Hi Daniel,

I have written a book, Microhydro: Clean Power from Water, that has various 
case studies
of hydropower situations like yours. If you're interested, just give me a shout 
at
[EMAIL PROTECTED]

Just like every site offers many unique elements, there are also often many 
solutions to
converting waterpower potential into electricity. One of the sites in the book 
transmits
power 1700 feet by generating three phase AC at high voltage and transforming 
and
rectifying it at the batteries. Energy Systems and Design has a specific 
configuration of
their Stream Engine for this purpose.

Just compare costs between the small, three conductor wire and transformers 
solution and
the large diameter wire solution. Remember that a couple of hundred watts, 
which case
study after case study has confirmed is adequate for many full time off grid 
residences,
is less than an amp at 240 volts. Also, wire losses matter less with abundant 
hydro power,
and so if you have power to spare, you can use much smaller wire.

Also, another case study in the book, pictured in this month's Mother Earth 
News, shows a
full time AC system of about 600 watts that did a remarkably good job of 
providing for a
full time off grid residence.

As I say in the book, "to find out how much power you need, by all means do not 
look at
your utility bill".  Efficiency is a lot more affordable than oversized civil 
engineering
projects, believe me...

Remember, many hands make lights work!

Scotty

-----Original Message-----
From: danieldykim [mailto:[EMAIL PROTECTED]
Sent: Friday, February 11, 2005 11:30 AM
To: [email protected]
Subject: [microhydro] AC vs. DC microhydro



Hello,

I'm kind of new to this microhydro subject, but I've been trying to
learn, after finding out that our newly acquired property has a year-
round stream... any help and info on this topic would be greatly
appreciated..

For our stream, the approx head is 120ft, flow is probably 70-80GPM
(what we can get out of the creek).  With that configuration, we're
probably looking at a 500w system... but the problem is this:

The creek is about 800ft away from the residence.  That's too far
for any DC current to travel on a reasonably-sized wire.  So some
people have pointed me toward AC hydrogenerators..  To have the AC
come up from the creek, and then convert it to DC (using the
inverter/charger) at the residence to charge the batteries.  (we
definitely want to go with the batteries instead of using the power
directly, since this is a weekend-high-usage situation)

Now the questions (if any of you could even answer just one or two,
that would be very helpful in getting me up to speed with this
topic):

1) I heard that AC hydrogenerators need to have some way of making
consistent AC voltage / frequency.. So does that mean I need to hit
the "lowest common denominator" by tuning the generator to produce
60Hz at the lowest flow time of the season?  Would that result in
wasting power?

2) How does the inverter handle the AC current from the
hydrogenerator, if it's not very consistent?  (like if there's lower
flow one week).  Does it matter?

3) Is it better & simpler to just get a DC generator (which is
cheaper), convert it to AC at the creek, and then move it up to the
residence, and then convert it back to DC?  Is there much power loss
during those conversions?

4) I'm thinking of getting a 4-nozzle pelton wheel system, but I
also heard of some other systems like "stream engine" which works
better at low flow situations.  Would my stream (120 ft head, 60 gpm
flow) work well with the pelton wheel?

Thank you very much for reading.  Any help would be greatly
appreciated.

--Daniel










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