Proton Exchange Membrane Fuel Cell

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A proton exchange membrane fuel cell (PEMFC) is a versatile fuel cell for diverse applications. The typical components are:

• ion exchange membrane (e.g. Nafion, see materials for FCs), subject to durability issues,
• electrically conductive porous backing layer (gas diffusion layer), providing the pathway for electrons, assuring mechanical support and lead product water away from the electrodes (i.e. with Teflon-like material),
• electro-catalyst layer between membrane and backing layer (electrodes, e.g. made with platinum, see materials for FCs), with a strong impact on stack costs,
• cell connectors and flowplates delivering fuel and oxidant to anode and cathode.

Possible designs are tubular or planar, with the planar bipolar type being the most favourite design for manufacturing and packaging reasons.

Metrics Table

Summary

A PEMFC is easy to handle and operate at low temperature. It is the most widely used fuel cell in transport applications: since 2000, more than 90% of all fuel cell vehicles on the road have been equipped with a PEMFC. The low temperature of operation and high power density, both at its operating temperature as well as during start-up, make it the most suitable fuel cell for transport applications. However, the transport applications also face problems concerning cooling systems. The large research and development efforts put into the PEMFC have made the PEMFC an attractive candidate for stationary applications as well.

When setting the system boundaries to the stack itself, GHG emissions are negligible during hydrogen operation. During operation with reformate, other emissions, namely CO, CO2, NOx and SO2, are present but at a very low level. Published data regarding noise usually is difficult to assess, as only FC system noise levels are available. A published value for noise emission is 60dB @ 1m for a stationary system. Due to the absence of moving mechanical parts, noise should be well under control for most FC stack types.

Efficiency data is well documented for PEMFC, indicating that it is higher than efficiency of competing technologies. The part load efficiency is 40-70% and a full load efficiency is 50-55%, although the measuring procedure for efficiency is mostly not communicated. The full load efficiency for stationary sector is 45 to 50%, 55% is a value given for portable PEMFC stacks.

Concerning the stack performances, cell power densities of 0.5 W/cm2 at a cell voltage of 0.7 V can be considered as state-of-the-art for PEMFC operating at 80°C or lower and at a pressure of 1.5 bar g. The power density of stacks especially for those developed for transport applications, is typically above 1 – 1.5 kW/l with a power density of 0.88-0.94 kW/kg.

Cost projections for Ballard's stack

In terms of performance (range, max. power), a PEMFC in the transport sector (FC vehicle) has different power development properties than ICE-powered vehicles. This is due to the electric drivetrain and the electric motor. Its strong side is low speed operation, where the electric motor can deliver high torque and thus deliver very good performance. Current hybrid vehicles use their electric converters mainly in low speed / low torque requirements.

Results from demonstration projects indicate a durability of the technology for transport and stationary sectors of more than 2000 (under real drive cycle testing conditions) and more than 18000 hours respectively.

Read more: Introduction to PEFC Operation

Costs

According to available cost data, a PEMFC stack costs around 15,200EUR (for 80 kW, in 2005).

A reasonable high volume manufacturing (500,000 unit per year) cost estimate has been by TIAX for Ballard: this cost, for 2005, is 73 USD/kW.

Cost data for typical stationary systems with 10 kW and 200 kW respectively are shown in the following table:

A further study called "Mass Production cost of PEM fuel cell by learning curve" from the 29^th International Journal of Hydrogen Energy states the cost per unit of energy to be 1522 €/kW, whereas an article about the GM HydroGen3 gives a figure of 500 $/kW for a transportation system, and a target value of 50 $/kW.

Read more: Hydrogen Pathway Cost Analysis

High Temperature PEM Fuel Cell

Volkswagen is developing a high temperature PEM fuel cell. In these cells, the membrane is saturated with phosphoric acid instead of water. To prevent the phosphoric acid from being washed out by the product water, the electrodes are coated with a special paste. By using phosphoric acid instead of water, the operating temperature of the cell can be raised to 160° C because of the higher boiling point of the acid. Therefore the cooling system can be dimensioned smaller. A further advantage of this cell type is that no humidification is needed for the fuel gases. So the whole fuel cell system is smaller than previous systems. According to Volkswagen, the cell has a power of 0.9 W/cm² , with a cell degradation of 6 % per 1000 hours of operation.

Key Issues

The key issue of PEMFC technology concerns costs, mainly due to the platinum loading, which remains at an unacceptable level for PEMFC mass market penetration despite major efforts to reduce its amount. Current manufacturing processes are far from mass production technologies and thus result in high production costs. Engineering efforts will probably lead to a solution to this problem.

Durability is also a key issue, whereas it only partly depends on the stack itself. While failure because of poor isolation of MEAs or because of dehydration can be traced back to stack design, deteriorating performance following membrane poisoning is an issue of fuel conditioning (e.g. CO removal from reformate gas) and must be addressed there. PEMFC behaviour at temperatures and pressures below or above regular operating conditions (cold-start response, failure of cooling systems) also needs to be investigated in more detail as too little information is available.

Other key issues, in particular related to the automotive applications, are the following:

• Tolerance of sub-zero conditions with a fast start-up from sub-zero conditions
• Reduced or even eliminated external humidification requirements
• Increased operating temperature

Data Lacking

Although much data is available about the technology for the transport sector, in the field of stationary and portable application, less data could be collected so far.

Reliable data on costs - either current costs, prospects or well-founded learning curves - would also be highly desirable.

Related Components

• Water and Air Management (Thermal Management)

• Heat Exchanger (Thermal Management)

• Reformer Technology (Fuel and Oxidant Conditioning)

• Compressors (Fuel and Oxidant Conditioning)

References

• J. Haubrock , G. Heideck , Z. Styczynski
  Electrical Efficiency Losses Occurred By The Air Compressor For PEMFC
  WHEC 16, Lyon France, 13 - 16 June 2006

• Bent Sørensen
  Comparison Between Hydrogen Fuel Cell Vehicles And Bio-Diesel Vehicles
  WHEC 16, Lyon France, 13 - 16 June 2006

• Renaut Mosdale, Annette Mosdale
  High Efficiency Portable Fuel Cells
  WHEC 16, Lyon France, 13 - 16 June 2006

• Ferraro Marco, Sergi Francesco, Cretì Pasquale, Dispenza Giorgio, Matera Fabio, Sapienza Cristoforo, Andaloro Laura and Antonucci Vincenzo
  Evaluation Of An UPS System Based On Direct Hydrogen PEM Fuel Cell
  WHEC 16, Lyon France, 13 - 16 June 2006

• Keith Wipke, Cory Welch, Holly Thomas, Sam Sprik, Sigmund Gronich, John Garbak
  Controlled Hydrogen Fleet And Infrastructure Demonstration And Validation Project: Fall 2006 Progress Update
  The 22nd International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exposition (EVS-22), Yokohama, Japan, Oct. 23-28, 2006

• Wolfgang Friede, Mark Kammerer, Naoya Kodama, Kevin Harris
  Fuel Cell Hybrid Midibuses for Niche Applications
  The 22nd International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exposition (EVS-22), Yokohama, Japan, Oct. 23-28, 2006

• Mikio Kizaki, Yoshiyuki Miki, Hideaki Mizuno, Tsuyoshi Takahashi, Nobuyuki Oogami
  Development of Fuel Cell Hybrid Vehicles in TOYOTA
  The 22nd International Battery, Hybrid and Fuel Cell Electric Vehicle Symposium & Exposition (EVS-22), Yokohama, Japan, Oct. 23-28, 2006

• H. G. Düsterwald, J. Günnewig, R. Heuss, P. Radtke,
  DRIVE - The Future of Automotive Power
  VDI-Berichte Nr. 1972, 2006

• F. N. Büchi, A. Delfino, P. Dietrich, S. A. Freunberger, R. Kötz, Daniel Laurent, Pierre-Alain Magne, David Olsommer, Dr. Gino Paganelli, Akinori Tsukada, Pierre Varenne, Daniel Walser
  Electrical Drive-train Concept with Fuel Cell System and Supercapacitor - Results of the „Hy-LIGHT" - vehicle
  VDI-Berichte Nr. 1972, 2006

• J. Schindler
  Bewertung von alternativen Kraftstoffen und Antrieben: Ergebnisse von Well-to-Wheel Analysen
  VDI-Berichte Nr. 1975, 2006

• N.N.
  Manual: Ballard Fuel Cell Power Module: Mark 902
  Ballard Power Systems

• B. Gnörich, L. Schlecht
  Wege zur Markteinführung alternativer Fahrzeugantriebe: Eine technisch-ökonomische Analyse
  Aachen & Berlin, December 2004

• N.N.
  Brennstoffzellenantriebsentwicklung: Input aus dem Forschungsfahrzeug F600 HY^GENIUS
  DaimlerChrysler, 17 July 2006

• N.N.
  Manual: HyPM Fuel Cell Power Modules 500 Series
  Hydrogenics corporation

• N.N.
  Manual: Ballard Fuel Cell Power: Mark 1030, Mark9 SSL
  Ballard Power Systems

• N.N.
  Manual: Fuel Cell Products for Uninterruptible Power
  GenCore Systems

• N.N.
  Report: GM Well To Wheel Analysis of Energy Use and Greenhouse Gas Emissions of Advanced Fuel / Vehicel Systems - A European Study
  L-B-Systemtechnik GMBH, Ottobrunn, Germany
  27 September 2002

• Jack Frost
  Hydrogen and Fuel Cells for Automotive Applications
  ImechE, London, 7 November 2006

• N.N.
  Manual: Membrane Electrode Assemblies for High Temperature PEM
  PEMEAS Fuel Cell Technologies

• N.N.
  Produktdatenblatt: CS 9782.050
  Rittal

• Jens Burfeind
  Betriebliche Aspekte von Hochtemperatur-PEM-Brennstoffzellen
  May 2006

• N.N.
  Fuel Cell Handbook, 7^th Edition
  EG&G Technical Services, Inc., U.S. Department of Energy, 2004

• N.N.
  Volkswagen Forschung: Weltpremiere der VW-Hochtemperatur-Brennstoffzelle
  Volkswagen AG, Oktober 2006

• R. Friesen
  Draft Fuel Cell Economic Analysis
  UCI Advanced Power and Energy Program, 2004; [4]

• N.N.
  The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs (2004)
  National Academy of Engineering (NAE), Board on Energy and Environmental Systems (BEES), page 32, [5]

• H. Tsuchiya, O. Kobayashi
  Mass Production cost of PEM fuel cell by learning curve
  International Journal of Hydrogen Energy 29, 985 (2004)

Notes

1. ↑ Back-up power generated based on PEFC with rated power of 1 kW, System realized at University of Cassino, Italy
2. ↑ Draft Fuel Cell Economic Analysis, R. Friesen, UCI Advanced Power and Energy Program, 2004; [1]
3. ↑ The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs (2004), National Academy of Engineering (NAE), Board on Energy and Environmental Systems (BEES), page 32, [2]
4. ↑ The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs (2004), National Academy of Engineering (NAE), Board on Energy and Environmental Systems (BEES), page 32, [3]
5. ↑ H. Tsuchiya, O. Kobayashi, Mass Production cost of PEM fuel cell by learning curve, International Journal of Hydrogen Energy 29, 985 (2004)