Comparing Cook Stoves (pdf)
Dean Still, Aprovecho Research Institute, ETHOS January 2006
Performance benchmarks for biomass cooking stoves were presented at the 2006 ETHOS (Engineers in Technical and Humanitarian Opportunities of Service) conference by Dean Still, Nordica Hudelson and Damon Ogle of Aprovecho Research Center. The benchmarks will be useful to stove designers and developers to compare their stoves against many others. The benchmarks were derived from tests of 20 stoves (9 replications each) in work funded by Shell Foundation and the Partnership for Clean Indoor Air (USEPA).
Using the Water Boiling Test (WBT) to compare stove performance Aprovecho concluded that stoves without a chimney should use less than 850 g wood (dry basis) to boil 5 liters of water and simmer for 45 minutes. Revised UCB tests showed that these stoves should produce less than 20 g CO and less than 1500 mg particulate matter (PM) to boil and simmer the 5 liters.
Stoves with a chimney should use less than 1500 g of wood under the same conditions resulting in indoor levels of 50 ppm CO anywhere within 30 cm of the stove.
(For examples of this testing see the ETHOS 2005 Stove Summer Camp and Test Results. The report, "Comparing Cookstoves", will be available from Aprovecho later in 2006.
Aprovecho pointed out that lab testing is useful for comparing stove performance and good for engineering and design but is "not close to reality" in the field. They recommend the controlled cooking test for field testing. Since the 2005 ETHOS camp Aprovecho has developed a Portable Emission Monitoring System (PEMS) which was demonstrated at the conference.
Conference presentations showed that a great deal is known about stove engineering at many scales and in many applications. Much of this is reflected in "Design Principles for Woodburning Cookstoves" (available on the PCIA and REPP websites.) Aprovecho test data showed that improving heat transfer to the pot dramatically reduced wood use. Improving combustion efficiency primarily decreased emissions but had little effect on wood use.
Many field tests were reported at the conference. Emissions tests in the lab and in the field were reported by Tami Bond (U of Illinois), Colorado State University, CEIHD (UC Berkeley) and others. Jim Jetter reported that USEPA will start testing emissions from cooking stoves this year and will collaborate with other labs around the world through the Partnership for Clean Indoor Air.
Conference presentations revealed an explosion of field experience around the world and in all areas of stove development, testing, health, safety, emissions and dissemination. We look forward to studying the proceedings and discussing the many topics presented at the conference. Presentations at the conference are available on the ETHOS (Iowa State University) website http://www.vrac.iastate.edu/ethos/ (Note that there is also an ETHOS website at University of Dayton, Ohio http://www.udayton.edu/~ethos/ )
The conference reviewed monitoring projects funded by Shell foundation and PCIA. See the PCIA website http://www.pciaonline.org Sharna Jarvis, Shell Foundation- Breathing Space, and Brenda Doroski, PCIA, both reported their organizations' objectives and strategies for stoves development and implementation.
Links to these proceedings can be be found on the Biomass Cooking Stoves
(REPP) website. The REPP stoves site also has reports and pictures from prior ETHOS testing camps conferences; stove test procedures used by Aprovecho (See Design and Testing); and links to the many organizations participating in the conference (see Organizations).
ETHOS is planning a meeting in Managua, Nicaragua in July/August 2006
Tom Miles January 30, 2006