Transcript SOFC Technology - The University of Toledo

SOFC
Technology
Solid Oxide Fuel Cells
• Intended mainly for stationary applications
with an output of 1 kW and larger
• They work at very high temperatures (some
at 1000ºC)
• Due to the high operating temperature of
SOFC's, they have no need for expensive
catalyst.
Fuels for Fuel Cells
• The primary fuels directly utilized
within fuel cell stacks today are
–
–
–
–
Hydrogen
Carbon monoxide
Methanol and
Dilute light hydrocarbons like
methane, depending upon the fuel
cell type.
Cont..
SOFC :The most
inherently fuel flexible
• The presence of sulfur is not
tolerated by fuel cells in general.
• SOFC is the most inherently fuel
flexible of the fuel cell types.
• MCFC units are also quite fuel
flexible.
Cont..
• (SOFC) use a hard, ceramic
compound of metal (like calcium or
zirconium) oxides (chemically, O2)
as electrolyte
• Efficiency is about 60 percent
• Operating temperatures of
800-1,000 °C (about 1,800 °F).
Simplified diagram of an
SOFC
Operating Principle
1. Oxygen is dissociated at the
cathode into O22. O2- migrate thru the crystal
structure of the electrolyte
3. Oxidize the hydrogen atoms at
anode
4. Yields electrons and produces
electricity
Cont..
SOFC Design types
• According to the type of cell
configuration and developer• Three major configurations for stacking
the cells together to increase the
voltage and power are:
– Tubular (as developed by Westinghouse
and Mitsubishi Heavy Industries),
– Flat plate (as developed by Ceramatec and
Mitsubishi Heavy Industries), and
– Monolithic (as developed by Allied Signal).
Applications
• Suitable for decentralized electricity
production
• While the major application of SOFCs
are seen in stationary plants, auxiliary
power units in
• Transportation vehicles
• On-board power for aircraft
• Power packs- small enough to be carried by
soldiers
has been motivated by DARPA
Drawbacks
• The high temperature limits applications
of SOFC units and they tend to be
rather large
• While solid electrolytes cannot leak,
they can crack.
• Complex materials
• Assembling
• Maintenance
• Design Cost & choice of material