members' bios (seriously under construction)
hi, i've just signed up on the solar cooking mailing list, and thought
i should introduce myself.
i am a home-schooler in canberra, australia, and my son found the www
solar cooking page last weekend. we were immediately fascinated and
all of us (me, my hubby, and our 2 kids) built a simple cardboard
cooker the next day. we are now trying to figure out how to use it
most effectively. i can't locate any books on solar cooking in our
local libraries. it is winter here, so we're not expecting great
things until the weather warms up...but i'm sure there are many hints
and methods that we need to know to use our cooker effectively.
so, we are complete novices, but intrigued by this "low-tech" solution
to cooking food (amongst other uses), and as "greenies" (as we're
called in australia) we are keen to find out more about alternative
technologies.
i am pleased to join this list as i am passionately interested in solar cooking. i am a dairy farmer and commercial beekeeper in prince edward island, canada, at 45 degrees north and in the gulf of st. laurence, which is ice covered and windy for four months of the year. i am active in an organization called farmers helping farmers which has projects involving women's groups in kenya and tanzania.
my energetic coworker is my young son, adam. he built a parabolic trough using a single sheet of newspaper printing transfer aluminum that could boil 250 ml. of water in less than fifteen minutes (on a sunny but below freezing day). when we put a skewer instead of a pipe along the focus we could cook hot dogs on it. the cost was next to nothing (25 cents for the aluminum sheet, some pipe scraps and some wood scraps). i have often thought since that such a simple small cooker would be well suited to a street vendor in a market cooking kebabs (instead of a charcoal grill).
the parabolic trough was a science fair project. another year adam built a simple tracking mechanism for it. he aligned the focal axis perpendicular to the sunpath, put a photocell at the vertex of the parabola in the shadow of the receiver pipe (when the reflector was focussed) and used one transistor, one variable resistor (to tune the photocell to the right light level), a small battery and a motor out of a toy and the thing tracked perfectly, and was unaffected by clouds (it would just catch up to the sun when it returned). that was a prize winning project.
adam and i now want to build a full size parabolic trough cooker with heat storage and an even simpler tracking device that is simple enough to be used in a developing country. now before you start flaming me with all the facts about how much more suitable box cookers are, let me say that i am already convinced of that. however, for some applications like institutional cooking or pasteurizing large quantities of water, i think that the design that we are thinking of might have some advantages.
we are thinking of aligning the parabolic trough perpendicular to the sunpath again and using a bag of dirt suspended from a rope through a pulley as the motive force for rotation and a bimetalic spiral (the blower thermostat from an oil furnace) to control the rope. the receiver would be a pipe which would convect up to a 40 gallon barrel (it will be on the second floor of our honey house) on its side (using the two threaded barrel bungs as pipe fittings). the heat transfer fluid will be waste oil. the barrel will have rocks in it, in addition to the oil, for heat storage, and will be insulated in a box of wood chips. the barrel will have a large cutout in it for the cooking pot/oven/water heater/pasteurizer. this will have a drain pipe going through the bottom of the barrel so if you are heating/pasteurizing water you can just fill the large pot, but the pot is big enough that you could put two or three small pots inside it to cook.
the advantages of this system (if it works) would be that you could cook in the early morning or at night. i know that i as a farmer am not around home much in the day time, and many of the women farmers that my organization works with in east africa are also out in the fields much of the time, and also might like a hot cup of tea before they go out to work which is usually just at or before dawn. it also might be capable of cooking large quantities of food for an institution. the parabolic trough reflector is very efficient and is easy to put a coating of aluminum foil or transfer sheets on without wrinkling, because it is curved in only one dimension. but it is the wrong shape for cooking pots, and it is not level if you want simple tracking (and it is useless if you do not have either manual or automatic tracking; it has to be in focus). using a heat transfer oil that could reach above the boiling point of water might solve these problems. there is no glazing necessary. while a large parabolic trough could be prone to wind problems, it would probably be partly dug into the ground so that the storage tank / oven would not have to be too high.
my apologies to the list for this lengthy introduction. i think it was supposed to be short :) i look forward to your comments and to learning from your experience. i repeat that i am already convinced that simpler cookers are what will be adopted for most solar cooking. this one will probably cost $200 to $300 to build, but except for the furnace thermostat spiral there are no hi tech components. i also realize that there are many safety considerations that i have not addressed. but one positive aspect is that the oil system is not under any pressure.
i first sent away for instructions for solar box cookers some 4 years ago and have done more work at schools than in the field. i have transportation problems and it is hard to get out to a remote area to do much work. (plus the time). this semester i am teaching ecology here at the university in puebla mexico as they have made it part of their obligatory classes that all students from all disciplines must take and i plan to do large-scale demonstations here.
my partner and i have developed solar water pasteurizer systems for use in third world countries to make safe drinking water. since solar pasteurization is a topic of the discussion group i would like to announce our products to the group in my introduction.
although we are a commercial business our main focus is making a meaningful contribution to the health and well-being of the billion people on planet earth that do not have safe drinking water. i do want to be sensitive to the issue of commercial promotion on the discussion group and certainly do not want to overstep boundaries or be perceived in any negative light.
i believe that the solar cooking discussion group would be genuinely interested in the solar pasteurization systems that we have developed, and our purposes are clearly aligned with each other. would you please advise me on how i can best let the members know of what we have to offer without being offensive with the commercial aspect?
what i have in mind is to introduce myself and then to breifly describe the products we have developed and their capabilities, then to ask people to contact me directly if they want more information, etc. i would be willing to have you review my introduction before i put it out to the members.
we will be launching a web site in the next couple weeks and would like to link with the solar cooking site. i will let you know when we are ready to go.
thank you for your assistance and the hard work you contribute to making the solar cooking discussion group happen.
wh@safewatersystems.com or grandsol@htdc.org