Ballard Stacks

DaimlerChrysler had a fleet of more than 100 F-cell fuel cell cars called the F-Cell which were used for worldwide testing. They have also built 33 fuel cell buses for 10 European cities as well as Beijing and Perth. DaimlerChrysler has invested over 1 billion in hydrogen fuel cell technology. The fuel cell vehicle fleet is powered by Ballard stacks. 

T. Ralph, G. Hards, J. Keating, S. Campbell, D. Wilkinson, M. Davis, J. St. Pierre, M. Johnson, "Low Cost Electrodes for Proton Exchange Membrane Fuel Cells Performance in Single Cells and Ballard Stacks," J. Electrochemical Society, Volume 144, No. 11, November 1997. 

Hards, G. A., Ralph, T. R., Wilkinson, D. R, and Campbell, S. A. Low cost electrode development and performance in Ballard stack hardware. Proceedings of 1996 Fuel Cell Seminar, Orlando, FL, Nov. 17-20,1996, 544-547. 

A Ballard stack is shown in the expanded stack of Figure 6.1. 

Figure 6.1 Exploded Ballard stack with flow plate and membrances...

The application to fuel cells was reopened by Ballard stacks using a new Dow membrane that is characterized by short side chains. The extremely high power density of the polymer electrolyte fuel cell (PEFC) stacks was actiieved not only by the higher proton conductance of the membrane, but also by the usage of PFSA polymer dispersed solution, serpentine flow separators, the structure of the thin catalyst layer, and the gas diffusion layer. Although PFSA membranes remain the most commonly employed electrolyte up to now, their drawbacks, such as decrease in mechanical strength at elevated temperature and necessity for humidification to keep the proton conductance, caused the development of various types of new electrolytes and technologies [7], as shown in Fig. 2. 

Ralph TR, Hards GA, Keating JE, Campbell SA, Wilkinson DP, Davis H, St. Pierre J, Johnson MC (1997) Low cost electrodes for proton exchange membrane fuel cells performance in single cells and Ballard stacks. J Electrochem Soc 144 3845-3857... 

DaimlerChrysler unveiled a series of FCVs using Ballard stacks such as the NECAR 1 (50 kW, Compressed Hz, 1994), NECAR 2 (50 kW, Compressed Hz, 1996), NECAR 3 (50 kW, liquid methanol, 1997), NECAR 4 (70 kW, liquid Hz,... 

A brief timeline for the development of FCVs by Honda is summarized below. Honda initially employed various 60-85 kW Ballard stacks in their initial FCVs such as the FCX-Vl (Metal hydride, 1999), FCX-V2 (Methanol, 1999), FCX-V3 (Compressed H2,2000), FCX-V4 with ultra-capacitors (Compressed H2,2001), and the FCX (Compressed H2, 2002) vehicle that was leased in Los Angeles. 

Figure 17.10 shows the performance in Ballard stack hardware of three different cell-reversal-tolerant electrocatalysts prepared by Johnson Matthey. In this case the MEAs have received significant prior cell-reversal periods to drive the anodes to the limit of their tolerance. The impact that inclusion of a water electrolysis electrocatalyst has on the ability of the anode to sustain water electrolysis is evident. At the standard 40 wt% Pt, 20 wt% Ru/Shawinigan carbon black-based anode, the water electrolysis plateau is so short that it is difficult to detect. Only by using a cell reversal-tolerant electrocatalyst in the anode water electrolysis are plateaus evident in Figure 17.10. As a result, the degree of carbon corrosion is significantly reduced by the cell-reversal-tolerant electrocatalysts. The...

If we make our cells with an active area of 15 x 25 = 375 cm, this means that the stack will need to contain 293,890 = 375 = 784 cells. This sounds like a very large number, but at the end of Chapter 4 we noted that the Ballard stacks used in the fuel cell bus engines (Figure 4.32) had about 750 cells each. These have a similar power, so we should not be too surprised. 

Siemens AG has been involved in R D on PFFCs, and Vickers Shipbuilding Engineering Ltd. (United Kingdom) is evaluating PFFCs from Ballard Power Systems for power generation. A 35-ceU stack was successfully tested for more than 300 h. Plans are under way to test a 20-kW PEFC. 

Fuel cell technology probably offers a new emerging area for polyheterocyclic polymers as membranes. Fuel cells are interesting in transport applications and are now being evaluated in Chicago in transit buses with a 275-hp engine working with three 13 kW Ballard fuel cell stacks. 

NEBUS appeared in 1997 and showed the fuel cell downsizing done by Ballard. It has ten of the company s 25-kilowatt fuel cell stacks in its rear compartment. It is a functional city bus, with a comparable range. It is similar but not identical to the buses Ballard has put on the streets of Vancouver and Chicago. 

There has been an accelerated interest in polymer electrolyte fuel cells within the last few years, which has led to improvements in both cost and performance. Development has reached the point where motive power applications appear achievable at an acceptable cost for commercial markets. Noticeable accomplishments in the technology, which have been published, have been made at Ballard Power Systems. PEFC operation at ambient pressure has been validated for over 25,000 hours with a six-cell stack without forced air flow, humidification, or active cooling (17). Complete fuel cell systems have been demonstrated for a number of transportation applications including public transit buses and passenger automobiles. Recent development has focused on cost reduction and high volume manufacture for the catalyst, membranes, and bipolar plates. 

This coincides with ongoing research to increase power density, improve water management, operate at ambient conditions, tolerate reformed fuel, and extend stack life. In the descriptions that follow, Ballard Power Systems fuel cells are considered representative of the state-of-the-art. 

Manufacturing details of the Ballard Power Systems cell and stack design are proprietary (18), but the literature provides some information on the cell and stack design. An example schematic of a manufacturer s cell is shown in Figure 3-1. 

This brief history of century-old investigations toward hydrogen interaction with solid materials and nanomaterials brings us to the current state of affairs when the hydrogen storage for fuel cell systems still remains to be solved. Indeed, in the first decade of the new Millennium, and at the advent of the Hydrogen Economy, fuel cell stacks for use in mass transportation, like those developed by Ballard Power Systems based in Canada, are ready for mass commercialization. Also, hydrogen... 

Sintering as a micro structuring (see the section above) and bonding technique was applied by Schuessler et al. [85] of Ballard for their compact methanol fuel processor (see Figure 2.94). The stack of plates and the endplate are connected in a single bonding step. 

Figure 2.94 Single plate and stack of plates with endplate of the integrated fuel processor fabricated at Ballard [85] (by courtesy of Elsevier Ltd.).

The core of the Ballard fuel cell consists of a membrane electrode assembly (MEA) that is placed between two flow-field plates. The flow-field plates direct H2 to the anode and Oz (from air) to the cathode. To obtain the desired amount of electric power, individual fuel cells are combined to form fuel cell stacks. Increasing the number of cells in a stack increases the voltage, and... 

Figure 5.40. Comparison of the ohmic resistance-corrected Nyquist plots of a Ballard Mark V 6-cell stack at different temperatures a 50 A, b 100 A, c 150 A...

Currently, the stationary power market penetration of the fuel cell is based on reduced local pollution rather than superior performance. Indeed the internationally demonstrated Ballard fuel cell bus generates more pollution from the power plant stack which generates its hydrogen supply from an inefficient incomplete electrolyser, than it saves by emitting steam from its exhaust. The industry has to rescue itself from this untenable position. 

Fuel cell stacks are assembled by Ballard and tested in application situations such as vehicles and stationary power. Operating experience... 

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