Model of a plant microbial fuel cell producing
electricity and driving a light source. Carbon dioxide is
fixed and released as rhizodeposits (e.g. root exudates)
by the plants and are utilized by micro-organisms that
return the carbon dioxide into the atmosphere. The
micro-organisms use the anode as electron acceptor for
gaining metabolic energy. These electrons flow due to
the potential difference, from the anode through an
electrical circuit with a load or a resistor to the cathode.
Hence, electricity is generated which can be used, for
example, driving a light source. To remain electroneutrality,
protons are transported through the membrane
into the cathode where oxygen is reduced with the
protons and electrons to form water.