PROPANE STEAM REFORMING FOR FUEL CELLS

1. PROPANE STEAM REFORMING FOR FUEL CELLS By Tamika Brown

2. e- e- H2 H2 H2 H2 H2 H2 H2 O2 O2 O2 O2 O2 O2 O2 H2O H2O H2O H+ H+ What is a Fuel Cell, and how does it work? • A fuel cell is an electrochemical device • that combines hydrogen fuel and oxygen • from air to produce electricity and water. • In a Polymer Electrolyte Fuel Cell, Hydrogen ions form at the anode, and • diffuse through the electrolyte and react • with oxygen at the cathode. • Anode: H2→ 2H + (aq) +2e- • Cathode: ½ O2 + 2H + (aq) + 2e- → H2O (l) Anode Cathode Electrolyte

3. Uses of Fuel Cells • Transportation: • Phosphoric Acid Fuel Cell • Anode: H2(g) →2H + (aq) + 2e- • Cathode: ½ O2 (g) + 2H+ (aq) + 2e- → H2O(l) • Portable: • Proton Exchange Membrane Fuel Cell • Anode: H2(g) → 2H + (aq) + 2e- • Cathode: Cathode: ½ O2 (g) + 2H+ (aq) + 2e- → H2O(l) • Stationary: • Solid Oxide Fuel Cells • Anode: H2(g) + O2→ H2O(g) + 2e- • Cathode: ½ O2 (g) + 2e- → O2-

4. Fuel Cell uses • Fuel Cell transit buses in Chicago (Ballard Corp) • Anode: H2(g) → 2H + (aq) + 2e- • Cathode: ½ O2 (g) + 2H+ (aq) + 2e- → H2O(l) • Energy Research Corp. • Anode: H2(g) + 2CO3 → H2O(g) + CO2(g) + 2e- • Cathode: ½ O2 (g) + CO2 + 2e- → 2CO3

5. Hydrogen • Hydrogen is the most abundant element in the universe • No known sources of gaseous hydrogen • Hydrogen generated from another energy source such as petroleum or from water through electrolysis • energy (electricity) + 2 H2O ->  O2  + 2 H2 SO HOW DO WE GENERATE AN ADEQUATE SUPPLY OF HYDROGEN FOR FUEL CELLS . . . . .

6. Fuel Processor/Reformer • Reformers convert hydrocarbon fuels into hydrogen • Steam and/or oxygen along with a catalyst are needed • Carbon dioxide is a byproduct Electric Power Conditioner Air Fuel Exhaust Fuel Processor Spent-Gas Burner Fuel Cell Stack Air H2 Thermal & Water Management

7. 3 Types of Reactions *Steam Reforming: • Hydrocarbon+ Steam + catalyst → H2 + CO2 • Partial Oxidation Reforming: • Hydrocarbon + Oxygen + catalyst → H2 + CO2 • Autothermal Reforming: • Hydrocarbon + Oxygen + Steam + catalyst → H2 + CO2

8. Why choose Steam Reforming? • Tailor to application • Ex. This particular investigation focuses on stationary uses such as power plants and industrial plants • Partial Oxidation (POx) can be tailored to meet certain vehicle regulatory standards • Autothermal Reforming (ATR) is a thermal balance between (POx) and Steam Reforming

9. What is Hydrocarbon Source? • Liquefied Petroleum Gas (LPG), • Consists mainly of propane, propylene, butane and butylenes in various mixtures. • In the U.S. the mixture is mainly propane.

10. Why choose LPG? • LPG can be used in the home, commercial businesses, industry, and transportation • The residential and commercial markets where LPG is used make up about 50% of the world total LP gas retail sales

11. Fuel Processor/Reformer Hydrocarbon + H2O(g) + catalyst → H2 + O2 1.Inlets to Reactor a) Water → Steam b) Fuel (liquid) → Vapor c) Fuel (gas) d) Air (POx or ATR) e) Catalyst 2. Reactor a) Sampling ports 3. Analytical Train a) CO/CO2 detector b) Mass flow indicator

12. What are the Goals of Experimentation? • Explore how operating conditions affect the reaction kinetics • Variables: temperature, flow rates, catalyst • Data from reactor model → kinetics → full scale reactor design for commercial use

13. Challenges of Reforming Process • Flow Rates: • High efficiency is desired at faster flow rates • Waste less fuel and energy, less catalyst • Cost: • Parts can be expensive, as well as precious metal coated catalysts. • Catalyst: • Catalyst needs to withstand impurities such as sulfur, but also produce the most amount of hydrogen possible • Temperature: • High efficiency needs to be achieved at lower temperatures • Less of a hazard, cost of parts is cheaper, and less energy is needed to maintain system

14. Challenges Continued • Response times: • Don’t want to have to wait periods of time for hydrogen to be produced in order for fuel cell to start working. • Durability: • Catalyst and Reformer need to be durable • Coking: • Carbon deposits in the reformer • This causes clogging in the system • Interference of components in fuel mixture • Alkenes interfere with alkane reforming • This is a problem for LPG, because it is not a homogenous mixture

15. Conclusion • If we switch to a hydrogen economy • More efficient than combustion • Less air pollution (NOx, SOx, COx) • Easily transportable • Save money (less imports) • Fuel Reforming for Fuel Cells is an intermediary technology for the production of hydrogen until a renewable source of energy can be discovered.

16. Acknowledgments I would like to thank John Kopasz for giving me the opportunity to participate in this and other research projects. I would like to thank Dan Applegate for his knowledge and helpfulness. I express sincere gratitude to Laura Miller for her patience, time, and wisdom. Last but not least, I would like to thank the U.S. Department of Energy for giving students a change to grow scientifically as well as professionally.

17. References • “What is a Fuel Cell.” Fuel Cells 2000. 2 March 2004. • http://www.fuelcells.org/whatis.htm • Carter, David, “Fuel Cell Power: What’s taking so long?” • IPMI 25th International Precious Metals Conference, June 9-12, 2001. • “Electrolysis: Obtaining hydrogen from water: The Basis for a Solar-Hydrogen Economy.” 4 April 2005. http://www.nmsea.org • “Chicago’s Fuel Cell Buses Mobilized.” Hydrogen Newsletter Winter 1998: Hydrogen Buses. 4 April 2005. http://www.hydrogenus.com/advocate/ad31cta.htm • “Pocket-size PEMs.” Pocket-size PEMs. 4 April 2005. http://www.memagazine.org/backissues/february2000/features/pems/pems.html • Miller, Laura, “Safety Review for Long Term Test Reactor CMT50-0006-EP-Rev 08 NEPA Document ER-281.” February 17, 2005 pp. 1-15. • Laura, Miller, “Science Careers in Search of Women Conference.” March 10, 2005. • “What is Propane?” Alternative Fuels Data Center: What is Propane?” 23 March 2005. http://www.eere.energy.gov/afdc/altfuel/whatisprop.html. • “What is LP Gas?” World LP Gas Association. 29 March 2005. http://www.worldpgas.com/mainpages/aboutpgas/whatislpgas.php.