CO2 Capture via Molten Carbonate Electrolysis in Fuel Cells
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Solution Overview
Problem
Current methods for capturing CO2 from solid oxide fuel cell anode exhaust are costly and inefficient, particularly due to the high expense of producing pure oxygen needed for anode gas oxidizers, which rely on air separation units.
Innovation Solution
A carbon dioxide capture system incorporating a solid oxide fuel cell and a molten carbonate electrolyzer cell to produce a stream rich in oxygen and carbon dioxide, with a gas oxidizer to further process the exhaust streams, resulting in highly purified CO2 and high purity hydrogen as byproducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If an air separation unit is used to produce pure oxygen for anode gas oxidizer, then the oxygen supply is sufficient for CO2 capture, but the system cost and energy consumption increase significantly
Solution Approach 1:
The patent combines the oxygen production function with the existing fuel cell system by using the fuel cell's own exhaust gases (CO2 and H2O) as feedstock for an electrolysis cell. This integration eliminates the need for a separate air separation unit, reducing system complexity and cost while providing the necessary oxygen for CO2 capture in the anode gas oxidizer.
Solution Approach 2:
The fuel cell system serves itself by using its own exhaust products (CO2 and H2O from the anode) as input for the electrolysis cell to generate oxygen. This self-service approach eliminates external oxygen production equipment and reduces overall system cost while maintaining adequate oxygen supply for CO2 capture operations.
2Quantity of substance
If an air separation unit is used to produce pure oxygen for anode gas oxidizer, then the oxygen supply is sufficient for CO2 capture, but the energy consumption increases
Solution Approach 1:
The patent merges the oxygen production process with the fuel cell's existing thermal and electrical output. The electrolysis cell uses electricity from the fuel cell and heat from its exhaust, creating a synergistic system that produces oxygen with minimal additional energy input compared to standalone air separation units.
Solution Approach 2:
Instead of discarding the CO2 and H2O exhaust from the fuel cell anode, the system recovers these gases and uses them as feedstock for the electrolysis cell to produce oxygen. This recovery approach converts waste products into valuable resources, reducing the energy burden of oxygen production while maintaining CO2 capture capability.
3Ease of operation
If CO2 is released directly from anode exhaust, then the system operation is simple, but environmental harm increases due to CO2 emissions
Solution Approach 1:
The patent converts the harmful CO2 emissions into a beneficial resource by feeding CO2-rich exhaust from the fuel cell anode into an electrolysis cell. The CO2 is transformed into oxygen through electrolysis, which is then used in the anode gas oxidizer to enhance combustion and generate additional energy, thereby eliminating emissions while creating value.
Solution Approach 2:
The electrolysis cell acts as an intermediary between the fuel cell anode exhaust and the anode gas oxidizer. It transforms CO2 and H2O into oxygen, which mediates the combustion process in the oxidizer, enabling CO2 capture while maintaining system operational simplicity through automated chemical conversion.
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
The system achieves efficient and cost-effective CO2 capture from fuel cell exhausts while producing valuable high purity hydrogen, minimizing energy costs and environmental impact by reducing CO2 emissions.
Implementation Method 1
Fuel cells are devices that are capable of converting chemical energy stored in a fuel, such as a hydrocarbon fuel, into electrical energy through electrochemical reactions
Implementation Method 2
one type of fuel cell is the solid oxide fuel cell (SOFC), which incorporates a solid ceramic electrolyte for the transfer of negatively charged oxygen ions from the cathode to the anode
Implementation Method 3
a molten carbonate electrolyzer cell configured to receive a portion of the first exhaust stream and output a second exhaust stream comprising oxygen and carbon dioxide
Implementation Method 4
a gas oxidizer configured to receive the first exhaust stream and the second exhaust stream and output a stream comprising water and carbon dioxide
Data Source
AI summary
A carbon dioxide capture system for capturing carbon dioxide from an exhaust stream. The system may include a fuel cell configured to output a first exhaust stream comprising carbon dioxide and water. The system may further include an electrolyzer cell configured to receive a first portion of the first exhaust stream and output a second exhaust stream comprising oxygen and carbon dioxide. The fuel cell may be a solid oxide fuel cell. The electrolyzer cell may be a molten carbonate electrolysis cell.