An Overview and Analysis of Hydrogen Fuel Cell Technology

A Literature Review by Alec Gugel

Contents6 Main Types of HFCs

Production Methods

Storage Methods

Discussion

PEMFCs

Electrolysis vs. Steam Reforming

Pressurized vs. Chemical Storage

References

Variants - AFCAFC - Alkaline Fuel Cell

Electrolyte: Alkaline solutions

Catalyst: Nickel

Operating Temperature: ~70ºC

Input: Hydrogen, Oxygen

Output (excluding power): Water

Variants - DMFCDMFC - Direct Methanol Fuel Cell

Electrolyte: water-based acidic polymer membrane

Catalyst: platinum–ruthenium (anode), platinum (cathode)

Operating Temperature: ~60-130ºC

Input: Methanol, Oxygen

Output (excluding power): Carbon Dioxide, Water

Variants - MCFCMCFC - Molten Carbonate Fuel Cell

Electrolyte: molten carbonate salt suspended in porous ceramic matrix

Catalyst: (non-precious metal)

Operating Temperature: ~650ºC

Input: Hydrogen or Hydrocarbons

Output (excluding power): Carbon Dioxide, Water

Variants - PAFCPAFC - Phosphoric Acid Fuel Cell

Electrolyte: liquid phosphoric acid in bonded silicon carbide matrix

Catalyst: finely dispersed platinum on carbon

Operating Temperature: ~180ºC

Input: Hydrogen, Oxygen

Output (excluding power): Water

Variants - SOFCSOFC - Solid Oxide Fuel Cell

Electrolyte: solid ceramic

Catalyst: (non-precious metal)

Operating Temperature: ~800-1000ºC

Input: Hydrogen or Hydrocarbons

Output (excluding power): Carbon Dioxide, Water

Variants - PEMFCPEMFC - Proton Exchange Membrane Fuel Cell (or Polymer Electrolyte Membrane)

Electrolyte: water-based acidic polymer membrane

Catalyst: Platinum-based

Operating Temperature: <100ºC

Input: Hydrogen, Oxygen

Output (excluding power): Water

Production - Steam Reforming

Steam Reforming

CH4 + H2O → CO + 3 H2

CO + H2O → CO2 + H2

Carbon Dioxide and Carbon Monoxide produced

Uses existing hydrocarbons

Production - ElectrolysisElectrolysis

2 H2O (l) + energy → 2 H2 (g) + O2 (g)

Uses water rather than fossil fuels

Can accept power input from dynamic sources (i.e. wind and solar)

Storage - PressurizedStandards

Housing: Aluminum/ CFRP (Carbon Fiber Reinforced Plastic)

Pressure Rating (based on Toyota Mirai/ Chevrolet Equinox): 70 mPa (~10,000 psi)

Other proposed physical storage methods include:

cryo-compression

carbon nanotubes

glass capillary arrays

Storage - ChemicalExamples of materials with properties that allow for reversible hydrogen storage (hydrogen released under heat):

Metal hydrides

Non-metal hydrides

Liquid organic hydrogen carriers (LOHC)

Synthesized hydrocarbons

Ammonia

Formic Acid

DiscussionPEMFCs ideal for mobile applications (transportation) due to:

Low operating temperature

Water = only waste product (no carbon dioxide emissions)

Accepts pure hydrogen

Some minor drawbacks include:

Expensive precious metal catalyst (platinum) used for optimal efficiency

Liquid based acidic polymer more corrosive than dry membranes

…DiscussionProduction Methods Comparison:

Environmental - electrolysis > steam reforming (electrolysis waste product is oxygen; steam reforming waste products are generally carbon monoxide or carbon dioxide)

Efficiency - steam reforming is faster and produces significantly higher yields relative to volume (main reason for which it is used to produce ~95% of all Hydrogen in the United States)

…DiscussionStorage Methods Comparison:

Pressurized storage is better for mobile applications based on:

ease of extraction

amount of hydrogen stored relative to volume

Current drawbacks include:

pressure limits

flammability

ReferencesPhotos

http://www.afcenergy.com/_userfiles/pages/images/Alkali-Fuel-Cell.png

http://www.dti.dk/_root/media/45686_DMFC%20princip.jpg

http://mypages.iit.edu/~smart/garrear/Fuel_C3.jpg

http://scopewe.com/wp-content/uploads/2013/06/phosphoric-acid-fuel-cell.jpg

http://mypages.iit.edu/~smart/garrear/Fuel_C5.jpg

http://media.web.britannica.com/eb-media/64/97264-004-127AEA3B.gif

http://o.aolcdn.com/dims-shared/dims3/GLOB/legacy_thumbnail/800x450/format/jpg/quality/85/http://o.aolcdn.com/hss/storage/adam/8a7e54208e350b5e50828137aeb46bda/toyotatank.jpg

http://jnm.snmjournals.org/content/48/7/1039/F1.large.jpg

http://www.fuelcell.sg/fcsc6_clip_image004.jpg

http://www.viewzone2.com/verichip-standard-electrolysis.png

Other

http://www.fuelcelltoday.com/media/1637138/fc_basics_technology_types.pdf

http://energy.gov/eere/fuelcells/hydrogen-storage

http://www.annualreviews.org/doi/abs/10.1146%2Fannurev.energy.24.1.227

http://www.eia.gov/oiaf/servicerpt/hydro/appendixc.html

http://www.sciencedirect.com/science/article/pii/S0378775312018113

http://www.fuelcelltoday.com/technologies/pemfc

http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/fuel-processor.htm