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!

User Feedback Can Make For Unexpected Improvements

In our newsletter “Making It Real,” we described how feedback from the field in Rwanda suggested that the Jet-Flame’s power cord would last longer if the whole device was inserted from the side of the combustion chamber. (It was originally designed to go through the door, with the sticks placed on top.) So of course we ran some tests, and discovered more benefits.

Is the Jet-Flame, when inserted into the combustion chamber from the side of the CQC stove, as effective in reducing emissions as when it enters through the fuel door?  

Yes, performance seems to have even improved a bit. After testing the Jet-Flame with side entry, it seems that it’s better to get the hot metal out from under the parts of the fuel that you don’t want to heat up. To burn cleanly, natural draft Rockets like to burn something like 8cm of the end of the sticks. Instead of laying the entire length of the sticks on the heated metal of the Jet-Flame, the side entry only exposes a limited amount of the sticks to high temperatures.

As seen in the photo, the sticks are now supported by a white homemade high mass brick and only the tips are exposed to Jet-Flame heat well inside the stove. It’s nice how a suggested change from Jean Marie Kayonga in Rwanda ends up having some unexpected benefit, not just better protecting the cord. Thanks again, Jean Marie! www.Jet-Flame.com

The time to boil, thermal efficiency, temperature in the combustion chamber, CO, and PM were improved with side entry while firepower rose. Excess air fell from 3.38 times stoichiometric to 2.57. I liked operating the stove because the sticks seemed to burn more at their tips as Dr. Winiarski described in the Rocket Design Principles. See: https://bioenergylists.org/stovesdoc/Still/Rocket%20Stove/Principles.html

Varying Fan Speed in the SSM Jet-Flame/CQC Stove

CQC stove set up for testing under the LEMS hood

ARC is investigating how to optimize the performance of the SSM Jet-Flame in the CQC earthen brick stove. Forty six thirty-minute ISO 19867 Water Heating Tests were completed under the LEMS hood at seven fan speeds. Two 4 cm x 4 cm douglas fir sticks were burned side by side. Five liters of water in a seven liter pot were heated, and the CQC pot skirt was used in all tests.

Results

Tier 4 ISO Voluntary Performance Targets:

  • Thermal Efficiency           40% to 49%
  • CO                                     <4.4g/MJd
  • PM2.5                               <62mg/MJd

Time to boil: The time to boil decreased with an increase in fan speed.

Thermal efficiency: The thermal efficiency stayed close to 35% in most cases and was higher at 3 and 8 volts (around 40%).

Firepower: The firepower rose to 6.8kW at 8 volts, starting at 2.6 kW at 2 volts.

Emissions of Carbon monoxide: Generally emissions decreased with increasing fan speed.

Emissions of PM2.5: 7 and 8 volts scored the best, at half of the result of 5 volts.

Combustion chamber temperatures: The mid combustion chamber temperatures rose with increases in fan speed from 382C to 730C.

Excess air:  Lambda fell as voltage increased from 4.1 to 1.9.

We recommend that the project do enough field testing to determine what settings are preferable to local cooks, remembering that higher voltages consume more power. In this way, the Jet-Flame/CQC stove can be tailored to regional cooking, keeping in mind the power output and use patterns of the CQC photovoltaic solar system.

Here’s what the flame looks like when varying the voltage:

Kabanyana Murabukirwa Domina and Jean Marie Vianney Kayonga in Rwanda

Making it real!

Kabanyana Murabukirwa Domina and Jean Marie Vianney Kayonga in Rwanda
Kabanyana Murabukirwa Domina and Jean Marie Vianney Kayonga in Rwanda

One of the roles of the ARC engineer is to give accurate technical information to the in-field decision makers who are directing the stove project. The folks on the ground have to make sure that cooks really like the stove, that the price is market based, that manufacturing is arranged for, etc. ARC engineers and the field team work closely together as the project evolves.

A New Project in Rwanda

In Rwanda, Kabanyana and Jean-Marie and their NGO, ENEDOM, are working on a carbon credit supported Jet-Flame project. We met Jean-Marie through the internet and realized that he is well known in the sector. In fact, he knows many of our friends in Africa. Dr. Dan Lieberman at Global Health Labs sent Jean-Marie twenty Jet-Flames, and he showed them around to many of organizations, like the World Bank, that have large projects in the country.

Real World Use Guides Product Improvement

Moving the Jet-Flame to the side of the CQC stove
Moving the Jet-Flame to the side of the CQC stove

When we envisioned the Jet-Flame we imagined that it would be inserted into the fuel door of a Rocket stove. Mr. Shen at SSM directed the effort to manufacture the Jet-Flame and it includes a beautiful stainless steel stick support that also protects the fan. However, it only took several weeks of trails for ENEDOM to make a strong recommendation to move the Jet-Flame to the side of the earthen stove. Cooks in their homes were accidentally burning up the cord!

We gratefully thank ENEDOM for helping us make fewer mistakes. It’s another great example of trying to make sure that reality is in the product.

We won the Tibbets Award!

ASAT, the for-profit arm of Aprovecho, has been awarded a prestigious Tibbetts Award by the US Small Business Administration. The Tibbets Award is given for demonstrating significant economic and social impact from the R&D funding provided by SBIR (Small Business Innovation Research) grants. ASAT received EPA SBIR grants that enabled the research and development of:

  • The Jet-Flame that increases combustion efficiency (costs around $11). See: www.Jet-Flame.com
  • An air cooled thermoelectric generator (water cooling is hard to install).
  • A low cost, easily cleaned electrostatic precipitator (90% reduction of soot).
  • The Integrated Stove. See: www.ssmstoves.com/project/m55/

We partnered with the Gates funded Global Health Lab to develop the Jet-Flame. They have recently supported sending Jet-Flame samples worldwide.

The clean combustion of biomass adds homegrown power to the energy mix here in the USA and in other countries. Without the EPA SBIR this would not have happened! To learn more about the Tibbets Award, visit tibbetsawards.com.

Sam Bentson trains Bernard Kabera and colleagues to use the new stove lab equipment

Setting Up a New Lab in Rwanda

Aprovecho’s General Manager Sam Benston recently returned from a trip to Rwanda, where he helped to set up a new ISO compliant cookstove lab. Here are some photos and information from Sam about his work there:

I was installing the LEMS (Laboratory Emissions Monitoring System) and PEMS (Portable Emissions Monitoring System) and the rest of the new ISO 19867 cookstove laboratory at the Rwanda Standards Board in Kigali. The lab started as an empty room full of equipment in boxes. I trained the laboratory staff on the set-up and use of the equipment for cookstove evaluations according to ISO 19867. Shortly after I left there was a Grand Opening to celebrate on the ISO’s World Standards Day. Here is a twitter link with photos:  https://twitter.com/REMA_Rwanda/.  Our new PEMS with the battery powered gravimetric system is visible.

The PEMS is visible here at the launch of the Cook Stove testing lab in Kigali
The PEMS is visible here at the launch of the Cook Stove testing lab in Kigali.
Photo via @REMA_Rwanda

Aprovecho provides a turnkey cookstove testing laboratory which is useful for cookstove performance certification, design, and basic research. The lab is centered around the ARC manufactured LEMS. It consists of a gas and particle analyzer with a pump and filter PM2.5 sampler, an emissions collection hood, and a dilution tunnel. The LEMS is the result of 20 years of development that started due to the lack of affordable and easy to use equipment suitable for cookstove emissions monitoring.

Testing a stove under the new LEMS hood.
Testing a stove under the newly installed LEMS hood.

Aprovecho develops its equipment as the need arises during research and development activities that occur in its laboratory. Aprovecho’s ability to commission the other instruments that makeup a cookstove testing laboratory is the result of a similar depth of experience.

Bernard Kibera and colleagues training to use the new stove lab equipment
Mr. Bernard Kabera and colleagues training to use the new stove lab equipment.
Sam Bentson trains Bernard Kibera and colleagues to use the new stove lab equipment
Sam Bentson trains Mr. Bernard Kabera and colleagues to use the new stove lab equipment.

It was remarkable to observe how the Rwandan people have protected themselves against COVID. It was a great honor to be part of their community at this time.

–Sam Bentson