We can create environmentally friendly
energy by imitating the energy conversion
system in living organisms |
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. |
Plants create both carbohydrates and oxygen
by photosynthesis from carbon dioxide and
water. Animals take up those carbohydrates and
oxygen and utilize them as an energy source
and release carbon dioxide and water. Then this
cycle starts again.
Since the carbon dioxide is recycled in this system,
the amount of carbon dioxide in the atmosphere
does not increase. If electrical energy could
be directly acquired from this cycle, we could
obtain more environmentally friendly energy
than that from fossil fuels.
Furthermore, renewable energy sources such
as glucose (which is present in plants and
therefore abundantly available) have an extremely
high energy density. One bowl of rice (about
100 grams) is equivalent to 160 kilocalories,
which corresponds to the energy about 64 AA
alkaline dry cells.
Therefore, this bio battery, which is based on
mechanisms used in living organisms, is not
only friendly to the environment but is also likely
to be of practical use as an energy source.
Sony has focused on these advantages since 2001
and has developed an electrical power generation
device that uses mechanisms similar to
those in living organisms. |
|
| Converting energy from “energy for
life” to “electrical energy” |
| . |
. |
When looking closely at energy conversion system
in living organisms, there are two enzymatic
reactions coupled together: the glucose
oxidation reaction and the oxygen reduction reaction.
The glucose taken by living organisms is
broken down into carbon dioxide. At the same
time, electrons and proton are extracted through
enzymatic oxidation reactions.
On the other hand, oxygen acquired from outside
the organism reacts with both the electrons
and protons through the action of other enzymes
to generate water through the reduction reaction.
Energy for activity, that is the ATP and thermal
energy commonly used in the living organism,
can be obtained from the exchange of the
electrons and protons through these two enzymatic
reactions.
To take advantage of this living organism
mechanism, the energy for activity from inside
the organism must be removed outside the
organism as electrical energy. That is, when the
electrons and protons move from enzyme to
enzyme, it is necessary to extract just the electrons
and divert them through a separate path.
Thus Sony used an electron transport mediator
so that electrons could be exchanged smoothly
between the enzymes and the electrodes
that are the entrance and exit to that detour.
The principles of the bio battery are based on
the energy conversion mechanism in living
organisms. However, in order to create the
bio battery, several technologies needed to be
developed. These include immobilization of
enzymes that are normally incompatible with
carbon and metal electrodes, electrode structures,
and electrolytes. |
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 Assuring that biomaterials exhibit their functionality and significantly increasing the power generation capacity |
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all articles with figures and tables.  |
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Vol.51 |
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