A positive electrode, a negative electrode, and an electrolyte intervening between
the positive electrode and the negative electrode are employed, and a molecule
capable of being excited due to absorption of light and electrochemically oxidizing
carbohydrate is provided at at least either the negative electrode or the electrolyte,
with production of electromotive force occurring between the positive electrode
and the negative electrode as a result of supply of carbohydrate while the molecule
is irradiated with light and oxidization of carbohydrate by the molecule at the
negative electrode. This method makes it possible for the chemical energy which
carbohydrates possess to be directly utilized as electrical energy.
