Appendix C
Fuel Cells
A fuel cell is a device that converts chemical potential energy (energy stored in
chemical covalent bonds) into electrical energy. Such device works on a reduction
and an oxidation process which occur at two separated electrodes so that electrons
can flow in an external circuit and be used by a utilizer. The two electrode
compartments are separated by a protonic membrane that allows H
+ migration
while keeping the solution at the same electric potential.
A typical fuel cell is based on the combustion of H 2 with O 2 .
In a direct combustion in a thermal engine, the process is represented as
H 2 þ 1=2 O 2 ¼ H 2 O þ Heat:
Therefore, water is formed and heat is released.
If the reaction is carried out at two electrodes in a cell the redox processes are
separated:
H 2 ¼ 2H
þ
þ 2e
À
oxidation
ð
Þ
1=2O 2 þ 2e
À
¼ O
2À
reduction
ð
Þ
In this case energy is, thus, released as electric energy instead of heat.
The two compartments of the cell are separated by a Proton Exchange
Membrane (PEM) that allows the transfer of protons with formation of water from
proton and oxide. The products of the reaction in the cell are water, electricity, and
some heat which is lost. The lost heat represents the loss in efficiency in the
© Springer Nature Switzerland AG 2021
M. Aresta and A. Dibenedetto, The Carbon Dioxide Revolution,
https://doi.org/10.1007/978-3-030-59061-1
237
Fuel Cells
A fuel cell is a device that converts chemical potential energy (energy stored in
chemical covalent bonds) into electrical energy. Such device works on a reduction
and an oxidation process which occur at two separated electrodes so that electrons
can flow in an external circuit and be used by a utilizer. The two electrode
compartments are separated by a protonic membrane that allows H
+ migration
while keeping the solution at the same electric potential.
A typical fuel cell is based on the combustion of H 2 with O 2 .
In a direct combustion in a thermal engine, the process is represented as
H 2 þ 1=2 O 2 ¼ H 2 O þ Heat:
Therefore, water is formed and heat is released.
If the reaction is carried out at two electrodes in a cell the redox processes are
separated:
H 2 ¼ 2H
þ
þ 2e
À
oxidation
ð
Þ
1=2O 2 þ 2e
À
¼ O
2À
reduction
ð
Þ
In this case energy is, thus, released as electric energy instead of heat.
The two compartments of the cell are separated by a Proton Exchange
Membrane (PEM) that allows the transfer of protons with formation of water from
proton and oxide. The products of the reaction in the cell are water, electricity, and
some heat which is lost. The lost heat represents the loss in efficiency in the
© Springer Nature Switzerland AG 2021
M. Aresta and A. Dibenedetto, The Carbon Dioxide Revolution,
https://doi.org/10.1007/978-3-030-59061-1
237