Subject: Re: Hyrdo power with no moving parts

From: [email-masked] (Bill Smythe)
Date: Thu, 25 May 95 23:42:08 GMT

[email-masked] ("Nigel Jarman") wrote:
>Is it possible to produce electric power using water falling
>through a tube without moving parts, eg. no turbine?
>
>As I seem to remember that a liquid flowing through a pipe
>produces some form of static charge and one has to ground the pipe
>so as not to risk sparks if moving gas about,

Moving liquid around can in fact generate a static charge. While in some
cases it is even enough to produce a spark that could ignite flamable
vapors (they are paranoid about this sort of thing in refuling airplanes) it
will not generate enough to do any usefull work.

> I also seem to
>remember a japanese boat being able to move itself by using
>electromagnets to to move the water though a pipe at the front of
>the boat and out at the back with no moving parts, has something
>already been designed that uses some of the princibles here to
>produce electricity from hydro power but without blades/etc?

This is probably for use at sea.  Seawater is reasonably conductive
due to the salt in it.  Using this one can pass a current through it and
then use electromagnets to apply a counter force to the magnetic
field that the current induces.  This is exactly the same way some
types of electric motors work (some just use fixed magnets for the
rotor) except that it uses water as a conductor.

Just as you can run some electric motors in reverse as a generator
(you still need to run a current through the field coils), you can produce
electricity with moving salt water. This is called a magneto-hydrodynamic
generator. Again it works exactly the same as a regular generator-- when
you move charge carriers (i.e. a conductor - in this case the salt water)
through a magnetic field, it induces a voltage.  Of course the problem
with this is that it will release free chlorine and oxygen at the positive
terminal and hydrogen and metalic sodium (which will imediatly react
with water to form soduim hydroxide and hydrogen) at the negative
electrode  ---Doooh!

There is actually a way to produce compressed air from a stream of
water with no moving parts by entraining bubbles in the flow and
then letting them float out in a chamber below the surface where
the water ultimately comes out. The water is then held under the
water presure of head #2 in the ascii art below.  The energy to
compress the air comes from head 1

 Water input
_______________                                                      ____
                             |      |                                                   |
                             |  |   |                                                   |
                             | \/  |                                                   |
                             |      |                                              Head 1
                             |      |                                                   |
                             |      |                     Water outlet          |
                             |      |                     ___________ ___ |_____
                             |      |             |      |        |
                             |      |             | /\   |        |
                             |      |             |  |   |        |  Head 2
                             |      |-------------|      |      _|_
                             |      |  traped |      |
                             |      |   Air      |      |
                             |_____________|

Bill

---

From: Peter Graham Thomas <[email-masked]>
Date: 26 May 1995 20:16:57 +0100

In article <[email-masked]>
           [email-masked] "Bill Smythe" writes:
> generator.

I'm sure Bill knows, but to avoid confusion, for electric motors 'reverse'
means reversing the 'direction' of the mechanical power to the motor shaft. 
In effect putting mechanical power into the system (a generator) rather than
taking it out (a motor). There need be no physical reversal of the direction
of rotation of the motor/generator shaft.

The eficiency of running a 'motor' as a 'generator' is another matter..
 
Regards.    
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Pete Thomas           |  "First you forget their names, and then their faces
Yr Wyddgrug           |   Next you forget to pull your zipper up
Welsh Wales           |   Then you forget to pull your zipper down"....
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