Just to confuse you even further :-)
>
>
>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..
More like 8-900 watts.
> 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.
Not really. At 48 volts it would be OK with #2 wire.
Or if you prefer you can get a high voltage stream engine unit from
Energy Systems and Design (producing about 200 VAc) and then
transform it down and rectify it at the battery.
http://www.microhydropower.com/ I have done this on a mile long wire
run. Probably not worth it for 800 feet. The big wire is simple and
safe.
I do not recommend the induction motor idea - I have tried this three
times and it is bad news every time. Induction motors are great for
AC loads (with a suitable load controller to regulate the voltage)
and you can also use them as an input to a Trace SW or similar
inverter. This works very well. But I do not find that it works
well with a transformer and rectifier. The output always disappoints
me.
> 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)
You will need a very big battery to store much of that 100
kilowatthours of energy Monday to Friday.
>
>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?
a four pole motor would give near to 60 Hz at your site. Assuming a 4" wheel.
>
>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?
It seems to have ben possible to synch quite well using Trace SW inverters.
>
>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?
It is simplest to use a big thick cable at 48 volts DC. DC hydros no
longer use DC generators though, and you can get a high voltage wound
alternator.
>
>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?
I think you have a free choice there.
--
Hugh
(NOTE I am off to Costa Rica from 17th February - 3rd March and may
not get much if any email during that period.)
Scoraig Wind Electric
http://www.scoraigwind.co.uk/
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