Ammonia-Fueled SOFC With Two-Stage Energy Recovery
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Solution Overview
Problem
Current fuel cell systems lack an efficient, zero-CO2-emissions solution for generating electrical and mechanical energy using ammonia as a hydrogen source, particularly in hybrid systems where ammonia-derived hydrogen is utilized to power a secondary energy conversion device.
Innovation Solution
A two-stage energy conversion system where ammonia is used to fuel a solid oxide fuel cell (SOFC) to generate electricity and a hydrogen-rich tailgas, which is then used to power a secondary energy conversion device such as an internal combustion engine (ICE) or gas turbine engine, with ammonia being cracked endothermically in the SOFC anode to yield hydrogen and nitrogen, and the hydrogen-rich tailgas being supplied to the secondary device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If ammonia is used as fuel for SOFC, then zero CO2 emissions and no coking are achieved, but system complexity increases due to ammonia storage and handling requirements
Solution Approach 1:
The patent introduces a solid ammonia storage medium (ammonia salt hydrate) as an intermediary between the ammonia fuel source and the SOFC. This solid medium releases ammonia vapor through controlled heating, eliminating the need for direct handling of liquid or gaseous ammonia while maintaining zero CO2 emissions and preventing coking in the fuel cell.
2Quantity of substance
If ammonia is cracked endothermically in the SOFC anode, then hydrogen is produced for fueling, but the anode temperature decreases affecting SOFC performance
Solution Approach 1:
The patent merges the ammonia cracking process with the SOFC anode reaction process. The endothermic cracking of ammonia to produce hydrogen occurs simultaneously with the exothermic electrochemical reactions in the anode, allowing heat integration where the heat generated from fuel oxidation provides the necessary heat for ammonia cracking, thereby maintaining anode temperature while producing hydrogen.
Solution Approach 2:
The patent changes the operational parameters of the SOFC by introducing ammonia as a fuel component and controlling its cracking rate through temperature regulation. By adjusting the ammonia feed rate and anode temperature, the system optimizes both hydrogen production from cracking and maintains sufficient temperature for SOFC electrochemical reactions.
3Loss of energy
If a two-stage energy conversion system is implemented, then overall efficiency increases by utilizing tailgas, but device complexity increases with additional components
Solution Approach 1:
The patent implements a two-stage energy conversion system where the SOFC anode tailgas, rich in hydrogen and other combustible components, is directed to a secondary energy conversion device such as a combustor or auxiliary fuel cell. This multi-functional arrangement ensures that energy in the tailgas is not wasted but converted into additional useful work, thereby improving overall system efficiency while managing the increased complexity through integrated design.
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 efficient, zero-CO2-emissions energy generation with minimized parasitic losses, reduced anode oxidation, and enhanced safety, while providing a versatile and scalable power solution suitable for vehicular and stationary applications with CO2 sequestration capabilities.
Implementation Method 1
Ammonia is cracked endothermically in the SOFC anode to yield hydrogen and nitrogen
Implementation Method 2
ammonia is released therefrom by waste heat from the SOFC
Implementation Method 3
solid oxide fuel cell (SOFC) to generate electricity
Data Source
AI summary
An energy conversion system comprising ammonia for fueling an SOFC stack to generate electricity and a hydrogen-rich tailgas. In the SOFC stack, ammonia is cracked to hydrogen and nitrogen. Ammonia is stored in a metal halide complex and is released therefrom as gaseous ammonia by waste heat from the SOFC. A heat exchanger is positioned across the SOFC cathode such that incoming air is tempered by the cathode exhaust air. In a two-stage energy conversion system, the hydrogen-rich tailgas from the SOFC is supplied as fuel to a secondary energy conversion device which may be, for example, an internal combustion engine or a gas turbine engine which may operate, for example, either a generator for generating additional electricity or a vehicle for motive power, or a second fuel cell stack.