Fuels - Hydrogen Fuel Cell.
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A fuel cell is not
the same as a battery.
A fuel cell
needs to be continuously supplied with a fuel
and oxygen
which react together to produce electricity.
When the fuel is hydrogen the fuel cell produces electricity plus water.
The fuel cell is
made from an anode and a cathode
with an electrolyte contained
between them.
The fuel cell generates
electricity. It is not
the same as an electrolysis cell
which needs to be supplied with electricity.
The electrolyte in an alkali fuel cell is potassium hydroxide (KOH).
The anode is a platinum
catalyst.
Hydrogen supplied to the anode
reacts with hydroxide
ions from the electrolyte to make water.
This is an oxidation
reaction in which electrons
are lost from hydrogen.
The electrons leave the anode
and travel through the external circuit
which the fuel cell is providing
the electricity for.
The cathode is
also a platinum catalyst.
Oxygen supplied to the cathode
reacts with water and
gains electrons to make hydroxide
ions in the electrolyte.
This is a reduction
reaction.
The overall reaction in the fuel cell is
hydrogen
+ oxygen
water + energy
2H2(g)
+ O2(g)
2H2O(l)
The electricity provided
by the fuel cell can be used
to run an electric vehicle
or to power other equipment.
Advantages of a hydrogen fuel
cell.
1. It can be a renewable source of electricity
if the hydrogen
comes from a renewable source. See advantages
of hydrogen as a fuel.
2. It does not
produce pollution or contribute to global warming
because the only product is water.
Disadvantages.
1. Each fuel cell
only makes a small voltage.
A large number of fuel cells must be
wired together
to produce a large voltage
or current. This is expensive.
2. Hydrogen is explosive and difficult to store.
3. If the hydrogen
does not come from a renewable source
but is made from methane
then the hydrogen fuel
produced is also not renewable.
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