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Photosynthesis
operates in fresh or salt water at 40 times the rate on land. There are many simple plants that
grow in any kind of water doubling their mass in 12 hours of sunlight if
they get enough carbon dioxide and they make a protein rich material that can
be dried and ground to be made into animal food pellets or consumed by bacteria
to make butanol.
Normal butanol or “n-butanol” the one with the hydroxyl at the end of the molecule and not on the second carbon atom or appended to the tertiary allotrope, is the one most common produced by the Clostridinium acetobutylicum bacillis. This is the second oldest known industrial fermentation and it is the fuel of the future.
The reaction
vessel is a 100 foot long transparent polycarbonate plastic tube with a diameter of three
feet. It may be seamless like a noodle or welded together from a ten foot wide sheet. The left top end has a tube
that is used to introduce CO2 and draw finished butanol. The right, or bottom, end has an operable
valve to open to admit sea or lake water. Ranks of the tubes are floated
on the surface for sunlight with CO2 pumped into them to feed the algae and
float the apparatus.
In operation the tube is floating on the surface and produces algae to the point where it is so packed
light will be blocked and photosynthesis will decline. The
pressure in
the tube will increase to make the tube rigid and signal it is time to
introduce bacteria and for the fermentation. The
bacteria will work best in warmer water. When the butanol
reaches 35% of the fermentation mass the process will stop. One
end of the tube is sunk to make the tube vertical then the entire tube
is lowered to watter at four Celsius degrees where the butanol
will separate. When the separation has butanol in the top 32 feet
of the tube the lower valve is opened and the finished product is drawn
off. Seawater from below enters the tube to replace the drawn
butanol.
The volume of butanol removed will be about 32 gallons per tube. In
ideal conditions the fermentation should take a few days, lowering and
separation about one day and then the process is repeated.
When the lower
valve is opened to the sea to admit water and the butanol drawn off by pump a
conductivity switch stops the process when conductive sea water reaches the
top. The lower valve is then closed and
the tube pulled to the surface for another cycle where algae and seawater are
in the tube. We only need to pump CO2
into the tube to promote photosynthesis and start the next cycle.
A rank of 70
such tubes in a 100 foot on a side square would occupy one quarter acre and produce
between 12,000 and 24,000 gallons of 100 octane motor fuel per year. An ideal location for this system would be