No subject
Sat May 10 06:46:04 EDT 2008
<font color="#3333ff">"Much of the swept area of a Savonius rotor is
near the ground, making
the overall energy extraction less effective due to lower wind speed at
lower heights."</font><br>
<br>
Yes, more height then you get more wind. You need 8 mph to get enough
wind energy to supply a house energy requirements. You can find this
kind of winds at 10 meters (30 feet) over the soil surface. When we
speak that you need some "heigth" we don't mean "altitude". There are
windy places in the peruvian coast (at 3 feet altitude) and there are
windy places in the high andes (at 15,000 feet altitude and more). In
both cases you need to get more "height" from the soil surface (those
10 meters or 30 feet)... then you need a tower. Yes, I know some
places (you must know some too) that at soil level you have strong
winds, but normally we need to setup the wind mill near to a house or
school... and that school is in the middle of a city or village...
then, thumb rule applies, you need a tower that is 2.5 times (height)
than the houses and trees in the area. Furthermore, villages are build
in "protected" places (in the middle of valleys tipically... ) not in
the top of the surrounding mountains... so we need to study every case,
but in general terms, if you need serious and more steady stream of
wind then we need a tower (unlucky we are... because the tower cost
money, big and important money).<br>
<br>
600 RPM is what the normal small car alternators require to produce
energy. So... we have two options: or we get alternators that need
lower RMP (easier) or we get a method to provide more RPM with human
movement (harder). To get (build) low RPM alternators we need to do
the next :<br>
a) Get bigger magnets (or more magnets).<br>
b) Install bigger (or more!) copper coils.<br>
c) Get more speed on the "turning" of the pulley/rotor in the alternator<br>
d) A combination of all the previous options.<br>
<br>
<font color="#3333ff">"Savonius turbines are used whenever cost or
reliability is much more important than efficiency."</font><br>
<br>
Sure. They are less expensive because there is no tower to build. It
can be mounted in the top of a roof. The issue is that we need to test
(aritmetically) what kind of gadget (pulleys and rotors, transformation
rate of one gear to the another one) we will connect to the Savonius
wind mill. IF we get a very low RPM alternator then it would be
possible to combine with a Savonius wind mill mounted in a normal roof
(no tower needed).<br>
<br>
I guess that we will end talking/thinking/looking for the spare parts
so we (all) can build our own electromagnet generator (alternator).<br>
<br>
Best regards,<br>
<br>
Javier Rodriguez<br>
Lima, Peru<br>
<br>
<br>
<br>
<br>
<br>
Caryl Bigenho wrote:
<blockquote cite="mid:BLU108-W604FD699A54E95939EF1CACCD20 at phx.gbl"
type="cite">
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</style>Hi Javier,<br>
<br>
Yes, I definitely agree that the folks using the technology should be
able to choose what they want and to participate in its construction.
If they can just be given simple plans for devices they can construct
at a modest cost, and that will work for them, it would be wonderful. <br>
<br>
This would also take away some of the suspicion the folks have of
outsiders who want to get them to do something new and different. Your
tale about the water wells was interesting and a good illustration of
this suspicion. I could tell similar tales of folks in Bolivia who
won't accept health care, from a medical doctor from the Catholic
church who has lived among them for decades, when a child becomes ill
with a potentially fatal but easily cured disease. They say it is God's
will whether the child lives or dies and they don't want to interfere.
Many children die needlessly.<br>
<br>
There is also a political concern. If the small villages of Peru are
anything like the ones in Bolivia (they probably are), there is a lot
of difficulty getting cooperation among the villagers to unite behind a
community project. Customs are ancient and really shouldn't be messed
with by outsiders. If individuals want to do something, that is their
business, but outsiders should not try to force things on a community
because it would be "good for them" (unfortunately things like potable
water, sanitation, power, communications, and the like fall into these
categories). Maybe when groups of children involved in the OLPC project
finish their educations and come back as doctors, nurses, engineers,
and the like, it will change. If, and it is a big if, they can be
convinced to come back.<br>
<br>
OK...enough of my rambling and ranting...here is what I really wanted
to write about...<br>
<br>
What do you know about vertical axis wind turbines like the Savonius
wind turbines? Here is a link to a wikipedia article about them:<br>
<br>
<a class="moz-txt-link-freetext" href="http://en.wikipedia.org/wiki/Savonius_wind_turbine">http://en.wikipedia.org/wiki/Savonius_wind_turbine</a><br>
<br>
There are lots of sites about them on the web...some with plans for
ones you can build. One even uses an old 55 gal oil drum cut in half.
Would these need a tower to work?<br>
<br>
Caryl<br>
<br>
<blockquote>
<hr>Date: Sat, 10 May 2008 01:56:31 -0400<br>
From: <a class="moz-txt-link-abbreviated" href="mailto:info at olpc-peru.info">info at olpc-peru.info</a><br>
To: <a class="moz-txt-link-abbreviated" href="mailto:cbigenho at hotmail.com">cbigenho at hotmail.com</a><br>
CC: <a class="moz-txt-link-abbreviated" href="mailto:josh at laptop.org">josh at laptop.org</a>; <a class="moz-txt-link-abbreviated" href="mailto:arjunsarwal at gmail.com">arjunsarwal at gmail.com</a>; <a class="moz-txt-link-abbreviated" href="mailto:carla at laptop.org">carla at laptop.org</a>;
<a class="moz-txt-link-abbreviated" href="mailto:peripherals at lists.laptop.org">peripherals at lists.laptop.org</a>; <a class="moz-txt-link-abbreviated" href="mailto:hbonwit at alumni.nd.edu">hbonwit at alumni.nd.edu</a><br>
Subject: Re: [Peripherals] Alternitive Power for Developing Countries<br>
<br>
<meta http-equiv="Content-Type" content="text/html; ">
<meta name="Generator" content="Microsoft SafeHTML">
Wind? No problem: you store the produced energy in batteries that will
feed your devices during the whole day.<br>
<br>
Some rules for wind powered projects:<br>
<br>
a) You need more than 8 miles per hour to produce energy for a home.<br>
b) You will need a tower. Don't trust the mills at the top of the
house or similar designs. You need a tower 2.5 times bigger than the
nearest building or tree. Normally you need a 10 meters tower (30 feet
aprox).<br>
c) Ask the people that lives in the area.<br>
d) Check some of the trees... if they are growing with some evident
tendency (right sided, left sided) then you can be sure that there is
some useful winds in the area.<br>
e) Wind mills use low RPM alternators if they want to be very
efficient. <br>
f) It is more efficient to set up the rotor/alternator/generator in a
direct connection to the "turning wheel" at the top of the tower.
Setting up a pulley system at the top and the
rotor/alternator/generator at the bottom of the tower is not so
efficient (there is lack of energy).<br>
g) Winds are not constant, they change according to the hours of the
day and the months of the year.<br>
h) In some areas of Peru there is huge resistance to introduce any wind
mill to extract water from the soil because they see like a weird
behavior to take the "blood" from the soil when mother nature doesn't
want to provide it in a natural way (like a river). In old times
(around 20 years ago) there was a group of Dutch engineers that was
killed in Puno area (the peasants warned... don't suck the "blood" from
the soil... they smile and they were confident that when the population
see the water running they will be more than happy... nope. They were
killed and buried.). Cultural things matter. Ask local people, get
the approval of the community BEFORE you start any study. Mining areas
are the most difficult because the past role that have develop the
mines in those areas during more than 500 years).<br>
i) There are many NGOs in Peru that have studied the issue (about
alternative source energy). But the problem keeps the same: all those
areas are without energy. I think is due to the size of the problem
(80,000 villages, 5 million people). There is not budget that can
provide enough help. If this is right (I am not sure) then we need to
think in lowering and lowering costs for wind mills and let that the
people of the village buy the plans and spare parts to assembly its own
solution (if that is a wind mill then fine, if it is a "energy"
pedaling device... is fine too!). If we provide spare parts, plans and
it is a easy and understandable design then they (the people) can
appropriate the idea and getting bigger and bigger results by
themselves. One village past the voice to other one (mouth radio).<br>
<br>
Best regards,<br>
<br>
Javier Rodriguez<br>
Lima, Peru<br>
<br>
<br>
Caryl Bigenho wrote:
<blockquote cite="mid:BLU108-W511A1A7B8598F5C23C93B6CCD20 at phx.gbl">
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</style>Hi PowerPeople!<br>
<br>
Javier and I are really "singing the same song". His spinning wheel
parts are very similar to my proposed sewing machine treadle. The
principle is the same. His wonderful table design is just about what I
had in mind for my used sewing machine mechanism. <br>
<br>
I don't see any problem having children use them at home. every child
could have their own and simply pedal as he/she uses the laptop. It
would be fun, like a learning toy, and that is just how they make it
work. Not child labor at all...just part of a learning game!<br>
<br>
There is, however, value in using something else at school for a more
centralized power source. That is where a large solar power, windmill,
water wheel or animal driven generator would be practical. <br>
<br>
We need to try some of these ideas with working prototypes and see how
practical they would be. I hope to find an old sewing machine when I
get to Montana in a few weeks. <br>
<br>
I may also have a chance to try something with a windmill. What
exactly is the problem with windmills at higher elevations? Why won't
they work? If I can get a small one, I might have a chance to test it
at about 3350 meters, 2000 meters for sure.<br>
<br>
Caryl in Southern California...soon to be Montana for a while.<br>
<br>
<br>
<br>
<blockquote>
<hr>Date: Fri, 9 May 2008 23:47:22 -0400<br>
From: <a moz-do-not-send="true" class="EC_moz-txt-link-abbreviated"
href="mailto:info at olpc-peru.info">info at olpc-peru.info</a><br>
To: <a moz-do-not-send="true" class="EC_moz-txt-link-abbreviated"
href="mailto:josh at laptop.org">josh at laptop.org</a><br>
CC: <a moz-do-not-send="true" class="EC_moz-txt-link-abbreviated"
href="mailto:arjunsarwal at gmail.com">arjunsarwal at gmail.com</a>; <a
moz-do-not-send="true" class="EC_moz-txt-link-abbreviated"
href="mailto:carla at laptop.org">carla at laptop.org</a>;
<a moz-do-not-send="true" class="EC_moz-txt-link-abbreviated"
href="mailto:peripherals at lists.laptop.org">peripherals at lists.laptop.org</a>;
<a moz-do-not-send="true" class="EC_moz-txt-link-abbreviated"
href="mailto:hbonwit at alumni.nd.edu">hbonwit at alumni.nd.edu</a><br>
Subject: Re: [Peripherals] Alternitive Power for Developing Countries<br>
<br>
<title></title>
Hello Josh and all,<br>
<p class="EC_EC_MsoNormal" style=""><font color="#3333ff"><span
class="EC_EC_827380313-08052008"><font face="Garamond">>Personally,
I
think the power requirements for the XO is too high for children to
charge them. Yes, I'm sure something can be created that children could
operate - but is this scalable and long term? Do we think that children
are going to want to do this everyday throughout their entire education?</font></span></font></p>
<p class="EC_EC_MsoNormal" style=""><font color="#3333ff"><span
class="EC_EC_827380313-08052008"></span><span
class="EC_EC_827380313-08052008"></span></font> <br>
Getting enough energy for a standard laptop from the pedaling in a
bicycle is possible (check YouTube.com... there are many working
examples). Even the most optimistic calculation or test that has been
done shows that is possible to do a fast pedaling for a short period of
time, then you are done and need some rest. That is due that you are
moving the whole leg to produce the rotation. And that kind of high
"torque" is needed because you are moving and object AND you are moving
a heavy weight (yourself). Not just moving a rotor against a "perfect"
rolling surface (pulley and internal parts of the alternator).<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
Then you have the other side of the coin: with spinning wheels (that
have been used by centuries) you move JUST your foot (right or left)
not the whole leg. People has been able to do this hours and hours
without showing any sight of damage or getting tired in the effort (I
know this from first hand because I have develop groups of spinners and
knitters in the high andes for projects developed in mining zones, all
of them using spinning wheels moved by the foot).<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
Our kids, peruvians, andean kids, are used to very hard working
conditions (most of them know very well how to wake up at 5:00 am and
push the sheep herd to the field, that coould be walking around 3 to 5
miles each day... then coming back to the house around 5 p.m. They do
this when there is no school or when the school just work 1 week in the
month or when they have to walk more than 2 hours to go to the school
(everyday) or when the teacher is out in the bigger nearest village).
That happens in the towns and villages over the 3,500 meters altitude
(80,000 tows and villages with a total of 5 million people there), not
in the small villages located at 2,500 meters altitude (this are the
ones that you can reach easily and have schools and teachers and kids
that look at your eyes like very poor children but are the not the ones
that are in the worst conditions). Any peruvian kid that lives in the
high andes, at 2,500 or at 3,500 meters altitude, will look at the
"pedaling" device in a spinning wheel like a toy, like at totally
integrated part of the "cost/benefit" system, and only the spoiled ones
will refuse to do it (there are "spoiled" children in any culture, time
and economic condition).<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
If that is too hard to accept (seeing as "children work" or any form of
"slavery") then we have to think that the ones that will use the
"spinning wheels" will be the teacher, fathers, bigger brothers that
can understand that they will benefit from generating its own energy
and that is depending on them and not in the force of the nature (wind,
water).<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
</p>
<p class="EC_EC_MsoNormal" style=""><font color="#3333ff"><span
class="EC_EC_827380313-08052008"><font face="Garamond">>I think
what
is
most important is to determine the sources of potential energy in areas
that need it, then design technology to utilize that.</font></span></font></p>
<p class="EC_EC_MsoNormal" style=""><font color="#3333ff"><span
class="EC_EC_827380313-08052008"></span>><span
class="EC_EC_827380313-08052008"><font face="Garamond">Javier I think
you
have mentioned that both water,
wind and sun are too variable to design a cost effective system around.
Can you think of energy sources that are readily available in these
areas that could be utilized?</font></span></font></p>
<p class="EC_EC_MsoNormal" style=""><font color="#3333ff"><span
class="EC_EC_827380313-08052008"></span></font><br>
Some person have talk about energy from potatoes. Yes, why not. And
from corn and soy and many other vegetables too. It is named as
"eco-oil" or "bio-oils"... but... there is huge controversy about how
much "conventional energy sources" are spend to produce this
"bio-oils". Furthermore, there is huge movement against using what the
people eats in poor countries to produce "sustainable oils" for use in
the first world. Example: in my country, Peru, the government has said
that the rise on the price of some food products is due to the rise of
the corn and soy in U.S. and Brazil. I have talk about this too much
with my own government but without success (politic stuff is not always
related to the law of the economy and sometimes is due to personal
conditions in managing some issues).<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
Some kind of a more integral aproach could be used: generating energy
from the gas that comes from composting the rest of the agricultural
production and the lefts of the animals. But that involves much more
money than getting, modifying, and installing some number of spinning
wheels.<br>
</p>
<p class="EC_EC_MsoNormal" style=""> </p>
<p class="EC_EC_MsoNormal" style=""><font color="#3333ff"><span
class="EC_EC_827380313-08052008"><font face="Garamond">>You don't
happen
to have an abundance of zinc ore in Peru do you?</font></span></font></p>
<p class="EC_EC_MsoNormal" style=""><span
class="EC_EC_827380313-08052008"></span> <br>
Zinc? Sure. Lots. I don't have information about producing energy
from Zinc. But... that is a work for a mining company, zinc is not in
the form of small rocks that you can pick up in the surface. You need
to dig, melt, separate and refine. Then you are a huge mining company.<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
Best regards and thanks for your interest in the issue.<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
Javier Rodriguez<br>
Lima, Peru<br>
<br>
</p>
<p class="EC_EC_MsoNormal" style=""><br>
<br>
</p>
<p class="EC_EC_MsoNormal" style=""> </p>
</blockquote>
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