ARC and The Breathing Space Project in India

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The Shell Foundation hired Aprovecho Research Center between 2003 and 2004 to bring Dr. Larry Winiarski’s Rocket stove technology to Southern India. 

Shell Foundation Breathing Space Project

The Mission: The goal was to develop an efficient and effective Rocket stove to lower fuel wood consumption and protect health by reducing indoor air pollution. Aprovecho found an established Co-Op of potters in Sri Lanka that was selling 250,000/year two-pot burnished ceramic stoves with chimneys for $4 in southern India. This design was originally promoted by Mahatma Gandhi in 1934 and was commercially successful, protecting health when the chimney was functional. ARC worked with the Co-Op to improve the design and production. ARC also developed a medium scale factory in Chennai, called Skill Mech that was intended to mass manufacture/sell sheet metal Rocket stoves. 

Woman cooking on an Envirofit stove, image from the Shell Foundation Report: Enterprise Solutions to Scale

The Outcome: Neither stove option was accepted by Shell Foundation. Eventually, a distribution partner Envirofit manufactured a sheet metal Rocket stove in China starting with 90,000 stoves made at Shengzhou Stove Manufacturer and sold in southern India. Aprovecho began working on other projects and assisted Dr. Mouhsine Serrar and Prakti Design Labs near Chennai to manufacture sheet metal stoves at Skill Mech. ARC also partnered with Shengzhou Stove Manufacturer in China resulting in ~ 7 million low mass Rocket stoves sold to date. SSM sells both lightweight, abrasion resistant refractory ceramic Rocket stove combustion chambers ($2.43 in a box) and stainless steel stoves. The majority of sales involve carbon credit revenue. The new International Refractory Ceramic Institute at SSM teaches local projects how to make market priced Tier 3/3/3 (or above) stoves using the refractory ceramic, lightweight combustion chambers.

Field Testing Crucial: Field testing with cooks in eighteen villages in Southern India revealed a major technical limitation. The natural draft Rocket stove was not burning clean enough to completely meet the health-protecting emission goals of Shell Foundation and University of California Berkeley and later as quantified in the ISO Tiers of Performance. ARC spent the following decades researching how to design and build affordable stoves with increased heat transfer and combustion efficiency. These stoves are being produced by various factories.

Shengzhou Stove Manufacturer: SSM began collaborating with ARC 19 years ago and sells a full range of health protecting cook stoves evolved from extensive lab and field-testing. They sell~ two million modern Rocket stoves per year as well as Tier 4/4/4 (or above) forced draft and natural draft Top Lit Up Draft stoves, Jet-Flames, institutional stoves with chimneys, charcoal stoves and a TLUD biomass lantern.

Osprey Foundation Support: A four-year (2026-2030) grant from the Osprey Foundation supports the new International Refractory Ceramics Institute at SSM and a global effort lead by ARC to bring less than $10 retail priced Tier 3/3/3 stoves into use. Coupling Tier 3 PM2.5 stoves with doubled or tripled Air Change Rate in the cooking environment can reach Tier 4 and 90% health protection.

What’s Cooking at Aprovecho

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A Four-Nation Design Collaboration

On their recent trip to SSM in Shengzhou, China, Nordica and Jaden were reminded that many minds are always better than one. SSM were gracious hosts to ARC, OffgridSun from Italy, and Tango Energy from Tanzania for a week. Together, they designed a stove for Tanzania that addressed cooks’ needs, had improved performance, and could be jointly manufactured at SSM and Tango Energy. Meeting in person turned a several-month-long process of emails and phone calls into a streamlined week of design. Maybe when it comes to stove design, there is no such thing as too many cooks in the kitchen.

ETHOS 2026

The ARC team attended another successful ETHOS conference, this year in Portland, Oregon. Sam and Dean hosted Stoves 101, providing a valuable crash course in cookstove design. We also presented on the effects of forced air in stoves, LEMS testing around the world, RTKC capacity building, and much more. ETHOS is always a great time for us to reflect on the work we did and what we learned throughout the year. It’s also wonderful to see what everyone else is working on.

LEMS Around the World: Now in Burundi

Our mission to ensure everywhere has the capability to perform stove emission testing continues. Sam traveled to Burundi where he set up a LEMS and trained (in French) a team at the Laboratoire de Biomasse et de Cuisson Propre et Économe/Université du Burundi. Over 10 ISO tests on various stove types were run with the lab team as well as lab CCTs, a vital test to measure stove performance while performing a cooking task. ARC is now working to add CCT capabilities to their open-source data processing software.

Working in another language takes patience but it allows ARC to work in cross-cultural settings where lab testing, stove design, and market testing come together.


What’s Cooking at Aprovecho

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Aprovecho Visits Tanzania

In September, Jaden traveled to Tanzania to help set up a LEMS at the Bureau of Standards. Tanzania plans to set minimum standards for biomass stoves on the market, ensuring that more clean and efficient stoves are sold. She also visited Tango Energy, a stove manufacturer with whom Aprovecho has worked on stove design. She got to work on building knowledge with them and visited a project site to talk to households about their experience with improved stoves. We are excited to establish such great connections in Tanzania and hope to work with them in the future.

Increased Support for RTKCs

Regional Testing and Knowledge Centers (RTKCs) help us with testing, design, fieldwork and valuable knowledge of local cooking practices. Without them, we would not be able to make the global impact we do today. With our new grant funding, we will be supporting RTKCs in an effort to increase their testing and design capabilities, as well as building a better-connected community of testing centers and their researchers.

Test Results To Be Published

We performed a field study in Oregon on cordwood heating stoves, with the goal of understanding how people use these stoves so we can make cleaner-burning designs that still meet user needs. The results from that study are on their way to publication. This paper combines anthropology and engineering, using survey data, semi-structured interviews, and emissions data to find common usage patterns and identify high-emissions events. This work has helped immensely in our development of new cordwood heating stoves. The full paper has been accepted for publication in the Journal Energy Research and Social Science with the title: Considering the user: An integrated assessment of residential wood heating practices in the United States and implications for wood heater design. We will publish a link on our publications page, once it is available.

Learning From People

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A rat proof box

When Dr. Larry Winiarski and I lived for a season at Rancho San Nicolas in Baja California Sur, Mexico we wanted to be helpful. We built cook stoves, solar cookers and other delightful inventions that we found interesting. But Larry was an insightful fellow and he started to listen to folks and ask them what problems they wanted to solve.

We had such a great time at the ranch, people were so nice, but Larry learned more than I did because he was born in Honduras and was more fluent in Spanish. It took me a couple of years to be able to understand what folks were saying. Speaking the language is important for many reasons!

After a while, Larry and I started working with the rancheros making rat proof boxes from available wire reinforced cement. Steel would have been great but was much too expensive and you couldn’t get it anyway. Rats were eating so much food and storage was a major problem. Stoves were great but homemade rat proof boxes took off like hot cakes. 

We started making boxes and became more helpful. Folks loved Larry anyway but now he wasn’t just good company. After a couple of years, I started fixing holes in boats.

What’s Cooking at Aprovecho

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Capacity Building with CSIR

Over the past 3 years, thanks to three grants from Fire Capital, Aprovecho has been working with CSIR (Council for Scientific and Industrial Research) in Ghana to expand their lab capacity. We have focused on teaching stove design principles through co-developing a stove retrofit for boarding schools in Ghana.

During the recent in-person workshop, Jaden visited the lab to help with the building of the prototype and plan for its installation at a local school. This prototype will go over an existing stove at the school, increasing thermal efficiency and reducing indoor emissions. With user, manufacturer, and lab result feedback, CSIR will finalize their design and give stoves to ten schools for a larger impact study. 

CSIR employees working on the new stove prototype

The LEMS in Bangladesh

Sam went to Bangladesh to update their lab and provide training. The Bangladesh University of Engineering Technology in Dhaka now has a lab that can test cookstoves according to ISO 19867 standards. This provides a useful development tool for the area as well as way to teach the next generation about cookstove development. Sam observed that while urban and peri-urban areas had access to gas and electricity, households couldn’t always afford it, highlighting the need for clean biomass stoves even in areas with access to alternative fuels. 

Sam also visited Life Green Energy, a stove manufacturer focused on forced draft stoves. Together, they developed a local Jet-Flame prototype aimed at saving fuel and reducing emissions. The prototype was able to burn green wood while other brick stoves could not. More development is planned to improve the product.

Sam Bentson testing at the lab in Bangladesh

Baseline Efficiency Paper Published

We were recently published in Environmental Science & Technology for our paper on the baseline thermal efficiency of wood and charcoal stoves: Quantifying the Efficiency and Fuel Consumption of Cooking with
Traditional Wood and Charcoal Stoves in Malawi, Ghana, and Kenya.

Aprovecho and Oregon State University paired with SunFire (Malawi), KIRDI (Kenya), and CSIR (Ghana) to conduct a total of 720 thermal efficiency tests on traditional wood and charcoal stoves. The goal was to compare the baseline efficiency of stoves with UNFCCC (United Nations Framework Convention on Climate Change) default efficiency, which had recently changed.

We developed a new test protocol, the UCET (Uncontrolled Cooking Efficiency Test), which measures thermal efficiency on any meal cooked. We found that the average thermal efficiency was between the new and old UNFCCC defaults. It was also found that firepower, pot/pan size, and cooking method are strongly correlated with efficiency. 

Women cooking during a UCET

The Water Boiling Test, Repeatedly

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In my opinion, the WBT* cannot be used, especially in the lab, to improve a biomass cook stove because all of the important field variables are not represented.

A successful cook stove needs to be evolved from field tests, as we did in Southern India for the Shell Foundation. Cooks in eighteen villages kept on changing the Rocket stove until it was acceptable, useful, and even likable. It took a while but it was a lot of fun and a great introduction to Southern India!

The WBT, with severely limited variables, can be useful in the lab for international comparisons of stove performance. The same pots, same amount of water, same fuel, same procedures and protocols limit the confounding variables in an attempt to isolate the stove as the reason for perceived differences.

As we did in India, both field and lab data can inform stakeholders. The successful stove has to please cooks, retailers, distributors, etc. and, at the same time, meet project goals such as reducing adverse health effects. We used the WBT in the lab and the CCT* in the field. Marketing tests, as suggested by Baldwin (1987) were very important, as well. We learned right away that the stove had to cost ~$5 to capture sustainable market share.

The lab based WBT is best used to inform researchers how stoves might be improved. Then, iterations in prototypes are tried in the field including cost, weight, color, height, firepower, fuel used, etc, etc.

This combined use of the WBT, CCT, and KPT* for stove development was suggested in the International Stove Standards, (1985). 

*Water Boiling Test “The Water Boiling Test (WBT) is a simplified simulation of the cooking process. It is intended to measure how efficiently a stove uses fuel to heat water in a cooking pot and the quantity of emissions produced while cooking.” – The Water Boiling Test Version 4.2.3

*Controlled Cooking Test “The controlled cooking test (CCT) is designed to assess the performance of the improved stove relative to the common or traditional stoves that the improved model is meant to replace. Stoves are compared as they perform a standard cooking task that is closer to the actual cooking that local people do every day.” – CCT version 2.0

*Kitchen Performance Test “The Kitchen Performance Test (KPT) is the principal field–based procedure to demonstrate the effect of stove interventions on household fuel consumption.” -KPT version 3.0

Find out more about testing protocols at cleancooking.org/protocols/

Supporting Best Practice

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Three stone fire 3

Cooking outdoors, making hot fires, burning the tips of sticks to use less wood and breathe less smoke (photo: Clean Cooking Alliance)

In 2003, Aprovecho was hired by The Shell Foundation to develop a Rocket stove in Southern India. We found a wonderful co-op of potters that was selling two-pot burnished $4 ceramic stoves with chimneys. They sold 250,000 stoves per year. Mahatma Gandhi promoted this kind of stove in 1934. The ARC staff thought that, while trying to introduce a new concept like a Rocket stove, helping the potters to update their facility and perhaps tweak the design might result in this established manufacturer with an existing market and distribution system becoming more successful. It was great to work with and learn from so many, highly motivated local folks!

Appropriate Technologists are encouraged to first survey technologies developed in the project area. ARC looked around lots of villages to try to find out what expert cooks were doing to use less wood and breathe less smoke. We were trying to find out what existing factories were making innovations, and which established markets and distributors were selling products. One constant was that almost every distributor said that stoves had to cost less than $5.

Appropriate Technologists read in textbooks that learning from local solutions is best practice. Hundreds of Indian women transformed the Rocket into a useful stove. ARC did not know so much information was needed to be successful! We had to learn from experts and try to get out of our own way (as Alan Watts titled his autobiography).

Cover image of The Winiarski Wood Fired Agricultural Food Dryer

Winiarski: Improving Agricultural Food Dryers

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Cover image of The Winiarski Wood Fired Agricultural Food Dryer

Sometimes it’s too cloudy for solar drying and a wood-fired dehydrator can help with large scale food preservation. In 2002, Dr. Larry Winiarsk helped farmers in the wet mountainous region of Nicaragua to design and build a prototype wood fired dryer for cacao beans. The ARC publication “The Winiarski Wood Fired Agricultural Food Dryer,” details construction of a rocket-style wood-fired dehydrator.

It’s estimated that the optimal temperature for drying is between 120 and 130 degrees F. Sustained temperatures over 130 degrees can begin to cook the food. (When starting to dry foods it can be most efficient to go up to 150 to 160 F. in the initial stages of drying when lots of moisture will be evaporating out of the food.) 

A successful food dehydrator sustains these temperatures in dry air passing through food at a constant rate with even distribution for a variable period of time, depending on the food being dried. 1.) Hot air temperatures increase the rate of evaporation. 2.) Air flow through the food is equally important.

WHY?

Efficient drying moves the water inside the food into the surrounding air. Wet air cannot absorb more moisture. Hot, dry air picks up the moisture and air flow created by draft replaces moist air with dry air. In a Winiarski food dryer, air is efficiently heated and sufficient airflow of dry air through the food increases the rate of dehydration.  

The food dryer features: a) burning biomass heating air b) is relatively air tight, c) has a large chimney or fan that removes moist air and moves dry air through the food. A large chimney usually creates the draft necessary for sufficient air flow.

Emission testing equipment set up at an Oregon home

What’s Cooking at Aprovecho

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The LEMS in Ethiopia

Jaden and the trainees in the Ethiopia lab

In March, Jaden traveled to Ethiopia to assist in the installation of the LEMS and train lab technicians on ISO testing for cookstoves.

15 trainees from all over the country attended the training. The LEMS was procured by SNV and their sponsors and was given to Ethiopia’s Department of Water and Rural Energy at the end of the training and installation.

The installation of LEMS in different countries is vital in creating clean cooking solutions that can be used throughout the world. We hope to continue working with the lab in Ethiopia to design new stoves.

Proyecto Mirador in the Lab

Proyecto Mirador testing their stove in their lab in Honduras

Proyecto Mirador has been working on improving the efficiency of their Dos por Tres stove. After successful tests in their lab, they traveled to Aprovecho from Honduras to confirm their results.

They got the same results in both labs, showing how effective iterative design testing with the LEMS can be. Now they can install stoves that use less fuel and cook things faster in Honduras and Guatemala.

Field Testing Results Published

Emission testing equipment set up at an Oregon home

In 2023, we measured the emissions from cordwood heaters in Oregon. There are very few studies that evaluate emission measurements in the field for wood heaters. As seen from our experience in cooking stoves, emissions in the field are often higher than lab tests, and field studies help us understand how people use their stoves so we can make better designs.

We’ve been using the data we collected to create lab tests that reflect user behavior and design clean and efficient heating stoves that meet user specifications.

The resulting paper, In-situ Measurements of Emissions and Fuel Loading of Non-catalytic Cordwood Stoves in Rural Oregon, was recently published in the Journal of the Air & Waste Management Association.

Market Driven Stoves

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Photo by Güldem Üstün on Flickr

One of the biggest mistakes I have made was thinking that I could predict what stove would sell in a market. If only I had always followed Sam Baldwin’s advice and done market testing before manufacturing! In Southern India, as part of the 2003-6 Shell Foundation project, we had outspoken distributors who yelled in meetings that a successful stove had to cost $5, that 5,000 had to fit on a truck, and that it had to be designed by cooks! The stove had to be short so food could be stirred and work well at the low firepower required by villagers around Chennai, toast a chapatti, etc., etc.

When the carbon market crashes, affordable stoves continue to be sold and used. When stoves are purchased the consumer is convinced of their utility. The trick is to try to bring best solutions into marketable products but, luckily, engineers love a challenge!

A pot skirt, SuperPot, constant cross sectional stove top, stick support, keeping a fire hot, can all significantly increase heat transfer efficiency. Even Jet-Flames can be made for around $5. TLUDs can be inexpensive. There are many techniques to improve the market driven stove! 

Check out the new Osprey funded book Improving Biomass Stoves, 2025  for examples?