Page 34 - Introduction to Transfer Phenomena in PEM Fuel Cells

The operating temperature is between 600°C and 700°C. At this
temperature, the carbonates are melted and are maintained by capillarity in
the matrix. Introduction to Hydrogen Technology 23
MCFCs are mainly used in stationary applications. An example is a 2
MW natural gas mini-plant in the United States that has been operating close
to 4,000 hours. The power range is between 500 kW and 10 MW.

1.2.1.5.1. Operating characteristics
Table 1.6 summarizes the characteristics and performance of the MCFC
[BOU 07].

Characteristics and performance
Operating temperature 650 to 700°C

Operating pressure One to several bars
Electrical efficiency 55%

Actual voltage 0.75 to 0.90 V
Current density Up to 200 mA/cm²
Start-up time Up to several hours

Response time to a rapid variation in Dependent on size
demand
Lifetime Several thousand hours

Table 1.6. Characteristics and performance of a MCFC

1.2.1.5.2. Advantages and disadvantages
The high operating temperature of these batteries gives them some
advantages:
– they have a better tolerance to compounds that contaminate hydrogen,
particularly carbon monoxide (CO), which can be used as fuel along with
hydrogen;

– the reforming of hydrocarbons (methane, propane, etc.) or of methanol
can be carried out inside the cell itself;