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dirigible wind turbines
30 nov 1997
towers are expensive, and there isn't much wind where i live. can a large
slowly-rotating structure with small wind generators attached to the edges
like perpendicular pinwheels moving against the induced wind lower the
tower cost and increase the effective windspeed?
it might be some sort of cubical hydrogen-filled balloon, with a tether
cable attached to one corner and 3 air-303s near adjacent corners.
it might look something like this from above:
w w is an air-303
p
p p is a 2" pvc pipe
. p .
~10' . p . . . . are tension ropes
. p .
. c . c is the cable connection
. . p p . .
. p p . the balloon would inscribe
. p . . p . the cube, and it would tend
p . p to augment the turbine wind,
p . . p as would the rotation of
w . w the large structure...
one wind generator might look like this from the side, with no wind:
w
w
w < --
pw
p w
^ p w
| p
p
the propellor might be mounted at an angle so that the wind that blows up
from the cable and onto the back side of the propellor exerts a force that
tends to rotate the large structure and force the propellor into the wind.
as the wind from the left in the diagram increases, the pipe would tilt
and translate to the right.
air weighs about 0.077 pounds per cubic foot, and hydrogen weighs about 1/15
of that, so h2 lift is about 0.072 lb/ft^3. a 10' cubical balloon could hold
up 72 pounds. a balloon might weigh 5 pounds, and 3 10' pieces of 2" pvc pipe
weigh about 15 pounds, leaving 17 pounds each for 3 13 pound 24v air 303s and
hardware. the hydrogen might come from on-board rainwater electrolysis, with
a water trap to let oxygen escape. the tether might have 2 conductors to
convey the series electrical output to a slip ring assembly attached with a
rope to a spiral ground stake. could this be an used auto alternator with a
couple of holes drilled into the shaft?
---
>...a baby hindenberg?
sure :-) one that spins...
>first, where does the faa stand on such a fixture...
interesting question, especially since i live 1500' from the end of a runway,
with a deed restriction that allows building no higher than 65'... perhaps
they'd like some rotating day-glo stripes and flashing lights at night.
>...the other problem that may creep in is severe weather. perhaps you can
>pull it back down into some sort of enclosure automatically with an electric
>winch if the wind exceeds a safe speed.
good idea, with a wind sensor, and the slip rings aloft. or maybe this
structure would be self-regulating, since it would bend like a tree...
>you'll need to consider the weight of your tether and wires
>coming down the tether too. perhaps it'll need to be bigger.
the pvc pipes might be 20' long. i wonder where to get a large long-lasting
balloon, and what the h2 permeability would be.
>but hydrogen? you're going to a dc generator on this thing?
sure, 3 of them, altho they are brushless.
>one spark in the wrong place and all your expensive hardware bounces
>off the dirt.
the electrical parts would be outside the balloon, and any small hydrogen
leak would quickly disperse, and a 50' fall to soft earth might not hurt
a $500 air-303 very much. it might have a lightning rod.
> it takes lots of power to do electrolisys.
i wonder how much, compared to the generated energy? how many kwh does
jade-mountain's electrolyzer need to make 1 ft^3 of h2? perhaps excess
h2 could flow down a tube to the ground for storage or other use.
suppose the balloon lost 1% of its volume each day...
>i think i'd want more than a spiral ground stake too. perhaps
>burying something heavy, like an old car...
i like that idea. maybe my 1975 ford pickup truck...
>good luck.
thanks,
nick
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