Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs)...

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Hydrogen Fuel Cells David Lorse ESS 315

Transcript of Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs)...

Page 1: Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs) are a type of electrochemical cell. HFCs generate electricity.

Hydrogen Fuel Cells

David LorseESS 315

Page 2: Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs) are a type of electrochemical cell. HFCs generate electricity.

What is a hydrogen fuel cell?•Hydrogen fuel cells (HFCs) are a type of electrochemical cell.

•HFCs generate electricity by reduction and oxidation reactions within the cell.

•They use three main components, a fuel, an oxidant and an electrolyte.

•HFCs operate like batteries, although they require external fuel.

•HFCs are a thermodynamically open system.

•HFCs use hydrogen as a fuel, oxygen as an oxidant, a proton exchange membrane as an electrolyte, and emit only water as waste.

Page 3: Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs) are a type of electrochemical cell. HFCs generate electricity.

How do they work?•Fuel (H2) is first transported to the anode of the cell

•Fuel undergoes the anode reaction

•Anode reaction splits the fuel into H+ (a proton) and e-

•Protons pass through the electrolyte to the cathode

•Electrons can not pass through the electrolyte, and must travel through an external circuit which creates a usable electric current

•Protons and electrons reach the cathode, and undergo the cathode reaction

Page 4: Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs) are a type of electrochemical cell. HFCs generate electricity.

Chemistry behind the technologyOxidation

At the anode of the cell, a catalyst (platinum powder)

is used to separate the proton from the electron in

the hydrogen fuel. Anode half-reaction:

2H2 4H+ + 4e-

Eo = 0.00V

Reduction

At the cathode of the cell, a second catalyst (nickel) is used to

recombine the protons, electrons, and oxygen atoms to

form water. Cathode half- reaction:4H+ + O2 + 4e- 2H2O

Eo = 0.68V

In electrochemistry, the Eocell value (energy) of a fuel cell is equal to the Eo

of the cathode half-reaction minus the Eo

of the anode half-reaction. For a hydrogen fuel cell, the two half reactions are shown above. So to calculate the energy of one fuel cell, we need to subtract the anode energy from the cathode energy. For a HFC, the Eo

cell = 0.68V – 0.00V which equals 0.68V

Page 5: Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs) are a type of electrochemical cell. HFCs generate electricity.

Uses of hydrogen fuel cellsThere are many different uses of fuel cells being utilized right now. Some of these uses are…

•Power sources for vehicles such as cars, trucks, buses and even boats and submarines

•Power sources for spacecraft, remote weather stations and military technology

•Batteries for electronics such as laptops and smart phones

•Sources for uninterruptable power supplies.

Page 6: Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs) are a type of electrochemical cell. HFCs generate electricity.

Problems regarding hydrogen fuel cells•Lack of hydrogen infrastructure

•Need for refueling stations

•Lack of consumer distribution system

•Cost of hydrogen fuel cells

•2009 Department of Energy estimated $61/kw

•Honda FCX Clarity costs about half a million dollars to make

•Carbon cost of producing hydrogen

•Problems with HFC cars

•Short range (~260 miles)

•Warm up time (~5 minutes)

Page 7: Hydrogen Fuel Cells David Lorse ESS 315. What is a hydrogen fuel cell? Hydrogen fuel cells (HFCs) are a type of electrochemical cell. HFCs generate electricity.

References

•http://www.fueleconomy.gov/feg/fuelcell.shtml

•http://www.howstuffworks.com/fuel-efficiency/alternative-fuels/fuel-cell.htm

•http://www.energy.gov

•Chemical Principles, Sixth Edition, Zumdahl