Chemistry - Fuel cells
Our most common sources of energy are the 'fossil fuels': coal, oil, and
natural gas. The chemical energy in coal and natural gas is converted into
electrical energy in relatively low efficiency power stations. Much more
efficient conversion of chemical energy into electrical energy is achieved
when gaseous fuels react with oxygen in special types of electrochemical
cells known as
Fuel cells are used to convert the chemical energy in some conventional
fuels directly and continuously into electrical energy.
In terms of energy, conversion fuel cells provide the same outcome as
galvanic cells but they are markedly different in that the reactants are
not contained within the cell - they must be continuously supplied. The key
structural features of a fuel cell are the is separation of the fuel from
the oxidant and the provision of a path for the transfer of electrons from
the oxidation of the fuel to the reduction of oxygen.
Further significant features of fuel cells include:
* the reactants and products are gases
* a continuous supply of reactants (fuel and oxygen) is needed
* electrical energy will be produced as long as the reactants are
* he electrodes are porous and impregnated with catalyst
* the conversion of chemical energy to electrical energy is highly
* minimal pollution is associated with the operation of fuel cells.
Because the fuel and oxidant are continuously supplied, fuel cells do not
have the limited life of primary cells.
While the basic structure of a fuel cell is relatively simple, the keys to
successful and enhanced efficiency fuel cells are:
* The electrodes that transfer electrons into, and remove electrons from
the external circuit.
* The electrolyte that carries charge between the electrodes in the
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