SOFC System Cost Structure

The main difference in SOFC stack cost structure as compared to PEFC cost relates to the simpler system configuration of the SOFC-based system. This is mainly due to the fact that SOFC stacks do not contain the type of high-cost precious metals that PEFCs contain. This is off-set in part by the relatively complex manufacturing process required for the manufacture of the SOFC electrode electrolyte plates and by the somewhat lower power density in SOFC systems. Low temperature operation (enabled with electrode supported planar configuration) enables the use of low cost metallic interconnects which can be manufactured with conventional metal forming operations. 

Detailed cost and design studies for both PEFC and SOFC systems at sizes ranging from 5kW to 1 MW were made that point to the fundamental differences between PEFC and SOFC technology that impact the system design and by implication the cost structure. These differences will be discussed in the following paragraphs. 

Arthur D. Little has carried out cost structure studies for a variety of fuel cell technologies for a wide range of applications, including SOFC tubular, planar and PEM technologies. Because phenomena at many levels of abstraction have a significant impact on performance and cost, they have developed a multi-level system performance and cost modeling approach (see Figure 1-15). At the most elementary level, it includes fundamental chemical reachon/reactor models for the fuel processor and fuel cell as one-dimensional systems. 

To provide some perspective on the viability of SOFCs in APU applications from a cost perspective, NETL sponsored an estimate of the cost structure of small-scale (5 kW), simple-cycle SOFC anode-supported system, operated on gasoline. The estimated manufacturing cost for such systems (see Figure 1-16) could well be close to that estimated for comparable PEM systems, while providing somewhat higher system efficiency. 

Figure 1-16. Projected cost structure of a SkWnet APU SOFC system. Gasoline fueled POX reformer, Fuel cell operating at 300mW/cm, 0.7 V, 90 % fuel utilization, 500,000...

The main differences in high-temperature fuel-cell stack cost structure relate to the fact that they do not contain high-cost precious metals, on the one hand, and that they demand more complex manufacturing process, on the other. It must be noticed therefore, that, the fuel-cell stack is, in many cases, responsible for less than one third of the total capital cost of a fuel-cell system, and that a large portion of the total cost is caused by fuel pretreatment (reforming, cleaning etc.), plant control, and power conditioning. For small-scale SOFC systems, the cost of the stack is of the order of 40-45% of the total cost. 

---