11-09-2013, 03:23 PM
Hydrogen Fuel Cells
Hydrogen Fuel.ppt (Size: 1.69 MB / Downloads: 35)
What is a hydrogen fuel cell?
A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent
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.
PEM FUEL CELL
Proton Exchange Membrane (PEM)
This is the leading cell type for passenger car application
Uses a polymer membrane as the electrolyte
Operates at a relatively low temperature, about 175 degrees
Has a high power density, can vary its output quickly and is suited for applications where quick startup is required making it popular for automobiles
Sensitive to fuel impurities
Alkaline Fuel Cell
Used mainly by military and space programs
Can reach 70% power generating efficiency, but considered to costly for transportation applications
Used on the Apollo spacecraft to provide electricity and drinking water
Uses a solution of potassium hydroxide in water as the electrolyte and operates at 75 -160 degrees
Requires pure hydrogen and oxygen because it is very susceptible to carbon contamination
Purification process of the hydrogen and oxygen is costly
Susceptibility to poisoning affects cell’s lifetime which also affects the cost
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
Problems regarding hydrogen fuel cells
Lack of hydrogen infrastructure
Need for refueling stations
Lack of consumer distribution system
Cost of hydrogen fuel cells
2013 Department of Energy estimated $30/kw
Hyundai i35x costs around $50000 and price of this is going to be reduced for the promotion
Carbon cost of producing hydrogen is high
Problems with HFC cars
Short range (~365miles)
Warm up time (~5 minutes)
Hydrogen occupies more volume than gasoline so less range
Hydrogen Fuel.ppt (Size: 1.69 MB / Downloads: 35)
What is a hydrogen fuel cell?
A fuel cell is a device that converts the chemical energy from a fuel into electricity through a chemical reaction with oxygen or another oxidizing agent
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.
PEM FUEL CELL
Proton Exchange Membrane (PEM)
This is the leading cell type for passenger car application
Uses a polymer membrane as the electrolyte
Operates at a relatively low temperature, about 175 degrees
Has a high power density, can vary its output quickly and is suited for applications where quick startup is required making it popular for automobiles
Sensitive to fuel impurities
Alkaline Fuel Cell
Used mainly by military and space programs
Can reach 70% power generating efficiency, but considered to costly for transportation applications
Used on the Apollo spacecraft to provide electricity and drinking water
Uses a solution of potassium hydroxide in water as the electrolyte and operates at 75 -160 degrees
Requires pure hydrogen and oxygen because it is very susceptible to carbon contamination
Purification process of the hydrogen and oxygen is costly
Susceptibility to poisoning affects cell’s lifetime which also affects the cost
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
Problems regarding hydrogen fuel cells
Lack of hydrogen infrastructure
Need for refueling stations
Lack of consumer distribution system
Cost of hydrogen fuel cells
2013 Department of Energy estimated $30/kw
Hyundai i35x costs around $50000 and price of this is going to be reduced for the promotion
Carbon cost of producing hydrogen is high
Problems with HFC cars
Short range (~365miles)
Warm up time (~5 minutes)
Hydrogen occupies more volume than gasoline so less range