A Methanation Method and System

Abstract

Disclosed is a methanation method comprising an electrolyser system, the electrolyser system (20) comprising an electrolyser (10) having at least one electrolyser cell (11), at least one fuel input (1

Claims

1. A methanation method comprising providing an electrolyser system, the electrolyser system comprising an electrolyser that has at least one electrolyser cell, at least one fuel input 5 through which fuel enters the electrolyser and at least one offgas output from which offgas exits the electrolyser, the method further comprising:supplying fuel to the at least one fuel inlet, the fuel comprising at least water and either or both carbon dioxide and carbon monoxide;operating the electrolyser system by powering the electrolyser cell with electricity to 10 electrolyse the fuel in the at least one electrolyser cell such that a part of the water splits into hydrogen and oxygen;wherein the electrolyser is operated at a temperature at or in excess of 150 degrees C;methanation occurs to the carbon dioxide and / or carbon monoxide in the electrolyser 15 and;the electrolyser cell is operating in an endothermic condition.

2. The method of claim 1, wherein the fuel is a mixture of steam and carbon dioxide.

3. The method of any one of the preceding claims, wherein separate streams of steamand carbon dioxide are fed to the fuel inlet.20 4. The method of any one of the preceding claims, wherein there are two offgas outputs,comprising a first for the methane and steam and a second for the oxygen.

5. The method of any one of the preceding claims, wherein the gas mixture released from the at least one offgas output is passed through a gas separation process to separate at least the methane from the gas mixture.25 6. The method of claim 5, wherein the gas separation process comprises a condensationstep to condense a majority of the water out of the gas mixture.

7. The method of claim 5 or claim 6, wherein the gas separation process comprises aCO2 separation step to separate a majority of the CO2 from the gas mixture.

8. The method of any one of claims 5 to 7, wherein the gas separation process comprises 30 a H2 and / or CO separation process to separate a majority of the H2 and / or CO from the gas mixture.04 08 259. The method of claim 8, wherein the H2 and / or CO separation process comprises a methane separation process to separate a majority of the methane from the H2 and / or CO in the gas mixture, a majority of the CO2 and H2O having been previously been removed from the gas mixture.5 10. The method of any one of the preceding claims, wherein unreacted gasses in the gasmixture are recirculated into the electrolyser via the one or more gas input.

11. The method of any one of the preceding claims, wherein the electrolyser is operated at a temperature between 500 and 600 degrees C, or more preferably between 525 and 575 degrees C, inclusive.10 12. The method of any one of the preceding claims, wherein a methanation catalyst isused in the electrolyser or the at least one electrolyser cell to improve the efficiency of the methanation occurring within the electrolyser.

13. The method of claim 12, wherein the methanation catalyst is a nickel based catalyst.

14. The method of any one of the preceding claims, wherein the ratio of the fuel gases is15 controlled to target a ratio of methane to unreacted gases of the electrolysis and methanation processes, in the offgas gas mixture, such that at least 10% of the total volume of the gas mixture exiting the at least one offgas output is methane.

15. The method of any one of the proceeding claims, wherein heat from the methanation reaction is used to heat fluids entering the electrolyser.20 16. The method of any one of the preceding claims, wherein the electrolyser is a solidoxide electrolyser.

17. The method of any one of the preceding claims, wherein the at least one electrolyser cell is part of a stack of electrolyser cells.

18. The method of any one of the preceding claims, wherein there are one or more stacks 25 of electrolyser cells in the electrolyser.

19. An electrolyser system configured to operate using the method according to any one of the preceding claims.

20. The electrolyser system of claim 19, wherein the electrolyser comprises a methanation catalyst.30 21. The electrolyser system of claim 20, wherein the methanation catalyst is located at alower temperature region of the electrolyser or stack or cells.LO CXICO22. The electrolyser system of claim 20 or claim 21, wherein the methanation catalyst is located at, near or towards an outlet end of the electrolyser cells.

23. The electrolyser system of any one of claims 19 to 22, wherein the electrolyser comprises a reverse water gas shift catalyst.5 24. The electrolyser system of claim 23, wherein the methanation catalyst is located at alower temperature region of the electrolyser or stack or cells.

25. The electrolyser system of claim 23 or claim 24, wherein the methanation catalyst is located at, near or towards an outlet end of the electrolyser cells.

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