2. INTRODUCTION
Fuel cells have been in production since the 1960’s
Fuel cells powered NASA’s Apollo Space Craft
Only emission is water and electricity
Slowly gaining popularity with auto manufactures for alternate
fuel vehicles.
Apollo Space Craft
3. FUNDAMENTALS OF FUEL CELL
OPERATION
A fuel cell converts the energy in a fuel into electricity.
This is done using a chemical reaction
Fuel is usually hydrogen
Some cells can use simple hydrocarbons like methanol and
natural gas
4. Each type of fuel cell has it’s owe unique operation.
All fuel cells have three general components
Three Basic Components
Electrolyte
Cathode
Anode
Source of fuel is the anode
Oxygen is typically the cathode
The type of electrolyte define the type of fuel cell
Basic Fuel Cell Diagram
5. POLYMER-ELECTROLYTE MEMBRANE FUEL CELL
(PEM)
Drawn significant attention in scientific community
Quick start up time
Simplicity
Flexible
Most popular automobile fuel cell type
6. Four Main Components in PEM Fuel Cells
Bipolar plate
Gas diffusion layer
Catalyst layer
Electrolyte membrane
Electrolyte membrane is unique because it blocks
the flow of gas.
Only allows positively charged ions to flow.
In the picture, note the positive ions flowing to the
cathode. PEM Fuel Cell Diagram
7. ADVANTAGES
Low Operating Temperature
Low operating temperature means quick start up times
This is the single most significant advantage of the PEM fuel cell.
Makes this fuel cell popular with auto manufacturers.
Auto makers require a low start up time to accommodate the
needs of their customers.
8. DISADVANTAGES
Intolerant to CO in Fuel
Concentrations of less than 1 PPM are enough to damage catalyst
Hydrogen fuel is rarely pure
When hydrogen is refined, small quantities of CO remain
Platinum catalyst is expensive
9. CURRENT USAGE OF PEM FUEL
CELLS
PEM fuel cells are used in the automotive alternate fuel industry
Toyota Mirai ----- 400 mile range
Hyundai Tuscan ----- 265 mile range
Honda FXC Clarity ----- 230 mile range
Vehicle range is limited by hydrogen storage capacity
10. IMAGES OF PEM FUEL CELL STACKS
This is a low cost fuel cell stack for a hobbyist or academic use.
This is the fuel cell stack in the Toyota Mirai.
11. SOLID OXIDE FUEL CELLS
Popular fuel cell in today’s market.
Certain features make it popular for stationary power supplies.
Primary advantages are fuel flexibility, high efficiency, and long
term stability.
12. Four Main Components in Solid Oxide Fuel Cells
Anode
Cathode
Interconnect
Electrolyte
Electrolyte is a solid ceramic compound, hence
the name Solid oxide fuel cell
Manufactures use a variety of materials for
anode, cathode and interconnect layer.
These layers must withstand high temperatures
Tubular Solid Oxide Fuel Cell Diagram
13. Solid Oxide Fuel Cell Operation
Different than PEM fuel cell
Electrolyte must reach 500˚ - 1000˚ C
Oxygen is reduced to ions in the
cathode
These ions flow through the
electrolyte to the anode gas
Electrons are released which flow
through a load and back to the
cathode
Solid Oxide Fuel Cell Diagram
14. ADVANTAGES
Solid Oxide Fuel Cells do not Require Pure Hydrogen
Cell can reform light hydrocarbons like natural gas internally
Many stationary solid oxide fuel cells use natural gas for fuel
High efficiency. Up to 80%
15. DISADVANTAGES
High operating temperature
Requires long start up times
Dictates material selection process
All materials in cell must withstand high temperatures
16. CURRENT USAGE OF SOLID OXIDE FUEL CELLS
Solid oxide fuel cells are popular for stationary power production
Bloom Energy manufactures stationary power supplies with solid oxide fuel cells
Current Boom power supplies are 200kW.
Can use light liquid, or gas hydrocarbons as fuel
Implemented as power sources for several fortune 500 companies.
17. This is a bank of Bloom Energy Servers
Fuel cell manufactured by Ceramic Fuel Cells Limited
18. ALKALINE FUEL CELLS
Alkaline fuel cells have been in production since the 1960s.
Implemented by NASA for their Apollo Space Craft
This was convenient because fuel cells produce electricity and water.
Used in Space Shuttle program as well
Not popular in toady’s fuel cell market
Alkaline fuel cell used in
NASA’s Space Shuttles
19. ALKALINE FUEL CELL OPERATION
Alkaline fuel cell operation is similar to solid
oxide operation
Oxygen reduction occurs in cathode and ions
flow to the anode fuel gas
Electrolyte is a liquid, unlike the PEM and solid
oxide fuel cell
This electrolyte is sensitive to CO2
Must have a supply of pure oxygen
Alkaline Fuel Cell Diagram
20. ADVANTAGES
Generally less expensive than PEM fuel cells. No precious metals
in catalyst
Higher power density than PEM fuel cells
Produces .85 volts per cell.
21. DISADVANTAGES
Requires a source of pure oxygen on cathode side
Major disadvantage
Alternative to this is supplying air that has been “scrubbed” of CO2
22. CONCLUSION
The PEM fuel cell, solid oxide fuel cell, and alkaline fuel cell have
been researched significantly in the scientific community
There are several other fuel cell types in production
The PEM fuel cell and solid oxide fuel cell have are included in my
presentation because they are currently the most popular fuel
cell.
A basic understanding of the alkaline fuel cell is important
because one of the first fuel cells developed.
