1. 1. FUEL CELL TECHNOLOGY Paul Nikstad
2. 2. INTRODUCTION Fuel cells have been in production since the 1960s Fuel cells powered NASAs Apollo Space Craft Only emission is water and electricity Slowly gaining popularity with auto manufactures for alternate fuel vehicles. Apollo Space Craft
3. 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. 4. Each type of fuel cell has its 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. 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. 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. 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. 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. 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. 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. 11. SOLID OXIDE FUEL CELLS Popular fuel cell in todays market. Certain features make it popular for stationary power supplies. Primary advantages are fuel flexibility, high efficiency, and long term stability.
12. 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. 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. 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. 15. DISADVANTAGES High operating temperature Requires long start up times Dictates material selection process All materials in cell must withstand high temperatures
16. 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. 17. This is a bank of Bloom Energy Servers Fuel cell manufactured by Ceramic Fuel Cells Limited
18. 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 toadys fuel cell market Alkaline fuel cell used in NASAs Space Shuttles
19. 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. 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. 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. 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.