National Geographic News
A biochar cookstove.

Cookstoves that can produce biochar, like the one pictured above in western Kenya, can be a key tool in fighting respiratory disease and boosting agricultural production.

Photograph courtesy ACON

Stacey Schultz

For National Geographic News

Published January 29, 2013

Like many of her neighbors in Amubri, an indigenous community at the southern tip of Costa Rica, Gloria Torress Buitrago relied for years on a fogón for cooking. The traditional open-fire stove is common in Amubri (map), and so are the dire health effects. "It was hard to look around and just breathe without feeling the smoke burning the eyes or throat," Buitrago said. One cousin suffered from asthma, and everyone in her family was constantly tearing up from the wood fire's smoke.

Buitrago was just one of three billion people worldwide who rely on such open-fire cookstoves. A recent global health study found that the fumes from those stoves was the largest environmental health threat in the world today, killing 3.5 million people a year—more deaths than caused by malaria and HIV/AIDS combined. (See related blog post: "Cookstove Smoke Is 'Largest Environmental Threat,' Global Health Study Finds.") Cookstoves that burn cleaner can help fight this epidemic, but they can do even more than that when configured to produce biochar, a dark, fine-grained residue that can become a prized asset for rural communities.

In regions as diverse as the high mountain valleys of Costa Rica and the agricultural fields of western Kenya, biochar cookstoves are being used to simultaneously clear the air and enrich the soil. Biochar, a type of charcoal produced when biomass burns in an oxygen-free environment, can boost water and nutrients in dry, depleted soil while serving as a vehicle for burying the carbon that contributes to global warming.

Breathing Easier

Groups like Seattle, Washington-based SeaChar, the recipient of a $72,000 grant from National Geographic's Great Energy Challenge initiative, have been testing new variations on clean cookstoves. SeaChar's Estufa Finca ("Farm Stove" in Spanish) burns biomass cleanly while turning it into biochar. It's not a fancy apparatus: Fashioned from local materials, its components include a five-gallon steel paint bucket, some corrugated steel roofing material, and half of a one-gallon tomato sauce can.

Gloria Torres Buitrago's family is one of 110 households that acquired one of the stoves last year through SeaChar's Estufa Finca program in Costa Rica's Talamanca region. Buitrago says the stove has relieved not only the smoke problem in her home, but also the effort required to keep fires burning. "The time and money it takes to get wood has been reduced a lot," Buitrago said in an interview with a SeaChar staff member, who then translated and emailed her responses. "This time can be used to share with family or just do other things in the garden." (See related story: "Protecting Health and the Planet With Clean Cookstoves.")

In addition to wood, the stove burns garden debris, dried animal dung, and food material such as dried corncobs and coconut husks. A family cooking a pot of beans will use 40 percent less wood with the Estufa Finca than with an open-fire stove, said SeaChar President Art Donnelly, who designed the stove. "Those are trees you do not have to cut down."

Donnelly said tests conducted by SeaChar show a significant reduction in exposure to harmful smoke. "In laboratory testing, these stoves reduced particulate matter emissions by 92 percent and the carbon monoxide emissions by 87 percent as compared to an open cooking fire," he said in an email. "These two are the big drivers of respiratory disease."

Another grantee of the Great Energy Challenge, the African Christians Organization Network (ACON), has been working since 2004 with local farmers to reduce deforestation and improve soil conditions in western Kenya. Introducing innovative cookstoves to local families is part of that effort, and ACON's Salim Mayeki Shaban said that feedback on the stoves has been positive.

"[Women] reported that the reduction of smoke in the house decreased irritation of their and their children's eyes, runny noses, coughing, chest discomfort, and difficulties in breathing, along with cost savings due to fewer hospital visits," Shaban said in an email.

Table-to-Farm Cooking

In Costa Rica, Donnelly said, many local families initially expressed interest in the new stove because it is smoke-free. "The real hook though, is the biochar," he said.

SeaChar offers a biochar buyback program, through which households can earn an extra $15-20 per month by selling the biochar produced by their cookstoves. Currently 22 households regularly participate in the program, and SeaChar has collected 273 feed sacks of biochar, paying families about $5 per sack.

The biochar is buried in the ground for research and demonstration projects, and used at locations such as cacao farms, large organic nurseries, and school garden projects, according to Donnelly.

A recent field study in Costa Rica on the effects of adding biochar and chicken manure to soil showed an increased crop yield of cacao. Juliano Hojah da Silva, a second-year graduate student at the Center for Tropical Agricultural Investigation and Education (CATIE) who led the study, said in an email that the biochar improved the soil's chemical and physical quality.

"All the applications made of biochar increased total soil carbon amounts, as well as soil organic matter, gains which were stable even after one year of implementation," Hojah da Silva said. "These gains are expected to be a persistent beneficial long-term effect." SeaChar will continue to study the effects of biochar on soil in the coming year, Donnelly said.

ACON also has observed benefits for crops treated with biochar. In 2009, it trained farmers in the use of biochar as a soil supplement to help with water and nutrient retention in the western Kenya region of Bungoma (map), which often experiences periods of drought. In subsequent field trials, ACON found that vegetable and cereal crops fared better in plots that were fertilized with biochar and a 15 percent solution of human urine.

In the process of researching biochar, ACON also has found a way to target an aquatic pest while easing resource strain on forests. The group harvests water hyacinth, an invasive species in nearby Lake Victoria that can be dried and converted into fuel briquettes for the cookstoves.

Buried Treasure?

Biochar enthusiasts say that in addition to helping boost crop production, it can be a powerful tool to fight global warming. The International Biochar Initiative, a nonprofit organization that promotes biochar applications, estimates that biochar could help store 2.2 gigatons of carbon annually by 2050.

Kurt Spokas, a research soil scientist with the USDA Agricultural Research Service in St. Paul, Minnesota, agrees that biochar can reduce atmospheric carbon dioxide concentrations, and he says there is scientific evidence that the carbon remains stable in the soil. "The difficulty is in extrapolating to the future," he said.

Projecting carbon sequestration over the long term, especially to the levels of multiple gigatons, would require infrastructure that is not currently in place, Spokas said. "In order to get to that scale, we would have to have industrial plants that are converting biomass into the biochar," he said. "When you look at those numbers, it's scientifically, technologically feasible, but we just don't have that type of infrastructure developed yet."

Spokas noted that the production of charcoal has historically evoked an economic conflict over its value as both a fuel and a soil enhancer. "The cookstoves are a very good model of a system where biochar can work," he says. "They need to burn biomass to produce energy for cooking, so they are not trying to wedge into a new economic scheme. Instead, they are modifying the stoves to simultaneously cook food and produce biochar for soil application."

In the coming year, SeaChar and ACON both plan to expand their projects. SeaChar is developing an Urban Stove for use in homeless encampments in the Seattle area, and is working to educate local farmers, gardeners, landscapers, and kids on the benefits of biochar. ACON's Shaban hopes to scale up his program to other parts of Kenya and to other regions around the world.

While some environmental benefits of biochar stoves may take time to materialize, the health impact remains immediate for the home cooks, so many of them women with children nearby, who finally can prepare meals without suffering devastating health consequences. (See related blog post: "Time to Clear the Smoke.") "The difference that a smoke-free stove makes in the household is very evident," said Gloria Torress Buitrago. "It is even better for the cook."

This story is part of a special series that explores energy issues. For more, visit The Great Energy Challenge.

Nilam Patel
Nilam Patel

 The use of renewable bio fuels for cooking and heating is helpful for both, human beings and environment. The similar bio fuel briquettes are produced from the bio waste in the briquetting plant equipment offers high energy in a clean way. So, it balance environment health and protect earth from global warming.

For more details, visit:

Salim Shaban
Salim Shaban

It is not only by blood that a family is made, but by a bond that ties individuals together. Though we are scattered across  countries,  the continual support, care and concern we provide each other truly makes us a family. We truly are bonded for life – the ‘Generation Snack-Time’ family. I cherish National Geographic  Family as each time my soul is re-invigorated by the emotional and spiritual support you all provide to  us here in Kenya. My dear friends, you all inspire me through the amazing work you are doing to better our world. I love you all!

Salim Shaban
Salim Shaban

It is not only by blood that a family is made, but by a bond that ties individuals together. Though we are scattered across  countries,  the continual support, care and concern we provide each other truly makes us a family. We truly are bonded for life – the ‘Generation Snack-Time’ family. I cherish National Geographic  Family as each time my soul is re-invigorated by the emotional and spiritual support you all provide to  us here in Kenya. My dear friends, you all inspire me through the amazing work you are doing to better our world. I love you all!

Bill Toone
Bill Toone

I am concerned by the particular stove illustrated.  First - invisible smoke is not safe smoke.  This design is easily knocked over and has hot surface areas making it very dangerous for kids.  Also it is portable - if you fund and promote these stoves you want to be able to monitor stove use and verify their existence - this allows you to followup on successes and failures.  Check out the Patsari stove as an example of a better idea - it needs to be modified depending on culture and fuel used but it is a better all round step in the right direction.

Tom Wilkinson
Tom Wilkinson

I believe the town in Costa Rica is spelled Amburi, and is located on the northern Caribbean slope of the Talamanca Mountains near the International Peace Park.

Tom Wilkinson
Tom Wilkinson

The key to increasing the use of biochar, as with anything, is creating more demand through marketing and sales. Production will increase to meet increased demand. Our new product "BioPreta" is a blend of biochar and vermicompost. One cup with a cubic foot of potting mix is producing remarkable plant growth for indoor gardeners, and comes in a vermicompost "TeaPot"

Erich Knight
Erich Knight

ACON is now training 6000 farmers in these protocols. A recent survey of 360 Biochar using households, some for over four years now, show an average increase of 25% in profitability.

For anyone interested in, or confused by, Biochar Soil Technologies, Please view my presentation and slides of this opening talk for the USBI Biochar conference in Sonoma California. This is the third US Biochar conference, after ISU 2010 and Colorado 2009.

Carbon Conservation for Home, Health, Energy & Climate

Modern Thermal conversion of biomass burns only the hydrocarbons in that biomass, conserving the carbon for the soil. At the large farm or village scale modern pyrolysis reactors can relieve energy poverty, food insecurity and decreased dependency on chemical fertilizers.

Please take a look at this YouTube video by the CEO of CoolPlanet Biofuels, guided by Google's Ethos and funding, along with GE, BP and Conoco, they are now building the reactors that convert 1 ton of biomass to 75 gallons of bio – gasoline and 1/3 ton Biochar for soil carbon sequestration.

The tagline of the company "The more you drive with our bio gasoline, the cleaner the atmosphere becomes"

If it's good enough for Google… It's more than good enough to me.

Ray Sanford
Ray Sanford does similar work in Central America. They help entrepreneurs  start factories to build fuel-efficient stoves. The factories employ local labor which boosts employment.

Erich Knight
Erich Knight

@Ray SanfordMy heroes are the engineers without Borders who have promoted clean cook stoves, Pyrolytic and Gasifing stoves that burn any biomass cleanly and 41% more efficiently. No black-lung no emphysema, no deforestation, all the while building soil carbon for continually sustainable yields. Please look at the work of the Biomass Energy Foundation. At scale, replacement of three rocks in a pot, across Africa would have the health impact equivalent of curing malaria and AIDS combined.
Biomass Energy Foundation (BEF) website

WorldStove has produced over 350,000 Lucia stoves and are now even producing a pyrolytic pellet stove for residential use here in the US. The flame so clean you never have to clean the front window.

 Here is a list of all the people I know doing clean stove work;

AirTerra Inc., (clean stoves to NGOs)
Aqueous Solutions, (Developing world micro-gasification for char water purification)
Carbon Roots International, (primary focus Haiti)
Chip Energy, (180K Btu/hr TLUD furnace, ,
Re-char, ((primary focus Kenya)
SeaChar, WA. (primary focus Costa Rica)
Whitfield Biochar LLC, (from inventor of the pelletstove, 20K Btu - 2M Btu units)
WorldStove, MA. (Africa, middle east, South America, Residential pyrolytic pellet stoves)
Vagga Till Vagga, SE. (Cook stoves in Zambia)
Vuthisa Technologies, SA. (EcoZoom Stoves & Kilns)

Carbon, as the center of life, has high value to recapitalize our soils. Yielding nutrient dense foods and Biofuels, Paying Premiums of pollution abatement and toxic remediation and the growing Dividends created by the increasing biomass of a thriving soil community.
Since we have filled the air, filling the seas to full, soil is the only beneficial place left.
Carbon to the Soil, the only ubiquitous and economic place to put it.
Thank you for your efforts.

Erich Knight
Erich Knight

@Ray Sanford

  • Home page of the Global Alliance.for Clean Cook Stoves
    The plan is 100 million clean stoves across the globe.

    The beauty of these small gasification and pyrolytic stoves is they make a wonderful replacement for your charcoal burning barbecue, instead you have a charcoal making Char–B-Q, from a simple tin can with the proper holes punched into it for proper airflow. These stoves called TLUDs, (Top Lite Up Draft) work just like a match burns. The flame as it burns down protects the wood from oxidation/burning. When you blow it out the charcoal remains, no ash. Since only the hydrocarbons gases are burnt there is no soot or particles of partial combustion. You get to use little sticks from your yard stead of buying charcoal. What's not to like?


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