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To All,
In playing the
"Sustainability" game which in my mind, humans always seem to lose, I
have came to the conclusion that biomass gasifiers in the .1 to 2 megabtu input
range may predominate. This is because in cold climates the need for heat will
make it important to do all processes by cogeneration or co manufacturing.
Another reason is that each region may be competing for its own biomass supply
and therefore biomass would not be shipped long distances. The energy cost of
transport will also play a role in reducing the number of very large plants. One
exception to this might be the pyrolization of biomass using solar mirrors. Then
of course the energy of the final product could be more than that of the biomass
input. The 70% efficiency of a large conversion plant is not good enough if we
are operating furnaces for heating
buildings.
Ideally one would
make methanol and power in a small converter stationed in a building, in
Winter, so that the waste heat would heat the building. The lock hopper and 50
atmosphere pressure needed would make this difficult. Furthermore the chemicals
derived from wood may become important. This suggests the possibility of a semi
pyrolizing furnace that would make fuel gases and fuel liquids while using the
waste heat for space heating. I looked at an old Chemical Engineering text
called Chemical Process Industries and discovered that wood chemicals have been
very important in the past, probably in particular for sailing vessels. Wood tar
would probably be very useful in a wooden vessel. It probably would also be
useful for water proofing a
building.
In the old way of
doing it the wood was pyrolized. They talk of pyroligneous liquids, acetic acid,
rosins, charcoal, and methanol as outputs from pine distillation. Any charcoal
would be useful in other energy operations. In a small low pressure process it
might be possible to separate the liquids out and later either convert them to
chemicals or pump them up to the necessary pressure to convert them into
methanol. We know that some methanol is produced even at atmospheric pressure.
Maybe catalysts would improve this low pressure yield. Electrical energy would
be obtained from a steam engine and from an IC engine burning the gases. What I
am saying is that maybe we need dirty gasification rather than clean
gasification because the by products are useful. I have no practical experience
with this but I can imagine that the liquid products would be messy and hard to
handle. However they must have done that in previous times. A hard coating on
heat exchangers such as that in wood stove chimneys would be hard to deal with.
In my opinion we have
to look for better ways of saving energy if humans are to survive. Also even if
I were just interested in this subject for commercial reasons, I would still
join the dogooders and push for massive tree planting programs.
Kermit Schlansker
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