Cleaner Burning Biomass Stoves: In Homes!

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The British Petroleum clean burning Oorja FD-TLUD stove from India

If protecting health and climate are important in stove projects, why not monetize the reductions of health/climate pollutants in carbon-offset projects?

Only the reduction in fuel use earns carbon income now!

With equal heat transfer efficiency, dirty burning stoves earn as much as clean burning stoves.

Dirty burning stoves are less expensive. “Market demand” reinforces the use of biomass stoves with low combustion efficiency.

Why not add income from reductions in CO, PM2.5 and Black Carbon, etc. to carbon projects to get cleaner burning stoves into use?

The approved 2017 Gold Standard Methodology already exists to do this! See: www.goldstandard.org/articles/black-carbon-and-other-short-lived-climate-pollutants

H.R.6316 – Clean Cooking Support Act

Following the COP26 international climate conference, Senator Susan Collins (R-ME) and Senator Dick Durbin (D-IL), have introduced a bill to accelerate access to clean cooking. Here is the opening text of the section defining the activities directed in the bill. H.R.6316 has been referred to the Subcommittee on Energy:

SEC. 5. CLEAN COOKING PROGRAM.

(a) Department Of State; United States Agency For International Development.—The Secretary of State and the Administrator of the United States Agency for International Development shall work with the Clean Cooking Alliance, founded in 2010—

(1) to engage in a wide range of diplomatic activities, including with countries across the globe and with United States embassies abroad, to support activities of the Clean Cooking Alliance and the clean cookstoves and fuels sector;

(2) to continue the clean cooking initiatives supported by the Climate and Clean Air Coalition, an intergovernmental organization formed in 2012, to reduce emissions of climate pollutants;

(3) to advance programs that support the adoption of affordable cookstoves that require less fuel to meet household energy needs and release fewer pollutants, as a means to improve health, reduce environmental degradation, mitigate climate change, foster economic growth, and empower women; and

(4) to carry out other activities authorized under this Act.

(b) Department Of Energy.—The Secretary of Energy shall work with the Clean Cooking Alliance—

(1) to conduct research to spur development of low-cost, low-emission, high-efficiency cookstoves through research in areas such as combustion, heat transfer, and materials development;

(2) to conduct research to spur development of low-emission, high-efficiency energy sources;

(3) to support innovative small businesses in the United States that are developing advanced cookstoves and improved cookstove assessment devices; and

(4) to carry out other activities authorized under this Act.

The bill continues on in sections (c) through (f) to direct the National Institutes of Health, Centers for Disease Control and Prevention, Environmental Protection Agency and other federal agencies to engage in supportive activities. You can read the full text of the bill at https://www.congress.gov/bill/117th-congress/house-bill/6316/text

African Mud Stoves with Chimneys

Damon Ogle was the Technical Director here at ARC

Damon Ogle and the ARC staff have a long history, starting in Central America and Mexico, listening to folks praising their stoves with chimneys. There are now millions of beautiful Latin American kitchens in which the dangerous smoke is transported out of the house, as it is in the USA/Europe. The Rocket stove can be about 50% more fuel-efficient compared to the open fire, so about half the smoke is made. But that is not good enough to protect health inside a home.

Although health-protecting chimneys are seen in Latin America and India, it’s rare to see chimneys in Africa.  

One simple African stove with chimney is seen above. A sunken pot (or pots) sits down near the fire exposing its bottom and sides to the flame. The pot seals into the hole and the smoke flows up the chimney, not into the lungs of the cook and her children. 

Since 1976, ARC has continued to work with local communities worldwide to try to save fuel and protect health. Trying to protect climate requires very clean combustion and we’re working on that, too.

The Not-Stove Intervention

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Cooking outside

When the air exchange rate is doubled, the concentration of smoke is reduced by half. The average house in low middle income countries is estimated to have around 12 air exchanges per hour (ISO 19867-3). When ARC measured the air exchange rate outdoors in a gentle breeze it was found to be about 120 per hour. Exposure to smoke could theoretically be dramatically reduced by moving outside.

Changing stoves costs money and the transition to an improved stove is often a time consuming process. ISO reports that even stoves with chimneys (that often leak) only reduce concentrations of smoke in houses by around 75%. Experimenting with increasing the air exchange rate is probably the most cost-effective intervention to protect health. 

When we went to villages where women cooked outside, Dr. Winiarski would frequently ask the women if digging a well, etc. might be more important than new Rocket stoves. That is one of the things that we loved about Larry!

How To Make An Institutional Stove With Chimney

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Dr. Mouhsine Serrar and the Rocket institutional stove designed by Dr. Larry Winiarski

There are at least three ways to make institutional stoves with chimneys, all of which work well and save fuel and decrease emissions. Here they are:

  1. Shell Foundation supported the making of an eight-part video, a step by step guide to making a 50 to 100 liter institutional Rocket stove, with a heat resistant metal Rocket combustion chamber. It is a great stove with lots of successful field testing but it costs the most to construct because heat resistant metals like 410 stainless or FeCrAl are increasingly expensive. The super insulated combustion chamber requires these types of metal. 304 stainless will not last. https://youtu.be/VdhLWMW7IXA
  2. Cooking With Less Fuel: Breathing Less Smoke shows how to make the same institutional stove using bricks for the Rocket combustion chamber. Construction details can be found at aprovecho.org in the publications section. The book was written with the World Food Program in Rome. This is a less expensive stove that is slightly less fuel efficient at cold start but lasts longer and is easier to make in places where 410 stainless and FeCrAl are not available.
  3. Making a VITA style institutional stove without a Rocket combustion chamber is the least expensive way to create an institutional stove. The open fire under the pot is supported on a grate and the hot gases flow up the inside of the skirt, down the outside of the skirt and exit out the chimney placed below the bottom of the pot as in the Rocket stoves shown above. You can find a video we made about constructing the VITA stove at: https://aprovecho.org/video-gallery/

Lots of manufacturers do not use the chimney but we think that protecting health is very important. We try to follow Don O’Neals advice (HELPS International) to always include chimneys whenever possible, imagining our mothers cooking and getting ill from exposure to the harmful emissions without the protection of the chimney.

A Recent History of the Rocket Stove: 2009

In 2009, The New Yorker published an article about the Rocket stove entitled Hearth Surgery: The quest for a stove that can save the world. One year later, USAID funded field tests in Africa showed that the insulated Rocket stove was not cleaner burning than the open fire. The Rocket with skirt saved 40% of the fuel to cook and emissions were only reduced by that amount.

Not a Planet Saver, yet!

The insulated Rocket combustion chamber raised temperatures but as Dr. Winiarski realized at the time, flame, air, and gases were not adequately mixed to achieve sufficient combustion efficiency. Larry knew that the Rocket was smoky but it was simple to make and with a pot skirt saved fuel. He wanted to provide folks with a stove that was helpful and he realized that it wasn’t perfect.

Larry’s idea went viral worldwide and continues to be a favorite on the internet and in many low- and middle-income countries. Millions of Rocket stoves are manufactured and sold yearly by factories large and small.

Going viral is great but can have a downside especially when the initial products are not technically mature. It’s normal for first generation products to be improved as time goes by. The process of development continues in 2022.

Introducing CPC in Bolivia

A major accomplishment of the past few years has been the creation of thirty Regional Testing and Knowledge Centers (RTKCs). Many of these facilities rely on emissions equipment and training from Aprovecho Research Center. They are usually created as an addition to a university in a developing country, and were initially funded by large development organizations such as the Global Alliance for Clean Cookstoves.

Once a month we’re turning our newsletter over to Sam Bentson, to tell you more about their activities:

Hello to everyone at the Regional Knowledge and Testing Centers (RTKCs), and to our newsletter readers, from Sam Bentson, General Manager at Aprovecho!

Sam was recently in Ghana and Senegal and then visited the Instituto de Investigación y Desarrollo de Procesos Químicos (CPC) in La Paz, Bolivia helping with stove testing and their LEMS emission hood. La Paz has the highest elevation of any government city in the world at an altitude of 3,650m!

The atmospheric pressure at CPC in La Paz is 20Hg. Our lab in Oregon is 241 meters above sea level where the atmospheric pressure is 30Hg. Sam and the CPC staff determined that at their high elevation, and with the voltage applied to the Jet-Flame motor increased to 8V, the mass flow in the Jet-Flame was 82% of the mass flow measured at the ARC lab.

Altitude had a big effect on boiling water and on the Jet-Flame!

CPC in La Paz, Bolivia from left to right: Libertad Mariana Casanova Velasquez, Dalia A. Borja, Sam Bentson, Jazmin Gidari Ruiz Mayta, and Karen Fabiana Paz Quispe

When Sam returned home, he started thinking about keeping in touch with all of his friends at the RTKCs and to share reports of activities. We are starting with CPC and highly recommend that anyone interested in doing research or a stove project make use of this wonderful resource in Bolivia!

Contact:

Marcelo Gorritty
Email: mgorritty@gmail.com
Calle Campos, Esq. Pasaje Villegas.
Edificio Artemis 367. PB Of. 7
La Paz, Boliviawww.cpc-bolivia.org

Dr. Kirk Smith and The Breathing Space Project

Dr. Kirk Smith, a hero

ARC worked closely with Dr. Kirk Smith (1947-2020) when we helped to include emissions in the Water Boiling Test, used to evaluate biomass cookstove performance, for the Shell Foundation. We included the first “Tiers of Performance” with a simple approach that divided stoves into two categories: improved and unimproved. It was great to know Kirk and I admired him tremendously.

Kirk was a professor at the University of California at Berkeley and was, in my opinion, the most effective advocate for the billions of people afflicted by breathing smoke. Kirk and ARC continued to work together during the Breathing Space project in India. Here is a video that ARC helped to produce in 2009, which describes the project. 

The goal of Breathing Space was to introduce the Rocket stove into India. We hoped that the Rocket stove, after being re-designed by women in 18 villages, would “go viral” and protect health. Eventually, Envirofit become the distributor and project manager. Envirofit and the Shell Foundation worked together to bring Rocket stoves into markets worldwide.

In 2011, Kirk Smith announced that switching to LPG seemed more likely to protect health. By 2017, Envirofit was including LPG and gas stoves in their catalog of options. Trying to create and disseminate truly clean burning biomass stoves had proven to be difficult and a more successful, wide scale intervention was needed. Although people liked it, the combustion efficiency of the Rocket stove just was not good enough. The Justa stove with chimney (with Rocket combustion chamber) that Kirk tested in Guatemala leaked, and when many stoves were in use the outside air became smoky. Maybe gas stoves, even though the fuel is not renewable, had a better chance to succeed?  

What would Kirk Smith recommend in 2022?

Can market driven biomass stoves (with hay boxes, solar stoves, pot skirts, SuperPots, Jet-Flames, etc?) successfully address health and climate change? Maybe we should keep working and find out?

I think that Kirk would not object.

Fred & Lise Colgan, founders of InStove

Rocket Stove Sterilization for Hospitals

Fred & Lise Colgan, from InStove

Fred and Lise Colgan created InStove, manufacturing and distributing institutional stoves initially designed by Dr. Larry Winiarski. They developed and sold large Rocket stoves that cooked food, sterilized medical equipment, and pasteurized water.

The autoclave, sold by Wisconsin Aluminum Foundry, works like a big pressure cooker and sterilizes quickly using steam and pressure. The unit fits into a Rocket stove that delivers the heat using less wood compared to traditional stoves. A chimney removes smoke from the room. The system can sterilize about 7 gallons of surgical instruments, dressings, and other medical supplies at a time, making them safe for either reuse or hygienic disposal.

These larger Rocket stoves combine the same strategies that are used in smaller versions. A pot skirt cylinder surrounds the sterilizer creating a narrow channel gap that is especially effective in transferring heat, in part because the pot is larger. Big pots have more surface area so increased percentages of heat pass into the water. When a chimney is attached to the stove, the hot gases are forced to flow down another channel on the outside of the pot skirt. In this way, adding a chimney to the stove does not diminish the fuel efficiency. A lot of the heat has already scraped against the pot and been absorbed before it exits out of the chimney. The light weight bricks used in a larger Rocket stove combustion chamber can be thicker and larger than bricks used in a smaller stove. The Institutional Stove described in the Institutional Rocket Stove pdf on the Publications page can handle pots from 50 to 300 liters. The downloadable Excel worksheet Institutional Stove Gap Calculator can help you determine the measurements of an institutional stove designed to fit the large pot you have available for use.

Factoring Practicality into Cook Stoves

Would any manufactured stove that you know of work well for this woman? Maybe not?

Working with local women to design cooking solutions is not hard when the team is located in the project area. It’s only natural to include the user in developing the product. But when wood stoves are created by foreigners, that invaluable input easily goes missing and the stove, although technically fine, usually misses other necessary attributes. That’s why ARC tries to develop stoves in the field, while learning how fire works in the lab.

Researchers associated with the Regional Testing and Knowledge Center in Accra, Ghana might agree with this strategy. They recently published a paper in which 20 biomass cook stoves available in Ghana were evaluated for high-power thermal efficiency, low power specific consumption rate, turn down ratio, high power CO emissions, high power PM2.5 emissions, low power CO emissions, low power PM2.5 emissions, affordability, fuel saving potential, operations and maintenance cost, time saving, indoor CO, and indoor PM2.5 emissions.

The authors concluded that none of the cook stoves satisfied the conditions of all of the performance indicators. The forced draft stoves were generally high performing on the technical and environmental attributes, but low performing on the economic and social/public health metrics like affordability, maintenance and operation costs, and fuel saving potential. The more traditional stoves did not perform very well technically and environmentally but ranked highest economically, being more affordable than the cleaner burning alternatives like forced draft stoves.

Available natural draft stoves were a better alternative considering the economic, technical, and environmental attributes.  The high cost of forced draft stoves (most are imported), their operation and maintenance cost, and the requirement of electricity resulted in adoption rates being low. The suitability to prepare Ghanaian staples, which require rigorous stirring, were also generally underestimated. Locally made natural draft stoves did not score well in terms of emissions but were much less expensive, did not require the preparation of fuel, and were made to prepare Ghanaian staple foods. 

The study highlights the need to consider all the performance criteria simultaneously in order to choose the “best performing” stove. 
The authors conclude with the hope that locally made stoves can be technically improved while maintaining the other necessary attributes. (Gloria Boafo-Mensah, et al., Biomass and Bioenergy 150, 2021).

It just so happens that our General Manager Sam Bentson is at the Regional Testing and Knowledge Center in Accra right now, working with Ms. Boafo-Mensah and the rest of the team on some exciting projects. We look forward to sharing Sam’s report about his trip when he returns!