of flow fields, an electrically conductive fluid in the conduit, a plurality of insulating layers arranged between a conductive surface of the plurality of flow fields and the conduit, and a plurality of openings in the plurality of insulating layers providing a plurality of fluid connections between the conduit and the plurality of flow fields.

A cathode electrode for a gas diffusion electrolytic flow cell that produces a carbon dioxide reduction product by reducing carbon dioxide, wherein the cathode electrode comprises a catalyst layer having a metal complex catalyst, a carbon material and an alkali metal salt, and a gas diffusion layer disposed on the catalyst layer.

A cathode electrode for a gas diffusion electrolytic flow cell that produces a carbon dioxide reduction product by reducing carbon dioxide, wherein the cathode electrode comprises a catalyst layer having a metal complex catalyst, a carbon material and an alkali metal salt, and a gas diffusion layer disposed on the catalyst layer.

An electrolysis system and an electrolysis method wherein the electrolysis system includes a pressure-electrolytic cell and a throttle in the catholyte line, by which the catholyte flow can be divided into a gas and liquid phase. In this way, (by-)products of the electrolysis can be recycled, while the electrolytic cell can be operated effectively at a high pressure.

An electrolysis system and an electrolysis method wherein the electrolysis system includes a pressure-electrolytic cell and a throttle in the catholyte line, by which the catholyte flow can be divided into a gas and liquid phase. In this way, (by-)products of the electrolysis can be recycled, while the electrolytic cell can be operated effectively at a high pressure.