ETHOS 2009 Stove Conference

This was my third ETHOS (Engineers in Technical and Humanitarian Opportunities of Service – a long name for people who often just call themselves “stovers”), and the Seattle suburbs are as cold as usual at this time of year. ~100 researchers came from around the world to compare notes on stove projects, stove designs, standards and testing procedures, health impacts, other associated appropriate technologies, and so on. More apparent this year was interest in carbon credit funding and biochar (terra preta) applications, and all year long there has been an increased emphasis on refugee camp stoves (and more testing of stoves in the field, versus in the laboratory) so this was more apparent at the conference. There was a raft of new stoves introduced this year, including the new BioLight thermoelectric-powered-fan one for camping and more, the likewise fan powered LuciaStove from WorldStove (shown with developer Nate Mulcahy), and the souped up Peko Pe natural draft gasifier presented by Paul Anderson (pictured with Crispin Pemberton-Pigott, wielding his ever present combustion analyzer). The dual venerable Dr. Larry Winiarski and Dean Still are also shown here with the upcoming finned pot atop StoveTec’s rocket stove - now 36,000 strong in the field just since last year. The trend toward stove models like all these, designed for mass manufacturing, continues, and this trend was recently discussed below. And yours truly demonstrated in light snow the new biomass gasifier (the big red one) from All Power Labs here in Berkeley. Look soon for Peter Scott’s new rocket stove design and application website. Past stove conference proceedings can be found here.

Coming of the Corporate Biomass Stove - Mass Manufacturing to Save the Day?

Many of the improved cooking stoves designed for the developing world have traditionally been built by hand, on location, in relatively small numbers - a deployment of 10,000 stoves would be quite an achievement, and we have only seen this a limited number of times (each worthy of note and praise); only in China have we been capable of deploying the necessary millions (+125!) of stoves. While technically well thought out stove designs have been around since the 1980's. it has been hard to develop momentum so that truly large numbers can begin to make a dent in global problems such as environmental degradation caused by firewood collection, health problems due to indoor air pollution from smoky fires in the kitchen, and most recently the specter of global warming due to poorly combusted fuels. The obstacles to be overcome for this to happen are many, including the challenge of introducing improved stoves in thousands of different communities (all with unique cooking practices, fuels, and just different cultures), a lack of disposible income (and just as important - cash flow) in target communities to pay for even obviously beneficial stoves, some memories of bad implementation experiences in the past, and a resistance by funding agencies to make a commitment to solving hard problems with an appropriate approach.

The World Health Organization (WHO) is a very visible agency with clear opinions on what to do to improve the situations of the 3 billion people who cook with biomass fuels, and they have taken responsibility for reporting the "proportion of the population using solid fuels" as an indicator for reporting progress towards Millennium Development Goal 7 - to ensure environmental sustainability. Their brochure Fuel for Life is an introduction to their views on the problems and solutions. It seems that, in their opinion, using traditional biomass fuels is not consistent with.... can I believe this?... a decent quality of life - essentially giving up on improved biomass fuels and stoves as viable alternatives to liquid and gas fuels (and electricity) as "approved fuels" for sustainable, healthy, and environmentally appropriate progress. My complaint is that this is despite the obvious gains made in the last few years to improve efficiency and reduce emissions!

What of the alternative - continuing to learn to use our ample biomass resources responsibly and appropriately? The vast majority of fuel choices originate as solid biomass, and going to the effort of transforming them to more modern fuels can't help but result in energy and carbon accounting distortions in their conversion/transportation steps. It doesn't help that I consider myself to be a bottom up development advocate, believing in putting in more field time to understand what is most locally appropriate. Proclamations like the Millennium Development Goals suffer from problems like paying little attention to responsibility and accountability... who will personally take charge of this ambitious fuel transition effort for billions of people, and then perhaps suffer when it proves impossible to realize? Setting manageable goals is the first step toward progress.

Indeed the present situation would seem to be overwhelmingly discouraging if it were not for new developments, of interest here are the ones from the private sector, that are cropping up all over. For the last year or three there has been a huge amount of activity in what I call "corporate stoving" - it is not as if corporations of one kind or another have not always had cooking wares for sale (certainly in the developed world!), but they have not always been this active in developing countries - the market certainly is huge, but the margins are uncertain and the customers non-traditional. I could speculate on their ulterior motives, but suffice to say they are welcome players - the more technology rich stoves they are testing have the potential to reduce fuel consumption by 50% and drop emissions significantly, and result in deployments of tens of millions of units each.

My first experience with one of these was at Aprovecho's 2006 Stove Camp where a bare bones Philips Electronics model was under testing - what a beautiful fire the swirling air made, and it just ate up the waste wood with never a trace of smoke. Even in this early form (without glossy exterior and internal battery) it was a marvel of efficiency, the culmination of 4.5 billion years of learning how to make biomass fires on planet Earth. It provides the right amount of air to the right places at the right times - I don't know if you can combust fuel much more efficiently (so now we need more work on transferring the heat more effectively to the pot and food, the other half of the technical problem). The Philips business model is admirable - fully support your customers' new "cooking appliances", backing them with spare parts, maintenance facilities, and a warranty. Since 2006 Philips engineers have presented regular progress reports, and testing goes on in India - customer acceptance is of course crucial, and the thermoelectricity powered fan (with a NiMH AA battery for starting) is a critical part of the reliability requiring extensive field testing. But the real challenge is developing mechanisms to teaching people the advantages of a radical new stove and way of cooking, necessitating lessons illustrating possible initial downsides as well (there always appear to be some disadvantages compared to their present stove - no one stove, or fuel, suits every situation) - the best technology counts for naught without a dynamite cooking culture change plan.

British Petroleum's Oorja stove is part of BP's Emerging Consumer Market (ECM) strategy to provide energy solutions to the billions of people cooking with biomass. The most extensive discussion of it is in a June 2007 article in The Hindu newspaper here, and it describes a computer fan powered batch loading stove running on compressed pellets (presumably like small U.S. heating stove pellets) costing ~$USD 15 - hundreds of thousands of stoves were in operation at that time. Village based businesswomen sell the stoves and the pellets made from agricultural waste - a new infrastructure for pellets (or other kinds of briquettes) will be needed to compete with existing firewood and charcoal ones if people are to make the transition to stove designed to use these more environmentally sustainable and benign alternatives. It resembles a top loading updraft type gasifier, with credit given to the Indian Institute of Science, and they have ambitious goal of 20 million sold by 2020; their promotional video of it is here, and Yale has an excellent overview here.

Perhaps I heard about the Bosch-Siemens plant oil stove next - though I have yet to see one. Again, the influence of corporate R&D expertise is obvious in its sophisticated design and attention to detail. Cooking stove oil appropriate biomass typically is purpose raised (hopefully not for its food value), and there are a wide variety of choices - jatropha is often mentioned these days as an example and small oil presses can be built locally to provide jobs and economic security right where the stove benefits are also located. We can always hope that there is room for regional variation and distributed manufacturing - they have a stated commitment to locally produced oils - let's pray that plant oils from locally appropriate crops will always be competitive with upcoming bioengineered and watered/fertilized mono crops. In volume they expect that the stove price will be $USD 20 and this article reports on the deployment of a first 100 stoves in the Congo earlier this year - like all of these stoves the Protos is in the development and testing phase, so we can expect to see changes and reports from far flung places around the globe (using its partners, this one is planned for field trials in a number of countries such as Indonesia, Philipines, India, and other parts of Africa) - and see the price drop as more efficient manufacturing is realized.

Aprovecho and the Shell Foundation have worked together for years developing stoves that have fewer emissions, and on refining the tests to measure them. The latest from the Shell Foundation is their collaboration with Envirofit, aiming to deliver tens of millions of Rocket stoves to the world before you know it. I have seen the simplest model and there are great design pictures out there for coming models) - we should expect a metal combustion chamber backed with an insulating ceramic, with various attractive shells - a glimpse of their future model in testing as reported here in the NYT. Their effort is evolving quickly so expect to soon find all kinds of additional information out there.
One of the things we expect to see from the biggest players is marketing of these new stoves as if they are any other new consumer product - focus groups, advertising, brand management, as well as hopefully a network of distributors for repair and spare parts (and perhaps even branded fuel). And it is expected that turning a profit will be part of their business models, but for now only they how - unfortunately subsidies have always been a part of improved cooking stove programs, since people rarely have the cash on hand (or cash flow - banks are mostly a developed world phenomena) to buy a stove even if the payback due to fuel savings is clear. Manufacturing economies of scale and consistent quality - plus new methods of outreach, financing, support, and attention to customer feedback - should favor capitalism finally, and if not then providing incentives is nothing new and can be considered. Later.

The Approvecho Research Center is anything but a global corporation (their emphasis has traditionally been on R&D), but they have just entered the stoving arena as a big player by rolling out their independent StoveTec line of products, manufactured in volume in China. They practically invented stoves made with a metal shell and fluffy ceramic Rocket elbow... and now they have a price that is just plain hard to believe - on the dock in Ningbo these can be $USD 6 in volume, and you can buy spare parts as well. A side fuel feed entrance (instead of the top loading versions that we are seeing from everyone initially) certainly is appropriate for a fuel flexible stove, and the folks at Aprovecho can be expected to come out with it first.

A "fan assisted" stove marketed for camping (a developed world activity only) is the Woodgas Campstove, an evolution of the one first proposed by long time biomass advocate Dr. Tom Reed - over the last 3 years this one has logically progressed from a rough design to the present polished stainless steel versions (two sizes) that should also appeal to the developing world. They are presently made in India, and we can only encourage then to experiment with local distribution there. Note that the Philips and BP ones also have a fan (you will also see the term "gasifier" used often), a term meaning that they usually require batteries or a cord to power them - at first this may not seem suitable for the developing world, so let's consider this further. In most cases these are destined for growing metropolitan suburbs where charcoal fuel tends to dominate, costing families as much as 1/3 of their income; these people tend to be familiar with technologies like cell phones so the arrival of a new battery powered appliance is not necessarily a complication. Given that these stoves can require only one watt of fan power to produce ~3000 watts of cooking energy from previously waste materials, there are some huge incentives to switch back to raw biomass - with a net benefit not just in fuel and cost savings, but a lighter impact the atmosphere.

There are a number of other stoves worth mentioning here which aren't backed by a multinational that may have trading carbon credits in mind too (efficient stoves are carbon neutral), all with the potential to scale their production up - if they have not already done so by the time you read this. These are already made professionally and when there is the demand they are designed to be made in volume with modern quality control methods, shipped around the world, and supported in the field. Examples pictured here are the Vesto stove from New Dawn Engineering (South Africa), 25,000 German made Save80 stoves are deployed in refugee camps (shown here being used in Nigeria), and the very promising Turbo Rice Husk Stove from the Philippines burns rice husks with absolutely beautiful flame characteristics. Stoves with chimneys, to address specifically indoor air pollution concerns, can be harder to mass produce because of their size, but in Central America two standouts producing more than their share are the Ashden Award winning factory-made concrete ONIL stove (Guatemala primarily) and the metal ADHESA/Trees Water People (Honduras).

ETHOS 2008 Conference

Again ETHOS (Engineers in Technical and Humanitarian Opportunities of Service - motto: "Changing the world...one household at a time") met in Kirkland, WA for its annual conference last weekend. This tends to be a meeting of mostly "stovers" (designing and advocating improved cooking stoves for developing countries) but it is slowly adding other topics that address broader global problems. It is a manageable enough size (~100 people) so that most people know each other, are usually conference returnees, and they form a comfortable "stoving community". For the first time there were 3 simultaneous sessions going on in different rooms - a sign of more talks than before (and more time allocated for each), but a difficult situation for those of us who want to see every one.

This year saw an increase in efforts to mass produce improved stoves in factories, to get more out in the field, faster - talks were presented by Philips (a beautiful fan stove now being test marketed in India), Aprovecho (the cheapest stoves and parts imaginable - newly available and looking for their first mass field trial), and Envirofit (a new and very ambitious program, with vision and lots of conceptual stove designs). For stoves manufactured outside of the countries where they will be distributed ("locally made" has long been a tradition, because of transportation costs and funding issues, and the lack of commercial interest in this market) some concern has been expressed - should we keep shifting carbon responsibilities around the globe? And some stove types may always be local because of the low volumes required - these places needs unique stoves, to meet very local needs. The ONIL stove in Central America should qualify as well as a volume producer, with thousands of new IAP stoves manufactured every month, and Trees, Water, People will be opening a new stove factory in Honduras soon, with AHDESA. When should we consider emulating proven, cost effective (and manufacturing/implementation optimized) programs in other locations/countries - perhaps 100 km apart so that we are local and have less transportation problems? But for similar sociocultural and cooking practice circumstances, why should we keep re-inventing the wheel? Certainly, at present things appear to be accelerating and building momentum as new manufacturing/distributing models are being tried.

In the background was always lurking modern publicized stove global goals, like the "billion stoves" challenge, and the U.N.'s "Millennium Project" (the stoves/IAP aspects, from the WHO perspective, are here) - though of course stover researchers and implementers work with these in mind every day. There is also a new appreciation of the role of cultural research/participation - someone commented that "the solution" may only be 2% engineering, less than my constantly decreasing estimate of 10%.

There were also talks on the results of finned pot experiments (the potential fuel savings with these is very impressive), new TLUD stoves and activities in India particularly, new tools available for quantifying emissions (from Aprovecho and the Berkeley Air Monitoring Group), health effects of traditional indoor cooking practices, stove efficiency testing and analyses of the validity of present common testing procedures (such as the WBT, KPT, and CCT), and a number on "integrated cooking" - where improved cooking stoves are combined with solar cooking and retained heat cookers, taking advantage of the benefits of each one. I can't list all the talks and the countries represented here (my favorite image was of a llama dung burning stove in Bolivia, since I used to raise them and know its easy collecting characteristics, courtesy of CEDESOL), but ETHOS will soon publish the full proceedings here, where you can also find the proceedings of the last few meetings.

One of the favorite parts of the meeting is always the burning stove event at the very end, where people bring their newest stoves to show off and get comments on them - its amazing how people drag some of the bigger ones there from all over the world!

Testing Your Stove Test - the Beauty of the Normal Distribution

We all have a regular need to show people how much we care about the accuracy and reliability of our claims for our products (I am assuming that the introduction of a new stove to a region is just like the introduction of any new consumer product to a "market" - we want lots of sales and satisfied customers) - as such we should have tests (for stoves and other products) in place that clearly show what the performance of our contributions are. Within industry, quality control (QC) is taken very seriously, and if everyone had to argue about the results of every quality test there would be a world of trouble. Instead everyone agrees on statistical methods that not only show that the performance of our stoves is what we say that it is, but we also can also use present data to predict the future performance of many more stoves in the field. We create tests to show how we test performance, but how do we test our tests - to indicate that people can trust our results?

The very first way to start evaluating the suitability of a procedure/test (time to boil, firepower, individual emissions, etc.) is to determine if the results of the test is "well behaved" - a somewhat un-technical expression that indicates that a set of data resulting from applying the test multiple times has the statistics of a "normal" (or Gaussian) distribution (see http://en.wikipedia.org/wiki/Normal_distribution). A large chunk of quality control (QC) is based on this mathematical distribution, which assumes that any measured variable (say the time to boil 2 liters of water with the WoodGas stove - just following the WBT procedure) has a real and precise value, but that small errors are introduced during the measurement process so that there is a spread in its actual measured values. We can discuss where these errors originate later, but the assumption is that they are random in nature, so the distribution has a single well defined peak. If not then there is a real question as to whether the test is reliable.

As an example, we can use Frank's (for once this is his real name) adobe brick crush strength measurements - 20 real measured data points taken with whatever his standard procedure is. In the first figure I show how we use Excel's "frequency" function to create a table of the probability distribution of his data values. Figure 2 shows that when the data is plotted indeed the distribution of the data appears well behaved (it has a nice, bell-shaped appearance), so that I think that he can assume that both his brick making and crush testing methods are sound and reliable (and therefore that he just has random sources of error). Tests that are "out of control" are ease to spot - the distribution may have no peaks or two peaks or worse. Frank can assume that his average and standard deviation define the distribution well, so he can use easy statistics to see if design changes are an improvement. Without this confidence in his consistency in manufacturing he could be wasting time as he explores changes, because he can't tell if they are effective!

Next I show that I have gone way overboard to actually demonstrate that his distribution quite closely (mathematically) matches a normal one, and now we can see what sort of shape he would get if he measured hundreds (or thousands) of bricks - for example he'll eventually get some points outside his present range, but not very many (these would fall in the tails of the distribution). I use two methods - one where I calculate the expected normal distribution based on just the data points that he has provided ("coarse") and the other one indicating what he might see if he performed thousands of tests ("fine" - assuming his resolution is 1 lb/in2); Frank's data and the two calculated distributions look very similar.

Now Frank is pretty confident that he can develop a specification that meets his needs for well engineered adobe brick wall structural stability, and he can make bricks by the thousands while testing individual bricks only periodically (always just as very few as is statistically necessary!), and his customers can clearly see that he has a quality operation. He would set up his brick performance specification so that walls made from his bricks fail only an acceptable percentage of the time - hopefully this doesn't mean that he has to reject most of his bricks; if this happens then either his manufacturing process is out of control, or alternatively his test method is not capable enough to do the job he is asking of it. Luckily we can do a separate evaluation of the test itself, just to see if it is up to the task of helping him maintain a particular set of specifications (this is called a Gage R&R).

But this does put a rather large onus on the SOP (standard operating procedure, e.g. for the WBT or the emissions tests) developer - it must be very clear (I suggest colored highlights and such to make filling in the blanks easier, and eventually there may be no need for all the calculated value cells to be shown, since the operator does not need these to do the job) and just about bombproof in every language. The SOP has to include every step, such as the actual measurement of the moisture content of the fuel. The present WBT is written so that it implies that every wood species, moisture content, wood size and shape, and operator skill level will result in the same adjusted (for species and MC) measured values. It may be best, as Dean suggests, to just use this test to compare preliminary designs, but any test should be "well behaved" and have this demonstrated early on. While we are learning, it is not unreasonable to use a standard fuel type to simplify things - for example the U.S. has a special agency (NIST) just for supplying industries with "standards" for their testing purposes. The fact that not every stove can use the same fuel type (nor is a world standard available) is certainly unfortunate, and hinders cross comparisons!

Besides being able to apply standard statistical techniques, the beauty of demonstrating that the results of a test are well behaved (and that a normal distribution is followed) is that we know can predict the behavior of future stoves - what stove developer, funding agency, or NGO wouldn't want this - and what climate change researcher wouldn't want to use such data in their analysis? We should all be interested in making sure our tests are reliable, and cover the costs of this simple start ourselves - build it into budgets upfront. Its all about just repeating trials enough, occasionally, so that you know that you are close enough to the mean for your goals. Don't be surprised if you find that you only can "know" the value of a measurement to plus/minus 30%, such that you can't tell the difference between a 5 liter time to boil of 21 minutes and one of 39 minutes (30 minute average +/-30%). And when we are all doing the same measurements as well as we can, I expect that occasional claims for incredible fuel savings (or amount of carbon avoided, or number of trees saved, or ecological/climate impact avoided) will not be as extreme as they are now - my work on the Darfur stove from Berkeley has taught me that we still have a way to go until we test and report appropriately.

The WBT keeps advancing but it is already plenty close for testing whether people can follow it reliably. First you develop the procedure (these days it always has photos when it is done, and we place big picture covered posters in all labs), then you see if the results are well behaved and the test is capable, then you test the process with an R&R once you have specifications... - it is the normal order of things, so this effort is right on time. And when you when you are done there is no more need to talk about test result uncertainties again.

All other studies of the impact on the test results of individual or combined variables unfortunately should to be briefly delayed until the test methods themselves can be proven capable; then (statistically) designed experiments can be quickly used to test the impact of a variable (say moisture content or fuel type/size/shape) or a combination of ones. The name of this formal-like process is "design of experiments" (or DOE), and it aims to determine the sensitivity of a test result to key variables - again, such as fuel moisture content, fuel species, and other factors that might be important in determining the outcome of the tests.

Stoving in Peru - Lessons and Observations

What if an alien spaceship hovered over your house and dropped in some new fangled thing that they said would improve your life - but sought no input from you, never considered your needs for such a device, and left no instruction manual? Now imagine that you live in a remote village in the developing world and well meaning Western engineers rappelled down through your roof and dropped off a cooking stove that assumed knowledge that you have never had a chance to acquire? If the technology/cultural discrepancy is too great then the probability that this new change will be embraced and used as intended (so that all of the promised benefits are realized) is about zero. No one trusts things arriving from an unfamiliar place, and improved cooking stoves are no different - without local participation there is virtually no chance that a new program will save effort, reduce deforestation, postpone climate change, reduce stove injuries, or improve the indoor air quality. No amount of intervening crack Special Forces personnel can force someone make a fundamental change to their life. If introducing fuel efficient or smoke free stoves was easy it would have been accomplished a long time ago!

It is not that Western ideas for improving the quality of life in developing countries are wrong, it just may be that they initially seem (to the local people) inappropriate for the situation - other people in different cultures may never understand the changes that you are introducing in the same way that you do. Get used to it - cultures are different, we learn mostly what our mothers taught us, and we are very reluctant to change just because strangers tell us that it might good for us sometime in the future. Change is hard, and it takes time - if we can ever be convinced that it is desirable or necessary for us. Be warned that local people will rarely comprehend your fears about deforestation, climate changes, etc. - Maslow postulated in his Hierarchy of Needs that until people satisfy their basic needs for food, shelter, social standing, and a good future for their children they will not be able to appreciate abstract ideas about the future like these.

My feeble few observations while helping to determine rural wood (or biomass - any dry plant matter that can yield energy) cooking stove requirements indicate that overcoming cultural barriers is 90% of the effort in introducing new stoves. What percentage of the world knows that water boils at exactly the local equivalent of 100 oC and it doesn't get any hotter than that so a bigger fire does not help (so that you can reduce the fire size once you reach a boil)? Or that it takes a huge amount of additional energy to go from 99 oC to 100 oC, but the food doesn't cook any faster in this case either (so a retained heat cooker is a good idea)? Or that poor thermal contact between a battered pot and a metal griddle makes a tremendous difference (so it is worthwhile flattening the pot)? Since some things like these can be hard to explain or demonstrate clearly, and for some reason cooking while actively trying to use the least of your scarce fuel is apparently not genetically favored or culturally encouraged, we might as well be trying to explain rocket science.

Some things are clearly beneficial - like the electric razor and the cell phone - so people adopt them readily and without our help. Other things are more important, in our opinion, but are frustratingly hard to teach by just repeating our opinion of the advantages over and over - or we may not understand the local priorities well enough, as when we introduced a smoke free stove when they really valued speed to boil far more than anything else (enclosed stoves are always slower than an open fire, when started cold). And we may not even be able to anticipate what people will like or dislike about a particular design - food that tastes less smoky turned out to be a great selling point in Darfur, but someplace else this would be a disadvantage and maybe a show stopper. We need new ways to listen better, teach more appropriately, listen even better, market stoves according to what people want and how they learn and make decisions, listen really well, and be patient. My present working definition of culture is "what your mother taught you", and this may never be more true than when it is applied to food and food cooking practices - you have a very strong tendency to reject life changes which are fundamentally in opposition to your life experiences. How do we overcome this? We may not be allowed to issue instruction manuals with stoves, but why not instructional comic books - in the local language? And this style can also be used for guerrilla marketing, tickling people into talking about your new thing, until they develop their own reasons for adopting it.

Once you learn that your close friends rarely think like you, and that people from different cultures never think like you, you may be ready to contribute to humanitarianism. Now what - how can you have your new idea/stove/practice/alternative succeed in an new place? Oddly enough, some changes you suggest may never be adopted - using candles or other purchased fuels to start fires, asking people to adopt a new pot type, suggesting that people add a milliliter of oil to reduce heat loss, efficient burning of corn cobs - in advance you may never be able to know which of your suggested changes may be implemented! The inability to be "predictive" creates all sorts of problems - including that you may not obviously be able to accomplish the goals of your projects (fuel saved, injuries prevented, smoke reduced). Your project may not be doomed, you just need to spend the requisite 90% of your effort working on persuading (and showing) local people why what you have brought really improves their lives; despite their suspicions.

In "The White Man's Burden" author William Easterly describes bottom up and top down development efforts, where the first endeavors to learn from the people what they want and continuously solicits feedback - a market based approach. Top down indicates that we (outside people) know what other cultures need to do to advance themselves so we just need more money and bigger projects, while bottom up implies that outsiders with resources should always involve local people from the beginning so that new proposed solutions are aligned with the existing cultural needs. And sometimes you just have to believe that there be may no agreement - such as when I tried to slice carrots when only prying chunks off of them will do. Or implying that siestas would be a good time to get additional work done, when plucking head lice has always been a more important social activity.

Developing New Cooking Stoves for Huamanzaña, Perú

Perhaps the latest big fork in my path to becoming a better "technical humanitarian" was when the EWB network led the student chapter of EWB-Princeton to me, as they looked for a "mentor" for their next visit to Huamanzaña, La Libertad, Perú. They have had a history with Huamanzaña resulting from a number of visits there (see Shannon Brink's blog at http://huamanzana.blogspot.com/ for more details, and recent posts - then see their photos of the village, people, and the surrounding landscape here), and their next project was to build stoves for each of the 35 families, to reduce indoor air pollution (IAP). It is always an honor just to be an invited guest, but I had to quickly check my qualifications - South America is my recent general area of interest (just due to the predominance of one language there), I am very fond of small villages and don't mind the hardships that come with that kind of territory, the problem size and scope was manageable as far as I could tell, and I wanted to get more experience with one of the few stove types new to me - what I call "chimney stoves", where an important goal is to reduce IAP (vs. all the other noble goals that fuel efficient stoves can achieve as well). I look for opportunities where my past, more corporate, experiences in R&D, new product development, marketing, lean manufacturing, etc. can be employed and this project seemed to have it all. As usual, no detailed information on what works best (materials or design) for these permanent, typically masonry, stoves seemed to exist, and the challenge of using only local (and unknown ahead of time) tools and materials is something that must be anticipated - little can be planned for, just show up and start solving problems.

After the typical laborious process of just getting there (taxis, buses, planes, buses, taxis, planes, worse buses, and then the minivan to the end of the line - Huamanzaña) I found myself in the foothills of the Andes - an extremely sandy (sand surfing on giant steep dunes!) area near the Pacific coast and southeast of Truillo (second largest town in Peru). Several small towns past consumer buying opportunities and electricity - perfect. Great students and townspeople to work with, few distractions from the work (nothing was there - they can't even afford vices), but almost no easily identifiable tools or materials to work with except for a broken hammer, 2 decrepit buckets, and lots of stones (the village is in a river valley). Chao is the nearest village with stores - the Pan American Highway runs through it and every hardware store carries the same poor collection of inferior quality tools. It is two hours away, and the minivan runs most days, but you can't get there and back in the same day - patience is everything.

Huamanzaña families use "stoves" typical of the region - nothing more than two rows of bricks with a fire burning between them, and some scrap metal pieces across the top that pots can balance on. They do use them very artfully though, placing pots at different distances from the center of the fire - to vary the temperature - and they can of course cook beautiful food, already, and many dishes at one time. Helping them cook better (or even with less cost or effort) is not why new stoves are desirable - the problem there is that they presently use no chimneys so the smoke at best filters slowly through leaky walls or wafts up toward a hole in the roof. And of course the smoke represents unburned fuel, requiring them to cut more wood than they actually need for their cooking tasks.

I believe in first doing a "resource analysis" for every new project - what things exist nearby (wood/burnables, construction/building materials, skills, traditions, raw materials, waste, etc.), what do they cost, and how far away are they? Basically, what can people burn for cooking (waste materials and other natural resources) and what local tools/materials can we martial to help them do it better? If its not local I don't want it (unless it is small, and key to a project - for this one it turned out to be just masonry blades for a hacksaw) - so we went around and introduced ourselves to all of the nearest merchants, bakers (they use stoves too), blacksmiths, auto junkyards (rare in Peru, but they have tools and access to metal), brickyards, lumberyards, hardware stores, carpenters, and anyone else who might know someone who might know someone who can help with a project. My favorite blacksmith "el Gordo" ("fatty" to his friends, but I call him Juan) kept us going in Chao - and will continue to in the future - because he shares the same vision in life that I believe in (work hard, learn everything, network, be passionate, kick ass, hopefully get ahead). Local construction materials included mainly sand, rock, soft bricks, cement, and wood ash - of course no electricity, and we could only borrow a wheelbarrow occasionally.

So we forged ahead... we found local bricks that had lots of holes (like U.S. "cinder blocks", and with thinner walls - up to 8 holes in each, so the cost per unit volume was better than solid brick) so good open area that could be filled with ash (the only insulating material we had, short of starting up a brick kiln), we decided to prepare for earthquakes by supporting the chimney internally with poured concrete inserts, and we were off - as long as the resident guinea pigs (called cui, an important source of protein) didn't object to construction in their kitchen homes.

We had been VERY lucky to happen upon "honeycomb" coal stoves (like in China, but bigger briquettes) used by outdoor cafes, and then found the refractory brick shop in Trujillo that made the liners for them (not porous, but heavy - he didn't know about the occasional benefits of holes) - since he would cut the "door" opening for us, it was an easy combustion chamber to use (instead of his rectangular bricks). The whole kit for each stove included this: the hollow bricks, ash from the bread ovens, cement, steel reinforcing bar, and 8 bricks for the chimney - plus the 6 mm thick plancha and the equally robust perforated steel grate (and some floor tiles, and...). Someday we'll know whether an ash insulated area is the best - for now it seemed to decrease the thermal mass of the stove as a whole and lead to faster boil times. We created an informal system where more insulative construction materials were required closer to the combustion chamber, and gradually less appropriately insulative materials (such as denser rubble - concrete, bricks, etc.) could be used as the local temperature was lower in that particular area. We were too rushed for many performance measurements, but it will be easy to later improve this design. It would be fantastic if we could eventually use the local stones for building stoves too. The plan was to design each kitchen for the individual cook - at least as far as surface height, stove layout, and food preparation space were concerned - providing obvious additional benefits should help cooks adopt the new stoves more readily. Using bricks of several varieties, it was possible to come up with a small variety of designs for different kitchens - our philosophy was to use as few parts (so larger bricks were favored) and steps as possible. Most of the hard work has been done since I left, so we look forward to how it all worked out - the latest reports on cook satisfaction sound great.

Unfortunately, our first home was not quite prepared for us, so just the 2 gringas and 2 gringos had to first do extensive repairs on the concrete base that took too long. And the first stove itself is always a challenge as you learn to work together efficiently. And since by then it was my last day, I was guilty of pushing everyone too hard - from my manufacturing point of view developing a good procedure is so important that I was worried that future stoves would take too long unless we worked out most of the details on the first one.

Meanwhile, back at the comedor - our test kitchen with the very first stove model - it was proving challenging to convince people that this was an improved stove for them - since both stoves and firewood are "free" there they found that the increased time to boil was a terrible disadvantage; they are people busy in their fields, so the time saved by putting pots right in the coals was important for them. We cooked and had a town party, and that plus improvements in the design after I left will hopefully result in them using the new stoves as they are designed. When there is even the tiniest flame there is no smoke coming out of the chimney, the outside of the stove stays cool for ages, and food continues to cook long after the fuel is gone.

And somehow we STILL had time to at least talk about and demonstrate a modern gasification stove (they thought of it as an electric campfire, to play with - reasonable when there are no light sources after the sun goes down), corn cob carbonization (in a stove they burn too slow to be used for high power cooking - too little lignin in them?), and general charcoal manufacture, the use of a bow saw, electric razor, and froe, and hopefully the benefits of a wood splitting platform. We'll all be waiting for more news and photos as Victor, Andreas, Shannon, Rebbecca, and Doba come home - and already there are signs that stoves can be cheaper in the future - we saw a concrete irrigation part that might work, and maybe the brick plant in Viru can make new shapes for these stoves. For me the end result was that I learned again that you can import all the change you want to a community, but you can't make them embrace it. The chances are that they will reject your change - just because it is not what their mothers' did - and your efforts might well be wasted. More on the nature of change as it applies to humanitarian work when I report next... but in the meantime more of my best photos from Peru (both more stoving, and more cultural) are here. And when the Princeton stovers return home there will be more. Going forward I am particularly interested in comparing stove design notes with other groups working on Central and South American stove implementation projects - there are dozens and dozens of us, with just as many stove designs. Let's compare our experiences, and we should be able to deploy better stoves, and more to those who need them most.

to be continued...

Exploring Biomass Gasifier Possibilities and Fuels in Central Guatemala

I was in Guatemala for 10 weeks recently, improving my Spanish for future stove projects, and I took a small commercial gasifier stove (Tom Reed’s WoodGas T-LUD) with me as an example of a fan assisted cook stove. At the last ETHOS stove camp this general family of stoves tested exceptionally high in efficiency (and low in emissions), and this particular model had exhibited the best combination of properties of any stove analyzed. Using
this stove as an example of the genre, I was determined to capture the hearts of Guatemalan cooks and easily convert them all over to fan stoves fueled by waste agricultural products!

As I expected, like in most developing countries that I have visited, the majority of the rural population there spends an incredible amount of time pursuing firewood to cook their meals – huge trees felled by highway crews disappeared within hours (first converted to neat piles of kindling right in place), every night at sundown I saw people streaming in from the hillsides with their backs and heads piled high with wood, and the local markets were filled with both firewood and carbon (charcoal) sellers. Rural cook stoves tended to be of the half barrel type – an outdoor split oil drum with a smoky fire, cook pots configured crudely around the sides of it to adjust their temperatures – or very cheap thin sheet metal charcoal stoves. My first attempt at a demonstration of modern stove technology was a near disaster – the village we visited was still in the rainy system so there was nothing dry to be found, requiring use of emergency fuels… charcoal started with ocote splinters, a pine fatwood used locally for starting fires only. The smoky mess that resulted (charcoal does not seem to start easily in general) did eventually end up heating the water for coffee, but it illustrated none of the potential of gasifiers or fan stoves for the neighborhood; as I packed the stove away, the only comment was “It certainly is attractive” and I knew I hadn’t made any converts.

The lesson I learned was the fuel comes first – people don’t want something new that isn’t at least as easy to use as their present cook stove (no instruction manuals please), and having an easy supply of consistent, appropriate fuel was essential if people weren’t to reach for the nearest inappropriate fuel first and become immediately discouraged.

I spent the next weeks scouring the Antigua area for waste biomass during the day (during “field trips” for my Spanish lessons), and doing stove experiments at night to stay warm. There are virtually no large industries so I chased stale tortillas in the tiny shops where they were made, woodchips and shavings from carpenter shops, searched in vain for enough avocado pits (they compost too fast to accumulate), used strange fruit pits (like jocote) and waste food products like rice/beans/corn/coffee, examined every imaginable tree pod or cone (the shade trees on coffee plantations had a very dense pod that burned beautifully!), tried old bread and cigarette butts, saw that coconut hull is the worst thing possible because of its low density, visited macadamia nut and coffee plantations to talk with the owners, and generally was a local nuisance. My “research” on local fuels for fan assisted stoves resulted in a few observations:

• Again, the fuel is everything. Using the wrong one just wastes time and black smoke billows everywhere every time you try to relight it. Nothing turns off a potential user faster than a smoldering fan stove.
• Many things burn well, but without a high density fuel, batch stoves with a small capacity can be too clumsy to use – many waste types burn great but new fuel has to be added every minute (as with tortillas), and the instantaneous pyrolysis that can occur then creates too much flame.
• The proper fuel packing characteristics are essential for gasifier stoves – the air spaces between the fuel particles are necessary for the right air flow, so they cannot be too small (as with rice). Hot fuel particles also need to radiate to nearby cooler ones properly, so the gaps cannot be too large – more knowledge about the necessary characteristics of fuel beds is needed it seems
• First the stove must be lit – up draft gasifiers can be tricky to light so we should expect that people will use anything flammable (plastic grocery bags, gasoline, noxious solvents, etc.) to start with unless we describe alternatives. Paraffin (candle wax) has huge amounts of stored energy, stove alcohol (alcohol de quemar – mostly ethanol) is readily available, and the traditional slivers of resinous ocote were suitable, but the choices are going to always be regionally specific.
• The addition of continuously variable fan speed control and a slightly higher voltage (from replacing two standard AA batteries with three rechargeable ones) to this standard stove resulted in somewhat better control characteristics, but mainly at lower power levels – it is difficult to adjust the firepower over most of the fan voltage range.
• Very few agricultural products actually go to waste – for example the coffee parchment (a thin skin removed from each bean) if compressed would burn beautifully, but one plantation owner I talked to already used it to feed worms and make compost, and he couldn’t quite envision the benefits of diverting some of it to replace the diesel fuel he purchased now to run driers or distill alcohol.

Macadamia nut shells have the best properties of unprocessed biomass fuels I saw. Not as dense (not the nut shell density, but the average bed density) as commercial wood pellets (this stove has a capacity of 430 cm3, accommodating 400 g of pellets and 340 g of random broken shells) but the highest of natural materials I found. The plantation I visited had no use for shells, and just used them for walkways or mulch, and there are also macadamia nut culls which are too small to be worth extracting the nut meat (but the oil high oil content causes them to burn uncontrollably). In another country these might be used as a metal polishing media, but here I had finally found good quality waste! Unfortunately this is a young industry in Guatemala so there is not much available.

A Castor bean (related to the more popular Jatropha) oil project came up while I was there – it grows as a weed easily and its seeds contain large amounts of oil of good quality; productivity per acre of biodiesel may be among the highest after palm and coconut, and the newspaper carried large articles touting its potential. Beside castor bean plantations, multistrata agroforestry is a nice name for intercropping trees with vegetable and bushes, so that a piece of land starts to produce cash rapidly, even when the most valuable crops are young. In Guatemala there are proposals for mixtures such as Silk Oak (Grevillea robusta – the Australian shade tree for coffee), Walnut, Castor bean, coffee, and vegetables where we see that there are several sources of food, oils, and biomass – potentially pods, shells, parchment, and dried pulp.

In conclusion, I believe that if you could identify key waste products then you would have a ready market for stoves – all Central American countries have a stove manufacturing industry (for propane fired tortilla stoves) that could be taught to fabricate metal stove parts, and there is enough of a ceramics industry to fabricate Rocket components. But there may not now be enough large supplies of ready to use biomass, or they may be spread too far apart. If it is not yet time for waste biomass stoves, affordable better wood burning stoves are still needed in the near term. For now, quasi-gasifiers (such as the new Philips stove, though this term has only recently been invented) and fan powered Rocket-type stoves will prove much more convenient in daily use, and that is what is required for widespread acceptance. Almost every place I visited had some electricity, and everyone there buys batteries for other uses (such as the ubiquitous radio for manual field work) – and luckily rechargeable batteries are becoming more common and affordable.

ETHOS 2007 Conference Report, and the Proceedings are Available

The Engineers in Technical and Humanitarian Opportunities of Service (ETHOS) held their 2007 annual conference January 26-28 (titled Building Foundations for Scale-Up) at Northwest University in Kirkland, WA with ~100 people attending for two and a half days of activities. ETHOS has typically been populated by technical researchers focusing on improving developing world cook stove technologies, but more and more fields have come to be included. Since ~3 billion people in the world use wood or other forms of biomass for cooking and heating, there in increased attention on biomass fuel practices because of concerns about deforestation, global warming impacts, the health effects of indoor air pollution and home safety, violence against women, and overall quality of life. Developing and implementing safer, more efficient stoves, with fewer emissions affects all of these, and requires that a broad range of technical skills be deployed. Each country requires a different approach (and different regions of many countries tend to have special needs), and then there are always different stoves for various applications – alas, there will never be a single solution so we will all be busy the rest of our lives with this work (job security for volunteers is not necessarily a benefit).

The proceedings of this conference just came out online and past conference proceedings are available nearby – presentation by presentation so you download only what you are interested in) but allow me to review just some of the work that caught my attention especially. Not everything of course is just about stoves, so read on even if you are not already a stover:

• Paul Anderson demonstrated extremely low cost alcohol stoves, perfect for disaster relief.
• Alan Berick described very thoughtful and elegant experiments he conducted to demonstrate the impact of pot shape and/or a thin oil film on the cooking water surface, both addressing the huge percentage of energy losses which are due just to the evaporation of water during cooking.
• Dale Andreatta's was one of 4 gasifier stove presentations, his describing “stove science” experiments relating to a natural updraft gasifier stove (so without the need for an electric fan).
• Rob Ballis (and others) discussed the Shell Foundation’s Household Energy and Health Project’s interests – particularly testing for emissions, including a great presentation by Chris Roden on emissions measurements and the potential impact of different emission types on global warming.
• There were ~5 different presentations relating to stoves with ceramic inserts (such as most Rocket stove designs) including kiln building around the world, high volume manufacturing of the ONIL stove in Guatemala, a different chimney stove scale-up in Honduras (by Trees, Water, and People), institutional stoves for India, and making stoves inside refugee camps in Africa.
• Most of us saw our first presentation (and the demonstrations later) on the commercial Philips gasifier-type stove, destined for widespread distribution soon - very nicely manufactured, and beautiful to watch in action.
  
• Indoor air pollution (IAP) was the topic of several presentations about stove trials in Peru, as well as more general aspects of IAP testing and implementation.
• And there were a host of other topics including solar cookers and concentrators, a thermoelectric generator concept, a new design for a moisture sensor, gasifier developments in China, Cambodia and the U.S., future inexpensive stove designs, reports from Ethiopia, Mali, and Kenya, microcredit strategies, and online networking for the biomass stove community.
• And of course there were lots of stove demonstrations! What would a stover meeting be if it didn't have people showing off their latest developments - gasifiers were in particular abundance this year.

Also there was a rollout of the first few copies of the new book Comparing Cook Stoves (Approvecho, Shell Foundation, and EPA), a beautiful compendium of technical results (both efficiency and emissions) for 17 popular developing world stoves (and the traditional 3 stone fire) using standardized tests. It is clearly pointed out that laboratory tests are only part of what is needed to evaluate and compare real stoves, and that further field and kitchen tests are required in addition to the standard water boiling test (the WBT, which can be found here, along with the standard kitchen and field test protocols) - but what a start this book gives us! The book compares all kinds of stove types – permanent ones with and without chimneys, fan powered, charcoal, liquid fuel, and one solar model – so that the characteristics of these general types can be compared. Stoves will continue to be improved, and new stoves introduced so even though individual stove-specific results are dated, the conclusions and extensive discussion presented here will be useful for years to come.

The stove data presented in this book can soon be used to begin to predict the impact of the widespread implementation of a particular stove type on global warming potential (though this is tricky because of the general lack of experience with correlating lab and field results). For this one would use the values for the different individual emissions weighted by the contributions of each type to warming/cooling (each emission species has a very different long term impact, for example black soot particles given off by inefficient stoves are particularly nasty because they absorb solar radiation and they persist in the atmosphere for years). Both the reduction in fuel needed for cooking with more fuel efficient stoves, and the reduction in emissions (and changes to the emissions mix) are tangible and measurable improvements that we can use to measure the effectiveness of our projects, and this new book is the first to cover both aspects.

In my opinion, we are seeing several important trends develop within the stover community:

• Stove implementation projects around the world are scaling up (into the hundreds of thousand or even millions of stoves per project - orders of magnitude more than in the past), and everyone is talking about how to do it in ways that will work.
• With large corporations and wealthy individual donors (many with technical backgrounds) becoming more involved, because of the growing appreciation for all the consequences of poor burning practices, we can expect more results-oriented philanthropy which will reward better and better stove research and implementation efforts. The old days of smaller implementations, less attention to local needs, and inadequate monitoring of performance and success are numbered, and there will be increased attention paid to each project’s measured outcomes.
• Gasifier stove designs (typically using electric fans) look like excellent choices for the long haul, when we have to address urban users with a little more disposable income for cooking “appliances”, additional fuel choices besides wood and charcoal, and stoves with the ultimate in high efficiency and low emissions. Besides just stove efforts, a new market infrastructure for processed "densified" waste biomass – such as briquettes – is going to be needed for gasifier stoves, and these efforts will benefit also the non-electric Rocket-type stoves which will dominate implementations in the near term. Getting away from ever cutting trees just for fuel, leaving them for lumber and ecological purposes, will be the end result, and China will lead the way there.
• Health (including both pollution and safety aspects) and global warming concerns will continue to grow the need for better stove R&D compared to the past, and will require that the stover community broaden even further to include more social science, medical, and emissions expertise. Stove contributions to climate change will soon put us in the news more and more, as the public becomes educated about what is being done globally to reverse present trends. Food crop based ethanol efforts, and similar popular Western approaches, will then be seen as very small bits of a very big picture, and better stoves will get the attention that they deserve.
  

Implementing New Stoves in Developing Countries

Everyone and their brother has written on their experiences, in every imaginable country, using every possible kind of stove. Which ones can we learn from? Which ones are the best? Here I have tried to distill the most relevant ones into a manageable package - not the main web sites, but the pages that have the exact information that you need.

• The UN High Commissioner for Refugees publishes a pamphlet just on introducing new cooking options (new stoves, fuels, techniques, etc.) in refugee camps here that should be a good start for anyone.
• The largest volume of information appears to be at the biomass discussion forums, and within their archives - so we don't have to track down everything individually, just scan the lists of reports.
• We might start by assuming that African projects are more relevant to us than those in other parts of the world... this country-by-country list is fantastic. The Biomass Cook Stove Discussion Group's specific dissemination page has all kinds of stories.
• The Renewable Energy Policy Project (REPP) produces a great biomass cook stove discussion site that has some overlap (in the form of Tom Miles?) with that last one (as well as an older www.crest.org site), but has a different flavor and feel. This mountain of world stove photos is a great start, and they even have a page on stoves for refugees and displaced persons! The exact type of stove introduced, or the country where it was introduced, should not be so important to us - we want to know what implemention efforts resulted in success, and what could have been done better.
• The Hedon Household Energy Network is a good site and it now publishes ITDG's Practical Action newsletter.
• Village Earth's compendium of cook stove book reviews is a great, but can be a little dated - some are out of print (ITDG and VITA have had some that sound like exactly what we need) but should be available on CD now.
• ProBEC is an organization promoting biomass conservation in southern Africa - implemented by a German organization (GTZ).
• A good informal discussion on energy saving stoves for southern Africa - not far from Sudan!
• An older but still relevant UN report (60 pages) is "What Makes People Cook With Improved Biomass Stoves"
• The development and commercialization of a new stove in Kenya - a relevant case study?
• Try this if you have a strong stomach - 88% of improved stove users in this community (the intersection of Uganda, Kenya, and Tanzania) believed that they were burning less fuel (50% savings had been projected), but a follow up statistical analysis showed no improvement. What a horror story!
  
• Verification of the impacts of an improved stove program (including IDPs) in Eritrea and here is the beautiful report Dissemination of Improved Cook Stoves in the Developing World that was associated with it, here is the link (to UCB, again!) on all their stove work in Eritrea - what an effort!
• A new site for me - the "lessons learned" page of the United Nations Development Programme, with dozens of brief reports on all aspects of energy for sustainable development projects. The more I look, the more I find.
• There are lots of good publications at Aprovecho's publication site - they have been leaders in stove development, testing, implementation, and everything else longer than almost anyone else.
• ETHOS is a great group (and the backer of Stove Camp) - organizing engineers for humanitarian efforts, similar to EWB and ESW (why are there so many different organizations?) and their conferences attract the best speakers - see Session 4, Mouhsine Serrar's presentation of implementation efforts (analyzing several different stove types) in Mauritania.

many thanks to Tom Miles (in advance), for letting me depend so much on the biomass cook stove sites that he maintains!

Measurements and Statistics for Stovers

The Berkeley Darfur stove development experience, comparing the efficiency of different designs, indicates that the noise in the measurements of the fuel use will make the clear demonstration of improvements in efficiency difficult – even with a very good testing method (designed just to reduce measurement uncertainties) a difference of 30% in performance between two tests (with different designs and/or cooks) may not be enough to show improvement. The statistical aspects of implementation are non-trivial and deserve plenty of attention, and good data retention practices.

In manufacturing we often have the need to compare two “populations” to see if there is a difference – say because the products are made on two different injection molding machines, are made during different shifts or at different factories, or because we are bringing out a new design. Here is how we go through the process, with just enough statistics to do the job:

• Develop a test – which is a carefully written procedure and a testing station – that seeks to minimize test to test variation, measuring the right things and using what we know about the product’s end application to make the test robust and reliable. For a stove we know that the start up phase is awkward so the test must be long enough to reduce the impact of this, and we know that losses from the pot due to evaporation are a problem because this changes from test to test. So we might decide that boiling more liters of water (a typical cooking surrogate – at this phase there may be no need to duplicate actual cooking, since that test comes later) for a longer time will reduce test-to-test variation. The test should be designed to most easily highlight the differences between a good product and a worse one, so extreme conditions may be considered – in the case of a stove perhaps a consistent wind is used (if this is a realistic condition) since this has been show to differentiate similar stoves.
• Analyze the test itself - a test is not good enough if there are too many variables impacting the results We must try hard to make sure that the differences between tests are due only to random variations, such as weather conditions, slight operator differences, random construction variations between stoves, etc. Systematic variations might include gross differences between manufacturing shops, poorly trained operators, or changes in construction materials – these are things that we are testing for (lapse in quality) so the test itself should eliminate their impacts as much as possible… In statistics we say that the test results should follow a “normal distribution” (also called Gaussian http://en.wikipedia.org/wiki/Normal_distribution), so that the variable that is being tested for – say the fuel consumption used for a specific task, such as boiling 5 liters of water for 45 minutes - has a central value that defines an average, and a bell shape due to the random fluctuations about this mean. There are many other types of population distributions (bimodal, etc.), but the normal distribution is the one that allows us to use the mean and standard deviation (and other traditional statistical tools) to describe its mathematical properties. In Excel you use the "frequency distribution" function to separate all your data points (each one is a value for fuel consumption from an individual test) into small ranges (or "bins") and then you plot the range values against the number of test results in each bin (just like in the figure). If it doesn't look like this figure then your testing method needs work for it to be reliable.
  
• Demonstrate that the testing process is “well behaved” – the basic tool used is the “gauge R and R analysis” – examining how repeatability (the same person, testing over and over) and reproducibility (different people testing) affect the outcome of controlled testing. For this test with a particular stove, several cooks perform the same task several times each, then these results (say time to boil or amount of wood used) are put into a special spreadsheet to mathematically determine how much of the observed variation (ideally there should be none – it is the same stove after all) is due to the testing method and stove, and how much is due to the differences between the techniques of each cook. It’s a challenge, but this kind of approach – technical without being obsessive – may be the way that engineers can help most; in this manner new stove designs and implementation approaches can be clearly shown to be effective and funding agencies can feel that they can invest with confidence that they will get results and people will be helped. Until then, we will only be able to make crude wishful projections about what the potential impact of a project will be – and this is not good enough. More detail on R&R measurements (from NIST) at http://www.itl.nist.gov/div898/handbook/mpc/section4/mpc4.htm but remember that you just have to plug your measurement results into a spreadsheet and the conclusions fall out.
• Improve the testing if necessary – if the distribution is not normal, or the gauge R&R results are too large (i.e. we can’t reasonably tell if one stove is better than another, even though one should be) then the test must be modified. Examples of changes might be a clearer written procedure, better operator training, or actual test changes (such as narrowing the allowable temperature range in a simmer test or using a longer boil time, to reduce startup/transient effects or brief operator errors). Remember, a poor test wastes time – it may make more testing necessary (so that results can be averaged) or require superfluous testing (like continual testing of the control stove). The goal is the minimum testing that demonstrates the smallest difference between dissimilar stoves. The results of each individual test must be trustworthy, so that the results are as clear as they can be. The R&R method is well worth the effort – in the case of a 3x3 evaluation (3 operators test the same stove 3 times each – done just one time, just to evaluate the test procedure) it may take 1 day for the R&R but it cuts the new stove testing time in half (because the control stove no longer needs to be tested every time) for the rest of the program life! And regular R&R testing at different locations (such as at Khartoum and Nyala and the IDP camps) eliminates uncertainty about place-to-place testing variations – a real worry when testing is geographically distributed and can only be lightly supervised.

With Brian in Khartoum and now making stoves for Darfur, it is worthwhile talking about new product introduction quality control – there are several ways to make sure that your new stove performs in every way like you designed it to, and you don’t necessarily have to build a fire in each one. In manufacturing we use several statistical techniques to prove within a certain degree of confidence that your manufacturing effort is good. The process goes something like this:

• Determine what it is about your stove that makes it work right – tight construction, the right pot gap width, weight (are the right materials used throughout?), time to boil X liters of water (firepower), amount of wood for a specific task (efficiency), etc. You are correlating some few things that says that new stove owners will be pleased, you want to make the correlation as reliable as possible, and you want the measurements be as easy and quick as possible.
• For just a few stoves you’ll be handling every one to see if it feels right – if you know how your stove tests well enough then you should be able to tell bad product, but LOTS of stoves means too much handling, so this start up phase is the time to practice inspections and testing. Do sloppy stoves mean bad efficiency and short life in homes? How sloppy is too sloppy? Nothing is perfect so some issues are OK (small gaps, poor joints, etc.) and have to be passed, and others are unacceptable; don’t sweat the small stuff.
• Decent measurements might be weight, air gap width using a standard pot (or no pot – just a measurement), and fuel efficiency. Often you can do the efficiency measurement only when you suspect it needs to be tested (new manufacturer, new materials, different city, etc.) – this test is the hardest and has the most error. In any case you should do a gauge R&R of the measurement, to see that the results are normally distributed so that you trust your measurements – how efficient your stove is will be something people want to talk about. Accumulate measurement numbers all the time and they will add up to a good record that someday you can publish to show the stove’s effectiveness.
• Set specifications – create some measurements that show obviously that something is either acceptable or not. The stove maker can use them, you can, people in different cities can. Any spec is better than no spec – you can’t talk about quality unless you have even a tiny amount of information on how things vary. The challenge of doing this in strange countries is there, but maybe you will get lucky and everything will be perfect - there is no variation to measure!
• The best quality technique is 6 Sigma (http://en.wikipedia.org/wiki/Six_Sigma, and see the section on DMAIC) – only a few defective parts in a million allowed. Here you measure parts even as they are made, so bad stoves are never created. If the parts are handmade and there are weighing scales available, then using can be quick method of checking craftsmanship. And there are lots of variations of 6 Sigma – I practice the “lean” version where the main goal is to eliminate as many parts and operations during manufacture as possible. Less parts = less things to worry about. Under ideal circumstances you do very little inspecting at the end, since why would there be a bad stove? But if you can’t be there while things are made, all you can do is simplify the design, and ask to get the first few asap.
• The government and other folks use the AQL method – specifying an Acceptable Quality Level – where there are tables to tell you how many out of each thousand to test, so that you don’t have too many bad stoves (all based on the statistics of a normal distribution). This website http://www.sqconline.com/ lets you plug your desired quality level into a on-line form and it tells you how many stoves to test, but you still have to decide what is an effective measurement. I have used this method but am not excited by it – it assumes that you accept bad parts, and that you don’t have good enough control of manufacturing. And this is true if you don’t have a good enough relationship with your machine shop.
• Continuous improvement is always a part of the equation – your first stoves need to be good or people will be disappointed and then you’ll spend the rest of your life answering questions and fixing things. Half of quality is about not wanting to waste time like this. Nip problems in the bud as quickly as possible, bring things to the attention of your stove man and emphasize why problems hurt his chances of future business. Keep reminding them of their defects – details about problems will hopefully keep them thinking about improving. Unfortunately, this is about the time when you need competitors, so that you have negotiating power. Having a second supplier is a great thing, because distributing business between them (even if one is a little more expensive) keeps both on their toes – you can have one make a much smaller percentage, but not having two will cause you problems eventually.

References on stove measurements and performance statistics:

• Peter Scott's World Health Organization Indoor Air Pollution workshop presention "Stove Design and Performance Testing" (Uganda, 2005)
• Dean Still's "Comparing Stoves and Proposed Stove Benchmarks" (ETHOS 2006 Proceedings, Session 6)
• The master UCB web page for modern (March 2006) stove testing methods - the lab WBT, the Controlled Cooking test, and the Kitchen Performance test is here.
  

Next: Links just on stove implementation experiences from around the world

Aprovecho Biomass Stove Camp 2006

At the very last moment Susan told me about a workshop for designing and testing biomass (wood, plus other natural burnables) stoves for developing countries being held near Eugene, Oregon. No time to prepare, just enough to make the long drive there. These have been held at the Aprovecho Research Center (and sponsored by ETHOS - Engineers in Technical and Humanitarian Opportunities of Service) for the last few years (see here for photos of the last few ones http://bioenergylists.org/en/node/380 and here http://www.vrac.iastate.edu/ethos/proceedings2006.php for delightful papers from past ETHOS conferences) and efficient biomass stoves researchers gather to share information and use the excellent testing facilities. It was a fantastic opportunity to meet with international experts, hear what was going on around the world, and use world class facilities to test our local (Berkeley-LBNL-EWB) stoves - not for just fuel efficiency but also for CO, CO2, and particulate matter emissions.

They have tons of experience with improved cook stoves from around the world, have written some of the best books and stove design guidelines, and we could select from a huge wall of stove models to test if we wanted to. Big things are happening around the methods for testing stove designs, and a new book is coming out from Aprovecho soon that compares the most popular world stove models in areas like fuel consumption, emissions, safety, and cost. This presentation by Dean Still is a preview of what it looks like, and includes data on the VITA stove, the early predecessor of our own stove designs. They use the standard "UC Berkeley Water Boiling Test" method, plus emissions measurements, to compare stoves, and have developed new benchmarks to indicate whether a stove design is generally improved compared to a traditional primitive "three stone fire".

Global warming impacts of biomass cooking stoves (3 billion people in the world still rely on them!) was a big discussion item, and I was surprised to learn that there was a very distinct difference between the impact of burning situations like slash and burn agriculture, rain forest burning, agricultural field burning, and the emissions due to cookstoves. Controlled fires (such as stoves) produce lots of flames resulting in black carbon particulates which absorb sunlight stongly (and heat the atmosphere), while smoldering fires - may actually contribute to global cooling. Global stove emissions are thus under increasing scutiny, and initiatives to improve cookstove efficiency thriving. This is a very different reason for improving stove efficiency - for our Darfur, Sudan project we mostly consider the impact of stove fuel efficiency on human effort and security, due to the huge expediture of human effort needed to collect scarce firewood there. The cooking there is mostly outdoors so the health impacts of indoor air pollution (another reason to improve efficiency) are perhaps negligible, and global warming effects pale compare to immediate human suffering impacts.

The new appreciation for the potentially immense impact of biomass cook stoves on global warming and human health and security has recently resulted in concern from all kinds of different organizations - the EPA, WHO, and major oil companies at the very least - and there are numerous new initiatives to implement improved cookstoves on a global scale (millions and millions). In my opinion, there is an increased emphasis on quantitative measurements which clearly indicate impact of the improvement in the performance of new designs (both reductions in fuel consumption to accomplish specific cooking tasks, and harmful emissions which impact health and environmental impacts) - when the likes of Bill Gates, Warren Buffet, Philips, and Shell donate billions of dollars to developing world improvements they want to know ahead of time exactly what impact their efforts might have. It is widely viewed that in the past, most money spent by NGOs on international development was wasted due to inefficiencies and poor measurements - no more. This is an excellent opportunity for engineers to become involved - we more than anyone else can design improved cook stoves, measure their real impact from data collected during implementation, and predict the cumulative impact of them!

Even if you do nothing else with this particular blog post, click here for the "big picture" of the impacts of improved cooking stoves, by the World Health Organization (WHO): http://whqlibdoc.who.int/publications/2005/9241593768_eng.pdf#search=%22UCB%20water%20boiling%20test%22. And then look briefly at the small list of key links at the bottom of the post.

The theme of this year's stove camp was "fan assisted stoves" - with 50% of the world living in urban areas we can expect that locations with at least some electricity must 3 year experience living in China and SE Asia showed me that much of the terrible pollution problem there may come from all of the biomass and coal stoves that urban people use. I never considered fan stoves before, but 2 recently introduced models, see http://www.research.philips.com/newscenter/archive/2006/060227-woodstove.html and http://www.woodgas-stove.com/ for descriptions of these 2 stoves) that we tested at Aprovecho showed me that these can be incredibly efficient and non-polluting! These may not be the present, but they certainly are the future. I believe that they are approaching the theoretical thermodymanic efficiency for both fuel combustion and heat transfer (to a cooking pot - what it takes to prepare an actual meal); speaking as a scientist, this is what we need to start to be predictive about the potential impact of better cook stoves! Fan stoves are certainly not applicable in all situations, but they may indicate benchmarks for fuel use and emissions that we can use to develop our our improved stoves - obviously, no stove can boil 5 liters of water with zero grams of fuel, but how much of the energy stored in biomass can we ultimately hope to use to cook food?

The human energy at stove camp was fantastic - everyone using the same stove testing method (no problem using the oversized assida pot I brought) - every surrogate testing method has its problems predicting performance in local cooking conditions, but some reliablly predictive standard test is needed that can be used by everyone to locally compare stove designs; until field tests in target countries can be conducted, as a second phase. For a description of the UCB test (+70 pages!), with comments on additional lab and field food cooking tests to demonstrate real world improvements, go to http://ehs.sph.berkeley.edu/hem/page.asp?id=42.

The key question is whether surrogate test results can be correlated with real cooking results, so that development tests are predictive of real world results.). Biogas stoves were paticularly popular and new to me - these use lower temperatures to first just release hydrocarbon vapors from the biomass fuel, via pyrolosis, then separately burn this gas using secondary air - the burning gas can even be used alone to power cars and lanterns and such, and infinitely usable charcoal is the only "waste product"! We cooked lunch on gasifier stoves and marvelled at how clean they burned - they often required prepared fuel, wood chips or consolidated agriculatural waste; developing the infrastructure for producing such simple fuels easily and cheaply from available biomass is another project that needs engineering expertise).

I tested some of our locally designed LBNL-EWB stoves (see http://darfurstoves.lbl.gov) using the UCB Water Boiling Test and it clearly distinguished between good and better stoves - this simpler test may be shorter and more reliable than our present test methods, and we should examine the differences further. Our own tests examine the impact of wind on performance, and use two different pot sizes - both are test modifiactions that reflect local Darfur cooking conditions. More work is needed to optimize our stove tests so that they are more reliable, take less time, reflect the local Darfur cooking situation, and can be used to compare our performance with that of other stoves from around the world.

There are way too many links on the potential beneficial impacts of improved cooking stoves (both local and global), various stoves that have been developed, testing methods, and on-the-ground implementation strategies than can be easily described here - see past blog posts, and here is a simple summary of good major improved cook stove sites that will link to the rest of the information on the web:

- The UCB water boiling test - all 71 pages of it
- newsletters and more from the Partnership for Clean Indoor Air, whose purpose is to reduce the health impacts of biomass stoves (particularly by increasing efficiency).
- The always important and recently revised Design Principles for Wood Burning Cook Stoves
- My favorite stove bible Biomass Stoves: Engineering Design, Development, and Dissemination - by Baldwin - and the video of building a Baldwin style VITA stove quickly, by hand (with music)
- An excellent detailed presentation by Peter Scott, on modern stove design and performance and including implementation, presented in Uganda last year; very clear and thorough, and finally some stove performance statistics discussion!
- The Renewable Energy Policy Project (REPP) biomass stove discussion group list archives - all kinds of stove resources listed in one place. Check out their Dissemination page for all kinds of case studies, plus a great diologue on the bottom about what makes stove introduction programs work (or not work) in the real world
- Biomass Cooking Stoves list server - an additional huge mass of information, sorted into helpful categories, and links to hundreds of organizations interested in biomass stoves for developing countries (click on the Dessemination page).

What is this Blog and How is it Used?

Dr. Charlie Sellers maintains this page as a resource for people interested in fuel efficient stoves - particularly improved biomass cook stoves for the developing world (to reduce deforestation, minimize the impact of stoves on climate change, reduce indoor air pollution and its effects on health, increase food security by reducing people's expenditures for fuel, and just to make the lives of people a little simpler and easier). My purpose is to try and collect the best existing FES stove information from the web and integrate these links into meaningful collections (woven together with some discussion - for people new to the field, or for easy reference when we are on the road), to have a place for periodic reports on new research and development on FES issues, and to serve as a discussion area. I and many other researchers post on more extensive on-line sites, such as the Biomass Cooking Stoves Discussion Group, but I felt there was a need for agglomerations with discussion of existing knowledge (as well as a place to highlight some of my own research and interests).

Blogs are beautifully easy to use - as a registered user you just come to the blog, click on the Blogger icon in the top left corner, type in your password (this keeps blog spammers from interfering with us), select "create" a posting, and start typing. We'll start off with the basics (just cut and paste things into the space), resulting is a linear look, and then I'll improve on it - with attachments, combining of posts on similar topics if that is appropriate and helpful, other pages off the main one for special topics, and so on. There should be a way to post just about any type of information, but sometimes we'll have to figure it out. For now try posting things like good web links, books that you feel are appropriate (add a little review of them), questions or comments for the group, photos, announcements (upcoming events, etc.), and more. A blog is only worth having if you use it regularly. If you wish use the "edit HTML" option to fine tune your posting, and always feel free to post photos using the photo icon. Look at other blog pages (including their HTML code) to see what is possible and effective. One of mine (a similar one covering the interests of the San Francisco Engineers Without Borders Appropriate Technology Design Team is http://ewbappropriatetechnology.blogspot.com/. Blogspot has information on how to improve your technique as well.

If you want to become a "member", so that you can post, or if you have comments or questions email me (Charlie Sellers) at csellers42@yahoo.com