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Looking for some guidance for my own power generation

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Posted by Phillip on February 10, 2009, 6:12 pm
I live in California (San Fran area)

My electrical usage (kWh) per month is as follows:

1011                  Average (24 month)
627                    Minimun over the last 24 months
1458                  Maximun over the same period

I have gotten 2 quotes for PV panels mounted to the roof and there were
between 35k and 40k.

So I have been doing some research. It looks like a very viable solution is
using 1 or more parabolic troughs, heating oil, to create flash steam and
then this would be powering a tesla turbine, which would then be attached to
a brushless induction generator

I have several issues that need to be resolved before I can start designing
the system.

Ideally, I would like to over produce during the day, and store in batteries
and also feed into the grid.

I would probably add the battery system in a later phase.

I need to find out how large of a system I would need.

I feel that if I spend a little more in the construction of the collector,
it would well pay for it self later on. I would probably create a first
layer mirror by having a polished piece of steel (4ftx8ft), silver plated.
The steel would be fairly thin and therefore easy to work with. I feel that
this would give me the highest effecienty. This would be using the lower
portion of the parabolic curve and thus being faily flat with a focal point
about 8"-12" above the bottom
This would be enclosed in a glass topped case with the focal point aimed at
the oil filled tube.

-or purchase a trough if I can find one, which I have NOT been able to do.
Any ideas where?

What I need to do is to try to figure out the size of generator that is
needed, how much power will be needed to produce the power I need, then
working backwards, figure out the size of turbine I should be using, and
then how many collectors I would need.

I know that there are general guidelines and formulas to figure this stuff,
but in all of my research, I have not been able to find this.

A few other peices of info I also need are where would be a good starting
point to have the plates for the turbine laser cut? I am feeling I probably
will be settling on a disk radia of about 10", but need to figure out how
many plates. from my research 10" will develope more HP at a lower RPM, yet
have more torque. Hard to start though...

I know I have asked ALOT, so if you can help with anypart, please let me


Posted by Ken Maltby on February 10, 2009, 11:03 pm

  Your post makes me feel a little guilty, I had started that
same project but kept putting it off, for other things needed

  There are a whole lot of caveats for a project like this the
first of which is don't bet the farm on it.  It is best to approach
it, (the first working attempt, at least) as a learning experience
and any actual practical benifit as a bonus.

  The next caveat is a biggie, working with any steam pressure
system that can provide the 20+ hp that you would need for
any real homepowering is - potentialy dangerious, expensive
to do legally, noisy, and not welcome in the average suburban

  The third caveat would be an extension of the first, it is highly
unlikely that; even if everything works out as planned,  you will
find that your power production is at all competitive economicly
with that provided by the power company.  If you have access
to the grid, that will always prove cheaper and less of an effort.
This is especially true when you factor in your "development
costs" and your own time.

  That said, you should find plenty of information to help you
through your project.  The Solar and Wind Power sites and
NGs (as well as this one) will provide the basic sizing
information/resources/"How-To" that you are asking for, the
data required being the same no matter how the power is
being produced.  You might approach it as if it "were what
size wind generator would you need", and use the data
provided to size that for your consumption.  The disscussion
of torque, rotational speed, and the various tradeoffs should
give you some basic figures to shoot for.

  I don't know where you would find data on steam pressure
and velocity for tesla turbine nozzels I have no idea, you may
have to make establishing such practical operating data a part
of the development project.

  For turbine disks you might start with 10" saw blades and a
plasma cutter.

  You can download graphic parabolic caculators to establish
the shape of your trough, with a focal point as you wish.

 A frequent poster here Morris Dovey can help with the trough:

  Safely creating the flash steam pressure from the hot oil, could
be the most difficult part, especially if you need to recover the
distilled water and re-inject it.  Perhaps building a model train
engine with its boiler and condenser (if such a model can be
found) and modifing it to run with hot oil as the heat source in
the boiler, instead of a fire.  You could also address the design
of a condensor and re-injector.


Posted by Gordon on February 10, 2009, 11:17 pm

There is a group of model train hobbiests that deal in live
steam.  Perhaps a Google search would help you hook up
with them. I'm sure that they can give you plenty of
tips and plans for opperating a live steam plant.

Posted by Ken Maltby on February 10, 2009, 11:22 pm

P.S  Another issue to look into is the pumping of the hot oil.
The regular commercial pumps rated for pumping high temp.
fluids are very costly.  (I've been thinking of "canning" a plain
hydraulic pump.)

Posted by Ken Maltby on February 11, 2009, 4:09 am

  P.P.S.  Here's a better link at Morris Dovey's site:

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