SOFC Reversible System with Methanation and Hydrogen Storage
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Solution Overview
Problem
High-temperature solid oxide fuel cells (SOFC) face challenges in thermal management when directly supplied with hydrogen, leading to inefficiencies and environmental concerns when using methane, such as high oxidant flow rates, seal integrity issues, and CO2 emissions.
Innovation Solution
A reversible system incorporating a SOFC fuel cell, a methanation reactor, and a hydrogen storage tank in a closed loop, where hydrogen from the tank compensates for water removal and methane is converted within the methanation reactor to circulate carbonaceous species, allowing for 100% fuel utilization and eliminating CO2 emissions by recirculating carbon species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high flow rates of oxidizer (air) are circulated to evacuate heat through gases, then thermal management is improved, but battery efficiency drops significantly due to compression requirements
Solution Approach 1:
The invention converts the harmful exothermic heat from hydrogen oxidation into useful thermal energy by introducing an endothermic reforming reaction. The reforming reaction absorbs the excess heat, converting it into chemical energy stored in reformulated fuel, thereby improving thermal management without compromising battery efficiency
Solution Approach 2:
The invention changes the chemical parameters of the fuel by introducing reforming reactions that convert hydrogen and carbon dioxide into hydrocarbon compounds. This parameter change allows the system to manage heat through chemical transformation rather than physical gas circulation, eliminating compression losses
2Temperature
If high flow rates are used to cool the fuel cell, then thermal management is improved, but pressure levels at the stack entrance become prohibitive for seal resistance
Solution Approach 1:
The invention converts the need for high-pressure gas flow into a beneficial chemical process. Instead of forcing high flow rates through compression, the system uses the exothermic heat to drive endothermic reforming reactions, eliminating the need for high-pressure oxidizer flow and protecting seal integrity
3Productivity
If high air flow is associated with low fuel flow to maintain high electrical efficiency, then electrical efficiency is improved, but pressure imbalances occur between fuel and oxidizer chambers
Solution Approach 1:
The invention converts the pressure imbalance problem into a beneficial chemical transformation. The reforming reaction consumes hydrogen and carbon dioxide to produce hydrocarbons, effectively balancing the pressure dynamics between chambers while maintaining high electrical efficiency through optimized fuel utilization
Solution Approach 2:
The invention recovers carbon dioxide that would otherwise be wasted by using it as a reactant in the reforming process. This recovery mechanism balances the fuel consumption and oxidizer flow, maintaining pressure equilibrium while preserving electrical efficiency
4Temperature
If methane is supplied directly to the fuel cell, then thermal management is improved through endothermic reforming, but carbon dioxide emissions increase causing environmental harm
Solution Approach 1:
The invention recovers carbon dioxide emissions by using them as a reactant in the reforming process. Instead of releasing CO2 into the environment, the system captures it and converts it back into hydrocarbon fuel through the reforming reaction, eliminating harmful emissions while maintaining thermal management benefits
Solution Approach 2:
The invention converts the harmful carbon dioxide emissions into a beneficial resource. By using CO2 as a reactant in the reforming process, the system transforms an environmental pollutant into a valuable fuel component, simultaneously achieving thermal management and emission reduction
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
This system achieves improved thermal management, increased efficiency, and reduced environmental impact by controlling heat sources and utilizing fuel effectively, enabling operation at higher temperatures with better electrical efficiency and reduced risk of cell damage.
Implementation Method 1
a methanation reactor, adapted to carry out a methanation reaction
Implementation Method 2
the oxidation of hydrogen within it which is a highly exothermic reaction
Implementation Method 3
a fuel cell (SOFC) comprising at least one elementary solid oxide electrochemical cell
Implementation Method 4
separating water from the gas mixture mainly comprising hydrogen (H2), carbon monoxide (CO), and carbon dioxide (CO2), at the outlet of the fuel cell
Implementation Method 5
supplying it directly with methane and water vapor to take advantage of the endothermic reforming reaction occurring in contact with the electrode nickel-zirconia cermet
Data Source
Figure 1~2
Figure 3
AI summary
The present invention relates to a reversible SOFC-based system (1) for generating electricity, comprising: an solid-oxide-fuel-cell (SOFC) stack (2) comprising at least one elementary solid-oxide electrochemical cell, each of which is formed from a cathode, an anode and an electrolyte intermediate between the cathode and the anode; a separator (3) of liquid and gas phases, which separator is connected to the outlet of the fuel-cell stack; a methanation reactor (4) suitable for implementing a methanation reaction, the inlet of which is connected to the outlet of the phase separator and the outlet of which is connected to the inlet of the fuel-cell stack so that the mixture issued from the methanation reactor is introduced into the fuel-cell stack; and a tank (5)for reversibly storing hydrogen, suitable for storing hydrogen, the outlet of which is connected to the inlet of the methanation reactor.