Stoves and Fuels (Monday)

Vi Rapp (Presenter), Julien Caubel, Rebecca Trojanowski, Tom Butcher, Lawrence Berkeley National Laboratory

Opportunities for advancing residential wood heating technologies

During the last two years, the U.S. Department of Energy has invested funds to advance U.S. wood heating technologies, such as biomass-fired space heaters, central hydronic heaters, and warm-air furnaces. To support DOE’s mission, Lawrence Berkeley National Laboratory and Brookhaven National Laboratory have joined forces to develop simplified test methodologies that will accelerate R&D and enable rapid performance testing that simulates real operating conditions. The simplified test methodologies will guide and inform design decisions prior to investing in costly certification, and they will provide guidance for conducting field measurements. During this presentation, we will provide an overview of the project, present our progress to date, and discuss wood heater innovation funding opportunities.

Dale Andreatta, SEA, Ltd.

Solar Household Energy-9 Ways to Use the Sun

This presentation covers 3 separate solar devices that provide household energy, energy in the form of heat used in the household.  Each device can serve multiple functions, but the bulk of the presentation covers water heating.

Dave Lello, Ekasi Energy

FabStove Gasifier: An open source forced-air gasifier engine kit design.

Biomass gasification combustion technology is well researched and is one of the best-known methods to burn biomass efficiently with very low harmful emissions. The FA-TLUD stove designed and invented by Tom Reed and popularized by Paul Anderson (DR TLUD) is used in a number of commercially sold products. Unfortunately, they are expensive relative to other improved cook stoves and thus have low installed bases.

The open source FabStove Engine design provides a modular framework for separating the stove structure from the gasifier/combustion engine, allowing the gasifier component to be adapted to many cooking applications and styles. By doing this the gasifier engine can be provided as a kit to stove integrators in different markets, and the common parts manufactured in volume at low cost. This will drop the price for consumers.

This approach is different to the way gasifier stoves have been viewed in the past. Ethos attendees will be provided with drawings and videos of the gasifier engine being used for different applications.

Mark Chiveya

The Unique and Advantageous Features of the Bhundu Tsotso (bush twigs) Stove

We present the wood-fuelled Bhundu Tsotso Stove (Bush Twigs Stove) – a unique product concept that meets users’ needs, aspirations and safety and reduces deforestation. Open fires are fuel inefficient leading to wasteful firewood consumption. Across Africa, rural villages are surrounded by denuded forest zones. The design starting point was to use a widely available but underutilised biomass resource – dead branches and twigs. The structure was optimised around the twig dimensions, typically 30 mm. Additionally, user utility, safety and aspirations were considered. The product suite includes 1-, 2- and 4-plate models, all including an oven.

The Bhundu Tsotso remedies many adverse effects of open fireplaces:

  • Looks and functions like a stove
  • Is fuel-efficient – a few twigs are sufficient to cook a meal
  • Has heat plates; no soot
  • A chimney to divert smoke
  • Enclosed combustion chamber;
  • Height-adjustable stand
  • Portable
  • Removable ashtray
  • Durable steel construction
  • Effective heat retention and transfer
  • Complete fuel combustion

The products will be attractive; practical to rural households dependent on woody biomass. Twig collecting differs from tree felling as a firewood source, thereby enhancing sustainable use of forest resources.

Kevin McLean, Sun24, Inc.

Rock Bed Update and Sawdust Stove Revisited

This talk presents a recently published journal article that addresses the effectiveness of rock beds (free) in open-fire cookstoves.  Testing in the lab and field demonstrates that rock beds increase efficiency by a third.  Annually, each cookstove improved with a rock bed will save almost one tonne of CO2e and 700 hours of firewood collection.  In Africa, with each 1 USD we can train 50 households.  Millions of households are now using rock beds but hundreds of millions of households still need training.  You do the math.  Massive and immediate climate mitigation can be realized with relatively little funding. Journal article:

Sawdust stoves can shift cooking from nonrenewable firewood to waste fuels like sawdust, rice hulls, rice straw, maize cobs, maize stalks, bagasse, banana peels and cassava peels.  These stoves are underutilized and should have greater testing and dissemination.

Ken Newcombe, CQuest Capital

CQuest Capital 2020-2021: Stove in a Box and the SSM Jet-Flame

Having invested through our Ener-G-Africa joint venture in pellet fuel production and pellet stoves in Malawi, we recognized that fuel supply  and cost factors made pellet fuels and stoves only a partial solution to  the devastating destruction of the charcoal trade and CQC was open to  other alternatives. By contrast, the Jet-Flame burns found or purchased sticks of wood.

In 2020, CQC assessed consumer’s response in urban Malawi to the Jet Flame in our brick and metal rocket stove as a cook stove and as a total household energy supply package.

Pete Schwartz, Cal Poly Physics

Insulated Solar Electric Cooking With Thermal Storage: More Power and Versatility!

With an Insulated Solar Electric Cooker (ISEC), a 100 W solar panel directly cooks food while providing off-grid electricity access; but it cooks slowly and only during the day. Storing the day’s energy by melting a phase change material allows ISEC to cook more rapidly as well as cook after sunset. By controlling supercooling/crystallization, erythritol (sugar-alcohol with a melting point of 118 C) becomes an ideal thermal storage material for cooking, and for other thermal-storage processes. The efficiency of thermal storage is comparable to that of more expensive systems using battery storage and induction cooktops. For the past 6 months, I’ve cooked primarily with ISEC at home and discovered that the convenience and utility improve as I adapt to ISEC’s unique opportunities and limitations. The next step is to gather experiences from a diverse community of innovators. Grace and Olivia discuss in a separate presentation how A Global Learning Community of researchers, funding agencies, nonprofits, student groups, and local enterprises develops the open source technology and subsidizes local production and dissemination.



Monitoring and Testing Systems (Tuesday)

Ryan Thompson, Mountain Air Engineering

Friday Night Slides

“Mountain Air’s current work in household energy, cookstove emissions, biochar emissions, field work, and space exploration”

David Evitt, Aprovecho

Monitoring Exhaust Oxygen for Performance Insights with Jet-Flame Under-Fire Forced Air

Automotive oxygen sensors complement cookstove testing and analysis with critical information about the fire. Several trends with excess air were observed testing with the Jet-Flame in the lab. The excess air level for cleanest combustion varies with Jet-Flame flow and firepower.

Sam Bentson, Aprovecho Research Center

Measuring real-time firepower while cooking with a portable total capture emissions sampler

Learn how to measure firepower in real-time during a Controlled Cooking Test using Aprovecho’s Portable Emissions Monitoring System. See how the percentage of time the cook spends at high, medium, and low power is used to define the weighting factors of the ISO 19867 performance metrics. Learn how to assign a single thermal efficiency to a stove for carbon credit reporting.

Olivier Lefebvre, Climate Solutions Consulting

Using Stove Use Monitors to measure the contribution of different PM sources to personal exposure in a context of fuel and stove stacking

Understanding the contribution of each source of PM2.5 to personal exposure is needed to craft better programs that will address these sources and reduce the overall exposure.

For example, a low reduction of PM2.5 exposure in the intervention group could come from 3 very different reasons:

–       field emissions of the intervention stove are not as low as expected

–       residual use of dirty stove is still contributing to a large portion of the personal exposure,

–       other -non cooking related- sources of PM are a major contribution

These 3 insights would elicit 3 very different changes in a program aiming at reducing exposure to PM2.5. We discuss here how combining the data from different sensors can help understand the contribution of multiple PM sources in complex systems.

PM exposure can be measured accurately with a gravimetric sampler, while light scattering sensors provide minute by minute measurements. Stove Use Monitors placed on every stove in the household indicate when these stoves constitute an active source of PM. We can then attribute the exposure to a specific stove (or to another source if no stoves are in use) and compile the contribution of each source to the overall exposure.

Brady S. Hales, Matthew R. Jones and Randy S. Lewis, Interdisciplinary Global Engineering Solutions, Brigham Young University

Systems to Monitor Cookstove Emissions Based on Low-Cost Sensors

Interdisciplinary Global Engineering Solutions (IGES) is a group of BYU faculty and students engaged in projects intended to address sociological and technological issues related to reducing poverty and to improving the lives of those living in developing regions around the world. This group is led by faculty from the Chemical and Mechanical Engineering and Sociology Departments at BYU.

IGES has been investigating low-cost sensors capable of measuring air quality and emissions from biomass cookstoves for several years. Recently, we have developed models of low-cost optical particle counters that allow rigorous assessment of the precision and uncertainty of these sensors. We are also developing low-cost gas sensors based on photoacoustic spectroscopy to measure concentrations of CO and CO2 in cookstove exhaust streams. This presentation will describe recent progress made in developing these sensors.

Kelsey Bilsback

A Laboratory Assessment of 120 Air Pollutant Emissions from Biomass and Fossil Fuel Cookstoves

Cookstoves emit many pollutants that are harmful to human health and the environment. However, most of the existing scientific literature focuses on fine particulate matter (PM2.5) and carbon monoxide (CO). We present an extensive data set of speciated air pollution emissions from wood, charcoal, kerosene, and liquefied petroleum gas (LPG) cookstoves. One-hundred and twenty gas- and particle-phase constituents—including organic carbon, elemental carbon (EC), ultrafine particles (10–100 nm), inorganic ions, carbohydrates, and volatile/semivolatile organic compounds (e.g., alkanes, alkenes, alkynes, aromatics, carbonyls, and polycyclic aromatic hydrocarbons (PAHs))—were measured in the exhaust from 26 stove/fuel combinations. We find that improved biomass stoves tend to reduce PM2.5 emissions; however, certain design features (e.g., insulation or a fan) tend to increase relative levels of other coemitted pollutants (e.g., EC ultrafine particles, carbonyls, or PAHs, depending on stove type). In contrast, the pressurized kerosene and LPG stoves reduced all pollutants relative to a traditional three-stone fire (≥93% and ≥79%, respectively). Finally, we find that PM2.5 and CO are not strong predictors of coemitted pollutants, which is problematic because these pollutants may not be indicators of other cookstove smoke constituents (such as formaldehyde and acetaldehyde) that may be emitted at concentrations that are harmful to human health.



Energy and Communities (Wednesday)

Grace Gius and Olivia Hansel, California Polytechnic State University San Luis Obispo

Global Learning Community for ISEC Development and Dissemination

Our research team at Cal Poly SLO has developed the Insulated Solar Electric Cooker (ISEC). To further the development of the ISEC and establish appropriate dissemination, a Global Learning Community was developed that educates students, practitioners and other interested stakeholders in the development of ISECs. This community consists of students taking classes at Cal Poly and performing research on technology, and dissemination partners in the regions where the ISECs will be used. Community partners that reside in the countries where the ISECs plan on being disseminated identify target communities, are knowledgeable of ISEC assembly, and have the ability to sell or distribute to local populations. Communication mediums include an online construction manual with instructional videos, a public forum where all are invited to discuss dissemination, building, and use of ISEC, and virtual weekly meetings with the entire learning community.

Rebecca Apica & Jonas Bervoets, International Lifeline Fund

Lessons on Uganda’s Stove Adoption and Market Development

Our team in Uganda will share firsthand experiences from humanitarian and refugee energy contexts, as well as emerging stove markets. This presentation will discuss challenges, insights, and lessons learned from 15+ years of close collaboration with rural communities and new findings from the frontier of establishing a social enterprise. The team may also share lessons from the market impacts of COVID-19.

Thomas Miles, International Biochar Initiative

Biochar is a Farmer’s Best Friend (Kenya)

Biochars have become important for increasing smallholder resilience. Local resources are used to clean water and as a component of natural fertilizers to produce healthy animals and abundant crops. An overview of production and use of biochar will be presented with a focus on applications in developing countries. Smallholders make biochars in cookstoves, small scale reactors, or collectively in larger reactors. Simple stoves and kilns have been used to make biochars for garden plots. Biochars are also made from concentrated processing residues like rice husks or coffee. The Biochar for Sustainable Soils (B4SS) project tested biochar production and use in China, Ethiopia, Kenya, Peru, Indonesia and Vietnam which resulted in useful        lessons, and training videos. B4SS techniques have since been deployed in other countries. Coffee producers in Vietnam, Peru and Brazil make biochars from residues. Small producers make biochars from rice husks in Cambodia and Kenya. The Elsa project demonstrated biochar stoves in Ghana, Sierra Leone, Togo and now in Burundi. The project resulted in the African Biochar Partnership. Hundreds of smallholders in Thailand, Malawi, Kenya and Ghana are having success with small scale biochar production guided by Warm Heart Worldwide and ETHOS experts in micro-gasification.

Lisa Tang, MIT D-Lab

Livable Himalayan Homes: Results from Preliminary Household Surveys

Household air pollution (HAP) resulting from indoor cooking is an urgent environmental and health challenge throughout the globe. In order to better work with impacted communities to address these issues, it is important to understand existing cooking routines and traditions. Rural communities in the Himalayan Region of India and Nepal were surveyed to collect information about local practices and attitudes regarding cooking and fuel collection. These communities primarily cook using traditional chulha fueled by firewood, and the survey results provide details about firewood collection and consumption, daily cooking routines, seasonal variation, and chulha perceptions and maintenance. 5 to 6 kilograms of firewood are used by the average household each day, and 92% of surveyed households indicated that smoke is an issue while cooking and heating. Chulha are typically operated twice a day, once in the morning, once in the evening. The stoves are reconstructed every two to three months using gathered materials at no cost to the household. The results also provide information on the use of chulha for indoor heating. Firewood use and HAP are the highest from November to February, indicating a significant contribution to firewood consumption and HAP from heating in addition to cooking.

Christa Roth, Food and fuel consultants

Progress on Chitofu 3in1, climate friendly fish processing technology in Malawi

At ETHOS 2020 I showcased a first prototype of a locally developed firewood-based device for frying and parboiling of fish in Malawi. I want to share the progress made: since we added a smoking cupboard, the users named it Chitofu 3in1 (vernacular for large stove),  as now they can use it for all three major fish processing methods with one single device in a climate-friendly way while increasing the quality of their products. Currently firewood savings are estimated to surpass 70% already and more gains are expected as processes are streamlined and time and firewood-wasters reduced. The design is maturing as user feedback trickles in. In January three masters student from the Aquaculture and Fisheries Science Department of the Lilongwe University of Agriculture and Natural Resources (LUANAR) will start their research comparing the new Chitofu 3in1 with the baseline processing methods for different fish species. They will look into aspects for the users (convenience, input savings, economic gains…), consumers (acceptance of new products, willingness to pay..) and nutritional values of the new Chitofu3in1 processed fish products.

Gemara Gifford and Sebastian Africano, Trees, Water, People

The Future of Biomass Cookstoves in Honduras: Public Health &  Community Development Perspectives

Colorado State University, Trees, Water & People, and the Asociación Hondureña para el Desarrollo have published the results of our 3-year, randomized controlled trial on the Justa stove’s impacts on fine particulate matter exposure. The Justa biomass stove is a community-accepted, and feasibly disseminated cooking solution that substantially lowers personal and kitchen PM2.5 in a region where LPG, electricity, and other fuels are unlikely to be available or acceptable for quite some time. Central Americans continue to struggle to access clean cooking alternatives and reduce household air pollution, which was exacerbated in 2020 by COVID-19 and its tumultuous economic and health impacts. Ongoing climate change impacts including widespread forest fires and back-to-back hurricanes also impacted the region at unprecedented scales. Trees, Water & People, and AHDESA are continuing their efforts to improve the circumstances of rural Hondurans by growing their Justa stove program which employs certified stove builders in eight departments, reaching 3,000 families per year, with significant potential to scale. In this talk, we share results from our published studies, as well as our plans to improve access to the Justa stove in Honduras.



Toward diverse testing methods for complex systems (Thursday)

Paul Medwell

A conceptual framework for evaluating clean cooking stove systems

We propose a framework for appropriate evaluation of cooking systems. We describe how those systems are embedded in other systems, and guide evaluators to develop a simple theory of change that connects performance of a small system of action to proxies and desired outcomes in a larger system. We outline features of evaluation protocols that render them fit for the purpose of gauging performance. Uncertainty caused by the system of action, and by influences that are external to that system, is key in choosing appropriate protocols and in drawing inferences about performance. This conceptual paper comes from a small working group within Working Group 1 (“Conceptual Framework”) of ISO TC 285.

Mouhsine Serrar and Jiddu Broersma

The Air Tray Concept and Test Methods-How Should Stoves be Tested

This presentation includes several sections.  First, the air tray stove concept is presented, including both the good features of the concept as well as the limitations.  The air tray uses a small blower to blow air up and through the fire.  This tends to lead to very low particulates and strong steady combustion even with highly non-ideal wood.  Next, test methods are reviewed, again including good features and limitations.  Finally, detailed results from the air tray and other stoves are presented as an example of the limitations of current testing methods.

Nikhil Desai

Stove Testing, Performance, and Use: Have we got it backwards?

This paper suggests a departure from the conventional practice embodied in the ISO TC-285 of defining progress in terms of moving a community of solid fuel users from an undefined baseline stove to a candidate stove for cooking. The extreme form of application of this paradigm is the call for total and irreversible change to clean fuels with the highest rating for PM2.5 emission rates.

Stove stacking, including within the class of candidate stoves and including hot plates, oven, kettles or other mechanical appliances, changes the cook’s time use, hence cooking sequence, because of different powers and controllability.

It has been established that the TC-285 TR 19867-3 ‘default values’ for PM2.5 emission rates cannot be obtained independent of a fixed fire power. Changes in cooking sequences, at the household and community levels, and over time, render these default values irrelevant for policy guidance.

Taking into consideration observed cooking behaviors, it is suggested that we should go backwards. examine the diversity of use first, then performance metrics that matter for the user, and only then come, first, to field testing and eventually to lab testing for finance by competent authorities.



Resources for Scale (Friday)

Emily Floess, Colorado State University

Animation to communicate Indoor Air Pollution

Knowledge about the health dangers of indoor air pollution has not reached many communities, decreasing the motivation to adopt better fuels or stoves. A collaboration between household air pollution researchers and Scientific Animations Without Borders developed an animated video to share ideas about health effects and immediate solutions. The video is low bandwidth and can be shared on mobile phones. There is a procedure to add voice-overs in any language and dialect with the participation of volunteer translators. The video’s success at communicating four “big ideas” is being tested in Spring 2021.

Dean Still, Aprovecho Research Center

Clean Burning Biomass Cookstoves 2nd Edition (2021)

Every five years Aprovecho Research Center updates our book “Clean Burning Biomass Cookstoves” describing what has been learned, new inventions, and providing a current textbook for stakeholders. The 2nd edition has new chapters summarizing experiments in the 30cf Test Kitchen with modeling of indoor and outdoor pollution and effects on health, post combustion reduction of PM 2.5 and CO, under air forced draft techniques to reduce emissions and improved understanding of how to increase combustion efficiency. The talk will describe the new chapters.

Paul Anderson, Woodgas Pyrolytics Inc

Financing cookstoves with a gigatonne of CO2 climate benefits per year

The climate crisis is already driving necessary changes in worldwide social and financial situations.  The need for both carbon dioxide mitigation and removal will bring funding opportunities for the dissemination and use of the fuel efficient, charcoal producing, Tiers 4 and 5 clean-burning gasifier cookstoves, aka TLUD stoves.  With specific real-world-based calculations, the  financial aspects are presented for undertaking projects that meet multiple Sustainable Development Goals (SDGs), including poverty, energy, human health, and the environment, especially for the global climate.  The differences between carbon offsets and carbon sequestration units are explained, including their monetary values and how such carbon units from cookstoves can total one Gt CO2-equivalent per year can be documented for certification.  This presentation is a fresh, stove-focused expression of carbon financing that is restructured in part from a climate perspective in the author’s white paper “Climate Intervention with Biochar” (Section XII) found at 

Anobha Gurung, Clean Cooking Alliance

Development of a spatial platform to support clean cooking in Nepal

The Clean Cooking Alliance (CCA) is working to build an online, open-source, and interactive spatial platform to support the Government of Nepal to achieve clean cooking for all in Nepal by 2030. The spatial platform will utilize location-specific data related to clean cooking and develop relevant tools to allow data-driven planning, coordination, and decision-making to support the uptake and adoption of clean cooking throughout the country. The online platform is envisioned to (1) synthesize location-specific data, (2) enable online geospatial analysis for assessing demand and supply in the clean cooking sector, and (3) share relevant information. The platform’s development is happening in close partnership with the Alternative Energy Promotion Center (AEPC), CCA, and the World Resource Institute (WRI). Using Nepal as a test case, this effort will develop a general framework for creating a platform that can be customized for different geographies based on the needs and priorities.

Chenkai Wang, Shengzhou Stove Manufacturer

Updates on manufacturing capacity at Shengzhou Stove Manufacturer (SSM)

SSM has recently invested millions of dollars to increase production capacity at the factory. The improvements include automated machinery, electrostatic spray painting of high temperature finishes, expedited movement of supplies, quicker loading of containers, and better assembly and packaging. The presentation walks the viewer through the process of how to manufacture millions of highest quality improved cook stoves at scale and affordably.