Fuel Cell Energy Storage During Startup Shutdown

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Solution Overview

Problem

Corrosion of amorphous carbon catalyst supports and metal catalysts in polymer electrolyte membrane (PEM) fuel cells during startup and shutdown leads to permanent performance decay, and existing solutions like inert gas purging and auxiliary loads are costly and inefficient.

Innovation Solution

Storing electrical energy generated during power reduction transitions in an energy storage device, such as a battery, using electronic switches and inductors to manage voltage differences between the fuel cell stack and storage system, eliminating the need for auxiliary loads and heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an auxiliary load is used to dissipate energy during startup and shutdown, then corrosion is reduced, but energy is wasted and heat dissipation infrastructure is required

Engineering Contradiction:

Improvefuel cell performance stabilityVSAvoidenergy dissipation

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent converts the harmful reverse current situation that causes corrosion into a beneficial energy source. During startup and shutdown transitions, the abnormal voltage conditions that previously required dissipative loads are now captured and stored in an energy storage device, transforming waste energy into usable stored energy while simultaneously protecting against corrosion.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent recovers energy that would otherwise be discarded during transient operations. Instead of allowing energy to be wasted through auxiliary loads during startup and shutdown, the system captures and stores this energy for later use, improving overall system efficiency while maintaining the protective function during transitions.

Inventive Principle:

Principle #34Discarding and recovering

2Reliability

If inert gas purging is used to prevent corrosion, then catalyst support degradation is reduced, but system complexity and cost increase

Engineering Contradiction:

Improvecatalyst support durabilityVSAvoidpurging system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential protective function from the complex inert gas purging system. By removing the need for external inert gas storage and delivery infrastructure, the system achieves corrosion protection through electrical control alone, significantly reducing device complexity while maintaining catalyst support durability.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The fuel cell stack serves its own protection needs through controlled electrical operations. The system uses its inherent electrochemical reactions and voltage control capabilities to protect against corrosion during transitions, eliminating the need for separate protective systems like inert gas purging infrastructure.

Inventive Principle:

Principle #25Self-service

3Reliability

If voltage control is achieved through resistive devices, then potential excursions are limited, but energy efficiency decreases

Engineering Contradiction:

Improvevoltage stabilityVSAvoidenergy efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent transforms the energy that would be wasted in resistive voltage control into stored energy. During voltage transitions, instead of dissipating energy through resistance, the system captures the energy flow in the reverse current situation and stores it, achieving both voltage stability and energy efficiency simultaneously.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Conserves energy, reduces corrosion, and avoids the need for complex and expensive inert gas purging systems, enabling efficient energy utilization during startup and shutdown cycles.

Implementation Method 1

An electrochemical reaction occurs between the fuel rich zone in the anode flow field and the oxygen rich zone in the anode flow field

Methodology Applied

Scientific EffectElectrochemical reaction: Fuel Cell

Implementation Method 2

an inductor, and when the switch is gated off, the current continues to flow through a unilaterally conducting device into the energy storage system

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS7790303B2Storage of fuel cell energy during startup and shutdown or other power transitions

Publication Date: 2010.09.07 AUDI AG

AI summary

During fuel cell startup and shutdown or other power reduction transitions of a fuel cell power plant, the excess electric energy generated by consumption of reactants is extracted by a storage control (200) in response to a controller (185) as current applied to an energy storage system 201 (a battery). In a boost embodiment, an inductor (205) and a diode (209) connect one terminal (156) of the stack (151) of the battery. An electronic switch connects the juncture of the inductor and the diode to both the other terminal (155) of the stack and the battery. The switch is alternately gated on and off by a signal (212) from a controller (185) until sufficient energy is transferred from the stack to the battery. In a buck environment, the switch and the inductor (205) connect one terminal (156) of the stack to the battery. A diode connects the juncture of the switch with the inductor to the other terminal (155) of the fuel cell stack and the battery.