Butterfly Expo

March 31^st 2008

Today AMADER (the Malian Agency for Domestic Energy and Rural Electrification), the group who financed the development of the Butterfly so far, had a demonstration for a department of the Ministry for the Promotion of the Woman, Child and Family. The object of the demo was to highlight the link between energy and the family. AMADER asked that I bring the Butterfly and Helios and do some cooking.

Here we are setting up the Helios on the edge of a soccer field. Once the mirrors started going up their curiosity got the better of them and they put the game on hold to come hang out while we set up the machine.

Some of the adults were concerned that the children would burn themselves with the Solar Fire, but teaching the kids some solar safety was easy, even if we didn’t speak the same language. The trick is to get them to put their hand in the focal point, but not at the point of most concentration. They exclaim and withdraw their hand, surprised by the heat. Then you get them to put their hand back in and slowly move towards the point of maximum concentration… they don’t get very close. Then you burn a stick and the message is clear.

Unfortunately we didn’t have time to organize any baking of cake, but gathering the ingredients to make a nice pot of rice wasn’t hard. Note the rolling boil we’ve got going on. That’s about 5L of liquid and 1.5kg of rice, plus some veggies and beef.

The ladies from the ministry were mightily pleased. Two of the biggest advantages they see are time saved gathering wood out in the bush and improved cleanliness. Cooking on a fire leaves the pot all black and sooty, which dirties hands, clothes and dishwater while solar cooking leaves the pot as clean as when you started (except if you burn the rice, which we almost did…)

Now granted I’m a little bit taller than the average Malian woman, but the ergonomics of the machine are still quite acceptable for women here. Traditionally, cooking is done on the ground over a fire, and overcoming cultural inertia is never easy, but a number of the women we’ve talked to have said the equivalent of ‘so what if I can’t cook on the ground if I don’t have to go gathering/buying as much wood?’

Now we’re going to embark upon more expensive testing and fine tuning of the Helios bread oven as well as the Iron Butterfly designs.

Meanwhile, administratively things have stalled a little bit. I had left the association to do its thing while I do tech development but their follow-up on the contacts we’ve made has been less than satisfactory. I’ve put my hand back in the mix and we’ll see how things progress over the next couple of weeks, at which point important decisions will have to be made.

High hopes, as usual.

Boiled water

The first step to forcusing is determining where we'l place the mirrors. Since we're talking about inclined mirrors arranged on a flat surface there is bound to be some shading/blocking issues. Here, Djadje moves two mirrors around the wing and draws a rough guide to mirror placement so that we can space the mirrors effectively.


To space the mirrors effectively we--
Wait! Stop everything! Emergency! The teapot is broken! All work ceases and Michel heroically breaks out the oxy-acetylene torch and welds it back together. Phew. OK back to work, nothing to see here.


Using the mirror map we drill holes and place three screws in a broad triangle beneath each mirror. By placing a mirror on the screw-tripod and by varying the height of the screws we can incline the mirror such that it reflects onto the pot. You can see one mirror is on target while another is hitting the building.


Once we have all the screws properly adjusted (it's not enough to do it for one time of day, it has to work all day, so once you do the initial focusing you have to keep it on target for a day or two and observe how the mirrors react to different insolation (INcoming SOLar radiATION) angles and adjust accordingly.) we can proceed to backing the mirrors. I'd settled on styrofoam/glue mix. We bought a large quantity of styrofoam for next to nothing and got to work busting it down.


It wasn't the easiest process:


But it did the trick. The problem was how to weigh down the mirrors so they would stay in contact with the screws. For our first try we makeshifted a fast solution because the glue was drying fast:


Afterwards we reflected and determined that we could glue the mirrors and then tie them down using wire. We found out that wire worked so well we didn't even have to glue them.


That means that we could mount the wing and adjust the mirrors a little bit while we saw how they behaved on the machine. They behaved pretty well! We managed to boil some water, and we're at only half power! I assume we're at around half power, but you never know what ol' bucket-o-rocks is up to.


This bodes well for the final product, but the hardest part is yet to come.

The next step is to build the mold, and then use that mold to stamp out copies of our original. It will not be easy. Again, if anyone has any ideas about how to effectively make a very large mold of these mirrors let me know.

Geometry Achieved

Today was a wicked day.

Not only did I get a drive to work (instead of spending an hour walking and taking a packed van) but we basically finished the frame for the Butterfly (my variation on the Papillon) and proved the geometry is sound).

There were a number of problems that I had foreseen (weight distribution, pot placement, spaces between mirrors, mirror shading etc) and had assumed that we would be able to solve with a certain amount of elegance. Kudos to us for actually being able to.

Also, the butterfly is a test of construction precision, because unlike the other Solar Fire technologies, this one is pretty rigid. The Vesta, Apollo and Helios, however, all have movable mirrors and can be modified fairly easily. The butterfly is a one-piece reflector that must follow a pretty precise line of movement to track and reflect the sun easily. Initial indications… indicate… that we achieved an acceptable level of precision. Must be due to all the vicegrips:


And our counterweight (speaking of elegant solutions, note the paintbucket filled with rocks tied opposite the wing):

The butterfly works like this: the two wings face the sun directly, and will eventually be covered with 10cm by 10cm mirrors (like the one I'm holding)
which will reflect the sun onto the pot at the center. The paintbucket-counterweight will eventually be replaced by another wing, so the weight will be balanced. We've substituted that wing for a counterweight because I didn't know how this experiment would turn out and didn't want to make two wings if their shape/construction weren't for certain. I reverse engineered this design by looking at some pictures of the papillon, and so nothing was for sure.

The mirror angles at the edges of the wings are pretty acute, which means that we'll have to fill fairly large spaces with the woodglue/sawdust or Styrofoam mix, but luckily I happened across another type of plastic foam with better cohesion than Styrofoam, so we'll be able to cut it to fill the majority of the space without using large quantities of glue:
However well things went today, the process is nowhere near finished. Once the geometry is finalized, we move on to calibrating the mirrors. There are 100 mirrors to calibrate, which will take a solid amount of time (especially with the heat of the sun these days!). After the configuration, we'll have what we call a master mold. That is, we'll have glued all the mirrors at the proper angle, but in order to avoid having to calibrate 100 mirrors each time we want to make a wing we're going to make a mold of the original wing.

That's a pretty big mold. The parallelogram that makes the wing is short side: 70cm, long side 150cm and width 100cm. We're probably going to go for rebar reinforced plaster or cement (plaster is way easier to work with since it doesn't bond to mirrors too fiercely) but I don't know yet. If you've got suggestions on how to avoid breakage, let me know. I'm slightly worried, but have faith in the guys I'm working with. I don't have extensive materials experience, but they sure know their stuff. I'll let you know how we solve the problem (and the various ways we might fail).

Consider protocol disregarded (surprise surprise)

Monday morning and I 'passed by AMADER to say hello' and incidentally wondered aloud about the state of the financing 'because the SAHABA 2008 is only three weeks away'. There had been some motion, but still no money. They had received tacit approval to include the creation of the domestic solar cooker in their 'global budget' for SAHABA, but had not yet compiled the global budget etc. I said look, if I buy materials now will I be paid back? She said she couldn't guarantee anything, since it's not in her power, but given the tacit approval and the general enthusiasm of the department, I could pretty much count on getting paid back.

Good enough for me. To the truck! To the store! To action!

And by action I mean careful contemplation of the task at hand:
Here is the first little science experiment to determine how we are going to back the mirrors on the papillon. If you check a previous post, there's a picture of a papillon made with curved polished aluminum. My idea is to use mirrors attached to plywood. The question is how to support the mirrors at the appropriate angle. Here I'm mixing various quantities of wood glue and sawdust, or crumbled styrofoam with wood glue. The goal is to have something rigid, lightweight and cheap.

During the long lonely nights while the cyber is closed I amuse myself by contemplating the geometry of the papillon by drawing it out to scale on my bedroom floor:


The results are in! Styrofoam is much lighter and more waterproof, but sawdust is more rigid. More tests to follow, including other materials etc, but already we've got something workable for the demonstration.


Have you ever heard the saying that you can learn a lot about a workshop by the size of it's drill-press?


Basic geometry and initial structural problems overcome. Tomorrow we should start with the mirror focusing to make the master mirror mold. In an upcoming post I explain the process in detail...


Here's a picture of the Malian Minister of the Environment lighting a stick with Solar Fire:


And this evening the association Tile Tasuma (Solar Fire in Bambara) had it's first meeting. From left, President Ibrahim C Tomota, Secretary General Faguimba Tounkara, Assistant Vice-President in Charge of Training and Technology Djadje Samake, Vice President in Charge of Training and Technology Lorin Symington, General Treasurer Lalla Samake, Responsable de la sensibilisation (responsible for public relations, more or less) Boubacar Sidibe. Not pictured are Karim Sanogo who is Secretary in Charge of External Relations and The Accountant):


In summary: tech development is in full swing, hooray!

The National Forum on the Environment

Right. Remember what I said about blog frequency and craziness? Yeah.

So Monday rolled around, and there was no action on the budget. Not only that, but the guy who was supposed to help bring the Helios to CNESOLER didn't show up. I decided to go to the director of AMADER's home energy dept to speed things up. He understood, but couldn't influence things. I told him about my decisions regarding CNESOLER and he agreed that it would improve chances to get funding if I partner with a government establishment.

I went home without having accomplished much.

Tuesday started out the same… I was in an office trying to move things along when a brochure on the lady's desk caught my eye. The Mali-Folkecenter is apparently hosting the National Forum on the Environment. MFC is a pretty big operation, and I hadn't yet made contact with them, though it was in the plan. It didn't really connect just yet that I am in Mali. I look at the date, it says 29th of Jan 2008, not knowing what date it is I think for a moment, that's a shame that I missed it. Wait a minute… that's TODAY! At this point I still have significant doubts that we'd be able to do the necessary paperwork to get a vehicle, or register me or whatnot. Still, might as well ask.

Bam. To the directors office! 4 hours later we had dis-assembled the machine and transported it to the Palace of Culture, where the Forum was taking place. They gave me 10,000 F CFA to buy food to cook for people and I was on my way.

The next day we(and by we I mean she) cooked up a big stew for everyone.
Solar Fire Style: maxed out thermometer (that means +200C)
Ibrahim C Tomota says: Solar Fire, awww yeah.
So much stew.
lol poor SK-14, all broken and neglected:
Then there's the Association of Women Engineers who had a stand promoting their use of cardboard and tinfoil cookers with a heat resistant bag. They have to be imported from Holland, but have the advantage of being able to be transported like 30 to a backpack.
Mmmm so much solar cake. We made the mistake of using pots that were too big for cake, and they were burning at the edges and not done in the middle, so we massacred it a little bit and put everything on the baking trays.
I probably served cake to like 100 people.


It was good to the last crumb.
Haha in our enthusiasm for cake we let the focal point wander… on this oven we built the exterior side walls out of wood to save on tinsmithing, but we'll probably not do that in the future, considering it smolders a little if the focal point hits the tin on front.
I made tons of good contacts, met the minister of the environment a couple more times, and impressed the people who work at CNESOLER (I was hosted by their stand at the forum). Everyone is really enthusiastic, so we'll see what we can cook up.

This weekend is catch up on sleep time and kit maintenance. This coming week, if the money isn't available to start the papillon prototype I'm just going to buy enough materials to get started... the Habitat Salon is less than 3 weeks away, and is important enough to disregard protocol (what? me? disregard protocol?)

Progress.

Work progresses adequately. Things have not gone as quickly as I would have liked, but that is primarily due to the lack of appropriate power tools. Additionally, a couple of the 'optimizations' I drew out in Google Sketchup 6.0 didn't work out as planned (note the picture below entitled surgery).


















However, in the timeline I envisioned, I took into account a number of mishaps of this sort and so we are not far off schedule. Here, Drisa (Diadie's apprentice) attaches a finished spider to the frame.












A spider is a small frame that we glue to the back of each mirror. Here are the spiders after we glued the spiders to the mirrors.


















The frame has eight 'arms' with screws at the end of them which permit us to deform the mirrors so that they approximate parabolas, yielding a focusing effect, seen here.

The balls of light you see between the mirrors are about 4 meters away, and are 10cm in diameter, while the mirror is a 30cm by 30cm square. In essence, each mirror focuses at 9:1 and there are 54 mirrors, so if we manage to focus perfectly we will have 486 intensities of the sun at the focal point.



Mirrors are not made to be flexed, though, and so some breakage is expected:


















Luckily, RV is on the case and he does his best to stay in the bounds of how much you can deform the mirrors.


Impatient for the oven to be finished, , Konan manages to roast a roast, Solar Fire style (even with only 2/3 of the mirrors mounted).

Meanwhile, Diadie 'makes with the oven':
Technology wise, things have slowed down a little with the making of the oven, as it is a precise process needing constant attention, so there is essentially only one working group. Compounding the slowness, RV has come down with some kind of illness and so has been out of action for two days. It's not too serious, but working all day in the sun requires a certain fortitude which he currently doesn't possess.

Politically, things are going well. The magical Tomota has done his thing, and has met with the Minister of the Environment to discuss the Solar Fire Project. The Minister is supportive and says he will 'accompany us, politically'. In real terms, that means he and his staff will attend our opening exposition.

The goal is to excite people as to the possibilities afforded by low tech solar power enough to create a research, development and training program which will develop technologies and train people how to build and use them to enhance their economic opportunities while promoting an ecological way of life.

Approx timeline: finish oven and any minor adjustments to the Helios concentrator by the 7th, have the array painted and pretty, set up at the Cite des Enfants by the 10th, commence preparations for the exposition and start actively promoting the technology on the 15th.

PEACELOVEHOPE

GOING.

RV and I get up at dawn, spend 10 hours a day at the workshop and then work on the computer until after midnight before sleeping until the pattern repeats. It’s working: I have anywhere from 1 to 7 people following my directions at any given moment in time when at the workshop. From the neighborhood children who sit around saluting us and chanting ‘toobaboo’ (whitey) at us while making us tea, to Diadié a shop man with impressive skill (it’s his workshop), his apprentice Drisa, RV, Konan, Yusuf (an economics student who wants to help promote the array) and a seemingly endless supply of interested randomers who have dropped by to lend a hand for the simple, long and repetitive work of making the spiders.

Today we finished the frame, and the mirrors have been glued up and ready for a couple of days now. Tomorrow is going to be a big and exciting day: we’re going to mount the mirrors, concentrate them, and start experimenting with local supplies for insulation (vermiculite and fiberglass insulation don’t seem to exist here). Next week, before Karim gets back on the 5th I hope to have painted the machine and built a hybrid oven/roaster, since two of the most interesting applications are bread baking and peanut roasting.

The real fun should begin then. For now, enjoy some pictures from around the workshop.

Proof that the solar arrays can be built just about anywhere:

Instead of giving the full explanation to every passerby (you never know who will be the vector that makes the connection to the precise person you want to talk to) I got the schematics printed up and I taped them to the wall of the ‘shop’ and they inform themselves, and if they’re interested (most are) they come over and talk it up.

RV at work slitting the spiders (if you’re interested in knowing more about the construction process, it is outlined in some detail at http://www.solarfireproject.com/spider )

Tea a la Mali is like teaspresso: they basically fill the teapot with green tea, fill up the between space with water, boil for half an hour, remove some water to add the sugar and then boil for another 15 minutes while pouring it back and forth ceremoniously. They then serve a half shot of it and you’re good to go for the next 45 minutes while 2nds gets made.

Here’s the jig we made to make sure the spiders get welded square (it’s important or else the screws fall outside the perimeter of the mirror and do nothing).

Work gets interrupted by Didier’s daughter; he gives her a coin and she goes to the corner store to get a candy (even though she can’t yet speak).

RV is good to go.

Didier isn’t impressed though:

By curving the main beam by weighting down the middle we’re able to weld some strap iron to make a tensor which strengthens the structure.

Warning: getting Bulldog glue out of the tube without the glue gun is surprisingly and amazingly difficult.

Headlamp to the rescue! We were able to glue up all the spiders.

On the way to work I stopped by the local bakery and found a bunch of jovial bakers willing to let me walk around and observe things. They didn’t speak to much French, but I got across that I was trying to build a bread oven and wanted to know how it worked. That’s not a wall behind them, that’s the oven. It’s over 2 meters tall by 3.5meters by 2 meters deep. It has two levels of bread and can make 240 baguettes measuring 80cm long at a time.

Finally we finished the frame. The mirrors are all glued up, and we’ve got a game plan for figuring out how to build the oven. Tomorrow, with the first sun of the new year we’ll light a Solar Fire.