SOEC Anode Tail Gas Recycling for Lower Power-to-Fuel Energy Loss
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Solution Overview
Problem
Existing Power-to-X processes face challenges in efficiently utilizing tail gas and methane-rich streams from fuel synthesis, leading to reduced energy efficiency and carbon dioxide utilization rates, particularly in the production of chemical products and fuels.
Innovation Solution
Recycling tail gas and methane-rich streams to the anode of a high-temperature solid-oxide electrolyzer (SOEC) as fuel, utilizing reforming and partial oxidation reactions to enhance energy efficiency and reduce electrical power demand, while maintaining a consistent hydrogen-to-carbon ratio for downstream synthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If tail gas and methane-rich streams are discharged without recycling, then the process is simple to operate, but energy efficiency and carbon dioxide utilization rates are reduced
Solution Approach 1:
The patent recovers tail gas and methane-rich streams that would otherwise be discarded, routing them back to the electrolyzer anode as fuel. This recovery process improves energy efficiency and CO2 utilization by converting waste streams into useful fuel sources for hydrogen production, directly addressing the energy loss issue while accepting increased process complexity.
Solution Approach 2:
The system implements a feedback loop where tail gas and methane-rich streams from downstream processes are fed back to the electrolyzer anode. This closed-loop approach allows the system to continuously utilize byproducts as fuel sources, improving overall energy efficiency and carbon dioxide conversion rates while requiring more complex process integration.
2Loss of energy
If tail gas and methane-rich streams are recycled to the anode as fuel, then energy efficiency and carbon dioxide utilization improve, but the device complexity increases
Solution Approach 1:
The electrolyzer anode serves multiple functions: it acts as both the electrochemical reaction site and a fuel processing unit where reforming and combustion occur. By making the anode multi-functional, the system reduces the need for separate fuel processing equipment, thereby improving energy efficiency while limiting the increase in overall device complexity.
Solution Approach 2:
The patent merges the fuel processing function into the electrolyzer by combining reforming and combustion reactions within the anode structure. This consolidation eliminates the need for separate fuel processing units and simplifies the overall system architecture, allowing tail gas recycling to improve energy efficiency without proportionally increasing device complexity.
3Productivity
If electrical power is used to produce hydrogen via electrolysis, then hydrogen can be generated for fuel synthesis, but electricity consumption increases operational costs
Solution Approach 1:
The electrolyzer system serves itself by using its own byproducts (tail gas and methane-rich streams) as fuel sources. The recycled streams undergo reforming and combustion in the anode to generate heat that drives the electrolysis process, reducing external electricity requirements and lowering operational costs while maintaining hydrogen production productivity.
Solution Approach 2:
The system changes the energy input parameters by introducing chemical energy from fuel combustion to supplement electrical energy input. By adjusting the mix of electrical and thermal energy inputs through controlled fuel recycling, the system optimizes hydrogen production efficiency and reduces overall electricity consumption while maintaining high productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves energy efficiency and carbon dioxide utilization by reducing electrolyzer electricity consumption and enhancing the production of chemical products and fuels, particularly methanol, through the use of recycled tail gas and methane as fuel sources.
Implementation Method 1
an electrolyte inserted between the cathode and the anode
Implementation Method 2
utilizing reforming and partial oxidation reactions to enhance energy efficiency
Implementation Method 3
utilizing reforming and partial oxidation reactions to enhance energy efficiency
Implementation Method 4
passing a first steam feed stream to a cathode of an electrolyzer... thereby producing a cathode effluent comprising hydrogen
Data Source
AI summary
A continuous method includes passing a first steam feed stream to a cathode of an electrolyzer including the cathode, an anode and an electrolyte inserted between the cathode and the anode, thereby producing a cathode effluent including hydrogen, passing a second steam feed stream and one or more of a recycled tail gas stream from a reactor unit and a methane-rich feed stream to the anode of the electrolyzer, wherein the one or more of the recycled tail gas stream and the methane-rich feed stream are utilized as fuel for producing the cathode effluent including hydrogen, and passing the cathode effluent including g hydrogen and a carbon dioxide feed stream to the reactor unit, thereby producing a chemical product or a fuel-based product.