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Encouraged by
a catalyst, the hydrogen atom splits into a proton and an
electron, which take different paths to the cathode. The
proton passes through the electrolyte. The electrons create
a separate current that can be utilized before they return
to the cathode, to be reunited with the hydrogen and oxygen
in a molecule of water.
A fuel cell system which includes a "fuel reformer"
can utilize the hydrogen from any hydrocarbon fuel - from
natural gas to methanol, and even gasoline. Since the fuel
cell relies on chemistry and not combustion, emissions from
this type of a system would still be much smaller than emissions
from the cleanest fuel combustion processes
| How
do Hydrogen Fuel Cells work? |
On the most basic level, fuel cells accept
hydrogen at their anode, where it is broken into 2H + ions
which travel through an electrically insulated, proton conducting
membrane to the cathode where they react with oxygen to
form water. The breaking of the hydrogen molecule into H
+ ions at the anode generates two electrons which have nowhere
to travel since the membrane is electronically insulated.
Also the formation of water at the cathode requires 2 electrons.
This creates a driving force for the electrons to travel,
so if an external circuit is attached to the anode and cathode,
electrons will flow from the anode to the cathode, this
flow can be harnessed to do work.
|
•
|
Phosphoric
Acid
|
•
|
Proton Exchange
Membrane or Solid Polymer
|
•
|
Molten
Carbonate |
•
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Solid Oxide |
• |
Alkaline |
• |
Direct Methanol Fuel Cells |
• |
Regenerative Fuel Cells |
• |
Zinc Air Fuel Cells |
• |
Protonic Ceramic Fuel Cell |
| Fuel
Cells Vs Traditional Electricity Methods |
In traditional
methods of generating electricity, the fuel and air are
burned, generating a high-temperature gas. In the case of
a coal-burning power plant, heat is transferred from this
hot gas to high-pressure liquid water that is boiled. In
the case of a gasoline, diesel or gas turbine engine, the
hot gas itself is at high pressure. The high-pressure steam,
or hot gas, is expanded in a mechanical device (e.g., cylinder,
turbine) and ultimately turns an electrical generator.
In a fuel cell, the same basic chemical reactions occur,
but generate electricity directly as an electrochemical
device and therefore, never go through the step of being
a high-temperature gas through normal burning. This direct
conversion of chemical energy to electrical energy is more
efficient and generates much less pollutants than do traditional
methods that rely on combustion.
As mentioned above,
the direct conversion of fuel and air to electricity is
much more efficient than internal combustion engines and
other methods of generating electricity. Therefore, fuel
cells can generate more electricity from the same amount
of fuel.
Furthermore, by skipping the combustion process that occurs
in traditional power-generating methods, the generation
of pollutants during the combustion process is avoided.
Some of the pollutants that are significantly lower for
fuel cells are oxides of nitrogen and unburned hydrocarbons,
(which together cause ground-level ozone), and carbon monoxide
(a poisonous gas).
-
compiled by Mr. Gaurav Chaturvedi, Technical Superintendent
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