To those who live in the developed world, it may come as a surprise to learn that more than two billion people still cook and heat their homes with primitive stoves or open fires, burning wood, straw, dung, or coal.
These inefficient technologies emit air pollution that can harm respiratory and cardiac health and exacerbate global warming. People struggle to gather enough biomass fuels to meet their needs. And in many cases, the demand for wood accelerates deforestation.
For nearly two decades a small group of researchers and development advocates has worked to improve household biomass energy technologies. Now concerns over global warming have added a new reason to accelerate the transition to cleaner biomass energy use in the developing world. New stove technologies can produce both heat for cooking and biochar for carbon sequestration and soil
building. Limited testing indicates that these stoves are much more efficient and emit less pollution
There are many challenges faced by stoves designers. These include:
1) Ensuring that biomass consumption is lowered.
2) Producing an affordable, durable stove that is easy to operate and maintain.
3) Producing a stove whose efficiency doesn’t decrease over time.
4) Understanding the potential added burdens of producing and distributing
biochar—especially for women.
5) Understanding behavioral and sociological barriers to new technologies.
Potential Benefits of Biochar-Producing Stoves
Health: Biochar-producing stoves are potentially much cleaner, with lower emissions of carbon monoxide, hydrocarbons, and fine particles.
Climate: Biochar-producing stoves have lower greenhouse gas (carbon dioxide and methane) and black carbon emissions, create biochar that can be used to sequester carbon in soils, and reduce the use of fossil-fuel based fertilizers.
Deforestation: Biochar-producing stoves use less fuel, can use a wider variety of fuels, and can replace inefficient charcoal production technologies.
Soils: Biochar-producing stoves create biochar that sequesters carbon in soils, may in some cases reduce emissions of nitrous oxide (a powerful greenhouse gas) from soils, improves fertility, and increases productivity in degraded soils.
Income Generation: Biochar-producing stoves can accommodate many forms of agricultural residues—some without further treatment. Collecting this residue is another income generating opportunity not presently available for most other stoves since they cannot utilize that type of fuel.
Black Carbon and Biochar-Producing Stoves
The UN Environment Program now recognizes that Atmospheric Brown Clouds (ABCs) are a major contributor to climate change (UNEP, 2008). ABCs are caused by particulate emissions from inefficient combustion of biomass and fossil fuels and they include both black particles (soot) that heat the atmosphere by absorbing sunlight, and white particles that reflect sunlight and contribute to cooling.
Black carbon has a significant effect on global warming, second only to carbon dioxide (CO2) (V. Ramanathan & G. Carmichael, 2008). However, the atmospheric residence time of black carbon is only a few weeks, while CO2 emissions stay in the atmosphere for more than a century. This means that we have an opportunity for immediate action to decrease climate forcing by reducing black carbon emissions.
While much of the black carbon is emitted by forest fires and diesel fuel used in industrialized nations, between 25 and 35 percent comes from household energy use in China and India (V. Ramanathan & G. Carmichael, 2008). Unfortunately, even some improved (non-biochar-making) cookstoves that are otherwise efficient users of wood still emit large amounts of black carbon. One study comparing improved cookstoves showed that a common design, the rocket stove, had black carbon emissions equal to those of an open fire (MacCarty & Bond, et al, 2008). The study found that gasifier stoves, both natural draft and fan-assisted, had very low black carbon emissions. These are the types of stoves that can be configured to produce biochar.
Biochar-producing stoves are not yet a mature technology, and indeed, the emissions from the few designs that have been developed have not yet been systematically tested. However, there are good reasons to believe that they will be as clean as or cleaner than other gasifier stoves that do not retain the biochar but combust it (P. Anderson, 2009).
The Status of Biochar-Producing Stove Technology
A number of researchers and programs world wide are devoted to producing efficient and cost-effective biochar-producing stoves, however, as yet there has been very little in the way of funding for these projects. Below is a description of some of the designs and programs that are in operation.
There are two basic types of stoves that can be used to produce charcoal and heat, the Top-Lit Updraft Gasifier (TLUD) and the Anila stove.
There are many variations on the TLUD, but the biggest distinction is between natural draft TLUDs and fan-forced TLUDs. The TLUD operates as a gasifier by creating a stratified pyrolysis/combustion regime with four basic zones: raw biomass, flaming pyrolysis, gas combustion and charcoal combustion (see diagram to the right, modified from Anderson & Reed, 2004).
The charcoal can be retained if it is removed at the proper time and quenched.
The modern Anila stove was developed by U.N. Ravikumar, an environmentalist and engineer with the Director of the Centre for Appropriate Rural Technologies (CART) at India’s National Institute of Engineering. Anila-type stoves use two concentric cylinders of different diameters (see diagram). Biomass fuel is placed between the two cylinders and a fire is ignited in the center. Heat from the central fire pyrolyzes the concentric ring of fuel. The gasses escape to the center where they add to the cooking flame as the ring of biomass turns to char. The center combustion chamber can be configured as either a rocket stove design (with a side opening door) or as a TLUD with primary combustion air entering from the bottom. (Anila diagram courtesy of Stephen Joseph).
Biochar Stove Programs
A large variety of stoves, including some biochar-producing stoves are demonstrated and discussed on the website bioenergylists.org
United Nations Ministerial Conference of the Least Developed Countries. 2007. Energizing the least developed countries to achieve the Millennium Development Goals: the challenges and opportunities of globalization. Issues Paper.
V. Ramanathan, et al. 2008. Atmospheric Brown Clouds: Regional assessment report with focus on Asia, Summary. United Nations Environment Program.
V. Ramanathan and G. Carmichael. 2008. Global and regional climate changes due to black carbon, Nature Geoscience 222.
N. MacCarty, et al and T. Bond, et al. 2008. A laboratory comparison of the global warming impact of five major types of biomass cooking stoves. Energy for Sustainable Development, Volume XII No. 2.
P. Anderson, Biomass Energy Foundation. 2009. CO and PM Emissions from TLUD Cookstoves. Presented at 2009 ETHOS Conference, 23-25 January 2009, Kirkland, WA, USA.
P. Anderson and T. B. Reed. 2004. Biomass gasification: clean residential stoves, commercial power generation, and global impacts, prepared for the LAMNET Project International Workshop on “Bioenergy for a Sustainable Development,” 8-10 Nov 2004, Viña del Mar, Chile.
For more information
For further information on stoves in general and stoves that produce biochar, see these links:
April 2014: Just released from Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH through the Programme “Poverty-oriented Basic Energy Services (HERA)” is the updated 2nd edition of Micro-gasification: cooking with gas from dry biomass; An introduction to concepts and applications of wood-gas burning technologies for cooking. It is authored by Christa Roth; with contributions by Dr Paul Anderson, Dr Hugh McLaughlin, Thayer Tomlinson and Kelpie Wilson
Understanding Stoves by Dr. Sai Bhaskar Reddy Nakka is an open source book with extensive information on stove design and use. Dr. Reddy covers biochar production as one important aspect of stoves GIZ Publication by Christa Roth – Micro-gasification Manual: Cooking with gas from biomass An introduction to the concept and the applications of wood-gas burning technologies for cooking
Project Profiles and Conference Reports
- New Partnership to Help Bring Clean Cooking to 100 Million Households by 2020, Nov 2014
- Typhoon Ketsana survivor makes a lifetime commitment to increase sustainability through biochar and gasifier stoves, April 2014
- Servals India presentation on charcoal buyback program and 1000 stoves, August 2013
- ETHOS 2012 Conference film highlighting stoves
- Biochar Stoves make a splash at the ETHOS conference, February 2012
- North Vietnam Villages Lead the Way in the Use of Biochar: Building on an Indigenous Knowledge Base
- Using Bamboo for Stoves in Uganda: Julius Turyamwijuka’s work with biochar stoves with the Uganda Industrial Research Institute (UIRI)
- Report from Honduran Gasification Camp, September 2011
- Report from Trentino Stove Camp, Italy in September 2011
- Report from BEF CHAB (Combined Heat and Biochar) camp in August 2011
- First TLUD Stove camp in Uganda: June 2011 stove camp report
- Using Improved Cookstoves and Biochar in Western Kenya: African Christian Organization Network (ACON) work in Kenya to improve cooking and farming techniques
- World Stove: Transforming Haiti and the World: Nathaniel Mulcahy’s work to provide biochar-producing stoves and jobs in Haiti
Projects, Research Centers, and Designs
- Paul Anderson’s Champion TLUD (and offshoots from that design)
- Rob Flanagan’s design efforts mainly in China, The Flana Stove
- Dr. Reddy in India, GoodStove
- iCan Design by Jock Gill
- Dome School design by Kelpie Wilson
- The Biochar Fund
- SCAD Farm Science Center
- ETHOS (sponsors an annual stoves conference in the USA)
- Appropriate Rural Technology Institute (ARTI)
- Approvecho Research Center
- HEDON (Household Energy Network)
- Partnership for Clean Indoor Air
- Biomass Energy Foundation
- Worldstove – the Lucia stove – can be specifically configured to produce biochar. See a video of the stove in action.
- Philips – the Phillips Woodstove – a fan draft TLUD stove that is capable of producing biochar, although not designed to do so.
- British Petroleum – Oorja Stove– a fan draft TLUD stove that is capable of producing biochar, although not designed to do so.