Carl von Ossietzky University of Oldenburg
Institute of Physics
A basic reference for renwable energies for high school students
- by Santiago Sanchez
- •
Scheffler reflectors are fixed focus, polar‐axis parabolic solar concentrators that can achieve significant concentration factors at relatively low cost. The technology is widespread in India, and gaining popularity for medium scale solar... more
Scheffler reflectors are fixed focus, polar‐axis parabolic solar concentrators that can achieve significant concentration factors at relatively low cost. The technology is widespread in India, and gaining popularity for medium scale solar cooking and process steam generation.
Among other features the reflectors require a flexible structure to cope with the seasonal variation of the position of the sun. deformation of the structure is accomplished by two telescopic bars fixed to the vertical ends of the reflector, which have to be adjusted manually every 3 to 5 days in order to get a good optical performance. It is reported that some operators do not do this often enough, because of the trouble of having to climb to the structure and adjusting the upper and lower telescopic supports in an iterative manner. The goal of the internship was the design and construction of a mechanism to adjust the upper side of the mirror automatically upon adjustment of the lower telescopic bar. Several
mechanisms were synthesized, and a simple device consisting of three bars and a mounting structure was selected, designed to detail and constructed. A fine tuning mechanism was included to cope with small variations in collector geometry and manufacturing errors.
Preliminary tests over the installed and calibrated mechanism show a very good agreement ( ~ 1mm error) with the calculated required positions of the upper mirror. A year‐round test is however required to verify if all the design assumptions hold under real operating conditions.
Among other features the reflectors require a flexible structure to cope with the seasonal variation of the position of the sun. deformation of the structure is accomplished by two telescopic bars fixed to the vertical ends of the reflector, which have to be adjusted manually every 3 to 5 days in order to get a good optical performance. It is reported that some operators do not do this often enough, because of the trouble of having to climb to the structure and adjusting the upper and lower telescopic supports in an iterative manner. The goal of the internship was the design and construction of a mechanism to adjust the upper side of the mirror automatically upon adjustment of the lower telescopic bar. Several
mechanisms were synthesized, and a simple device consisting of three bars and a mounting structure was selected, designed to detail and constructed. A fine tuning mechanism was included to cope with small variations in collector geometry and manufacturing errors.
Preliminary tests over the installed and calibrated mechanism show a very good agreement ( ~ 1mm error) with the calculated required positions of the upper mirror. A year‐round test is however required to verify if all the design assumptions hold under real operating conditions.
This work explores how the performance of a high-temperature polymer electrolyte membrane fuel cell is affected by the degree of compression. Contact pressure measurements in the range of 2 to 25 bars have been conducted on commercial... more
This work explores how the performance of a high-temperature
polymer electrolyte membrane fuel cell is affected by the degree of compression. Contact pressure measurements in the range of 2 to 25 bars have been conducted on commercial membrane-electrodeassemblies (MEAs). When increasing the contact pressure, the MEA performance continuously decreases for lower current densities and increases or goes through a small maximum for higher current densities. The electrochemical characterization
reveals a decrease in membrane as well as contact resistance and shows an increase in mass transport restriction, hydrogen crossover as well as electrical short circuits. The electrochemical active surface area is not affected by contact pressure rising. A
comparison of two flow field types illustrates that the MEA
performance not only depends on the geometry of the analyzed
flow fields, but it is also influenced by the real contact area
between flow field and MEA surface.
polymer electrolyte membrane fuel cell is affected by the degree of compression. Contact pressure measurements in the range of 2 to 25 bars have been conducted on commercial membrane-electrodeassemblies (MEAs). When increasing the contact pressure, the MEA performance continuously decreases for lower current densities and increases or goes through a small maximum for higher current densities. The electrochemical characterization
reveals a decrease in membrane as well as contact resistance and shows an increase in mass transport restriction, hydrogen crossover as well as electrical short circuits. The electrochemical active surface area is not affected by contact pressure rising. A
comparison of two flow field types illustrates that the MEA
performance not only depends on the geometry of the analyzed
flow fields, but it is also influenced by the real contact area
between flow field and MEA surface.
- by Peter Wagner
- •
"In order to increase the efficiency of nowadays fuel cells it is important to understand degradation processes. This paper focuses on defects related to compression of the Membrane-Electrode- Assembly. A particular useful tool... more
"In order to increase the efficiency of nowadays fuel cells it is
important to understand degradation processes. This paper focuses
on defects related to compression of the Membrane-Electrode-
Assembly. A particular useful tool therefore is the micro-computed
tomography, as it allows a non-destructive insight into the MEA.
The results from this imaging method are compared to classical
electrochemical characterizations procedures. MEAs with different
Gas Diffusion Layers (cloth and paper) are investigated and their
individual behavior upon compression is evaluated."
important to understand degradation processes. This paper focuses
on defects related to compression of the Membrane-Electrode-
Assembly. A particular useful tool therefore is the micro-computed
tomography, as it allows a non-destructive insight into the MEA.
The results from this imaging method are compared to classical
electrochemical characterizations procedures. MEAs with different
Gas Diffusion Layers (cloth and paper) are investigated and their
individual behavior upon compression is evaluated."
- by Peter Wagner and +2
- •
This paper shows by thorough electrochemical investigation that (1) the performances of high-temperature polymer electrolyte fuel cell membrane electrode assemblies of three suppliers are differently affected by compressive forces. (2)... more
This paper shows by thorough electrochemical
investigation that (1) the performances of high-temperature
polymer electrolyte fuel cell membrane electrode assemblies of three suppliers are differently affected by compressive forces. (2) Membrane thickness reduction by
compressive pressure takes place less than expected. (3) A
contact pressure cycling experiment is a useful tool to
distinguish the impact of compression on the contact
resistances bipolar plate/gas diffusion layer (GDL) and
GDL/catalytic layer. A detailed visual insight into the
structural effects of compressive forces on membrane and
gas diffusion electrode (GDE) is obtained by micro-computed X-ray tomography (l-CT). l-CT imaging confirms
that membrane and GDEs undergo severe mechanical
stress resulting in performance differences. Irreversible
GDL deformation behavior and pinhole formation by GDL
fiber penetration into the membrane could be observed.
investigation that (1) the performances of high-temperature
polymer electrolyte fuel cell membrane electrode assemblies of three suppliers are differently affected by compressive forces. (2) Membrane thickness reduction by
compressive pressure takes place less than expected. (3) A
contact pressure cycling experiment is a useful tool to
distinguish the impact of compression on the contact
resistances bipolar plate/gas diffusion layer (GDL) and
GDL/catalytic layer. A detailed visual insight into the
structural effects of compressive forces on membrane and
gas diffusion electrode (GDE) is obtained by micro-computed X-ray tomography (l-CT). l-CT imaging confirms
that membrane and GDEs undergo severe mechanical
stress resulting in performance differences. Irreversible
GDL deformation behavior and pinhole formation by GDL
fiber penetration into the membrane could be observed.
- by Peter Wagner and +1
- •
- PEM fuel cells
The Gas Diffusion Layer (GDL) plays an important role in the performance of a fuel cell, but it also strongly controls the durability of the membrane-electrode-assembly (MEA). Mechanical damages like fiber intrusion at high contact... more
The Gas Diffusion Layer (GDL) plays an important role in the
performance of a fuel cell, but it also strongly controls the
durability of the membrane-electrode-assembly (MEA).
Mechanical damages like fiber intrusion at high contact pressure can lead to hydrogen crossover and electrical short circuit formation. In this paper a non-woven GDL is analyzed by
electrochemical methods in a fuel cell test station under contact
pressure cycling between 0.2 and 1.5 MPa. These results are
compared ex-situ with the microscopic structural changes in the material investigated by micro-computed tomography in
combination with a specially designed compression tool. The
optical measurements allow the identification of GDL defects. A
clear correlation between the loss of internal resistance and
hydrogen crossover current and the emerging of small cracks and fiber intrusions could be established.
performance of a fuel cell, but it also strongly controls the
durability of the membrane-electrode-assembly (MEA).
Mechanical damages like fiber intrusion at high contact pressure can lead to hydrogen crossover and electrical short circuit formation. In this paper a non-woven GDL is analyzed by
electrochemical methods in a fuel cell test station under contact
pressure cycling between 0.2 and 1.5 MPa. These results are
compared ex-situ with the microscopic structural changes in the material investigated by micro-computed tomography in
combination with a specially designed compression tool. The
optical measurements allow the identification of GDL defects. A
clear correlation between the loss of internal resistance and
hydrogen crossover current and the emerging of small cracks and fiber intrusions could be established.
- by Peter Wagner and +1
- •
Nowadays high temperature polymer electrolyte fuel cells suffer from performance and long-term stability issues. Detailed understanding of the degradation effects is thus a key aspect for the improvement of this type of fuel cells.... more
Nowadays high temperature polymer electrolyte fuel cells suffer from performance and long-term stability issues. Detailed understanding of the degradation effects is thus a key aspect for the improvement of this type of fuel cells. Degradation can be categorized into thermal, (electro-) chemical and mechanical effects. This paper focuses on the latter process, investigating two different types of membrane electrode assemblies by accelerated stress tests at high current densities in which, compared to common procedures, the device is driven at higher current densities between 0.6 – 1.0 A/cm². In addition to voltammetry and polarization curves, the assemblies are analyzed by electron microscopy methods and especially micro-computed tomography which allows a non-destructive investigation of the hidden interfaces within the MEA structure, giving a direct view on mechanical defects. Load cycling at high current densities revealed significant contributions to the degradation of the catalyst layer.
But no influence on the membrane could be found.
But no influence on the membrane could be found.
- by Peter Wagner and +1
- •
Contact pressure cycling experiments have been conducted with various commercial high temperature PEM membrane electrode-assemblies based on phosphoric acid doped PBI. Two different membrane-electrode-assembly types have been... more
Contact pressure cycling experiments have been conducted
with various commercial high temperature PEM membrane electrode-assemblies based on phosphoric acid doped PBI. Two different membrane-electrode-assembly types have been electrochemically investigated employing linear sweep voltammetry, electrochemical impedance spectroscopy and polarization curves, but also micro-computed tomography imaging has been used as post-mortem investigation technique.
Thickness displacement changes on the membrane-electrode-assemblies (MEA) during the experiences have also been recorded. Reversible and irreversible effects have been observed in MEA behavior during the three contact pressure cycles. Furthermore, the micro-computed tomography tool allows a detailed visual insight into the structural effects of compression forces on the MEA. The electrochemical characterization has revealed that damages under contact pressure cycling have been induced in both kinds of MEAs. Moreover, once MEA damages have appeared, they are facilitated from cycle to cycle. These damages are related to hydrogen crossover and short circuit formation that develop fuel cell performance deterioration. Thus, micro-computed tomography imaging investigations reveal defects, pin holes or cracks within the catalyst layer and membrane e.g., which may cause degradation aspects like hydrogen crossover or loss of
electrical isolation already observed by the electrochemical
characterization.
with various commercial high temperature PEM membrane electrode-assemblies based on phosphoric acid doped PBI. Two different membrane-electrode-assembly types have been electrochemically investigated employing linear sweep voltammetry, electrochemical impedance spectroscopy and polarization curves, but also micro-computed tomography imaging has been used as post-mortem investigation technique.
Thickness displacement changes on the membrane-electrode-assemblies (MEA) during the experiences have also been recorded. Reversible and irreversible effects have been observed in MEA behavior during the three contact pressure cycles. Furthermore, the micro-computed tomography tool allows a detailed visual insight into the structural effects of compression forces on the MEA. The electrochemical characterization has revealed that damages under contact pressure cycling have been induced in both kinds of MEAs. Moreover, once MEA damages have appeared, they are facilitated from cycle to cycle. These damages are related to hydrogen crossover and short circuit formation that develop fuel cell performance deterioration. Thus, micro-computed tomography imaging investigations reveal defects, pin holes or cracks within the catalyst layer and membrane e.g., which may cause degradation aspects like hydrogen crossover or loss of
electrical isolation already observed by the electrochemical
characterization.
- by Peter Wagner and +1
- •
Within this study we present experimental data on the performance of a single cell PBI-based high-temperature fuel cell operated with synthetic reformate and oxygen enriched air. A test studying different concentrations of oxygen in... more
Within this study we present experimental data on the performance of a single cell PBI-based high-temperature fuel cell operated with synthetic reformate and oxygen enriched
air. A test studying different concentrations of oxygen in cathode air revealed that 30% V/V oxygen concentration allowed kinetics improvement and could prevent corrosion occurring with higher oxygen concentrations. A long term accelerated stress test, consisting of load cycling between open circuit voltage and a load of 0.3 A/cm² was implemented to
investigate fuel cell degradation. A degradation rate of -81 µV/h has been determined under such harsh operating conditions. Electrochemical characterization has been performed to clarify the causes of degradation. Loss of the electrochemically active surface area seems to be the major contribution caused by the accelerated stress test.
air. A test studying different concentrations of oxygen in cathode air revealed that 30% V/V oxygen concentration allowed kinetics improvement and could prevent corrosion occurring with higher oxygen concentrations. A long term accelerated stress test, consisting of load cycling between open circuit voltage and a load of 0.3 A/cm² was implemented to
investigate fuel cell degradation. A degradation rate of -81 µV/h has been determined under such harsh operating conditions. Electrochemical characterization has been performed to clarify the causes of degradation. Loss of the electrochemically active surface area seems to be the major contribution caused by the accelerated stress test.
- by Peter Wagner and +1
- •
Phosphoric acid is utilized as electrolyte in high temperature polymer electrolyte (HT-PEM) fuel cells to guarantee proton conduction. Loss of electrolyte may be identified as one of the main degradation aspects. The data presented in... more
Phosphoric acid is utilized as electrolyte in high temperature
polymer electrolyte (HT-PEM) fuel cells to guarantee proton
conduction. Loss of electrolyte may be identified as one of the
main degradation aspects. The data presented in this paper focus on a better understanding of the degradation paths caused by acid loss from the membrane-electrode-assembly. Therefore this investigation examined the phosphoric acid distribution in an experimental fuel cell setup. Two operational strategies with long term tests under constant load conditions at 0.3 A/cm² and load cycling tests between high current densities of 0.6 A/cm² and 1.0 A/cm² have been performed. The detection of acid content in the various fuel cell components in combination with imaging methods for the identification of changes in surface structure on the bipolar plates provide good instruments to investigate the influences of acid loss during fuel cell operation.
polymer electrolyte (HT-PEM) fuel cells to guarantee proton
conduction. Loss of electrolyte may be identified as one of the
main degradation aspects. The data presented in this paper focus on a better understanding of the degradation paths caused by acid loss from the membrane-electrode-assembly. Therefore this investigation examined the phosphoric acid distribution in an experimental fuel cell setup. Two operational strategies with long term tests under constant load conditions at 0.3 A/cm² and load cycling tests between high current densities of 0.6 A/cm² and 1.0 A/cm² have been performed. The detection of acid content in the various fuel cell components in combination with imaging methods for the identification of changes in surface structure on the bipolar plates provide good instruments to investigate the influences of acid loss during fuel cell operation.
- by Peter Wagner
- •
One important task of the European project CISTEM is the investigation of degradation processes, which may be caused by different operating conditions. The possibility to use different fuels and oxidants makes a HT-PEM fuel cell much more... more
One important task of the European project CISTEM is the
investigation of degradation processes, which may be caused by different operating conditions. The possibility to use different fuels and oxidants makes a HT-PEM fuel cell much more flexible and versatile for application. Therefore, some degradation effects induced by varied reactant gases will be described in this work.
Intensive investigation of MEAs under equal test conditions (H2/O2, constant load at 0.3 A/cm²) provided contradictory degradation results with degradation rates of -8.0 μV/h and 70 μV/h for the same MEA type. The same trend has been observed with other fuel supply options. Fuel cells operated with hydrogen/air or with synthetic reformate/air show similar low and high degradation rates. This paper discusses a possible explanation for such differences. Post-mortem analysis on MEAs with high degradation rates are performed to provide a better understanding of causes leading to such high degradation rates.
investigation of degradation processes, which may be caused by different operating conditions. The possibility to use different fuels and oxidants makes a HT-PEM fuel cell much more flexible and versatile for application. Therefore, some degradation effects induced by varied reactant gases will be described in this work.
Intensive investigation of MEAs under equal test conditions (H2/O2, constant load at 0.3 A/cm²) provided contradictory degradation results with degradation rates of -8.0 μV/h and 70 μV/h for the same MEA type. The same trend has been observed with other fuel supply options. Fuel cells operated with hydrogen/air or with synthetic reformate/air show similar low and high degradation rates. This paper discusses a possible explanation for such differences. Post-mortem analysis on MEAs with high degradation rates are performed to provide a better understanding of causes leading to such high degradation rates.
- by Peter Wagner
- •
a b s t r a c t PEMFC operating at high temperature (100-200°C) are expected to have significant advantages but face big challenges in the development of suitable proton exchange membranes. This communication describes novel PBI-OO/PFSA... more
a b s t r a c t PEMFC operating at high temperature (100-200°C) are expected to have significant advantages but face big challenges in the development of suitable proton exchange membranes. This communication describes novel PBI-OO/PFSA blend membranes, which facilitate proton conduction under anhydrous conditions based on a ''proton donor-proton acceptor" concept. The proton conductivity of the blends under anhydrous conditions exceeded that of PFSA by a factor of 50 at ambient temperature and of 2-4 at elevated temperature. Intermolecular interaction between two polymer components was investigated by FT-IR spectroscopy. After incorporation of inorganic electron-deficient compounds (BN nanoparticles), the anhydrous proton conductivity of the composites was higher than that of the bare PFSA by three orders of magnitude at ambient temperature and more than one order of magnitude at 140°C.
This work will provide details on some of the high temperature polymer electrolyte membrane (HTPEM) membrane-electrode-assembly (MEA) performance targets most recently achieved by Danish Power Systems. These include (i) MEA performances... more
This work will provide details on some of the high temperature polymer electrolyte membrane (HTPEM) membrane-electrode-assembly (MEA) performance targets most recently achieved by Danish Power Systems. These include (i) MEA performances of >0.67 V at 0.2 A cm À2 using dry H 2 /Air, (ii) MEA lifetime of 17.000 h at 0.24 A cm À2 using dry H 2 /Air with an average degradation rate of 9 mV h À1 , and (iii) an integrated 5 kW stack/reformer system using methanol reformate as fuel. Post mortem SEM, TEM, micro-tomography and XRD showed membrane thinning and catalyst particle growth that is typical for PEM fuel cells. Platinum particles grew from an initial 2e3 nm to 6e8 nm at the cathode and 4e5 nm at the anode, while the membrane showed thinning from an undoped 40 mme18 mm in some areas after testing. Studies using reformate have also led to promising initial results, while the rate of degradation for an MEA supplied with wet H 2 (30 mol%)/Air for 2000 h was found to be very similar to the rate when supplied with dry H 2. In addition to reaching these performance benchmarks, a reduction in the standard deviation for MEA cell voltage at 0.2 A cm À2 to <1% has been achieved through efforts aimed at improving the uniformity of the membrane and catalyst layer thicknesses.
- by Peter Wagner and +2
- •
Within this study we present experimental data on the performance of a single cell PBI-based high-temperature fuel cell operated with synthetic reformate and oxygen enriched air. A test studying different concentrations of oxygen in... more
Within this study we present experimental data on the performance of a single cell PBI-based high-temperature fuel cell operated with synthetic reformate and oxygen enriched air. A test studying different concentrations of oxygen in cathode air revealed that 30% V/V oxygen concentration allowed kinetics improvement and could prevent corrosion occurring with higher oxygen concentrations. A long term accelerated stress test, consisting of load cycling between open circuit voltage and a load of 0.3 A/cm 2 was implemented to investigate fuel cell degradation. A degradation rate of À81 mV/h has been determined under such harsh operating conditions. Electrochemical characterization has been performed to clarify the causes of degradation. Loss of the electrochemically active surface area seems to be the major contribution caused by the accelerated stress test.
- by Peter Wagner and +1
- •
in Wiley Online Library (wileyonlinelibrary.com) The investigations have been conducted with different oxidants and fuels with the aim of determining the state-of-the-art of commercially available high temperature polymer electrolyte fuel... more
in Wiley Online Library (wileyonlinelibrary.com) The investigations have been conducted with different oxidants and fuels with the aim of determining the state-of-the-art of commercially available high temperature polymer electrolyte fuel cells based on polybenzimidazole for its application in combined heat and power generation systems. The fuel cell test performed with synthetic reformate (263 lV/h) showed an increase of anode charge and mass transfer resistances. This behavior has suggested that CO may be generated from the CO 2 included in the synthetic reformate via reverse water gas shift reaction. The fuel cell test performed with pure O 2 developed the highest degradation rates (270 lV/h) due to fast oxidative degradation of membrane electrode assembly materials such as cathode catalyst and membrane. Fuel cell operation with H 2 /air exhibited the lowest degradation rates (257 lV/h) and it requires longer investigating times to identify the different degradation mechanisms. Moreover, fuel cell tests performed with air suggested longer break-in procedures to complete catalyst activation and redistribution of electrolyte. V C 2015 American Institute of Chemical Engineers AIChE J, 62: 217–227, 2016
- by Peter Wagner and +1
- •
One important task of the European project CISTEM is the investigation of degradation processes, which may be caused by different operating conditions. The possibility to use different fuels and oxidants makes a HT-PEM fuel cell much more... more
One important task of the European project CISTEM is the investigation of degradation processes, which may be caused by different operating conditions. The possibility to use different fuels and oxidants makes a HT-PEM fuel cell much more flexible and versatile for application. Therefore, some degradation effects induced by varied reactant gases will be described in this work. Intensive investigation of MEAs under equal test conditions (H 2 /O 2 , constant load at 0.3 A/cm²) provided contradictory degradation results with degradation rates of-8.0 µV/h and 70 µV/h for the same MEA type. The same trend has been observed with other fuel supply options. Fuel cells operated with hydrogen/air or with synthetic reformate/air show similar low and high degradation rates. This paper discusses a possible explanation for such differences. Post-mortem analysis on MEAs with high degradation rates are performed to provide a better understanding of causes leading to such high degradation rates.
- by Peter Wagner and +1
- •
Start/stop cycling are dynamic durability tests designed to simulate the fuel cell system shutdown and restarting that occurs in actual system operation. In the present work, commercial PBI-based MEAs were evaluated in a start/stop... more
Start/stop cycling are dynamic durability tests designed to simulate the fuel cell system shutdown and restarting that occurs in actual system operation. In the present work, commercial PBI-based MEAs were evaluated in a start/stop cycling test designed for combined heat and power application. Moreover, the start/stop cycling strategy has not been conducted under protective conditions that mitigate degradation of fuel cell materials over cycles. Instead, start/stop of the fuel cell has been conducted on a daily basis until completing 60 cycles or reaching end-of-life. Two idling temperatures after shutdown have been investigated: 25 and 100 C. Thus, the effect of idling temperature has never been studied before in this fuel cell technology. Polarization curves, electrochemical impedance spectroscopy, cyclic, linear sweep voltammetry and m-CT were utilized for MEA characterization. It was observed that system temperature during idling periods played an important role for HT-PEM MEAs lifetime. The test performed at the highest idling temperature exhibited larger degradation (À57 mV/h or À2.4 mV/cycle) than that at lower idling temperature (À13 mV/h or À0.6 mV/cycle). Thus, it was found that performance was mainly reduced due to catalyst deactivation and increased mass transfer limitations. Besides, electrochemical investigations showed both anode and cathode catalyst deterioration and m-CT images also confirmed anode catalyst layer local thinning.
- by Peter Wagner and +1
- •
Optrodes based on Prussian blue (PB) are promising for hydrogen peroxide detection within PEMFCs to study the Membrane-Electrode-Assembly degradation. The PB film is however required to sustain the harsh environment of PEMFCs. In this... more
Optrodes based on Prussian blue (PB) are promising for hydrogen peroxide detection within PEMFCs to study the Membrane-Electrode-Assembly degradation. The PB film is however required to sustain the harsh environment of PEMFCs. In this work, PB films were deposited through different conditions and soaked in Phosphate-Buffer-Solutions with pH 2 at elevated temperatures for a day. These PB films were characterized using FTIR to analyze their stability following PBS processing at operating temperature and pH corresponding to an operating PEMFC. The PB film prepared using the single-source-precursor at the temperature of 60 • C is found to be the most stable.
- by Peter Wagner
- •
One of the major advantages of polybenzimidazole (PBI) based high temperature polymer electrolyte (HT-PEM) fuel cells compared to the low temperature representatives of this type of fuel cell technology is the higher tolerance against... more
One of the major advantages of polybenzimidazole (PBI) based high temperature polymer electrolyte (HT-PEM) fuel cells compared to the low temperature representatives of this type of fuel cell technology is the higher tolerance against impurities like CO. Nevertheless lifetime and durability are still an issue. In this work, an improvement in degradation rates and therefore an extension of lifetime of HT-PEM fuel cells will be presented. Extended long term tests have been performed at different facilities under similar test conditions. After 3,000 h of operation, an average degradation rate of -1.7 µV/h has been achieved. One of the tests is still under operation; this MEA already reached a lifetime more than 9,000 hours with an actual degradation rate of -3 µV/h.
- by Peter Wagner and +4
- •