How a Special Reactor Makes Methane Fuel Without Constant Electricity

This patent describes a method for a Solid Oxide Electrolyser Cell (SOEC) reactor to produce methane, even when electricity is scarce, by switching from electrolysis to a heat-generating chemical reaction.

What it covers

This patent details a two-step process for operating a Solid Oxide Electrolyser Cell (SOEC) stack reactor, where the cathodes are made of catalytic material. First, when electricity is available (step a/ of claim 1), the reactor performs high-temperature electrolysis, splitting steam or a mix of steam and carbon dioxide to produce hydrogen or a mix of hydrogen and carbon monoxide. Second, when the electricity supply becomes insufficient for electrolysis (step b/ of claim 1), the reactor switches modes. It is then supplied with a mixture of hydrogen and carbon monoxide (synthesis gas) or hydrogen and carbon dioxide. This mixture undergoes a methanation reaction at the same cathodes, producing methane. This methanation reaction is exothermic, meaning it releases heat, which helps keep the reactor at its operating temperature without needing continuous electricity. For example, a reactor powered by solar panels could produce hydrogen during the day and then use that hydrogen to make methane at night, keeping itself warm.

What it doesn't cover

• —Does not cover methanation processes that do not occur within an SOEC-type stack reactor where the cathodes are specifically made of methanation catalyst material(s).
• —Does not cover systems where the reactor is only used for electrolysis or only for methanation, without the ability to switch between these two modes based on electricity availability.
• —Does not cover methanation reactions that are not performed by 'heterogeneous catalysis' at the cathode.
• —Does not cover producing methane when electricity is fully available for electrolysis, as the patent specifically addresses operating when the electric current is 'insufficient' for electrolysis.
• —Does not cover reactors that lack the specific arrangement of electrical and fluid interconnectors between adjacent elemental cells as described in claim 1.

The clever bit

The core innovation is using the *same* SOEC reactor, with its catalyst-embedded cathodes, to perform *both* high-temperature electrolysis (when electricity is available) and exothermic methanation (when electricity is not), using the heat from the methanation reaction to keep the reactor at operating temperature.

Why it matters

This patent addresses a significant challenge in renewable energy: its intermittent nature. By allowing a single reactor to both produce hydrogen/syngas when electricity is abundant and then convert it to methane when electricity is scarce, it offers a way to store excess renewable energy in a chemical form. Methane is easier to store and transport than hydrogen and can be integrated into existing gas infrastructure, making renewable energy more reliable and usable on demand.

Real-world examples

• 1.Power-to-gas energy storage systems
• 2.Synthetic natural gas production from renewable electricity
• 3.Industrial processes for carbon dioxide utilization
• 4.Chemical energy storage for grid balancing