Page 296 - Biofuels Refining and Performance

Fuel Cells 275

system, quiet operation, and high efficiencies. Westinghouse has worked
at developing a tubular style of the SOFC that operates at 1000 C (see
Fig. 9.10) for many years [1–3, 26, 27]. These long tubes have high elec-
trical resistance but are simple to seal. Many other manufacturers are
now working on a planar SOFC composed of thin ceramic sheets which
operate at 800 C or even less. Thin sheets offer low electrical resistance,
and cheaper materials such as stainless steel can be used at these lower
temperatures [3, 6, 26]. One big advantage of the SOFC over the MCFC
is that the electrolyte is a solid. Therefore, no pumps are required to cir-
culate a hot electrolyte, and very compact, small planar SOFC systems
of a few kW range could be constructed using very thin sheets.
A major advantage of the SOFC is that both hydrogen and carbon
monoxide are used in the cell. Therefore, in the SOFC, many common
hydrocarbon fuels such as natural gas, diesel, gasoline, alcohol, and coal
gas can be safely used. The SOFC can reform these fuels into hydrogen

Interconnection
contact
Interconnection

Electrolyte

Air electrode

Fuel electrode

Tubular SOFC design

Anode

Electrolyte

Cathode
Electrolyte-supported planer SOFC Anode-supported planer SOFC
Figure 9.10 Tubular and planer solid oxide fuel cell.