We are currently studying products that help households in rural developing communities to meet their basic needs. Our goal is to develop a catalog of the most affordable, durable, usable, functional products available that have been rigorously user-tested and optimized. To help us choose where to start, could you please take 5 minutes to let us know what sort of products would be most needed in the communities that are experiencing energy poverty where you work? Please forward to your colleagues who work closely with these communities.
https://aprovecho.org/wp-content/uploads/2026/03/ARC-Logo-1.jpg10001000Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2026-03-13 12:43:412026-03-13 12:54:31Requesting input: What technologies are most needed in households?
It’s great to have colleagues whose opinions are trusted. Dr. Larry Winiarski was usually right, by which I mean, that when we built and tested his inventions they might not have been perfect but were significant improvements, good starting places for further development. I always appreciated talking to Dr. Tom Reed, inventor of the TLUD, for the same reasons. Hui Yang Shen, the head of Shengzhou Stove Manufacturer, has been an almost-always-right resource about manufacturing. In 1987, Dr. Sam Baldwin wrote a book on cook stoves that I still refer to frequently.
In the same way, Google’s Gemini AI has become an interesting resource for me. It has been fascinating to encounter such an accessible way to find another reasonable opinion. One question to AI every morning has become part of my routine although I don’t have time for more. Google AI gives many references for each summary and I try to at least scan them.
At ARC, we have the great advantage of doing experiments to learn. Reading what others have written is interesting, however I much prefer and believe that progress is faster when doing iterative development of prototypes under an emissions hood. As importantly, going into the field to do R&D with cooks, distributors, manufacturers, etc. is necessary to make things that work. Reading alone cannot get you to success but it is a sturdy third leg of the stool: Literature searches, lab and field R&D.
Glad whenever I get out of the box.
https://aprovecho.org/wp-content/uploads/2025/09/Untitled.jpeg300600Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-09-18 13:58:452025-09-18 13:58:46AI: Great but Stuck in a Box
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.
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.
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.
https://aprovecho.org/wp-content/uploads/2025/08/UCET_test.jpg473600Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-08-13 11:55:502025-08-13 12:00:44What’s Cooking at Aprovecho
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).
https://aprovecho.org/wp-content/uploads/2025/06/3-stone-fire.jpg375500Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-06-27 14:22:222025-06-27 14:22:23Supporting Best Practice
The new Osprey funded book is a compilation of fifty-one updated newsletters, reflecting the current state of knowledge at ARC.
Stove experiments fail to improve prototypes as often as they succeed. One of the great things about iterative development (testing effects of single changes in prototypes under the emission hood) is that you learn as much from failures as from success! Every day moves us forward.
How to achieve close to complete combustion and close to optimal heat transfer efficiency are describable in single page summaries.
Aprovecho is helping to manufacture biomass cooking and heating stoves that are clean burning enough to protect urban air quality and meet the Paris Agreement. Most of the stoves that we help to make are not this clean burning, but how to achieve cleaner combustion is better understood and less expensive to achieve.
The hope is that these short summaries will be more accessible and more fun to read compared to previous longer-winded attempts at communication.
Our lab is open to visitors and we try to be good hosts. After years of trying, the coffee is becoming more palatable.
Come on by!
https://aprovecho.org/wp-content/uploads/2025/04/improving-biomass-stoves-tile.jpg200841Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-05-02 13:17:482025-05-02 13:17:49New on the Website! Improving Biomass Stoves, 2025
In 1982, the original cook stove consultants returned from global travels to Oregon, bought 40 acres of forested land at the end of a road, planted a garden and started talking to Dr. Larry Winiarski, (Oregon State University) learning how to improve combustion and heat transfer efficiency.
Dr. Nordica MacCarty, an associate professor at OSU, is the Executive Director of ARC and continues investigations of how wood fires can better help humanity. She has worked at ARC off and on for 25 years. Rigorous science-based experimentation, field learning, publication of peer reviewed journal articles and market-based manufacturing and distribution intertwine as ARC matures.
Learning from experience, eating a thousand kinds of food, succeeding now and then, is always great!
https://aprovecho.org/wp-content/uploads/2024/03/MacCarty-Headshot-2022-scaled.jpg17072560Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-04-25 14:10:212025-04-25 14:10:35Aprovecho Research Center, 2025
In 2018, the World Health Organization published the book “Air pollution and child health: prescribing clean air”. The report concludes, “Every day around the world, billions of children are exposed to unsafe levels of air pollution. The result is a global public health emergency.”
The WHO suggested “prescriptions” to clean the air and protect health:
Use clean household energy for cooking, heating, and lighting.
While waiting for clean to be available, use technologies and fuels that reduce exposure such as low-emission biomass cook stoves.
Minimize the time children spend around smoky fires.
Increase ventilation or install a chimney.
A combination of interventions is usually most cost effective.
ONE
Help to make clean burning stoves available.
Promote solar lighting.
TWO
Forced draft stoves can burn up a lot of the smoke.
An adjustable Pot Skirt forces the hot gases to scrape against the sides of the pot as well as the bottom reducing fuel use by about one-third. That results in one-third fewer emissions!
A light weight, abrasion resistant Rocket combustion chamber can burn up ~ 50% of smoke compared to the open fire.
Winiarski designed stovetops can increase heat transfer efficiency by ~8%.
THREE
Promote reduction of exposure to family members, especially to women and children.
FOUR
Doubling the air change rate reduces smoke in half.
Locate the fire under a window on the low pressure side of the house.
Cook outside.
Chimneys have been a part of traditional houses for centuries.
Cook with a chimney!
https://aprovecho.org/wp-content/uploads/2025/04/bluesky.jpeg344600Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-04-18 16:15:552025-04-18 16:15:56Building Blocks to Health
Last week Dean and Travis went to the Hearth, Patio & Barbeque Association Expo in New Orleans to get updated on the latest heating stove technologies and to meet and talk to stove companies. Three days was a short time but we made many friends and learned a lot!
The CENTRAL BOILER outdoor log and pellet furnaces stood out as one of the newest innovations. It can be imagined that in a sustainable biomass future, heating big buildings (even high-rise apartments?) with logs or pellets might be as useful as freestanding stoves heating rooms. The same (bigger/smaller) clean burning combustion systems deliver renewable, home-grown heat to occupants in bigger/smaller buildings. Maybe pellets could be poured down the same delivery chutes that are used for heating oil in New York City buildings?
Admiring the automated house-sized furnaces on display at the Expo made the possibilities seem so much better defined.
Schoolhouse Creek, filled with late winter run off, rushes along next to the Cafeteria building
The Aprovecho lab is in a green forest, eight miles east of Cottage Grove, Oregon, a town of ~10,000 people.
Working in a forest to design, manufacture and sell clean burning biomass cooking and heating stoves makes sense.
Heating and cooking with renewably harvested biomass is easy to imagine when surrounded by a forest.
Eating food from our gardens, grown with fertilizer from animals we enjoy, means that we know a lot about the food we eat.
Learning more about burning biomass cleanly enough to join solar, wind, hydro, and geothermal as sustainable energy resources, is intrinsically optimistic work.
We hope that you can visit our stove lab at Blue Mountain one of these days! Contactdean@aprovecho.org
https://aprovecho.org/wp-content/uploads/2025/02/IMG_2575.jpg480640Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-03-07 13:27:062025-03-07 13:36:18Working in a Forest
Two dollar and fifty cent SSM adjustable pot skirt
Aprovecho staff travel around the world assisting stove projects. We experience that almost all biomass stoves in Low Middle Income Countries markets are sold for $10 USD or less. It seems to us that more expensive stoves are supported by carbon revenue, or sold in cities to the middle or upper classes.
Depending on carbon revenue works well when prices do not fall, or when events don’t restrict trade. Aprovecho has learned a lot about the carbon market and helps projects to make best use of opportunities.
Aprovecho also develops market-based products trying to create sustainable businesses independent of carbon. Dr. Winiarski was a great proponent of market-based solutions that reduce fuel use and harmful emissions. He pointed out that improved thermal efficiency can be added to traditional stoves sold in markets without increasing cost. Week-long Partnership for Clean Indoor Air seminars (2002-2012) in Asia and Africa reduced fuel use by an average of ~ 30% with simple changes.
The size of the combustion chamber in a charcoal stove has been shown to be the most significant factor in fuel use. Maybe reducing the size of the combustion chamber in a traditional charcoal stove currently being sold would end up saving fuel in real life? See: The influence of initial fuel load on Fuel to Cook for batch loaded charcoal cookstoves (Bentson et al, 2013)
The $2.50 USD SSM adjustable pot skirt has reduced fuel use by 20% to 25%. Aprovecho hopes that factories/stakeholders can improve popular stoves by applying easy-to-teach changes.
There are many no extra cost improvements that are incremental first steps.
They tend to be affordable and market based, which made Dr. Winiarski happy.
https://aprovecho.org/wp-content/uploads/2023/06/1.-Pot-Skirt.jpg501800Kim Stillhttps://aprovecho.org/wp-content/uploads/2015/11/Aprovecho-Logo.pngKim Still2025-01-30 16:16:172025-01-30 17:01:24Improving Market Based Products to Reduce Wood Use and Emissions
