Hi Peter,
Assuming that the resource is not in question, a 2kW system is not ideal for DC
system operation.
1. Typical DC alternators are rated below 500W, so you might have to
operate several units in parallel, which is not practical.
2. If the total simultaneous load does not exceed 2kW, you will be better
off just using 220VAC direct generation without a battery bank. Typical
3kVA/220VAC synchronous generator costs $150 here in the Philippines.
3. Low cost inverters are notoriously inefficient and you still have to
maintain a battery bank to operate it. An inverter needs a stable DC supply for
proper operation. An alternator generates pulsating DC: some AC harmonic
contents are present.
4. DC appliances are usually more expensive than AC appliances.
A 300W system is more suited for DC operation with battery bank.
1. It could generate a total of 300Wx24h=7.2kWhr every day, more than
enough for typical household use in a third world country.
2. A 200Ah/12V battery (about $120) could serve as storage.
3. It is more cost effective, more convenient, and more efficient to use a
good medium sized inverter (500VA - 1kVA, about $50 - $100), except for direct
heating applications.
4. You can use for penstock the ordinary 2" - 4" diameter uPVC pipes used
for water supply (blue color), a little bit more expensive than drainpipes but
a lot tougher, as long as the head does not exceed 30meters gross head. Plastic
uPVC pipes for watermains are rated up to 100psi, equivalent to about 70m gross
head. I have even used the ordinary 2" BI tubes on one installation (20m head,
200W).
It is ok to use temporary materials for the weir and canal, based on my
experience. However, I don't recommend using wood and sheet metal in making a
runner. Scrap metals of the proper dimension for fabricating the turbine could
be bought from scrap dealers in 3rd world countries. You might spend $200-400
for a complete turbine, including labor and materials, assuming that your hydro
site is ideal for the crossflow turbine.
The info I'm sharing is based on experience from personally designing,
fabricating, and installing more than 30 microhydro installations (distributed
220VAC), of which the smallest is 300Wand the largest is 30kW.
Hope it answer some of your questions.
Eilrem
HYDRO <[EMAIL PROTECTED]> wrote:
N. Peter Evans:
You just expressed the DREAMS of many "fools ! ?".
1)You say:
>Say I want a 2kW system and I have plenty of potential is the stream.
2)Then:
>For a turbine I could make a banki out of wood and some sheet metal.
3)Then:
>For a generator use a truck alternator from a junkyard
4)Then
> Is this practical?
NO ! Why ?. Because 2 & 3.
Nando
----- Original Message -----
From: "peterevans_33" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, August 01, 2005 5:10 AM
Subject: [microhydro] naive beginner question
> hi all, I apologise for my ignorance in advance
>
> If I travel to a thrid world country and would like a micro hydro for
> very small cost, what do I need? How much will it cost me. Say I want
> a 2kW system and I have plenty of potential is the stream.
>
> I can make a small weir out of wood and stone and some cement. I can
> make a penstock out of a 6" plastic drainpipe. The downflow a similar
> material. For a turbine I could make a banki out of wood and some
> sheet metal. Yes I know that the banki needs a medium to high flow.
> The banki will need an axle and I may need a V belt - flat belt pulley
> system to increase generator rpm.
>
> For a generator use a truck alternator from a junkyard. I need a box
> to keep the generator dry, and some mountings to keep the generator
> box up high and off the uneven ground.
>
> Can I then have a pure DC system with DC lighitng, DC fridges and use
> a $50 ineffecient inverter for those applicances used infrequently
> that run on AC only?
>
>
> Is this practical? do I need expensive battery storage, inverters,
> control boxes etc. I know that this is not a particularly effecient
> setup but my priority in this case study is low cost. On the radio
> today they said 5 billion people live on $3 a day or less, thus the
> emphasis on homemade equipment and eliminating batteries and expensive
> inverters etc.
>
> Please feel free to tell me it is all wrong and will not work. Yes I
> know that no battery storage means I am hostage to reliable stream
> flow. Remember priority is low cost rather than high effeciency. And
> yes it is just a hypothetical question for someone that may or maynot
> do something like this one day.
>
> N. Peter Evans
>
>
>
>
>
>
>
>
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