APC 400kW1MW User Manual download pdf (Page 20)

they are not poisoned by trace levels of carbon monoxide. Like other fuel cells, the anodes in

SOFCs are poisoned by sulfur [17, p. 50; 25, p. 116].

An advantage that SOFCs have over other fuel cell types is that there are no precious

metals used in their construction, reducing the overall cost of the fuel cell. Another advantage is

that they have high electric generation efficiencies at both full and part loads. Electrical

generation efficiencies range from 45% to 60%. SOFCs are able to produce exhaust at around

500°F, making them applicable for CHP systems with absorption cooling. Efficiencies can reach

up to 85% for an SOFC used in a CHP system [25, p. 117].

Because fuel cells are one of the most attractive technologies for generating electricity,

the Solid-State Energy Conversion Alliance (SECA) was formed by the Department of Energy

(DOE) in 1999. The alliance was formed in order to accelerate the commercialization of SOFCs

from 3kW to 10kW for stationary, transportation, and military applications [26, para 1]. The goal

for SECA is to have factory costs of SOFCs to be $400/kW by 2010. Zogg et. al predicts that

the installation costs would be two to three times higher. The cost targets made by SECA were

made assuming that there is a successful market introduction with high production volumes

around 500,000 units per year by a single manufacturer [25, p. 117].

SOFCs are expected to be used for high heating loads, such as data centers [12, p. 5].

Their maximum power output range is 200kW to 250kW.

2.2.5 Summary of Fuel Cell Types

Table 2-1 compares the PAFC, MCFC, PEMFC, and SOFC. The MCFC is able to

obtain the highest electrical generation efficiencies, while the SOFC has the highest possible

efficiency in a CHP application. The different characteristics of the fuel cell types are important

for a designer to be aware of when making a fuel cell type selection. These characteristics will

be referred to throughout the remainder of the report.

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APC 400kW1MW User Manual Page 20