Dr. Larry Winiarski
Dr. Larry Winiarski
Dr. Larry Winiarski, 1940-2021

Dr. Larry Winiarski, the Technical Director of Aprovecho Research Center (ARC), died this past week at the age of 81. In the 1980’s and 90’s, Dr. Sam Baldwin defined how to improve heat transfer efficiency in biomass cook stoves (pot skirts, etc.), Dr. Tom Reed created the TLUD, and Dr. Winiarski invented the Rocket stove. The saying “We stand on the shoulders of giants” certainly applies to the stove community.

Larry led teams from ARC around the world starting in Central America, where the plancha stove was evolved, after he found that a floor tile called a baldosa made a long lasting and relatively low mass combustion chamber that was surrounded by wood ash, a great natural source of refractory insulation. Larry discovered that Rocket type stoves, like plancha stoves, can be described by ten design principles and that these simple engineering principles could be taught to indigenous people, mostly women, who were the experts in using the stoves. My memories of Dr. Winiarski, who was born in Nicaragua, are often about him having a wonderful time speaking Spanish as stoves were constructed and flavorful food prepared.

It is not an exaggeration to say that Larry had a heart of gold. He picked up sick kids and walked from the city dump in Managua to a distant hospital. He slept on cement floors for months at a time in Haiti. Larry lived as others lived in Africa for years and because of his character was loved and respected in villages worldwide. His Rocket stove found a place in people’s homes in the same way that Larry was cared for, accepted, and loved by strangers. Larry is missed by thousands of friends and he was blessed with a life well lived.

There will be a Celebration of Larry’s Life on Saturday, August 28, 2021 at 1:30 PM, at Colgan’s Island, 79099 Hwy 99 N in Cottage Grove, Oregon.

Aprovecho Research Center is pleased to announce that it has just been awarded a $50,000 grant from The Osprey Foundation in support of expanding research into the connection between biomass combustion and climate change.

To date, a handful of lab and field studies have resulted in relatively little information on how stove/fuel interventions could impact emissions. The Gates funded GH Labs has partnered with us in this project because information is vitally needed to make sure that stove interventions are most productive.

Research has identified renewable biomass as carbon neutral but only when burned without making climate forcing emissions.  Aprovecho manufactures and sells the Laboratory Emissions Monitoring System (LEMS) as a tool to characterize cook stove performance. The LEMS enables ARC to develop stoves addressing climate, health, and effectiveness. It has become the centerpiece of more than 60 cookstove laboratories worldwide.

The LEMS measures thermal efficiency and the emissions rates of PM2.5, CO, CO2, and Black Carbon. Minimizing those emissions is important for addressing climate change and protecting human health. The effectiveness of the stoves is assured when cooks are deeply involved in designing them.

Non-methane hydrocarbons (NMHC) and methane contribute to a significant fraction of the global warming potential, especially from charcoal burning stoves, but to date have not been measurable with the LEMS.

The Osprey Foundation sponsored project goals are:

  • Adding the measurement of methane and NMHC to the LEMS.
  • Surveying the global warming potential of wood burning stoves and charcoal stoves and creating market driven designs that address climate/health/effectiveness.
  • Widely distributing open source information (including CAD drawings) describing how to minimize climate forcers in biomass stoves.

At the Leaders Summit on Climate hosted by President Biden, the U.S. government pledged to help countries achieve their climate ambitions through expanding access to clean cooking. We feel very lucky to be investigating how to manufacture improved biomass stoves that cook well, are affordable, and protect personal and planetary health. Thank you, Osprey Foundation!

Prices of carbon credits used by companies to offset their emissions are currently low, due to an excess of supply built up over several years.

According to recent research at the University of London, without the excess supply, prices would be around $15/tCO2e higher, compared to $3-5/tCO2e today. (tCO2e means tonnes of carbon dioxide equivalent, “carbon dioxide equivalent” being a standard unit for counting greenhouse gas (GHG) emissions.)

The paper predicts that the surplus will not last forever, with demand for carbon credits expected to increase five to ten-fold over the next decade as more companies adopt Net Zero climate commitments. This growth in demand should see carbon credit prices rise to $20-50/tCO2e by 2030, as more investment is required in projects that take carbon out of the atmosphere in the long-term. With a further increase in demand expected by 2040, carbon credit prices could rise in excess of $50/tCO2e.

Guy Turner, CEO of Trove Research and lead author of the study said “It is encouraging to see so many companies setting Net Zero and Carbon Neutral climate targets. What this new analysis shows is that these companies need to plan for substantially higher carbon credit prices and make informed trade-offs between reducing emissions internally and buying credits from outside the company’s value chain.”

Imagine the stoves that could be supported by a $20 price for an avoided tonne of carbon dioxide. Stoves with good thermal efficiency can save three tonnes or more per year making long lasting, super clean stoves with chimneys a great deal for carbon developers and investors.

And a great deal for consumers.

Report: https://trove-research.com/wp-content/uploads/2021/06/Trove-Research-Carbon-Credit-Demand-Supply-and-Prices-1-June-2021.pdf

In addition to the recent Tibbetts Award, ASAT has just received EPA recognition for our success. ASAT (the for-profit arm of ARC) was awarded a 2021 EPA Administrator’s Small Business Program Award for Outstanding Accomplishments by a Small Business Contractor. This award recognizes ASAT’s contributions in Fiscal Year 2020 and our efforts to promote EPA priorities of protecting human health and the environment.

ASAT Inc. staff pose with their Tibbetts Award. From left to right: Sam Bentson, David Evitt, Jill Allen, Dean Still, Kim Still, and Dr. Nordica MacCarty.

EPA SBIR funding enabled ASAT to research and develop commercially viable inventions. We developed the Integrated Stove (seen below) that includes stand-alone accessories including the Jet-Flame www.Jet-Flame.com, an air cooled thermoelectric generator, and an electrostatic precipitator that reduces emissions of smoke from chimneys.

The Integrated Stove with Air Cooled 20 Watt TEG Prototype.
A woman sits next to two rocket stoves.
A woman sits next to two rocket stoves.
Firewood is stored between a pair of CQC’s TLC Rocket Stoves.

C-Quest Capital recently announced a collaboration with Macquarie Group Ltd., a financial services company with A$550 billion in assets under management and 16,000 employees in 35 countries. The two firms will fund and deploy efficient cook stoves with pot skirts to one million rural households across Malawi, Zambia and Tanzania. CQC’s preferred rural stoves project standard is two stoves per household to decrease user fallback on three-stone fires.

USAID in-field testing in Africa showed that Rocket stoves with pot skirts reduced smoke emissions by 40% due to the use of less wood while cooking. Addressing health by increasing the air exchange rate in the kitchen and home is a fundamental component of this project. This is done by strategic placement of windows and doors, and promoting half-wall kitchens or well-protected external cooking spaces. A minimum of one visit per year by trained staff to each household to help repair, maintain, and ensure good use of the Rocket stoves is also essential to elevating adoption rates in the targeted areas.

Over the next decade, this investment will deliver over 40 million high quality carbon credits with verified Sustainable Development Contributions to the Voluntary Carbon Market. It is the first leg of a three-pronged program to transform the lives of low-income communities across Sub-Saharan Africa at scale. Ken Newcombe, CEO of CQC, comments, “Our hope is to include something like 100,000 Jet-Flames, assembled by Ener-G-Africa in Lilongwe, Malawi, in the project. Field tests have indicated that the Jet-Flame dramatically reduces PM2.5 emissions and exposure to cooks and their families, further protecting health. If the deployment doesn’t get to 100,000 sold by end of next year it’s not because of the demand – it’s because we couldn’t get the working capital and distribution channels to get the product to the market. Of course, we are exploring all possibilities.”

Manufacturing pot skirts

In 2013, C-Quest Capital (CQC) began distributing and installing the TLC Rocket Stove (TLCRS), a high-efficiency, long-life metal and brick improved cookstove, to the rural poor of Malawi. Early learning has resulting in many upgrades to the stove to improve sustained use and a long life. Over the past two years, CQC has installed the TLCRS in 450,000 Malawian households. Beginning in January 2020, Ener-G-Africa (EGA), a Malawian entity formed by CQC and Malawian entrepreneurs, began manufacturing all the metal stove parts for CQC’s sub-Saharan Africa TLCRS program and has since produced more than 300,000 sets of parts.

Interior view of EGA Stove factory in Lilongwe, Malawi
Stove Kits ready to ship at Ener-G-Africa’s factory in Lilongwe, Malawi

More recently, in February 2021, CQC placed irrevocable orders for the first 10,000 Jet-Flames from Shengzhou Stove Manufacturer in China, marking the first large scale commercial commitment to Jet-Flame distribution in the world. With CQC’s funding, EGA’s factory in Lilongwe is currently building the second solar panel assembly plant in sub-Saharan Africa and will begin manufacturing the solar panels, and eventually the batteries, needed for the Jet-Flame Kit.  CQC is hoping the superior cost and cooking amenity provided by the Jet-Flame will make serious inroads to the charcoal user market.

Through the growing partnership between CQC and EGA, the TLCRS will be installed on a two stove per household basis in three million households across eight sub-Saharan African countries in the next four years. Together, CQC and EGA are setting a new standard for cookstove projects in rural Africa. 

Manufacturing pot skirts
Welded pot supports
Parts ready for packing
Manufacturing area at Ener-G-Africa’s factory in Malawi
cover of Clean Burning Biomass Cookstoves 2nd edition
Click here to download the free pdf file (16mb)

If stoves pollute in the lab, they certainly will in the field. We estimate at least 3 times more. Commercially available biomass cookstoves that meet WHO standards are very rare. ARC continues to be committed to doing research and development to help to get the needed new stoves to market so that field studies will show success in sales, protecting health, saving wood, and making cooks happy. We believe that sharing what we learn is very important! So, we updated our “textbook” and it’s available for free here. The chapters have been updated and rewritten to try and share everything that we have learned in the lab in the last five years.

Enjoy!

Here are some highlights:

  • With clean outdoor air, doubling the air exchange rate halves the concentrations of PM and CO in the kitchen.
  • Using an EPA model of Oakridge, Oregon, the outdoor air concentration of PM2.5 would only be increased from 13.1 μg/m3 to 13.3 μg/m3 if homeowners used an ISO Tier 4 PM2.5 cooking stove.
  • A catalytic converter works well with gases (30-95% reduction of CO) but not with smoke (30-40% reduction of PM2.5) (Hukkanen et al., 2012).
  • We think that the Harris TLUD is perhaps the first “close to optimal” cookstove. It scored 0.7mg/minute PM2.5 with pellets at Lawrence Berkeley National Laboratory. It has a 3 to 1 turn down ratio. Large natural draft static mixers create thorough mixing. Decreasing primary air reduces the rate of reactions (production of wood gas) if the air/fuel mixture becomes too rich. A stationary fan blade spins the flame for longer dwell time. And cooks at ARC love to use it.
  • When carefully tested at ARC, the SSM Jet-Flame in the CQC earthen stove scored Tier 4 for thermal efficiency, CO, and PM2.5.
  • Renewably harvested biomass can be a carbon neutral energy source when burned very cleanly.

We are getting closer to practical solutions! The ones we know about are in the book.

Home made CQC rocket stove (L) is easily improved with the addition of a Jet-Flame (L).

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. C-Quest Capital (CQC) has completed several pilots and has plans to do projects in Africa, Asia, and India. A factory in Malawi is gearing up to build Jet-Flames and solar systems with carbon credits from CQC. 

Home made CQC rocket stove (L) is easily improved with the addition of a Jet-Flame (L).
The CQC home made brick Rocket stove is updated with the Jet-Flame in Malawi

“C-Quest Capital is committed to the Jet-Flame as a truly breakthrough technology. Our stoves in Malawi now use less wood, women save time cooking, and breathe a lot less smoke.”

Ken Newcombe, CEO, C-Quest Capital

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.

Chart showing how more air exchanges reduces indoor air pollution from cooking
Chart describing the influence of air exchange per hour rates on the concentration of PM2.5 in a 30 cubic meter room. Higher air exchanges equal lower PM2.5 concentrations.
Using the ISO box model, Sam Bentson has calculated how increased ventilation helps a classic Rocket stove (around 30 mg/minute of PM2.5) and a modern TLUD burning pellets (about 5mg/minute PM2.5) to protect health.

In the lab, we are used to thinking of the ISO Tiers as static, based on how much pollution enters a 30 cubic foot kitchen during four hours of cooking with 15 air exchanges per hour. However, in 2018 ISO published 19867-3 that further explains how, for example, increasing the air exchange rate (ACH) changes the Tier rating. Generally, doubling the air exchange rate cuts pollution (PM2.5 and CO) in half.

In a low ventilation situation (10 ACH), Tier 4 requires that the emissions of CO are lower than 2.2 grams per megajoule delivered to the pot (g/MJd). But in a higher ventilation condition (30 ACH) the stove can be three times dirtier, emitting up to 7 g/MJd, and still be in Tier 4. Cooking outside is often employed by the cooks we work with because smoke is bothersome and unhealthy.

ISO 19867-3 reports that studies of air exchange rates have found a lot of variation in ventilation, from 4 ACH in very tight buildings to 100 ACH outside in the fresh air. When I lived on a ranch in Mexico, most of the cooking took place outside under a veranda (which also made it easier to smell the wonderful homemade coffee brewing in the early mornings). When Sam Bentson carefully measured the ventilation rate under our veranda in Oregon he also found that when a gentle breeze was blowing (2 MPH) the air exchange rate per hour was around 100.

At 100 ACH, with so much dilution occurring outside, achieving Tier 4 for PM2.5 and CO is easier. In our experience, the most successful and cost effective interventions are situation dependent. We find that a combination of approaches to protecting health enables a welcome adaptability to the actual and interwoven circumstances.