We’re targeting our wood burning cook stove at countries where deforestation is a major problem.  Wait…a wood burning stove is going to help in the fight against deforestation?

At first glance, this seems like a really bad idea.  Other technologies like gasification are more efficient and can use almost any organic material, but there are 2 major problems: they’re unfamiliar and they’re more expensive.

Of the women we’re designing our stove for, very few have ever cooked on anything other than an open flame.  As you can imagine, when you do something one way your whole life, you get quite good at it.  The further a technology is from a simple open fire, the less familiar it is, which translates to our users trusting it less initially.

The other problem is up front cost and risk of new technologies.  Most of the stoves that are available in the area don’t last very long because they’re made cheaply (thin metal) or use fragile materials (ceramics).  Users will pay up to a couple dollars for these stoves, and not get more than a couple months use from them.  This is why the marketing aspect is so important.

But marketing can only take you so far; you can’t get someone to pay a month (or more) of their salary for a stove–no matter how technically superior it is.  And even with great marketing, it’s hard to convince someone to cook in a manner that’s completely alien to them.  This is why we’ve developed a stove that’s more efficient and which looks high tech, but that fits pretty seamlessly into the existing cooking culture.

We do believe that there’s a place for gassifiers, solar cookers, etc.  But we also believe the best way to get there is baby steps.

We did it!  Our team is in the finals for IdeaBlob.  And now we need your help.  Please, please, please take a minute or two and vote for us.  Every vote gets us closer to the $10,000 prize.  Precise instructions on how to vote can be found here.

Winning IdeaBlob will definitely open some doors for us.  Right now, we’re paying for everything out of pocket, which does limit our reach.  Although our stove is designed to be very low cost, the prototypes do cost a non-trivial amount of money.  (Raw materials cost more money when you’re not buying in bulk, and there’s some equipment we don’t have access to unless we buy shop time.)  But, the big cost is travel.

If you’ve read many of our blog entries, you know that our entire process revolves around end-users.  To do this, we need to work very closely with partners in the country, and we need to talk to our actual users.  Both of these necessitate at least one trip up front to do needs finding and to get face time with potential partners and to create a plan for our collaboration.  It’s not easy to do this without money for travel.

There are other avenues to funding, but every hour we spend trying to fund ourselves is an hour we can’t spend making our stove better.  It’s our hope that, with your support, we can win this and continue focusing on what really matters.  That said, we’d love to hear suggestions on other avenues of funding!  As always, you can get ahold of us at team@3brickdesign.com.

Thanks for your continuing support!

Word of the day: Frustum-a portion of a solid that lies between two parallel planes cutting the solid.

Our inverted lampshade-like pot skirt is a frustum of a cone, or so we discovered when we tried to construct it from sheet metal. It’s not as easy as it seems; you can make a cylinder from a rectangle or a cone from a semi-circle, but a frustrum is constructed from a “rainbow”-shaped template whose dimensions determine the height and diameters of the part’s top and bottom surfaces.

Because we didn’t know that our pot skirt was formally called a frustum, figuring out how to build it was an adventure. Matt (a former teammate) and I had a friendly competition: he tried looking for the equation on the Internet while I made a barebones paper frame of the shape we wanted and then unfolded it to get a rough outline of the template. I like to say I figured it out first, but he found a neat little frustum dimension calculator that proved very useful for trying different pot skirt heights and widths!

I mentioned in my last entry “Skirting the Issue” that most pot skirts are actually cylindrical. So why in the world did we go through all this trouble to make such a tricky shape? There is an ideal gap for efficient air flow (about ¾”) between the pot and the pot skirt. When the team was in Myanmar, we saw that the women there cooked with an astounding range of pot sizes , with the smallest one having about a 5″ diameter, to the biggest one about 16″. To make matters more complicated, women often cooked on a wok as well. Thus, our pot skirt had to be designed to create the same ideal gap for multiple pot sizes. The “inverted lampshade” shape allows smaller pots to sit lower and bigger pots to sit higher on the skirt, creating a reasonable gap for air to pass through.

However, one of the difficulties with this design is that women have to reach further inside the pot skirt to take a small pot out. Since the air between the pot and the skirt is VERY hot, this poses a significant burning hazard for women. This safety issue is one reason why we are still hard at work at improving our initial concept!

A big component of our stove is its insulation.  Between the inner chamber (where combustion happens) and the outer walls is a lot of space.  If we simply left it empty, then hot air would move around and carry heat from the inside to the outer walls in much the same way your oven cooks food.

The obvious answer is to use insulation.  But what kind?  Often ceramics, sand, and earth come up.  It’s true that these would slow down the transfer of heat from the inner wall to the outer wall, but they do it by absorbing energy.  In scientific terms, they have a higher specific heat capacity than air which means that, for every degree they change, they absorb more energy.  This is helpful for safety, but it can actually decrease the efficiency of a stove.

In order to have an efficient stove, you need materials that don’t transfer heat very well–or, in other words, materials that are not very thermally conductive.  Air is actually pretty good with respect to this, but it’s a problem when it moves around freely.  Many of the best insulators simply work by trapping air in small pockets.  This is how down blankets work.

Our initial prototype used perlite, but it’s not readily available in Myanmar, so we’ve been exploring the possibility of importing it and other materials.  Ash is readily available and a pretty good insulator.  We’ve also been looking at special clay mixtures which are much lighter (and thus have a lower specific heat capacity) than normal ceramics.

As always, we’d love to hear from anyone with thoughts/advice on the manner!

A year ago, after we had just completed a prototype of a stove design we liked (it was literally made from an old metal trash can!) we decided to try adding a “pot skirt” to see how much it would improve our stove’s efficiency. We had read about these heat shields in other stoves before; the basic idea is to surround the pot on all sides with a thin metal shield that creates about an inch-gap for hot air to pass through. The pot skirt thus prevents heat from the stove from escaping to its surroundings, keeping it close to the walls of the pot and increasing the heating surface.

The idea sounded interesting, so we set to work building a prototype and testing it out! (My next post, “Frustrated by Frustums” will explain why our prototype is the shape it is-most pot skirts are actually just cylindrical.) The result was… WOW.

Adding the pot skirt cut down our rocket stove’s boiling time almost in half. The rocket stove itself was already able to boil water in maybe half the time it took an open flame, but with the pot skirt, we were boiling water at incredible speeds: up to a third of the time it takes to boil water on an open flame. Whatever we expected, I don’t think it was as drastic as this.

As great as it may sound though, our pot skirt idea still needs a lot of work. Adding that much material to our stove makes it more expensive and difficult to manufacture, not to mention clunky looking. Because it traps hot air, the skirt metal gets really hot too, posing a potential burn hazard to our customers. Our first prototype didn’t allow the cook to see the flame very well either (we fixed that issue by cutting out holes into the skirt).

Right now, we’re starting to explore new skirt designs, as well as some completely new concepts. One of the things we’d like to try is something similar to a “heat exchanger” which traps hot convective air at the bottom of the pot. The Jet Boil camping stove uses a mechanism like this. Such a design wouldn’t increase our heating surface area, but it will at least increase the concentration of hot air, which may be enough.

If you have any ideas about this engineering challenge, we’d love to hear them!

We’ve been talking a lot about our philosophy approaching this project, but I think it’s time to explain a little bit more about our actual stove technology. The stove prototype we’ve built for women in Myanmar is based on the Rocket Stove created by Dr. Larry Winiarski at the Aprovecho Research Center. Many such stoves have been modeled after Dr. Winiarski’s design, including the Berkeley Darfur Stove as well as other home-made versions (there are tons of videos online for how to make your own).

We chose to adapt the rocket stove design because its use of low mass insulation is very effective at keeping the fire hot and transferring most of the heat to the pot.  In my next couple of posts, I’ll explain how a hot fire and a design that channels heat to the pot are both important for improving the overall efficiency of the stove (I’m trying to keep my posts shorter :p).

If you’re wondering why we chose to design our own version of the rocket stove rather than partner with one of the other organizations that are building them,  please read our post about the importance of tailoring the stove to the local culture.  We aren’t seeking to compete with other groups; instead, we learn from them and share our own ideas. Building on someone else’s great technology also gives us time to focus on equally important issues of manufacturing, marketing, distribution, and education, all of which are crucial in getting our stove into the hands of women.

Cool.  The guys/gals at the Cool Product Expo put up a short blog post about us.  Astute readers will remember our original writeup on our participation of the event.

Thanks a lot CPX.  Excited to see you again next year!  :-)

In my last entry, I  promised to offer a few thoughts about what it means to embed a culture of dignity in this cook stove project. I call dignity a culture because I hope that each piece of our work—from conceptualizing the product to getting it into the hands of women–reflects truly humanizing experiences for everyone involved, including ourselves.

Our stove gives women agency by making cooking the center of their activity. Not tending the fire, not gathering wood, but cooking. I think people find dignity in their work especially if they do it out of love for others. Women in Myanmar cook all day for their families. This can be an arduous task, or it can be an act of love. By making it as easy as possible to cook with our stove, we hope that we make the woman’s role less menial and more meaningful.

We firmly believe in creating a stove that can be sold at an affordable price to women, not given to them as an act of charity; I think there is dignity in being able to choose a quality product that you need, instead of being given one because someone else feels sorry about something you lack. We also plan to manufacture our stove to fit local expertise and ability because we believe that the work of improving each others’ lives is something that the community should be able to own.

I don’t claim to know everything about how to make this vision of a culture of dignity a reality; I’m still defining for myself what dignity is in relation to design. One day, I hope to even be able to measure it. For now, we’ve made a commitment to hearing what our customers are saying at all costs, because we believe it humanizes our product. I believe that creating a culture of dignity is the biggest impact we can make, and hope to continue to work towards it.