Cell and Stack Performance

Ceramatec, in partnership with the Idaho National Laboratory, has been evaluating cell and stack performance in the HTE mode of operation. Photographs of components and a manifolded 10-cell stack are shown in hgure 3.4. 

The cell and stacks that compose the power section have been discussed extensively in the previous sections of this handbook. Section 9.1 addresses system processes such as fuel processors, rejected heat utilization, the power conditioner, and equipment performance guidelines. System optimization issues are addressed in Section 9.2. System design examples for present day and future applications are presented in Sections 9.3 and 9.4 respectively. Section 9.5 discusses research and development areas that are required for the future system designs to be developed. Section 9.5 presents some advanced fuel cell network designs, and Section 9.6 introduces hybrid systems that combine fuel cells with other generating technologies in integrated systems. 

Numerous demonstrations in recent years have shown that the level of performance of present-day polymer electrolyte fuel cells can compete with current energy conversion technologies in power densities and energy efficiencies. However, for large-scale commercialization in automobile and portable applications, the merit function of fuel cell systems—namely, the ratio of power density to cost—must be improved by a factor of 10 or more. Clever engineering and empirical optimization of cells and stacks alone cannot achieve such ambitious performance and cost targets. 

SRU and stack performance were evaluated through current density-voltage (i-V) measurements. I-V curves were plotted until a maximum cell voltage of 1.5 V. Short-term durability tests were conducted on the stack over a few hundreds of hours, the stack being galvanostatically controlled to reach an initial average voltage around 1.3 V per cell. 

The programme is investigating key technical issues for the development of HI E for nuclear application and developing plans for experimental demonstration at the various scaling levels. Components for laboratory-scale experiments have been fabricated and button cell and stack experiments conducted to evaluate candidate electrolyser characteristics and performance. 

Since the mid-nineties several generations of SOFC stacks have been designed and tested based on the anode substrate type cells developed in Jiilich. The main topics addressed in the development of the cell and stack technology are high performance, low degradation and the potential for low-cost production. 

Ballard Power Systems (Canada) is the world leader in stack development and manufacturing. Its stacks are reliable and offer very uniform cell-to-cell and stack-to-stack performance. Figure 5.4 is a picture of a Ballard FCgen-1020ACS series air-cooled stack with 80 unit cells. The honeycomb-like... 

Traditionally, the majority of SOFC modeling efforts have taken place at the macroscale and have provided valuable insight into the operation of SOFC cells and stacks [15, 36-38], In macroscale modeling, simplified models of the SOFC multi-physics are used to simulate the operating conditions and performance of the SOFC. Macroscale models are used to investigate the performance of experimental cells and stacks [35, 39], SOFC system-level operation and controls [40, 41], and thermal stresses and strains in the cells and stacks [42-44]. 

In the following sections, the individual cell and stack components are discussed in view of their performance and cost. 

---