Partnership for Clean Indoor Air

Test Results of Cook Stove
Performance
 Wood burning stoves without chimneys


                                        -•au at,

              Wood burning stoves with chimneys
 Wood burning stoves with
 electric fans
     Liquid fuel stoves
                        Aprovecho Research Center
                                 Shell Foundation
         United States Environmental Protection Agency

-------
The Partnership for Clean Indoor Air was launched by the U.S. Environmental Protection Agency (EPA)
and other leading partners at the World Summit on Sustainable Development in Johannesburg in September
2002. Its mission is to improve health, livelihood and quality of life in developing countries by reducing people's
exposure to indoor air pollution from household energy use. More than 460 organizations are working together to
increase the use of clean, reliable, affordable, efficient and safe home cooking and heating practices. For more
information, or to join the Partnership, visit www.PCIAonline.org.

This document was developed by Aprovecho Research Center under a grant from the Shell Foundation to
provide technical support to household energy and health projects and to ensure that the projects' designs
represent the best available technical practices. The emissions testing equipment used to evaluate the stoves in
this book was provided by a generous grant from the M.J. Murdock Charitable Trust. Additional financial support
was provided by The Woodard Family Trust Foundation. The principal authors of this publication are Dean Still,
Nordica MacCarty,  Damon Ogle, Dr. Tami Bond and Dr. Mark Bryden. The participation of Dr. Bond and graduate
student Christoph Roden was made possible by the U.S. National Science Foundation and the University of
Illinois. The journal article "Fuel use and emissions performance of fifty cooking stoves in the laboratory and
related benchmarks"1 adds to Aprovecho's survey of household stove performance.

Aprovecho is a center for research, experimentation and education on alternative technologies that are
ecologically sustainable and culturally responsive. The Advanced Studies in Appropriate Technology
Laboratory at Aprovecho works to develop energy-efficient, nonpolluting, renewable technologies that reflect
current research and can be made in almost any country. For more information on Aprovecho,
visit www.ADrovecho.org.
1 MacCarty, N., Still, D., and Ogle, D. (2010). Fuel use and emissions performance of fifty cooking stoves in the laboratory and
related benchmarks. Energy for Sustainable Development 14. 161-171.
Layout and Design: Jeremy Roth
Illustrations: Stephanie Korschun
Photos: Bill Loud

-------
Preface

Cooking fires and cook stoves are some of the earliest technologies. Therefore, it is often assumed that we
thoroughly understand cook stoves and there is little improvement to be made in cook stove design. Yet we
continue to learn about how to build cook stoves. There are no internationally accepted design standards for
stoves burning biomass.

Users of this guide are encouraged to think of it not as the final answer, but as a step in a journey towards
better, safer and more functional cooking systems. We encourage them to contribute ideas, thoughts and
experiences at any of the many forums for sharing experiences with stoves, including Internet-based lists,
websites, and conferences.

We hope that our work with stoves is helping to develop a model for how technology can be improved and
implemented in a way that can change people's lives.

Household technologies are essential. By thinking beyond stoves we can have an even greater
impact on the world around us. We can and we will change the world in the same way that we are changing
stoves, by investigating what works in the lab and what works in the kitchen.

-------

-------
Test Results of Cook Stove
Performance

Contents
Introduction 	7
   Reducing fuel use and lowering emissions	8
   Learning from the 3 Stone Fire	8
   Testing cook stoves	8
   The 3 Stone Fire in the laboratory and in the field	9
   Many good stoves	10
   Improving stoves	10

Chapter 1 - Stove Descriptions and Performance	11
  Wood-burning stoves without chimneys	14
   3 Stone Fire	14
   Ghana Wood	16
   20 L Can Rocket	18
   Mud/Sawdust Stove	20
   VITA Stove	22
  Wood-burning stoves with chimneys	24
   Justa Stove	24
   Uganda 2-pot	26
   Patsari Prototype	28
   Onil Stove	30
   Ecostove	32
  Wood-burning stoves with electric fans	34
   Wood Flame	34
   Wood Gas	36
  Charcoal burning stoves	38
   Mali Charcoal	38
   Gyapa Charcoal	40
  Liquid fuel stoves 	42
   Propane	42
   Alcohol - Clean Cook Prototype	44
   Kerosene...                                                  .. 46

-------
Contents
  Solar stove	48
    Parabolic Solar Cooker	48

Chapter2 - Stove Rankings	50
    Time to Boil	51
    Fuel to Cook	52
    Energy to Cook	53
    Carbon Monoxide Emissions	54
    Particulate Matter Emissions	55
    Safety Ratings	56
    Cost to Purchase	57
    Monthly Fuel Use	58

Chapter 3 - Learning From Improved Cook Stoves	59
    Why do some wood-burning stoves boil water faster?	59
    Why do some wood stoves use less fuel?	61
    Why do some stoves emit less carbon monoxide?	62
    Which wood-burning stoves produce less particulate matter?	63
    What was the average firepower and turn-down ratio?	64
    What is the effect of adding a chimney to a wood-burning cook stove?	66
    How does ventilation affect pollution in a kitchen?	68
    How do fans improve wood-burning cook stoves?	71
    How do wood- and charcoal-burning  stoves compare?	72
    How does a retained heat cooker help when cooking?	74
    What is efficiency?	76
    Does increasing heat transfer efficiency have to decrease
    combustion efficiency?	78
    Does CO predict PM?	80
    How do hydrocarbon emissions compare?	82
    How does emission  testing with a hood or in a test kitchen compare?	83
    What is an "improved" cook stove?	85
    How can wood-burning cook stoves be improved?	88

Appendices	91
    Appendix A: Glossary	91
    Appendix B: Testing Methods	93
    Appendix C: Testing Data	97

-------
Test Results of Cook Stove Performance
                                                                                            Introduction
Introduction
More than half of the world's population cook their
food and heat their homes by burning coal and bio-
mass, including wood, dung, and crop residues, over
open fires or in rudimentary stoves. Besides releasing
greenhouse gases into the air, indoor burning of
these solid fuels releases dangerous particulate matter
(PM), carbon monoxide (CO), and other toxic
pollutants and leads to indoor air pollution levels that
are often 20 to 100 times great than the air quality
guidelines of the World Health Organization (WHO).
Unfortunately, the health risks and threats to the
environment are on the rise: the International Energy
Agency estimates that 200 million more people will
use these fuels by 2030.

Exposure to smoke is associated with chronic
obstructive lung diseases and acute lower respiratory
infections. WHO estimates that about 1.6 million
people die prematurely each year due to breathing
smoke. Although breathing CO is dangerous,
especially for pregnant women, the elderly, and
people with heart or respiratory disease, PM is
probably the single most important health-related
risk in breathing wood smoke.2

Breathing in even small  amounts of PM can lead
to increased mortality. The increase in rates of
mortality caused by inhaling very high levels of PM
has yet to be determined. However, a national study
in the U.S. concluded that there is a 0.5 percent
increase in the relative rate of death from all causes
for each increase in the PM10 (particles up to 10
micrometers in diameter) level of 10 ug per cubic
meter. The estimated increase in the relative rate of
death from cardiovascular and respiratory causes was
0.68 percent for each increase in the PM10 level of
10 ug per cubic meter.3

In 2002, the World Summit on Sustainable Devel-
opment identified the inhalation of smoke as a
major health hazard in countries where solid fuel is
used for cooking, heating and illumination. Their
resolution to reduce indoor air pollution has focused
greater attention on the clean combustion of
biomass fuels. Researchers have realized that both
improved fuel efficiency and cleaner combustion
can be achieved in improved cooking stoves.

The goal of reducing indoor air pollution is met by
many interventions (increasing kitchen ventilation,
using a chimney, etc.) that protect the health of a
family. Cleaner burning stoves have many other
benefits beyond improving health including time
savings, cleaner kitchens, reduced effort to gather fuel
and more sustainable use of a diminished energy
resource. Stoves that use less wood and make less
smoke are the result of the efforts of hundreds of
people who have developed solutions over the years.

Over the past 30 years, awareness of the environ-
mental and social costs of using traditional fuels
and stoves has grown, as has understanding about
how to reduce emissions from these stoves. Yet the
improved stoves currently available do not always
represent best practice or an understanding  of
design based on modern engineering. The authors
of this guide intend to provide all stakeholders—
people with an interest in stove design and
dissemination—with information about certain
consequences of their stove choices.

The challenge of cook stove design is that it is not
only a technical issue, but also a human issue. How
and what we cook is tightly coupled to our culture,
lifestyle and resources.  Cook stoves are used exten-
sively and continually. They need to be able to boil
water quickly, simmer food, and cook an almost
infinite variety of foods in different ways depending
on the culture. Cook stoves need to be easy to use,
require little attention and respond quickly when
needed. They need to be safe, efficient and nonpol-
luting. Cook stoves need to be pleasing to the eye.
 Naeher, L., Smith, K., Brauer, M., Chowdhury, Z., Simpson, C., Koenig, J., Lipsett, M., and Zelikoff, J. (2005). Critical review of the health
effects of woodsmoke. Air Health Effects Division, Health Canada, Ottawa.
 Samet, J., Dominici, R, Curriero, R, Coursac, I., and Zenger, S. (2000). Pine particulate air pollution and mortality in 20 U.S. cities, 1987-
1994. The New England Journal of Medicine 2000; 343: 1742-1749.

-------
Test Results of Cook Stove Performance
                                                                                           Introduction
These multiple and sometimes conflicting goals
obviously require an integrated approach to cook
stove design an implementation. The cook and the
engineer are both "experts."

Test Results of Cook Stove Performance represents
a major step forward in developing an integrated
approach to cook stove design. For the first time,
a variety of stoves from across the world have been
tested in a variety of ways and the results presented
here for all to review. One stove is more efficient,
another heats quicker, others are safer, and each of
these stoves pollutes more or less than others. Stove
designers can pick and choose stove design options
to create stoves that serve local needs.

                     use


One of the major motivations for the "first wave"
of improved stove dissemination was to reduce fuel
use and thereby affect the rate of deforestation.
Stoves were designed with fuel efficiency as a major
goal. Improved wood-burning stoves probably
saved between 30% and 50% of the fuel used to
cook with the 3 Stone Fire.'1 Unfortunately, the
first-generation improved stoves were not always
designed to also reduce emissions. Most early stove
researchers did not have the equipment to measure
harmful pollutants. In fact, researchers found that
some of the fuel-efficient designs could actually
increase emissions.

Reducing deforestation proved to be a difficult goal
for the first wave of stove projects to achieve. Studies
showed that to have an effect on deforestation, the
projects would have to make fuel-efficient stoves
available to a much larger percentage of the wood-
using population. Even when stoves were shown to
be cost effective, the need to distribute millions of
stoves was daunting.

Between 1970 and 1980 many cooking stoves
were developed, some were more fuel efficient
than others. The thermal efficiency of stoves was

 Appropriate Technology Sourcebook, 1997.
studied by researchers, and books were written
that have helped create a general consensus about
how to improve cooking stoves. The improved
understanding of the thermodynamics of cooking
with wood has been useful for the various stove-
building projects around the world in their efforts
to manufacture and distribute a new generation of
fuel-efficient and cleaner burning stoves.

              from the 3          Fire

As with any tool, the skill of the operator
determines how well the work is accomplished. The
3 Stone Fire can be operated cleanly, or it can be
very dirty and wasteful. Open fires tend to go out
easily, however, and It Is a natural Inclination to
make an overly large fire or leave smoking wood
under a simmering pot while attending to other
work. The fact that the 3 Stone Fire can be operated
with very different results was confusing to early
Investigators.

In some kitchens, large fires made for cooking
use a lot of wood and make a great deal of
smoke. Small fires are also made that cook food
relatively cleanly. Watching indigenous experts in
the field cook with fire has led to a better
understanding of effective biomass fuel use. Cooks
who are trying to conserve wood tend to meter fuel
by pushing wood into the fire, slowly burning the
wood at the tip of the stick. Knowledgeable cooks
only need a small, hot fire close to the pot to quickly
boil water. Improving upon a well-made 3 Stone
Fire was more difficult than the first generation of
designers had expected. Learning from expert users
helped teach engineers how to make better stoves.



The emission collection system provides real-time
data, is relatively Inexpensive and has been used by
other researchers. (See page 94 for emission hood
details.)

The research staff at Aprovecho decided that It
would be valuable to test a variety of cooking
stoves from around the world. The intention was

-------
Test Results of Cook Stove Performance
                                                                                          Introduction
to provide all stakeholders with information about
how to make the best stove choice.
Eighteen stoves were tested in three ways:
1.  Boiling 5 liters (L) of water in a standard 7-liter
    pot (cold and hot start), simmering the hot
    water for 45 minutes and carefully weighing
    the water remaining and the wood used for
    high power (bringing to boil) and low power
    (simmering) stove operation. The revised
    University of California Berkeley (UCB) Water
    Boiling Test (WBT) protocols were used (three
    repetitions per stove). The revised UCB/WBT
    protocols can  be found in Appendix C and at
    www. aprovecho. org,
2.  The stoves were tested three times again,
    using the revised UCB Water Boiling Test
    under the emissions hood, which measures the
    levels of CO, carbon dioxide (CO2), PM and
    hydrocarbons. The  data are displayed as they are
    being measured in real time. Due to technical
    problems, data from only one of the three Water
    Boiling Tests accurately measured PM.
3.  The stoves were also tested three times boiling
    water and then simmering the hot water
    for 30 minutes in a 15 m3 test kitchen with
    approximately three air exchanges per hour.
    Portable emission equipment was used to
    measure the levels of CO, CO2, and PM.

Testing methods are explained in detail in Appendix B
on page 93.

The results of testing are presented in this book.
The following chapter describes how each stove
performed at high and low power in the following
categories:
•   Time to boil
•   Fuel used to cook
«   Energy used to cook
•   CO emissions
»   PM emissions
»   Safety ratings
•   Cost to purchase
•   Monthly fuel use
Chapter 2 ranks each stove on eight important
performance indicators. The stoves are frequently
compared to the 3 Stone Fire. These comparisons
point out what modifications can reduce emissions
and fuel use.

Chapter 3 of this book attempts to answer
frequently asked questions, such as:

»  Why do some stoves boil water faster?
•  Why do some stoves use less fuel?
•  Why do some stoves make less CO?
«  How do wood- and charcoal-burning stoves
   compare?
•  What is the effect of adding a chimney to the
   stove?
»  How can stoves be improved?


The 3           Fire  in the
      in

It is important to remember that in the Aprovecho
lab testing the  3 Stone Fire used less wood and
made less pollution than cooking fires in the field.
All of the fires  in these tests were carefully made
using dry and uniform sticks of Douglas fir fed
into the fire in a controlled way to optimize the
performance of all stoves.

Well-constructed 3 Stone Fires protected from wind
and tended with care scored between 20% and 30%
thermal efficiency. Open fires made with moister
wood and operated with less attention to the wind can
score as low as 5%. The operator and the  conditions
of use largely determine the effectiveness of operation.
Stoves must be tested with careful repetition in order
to  minimize variables in test results.

Because there are so many differences between
laboratory and field results,  it is difficult to  use
the results of laboratory testing to predict how
stoves will perform in the  real world. However,
side-by-side comparisons can be used to estimate
performance. An automobile that gets 40 miles
per gallon on a dynamometer is more likely to use

-------
Test Results of Cook Stove Performance
                                                                                         Introduction
less gas on the highway than a car that only gets
20 miles per gallon in the same test. A cooking
stove that used less fuel or made less pollution In
a standardized test will, one hopes, translate into
reductions In the field, but only field surveys can
establish the actual performance.

Many good

Several types of stoves were significantly better than
the 3 Stone Fire on most tests, which indicates
that biomass-burning stoves can be both more fuel
efficient and cleaner burning. Stoves equipped with
chimneys can be used safely indoors. Adding a
lightweight rocket-type combustion chamber to a
stove reduces CO by approximately 75% and PM
by about 50% compared to an open fire. Adding a
fan to a wood-burning stove dramatically reduces
emissions.

The 18 stoves covered in this book embody effective
solutions that are now in use in countries around
the world. Having options will enable interested
people to create appropriate solutions tailored to
their needs. There are various successful approaches
to cooking and cooks have the opportunity to
choose their favorites.

Perhaps most important to a cook is how a stove
prepares his or her favorite foods. This factor can
outweigh the advantages of less emissions and
decreased fuel consumption. Stove choice is often
based on far more subjective variables. Reducing
harmful emissions and fuel use will help the cook
and family, but if a stove does not please the cook, it
may not be used.


Improving

Engineers have been studying fire for many
generations,  and there is general agreement that
certain modifications will improve the effectiveness
of biomass fuel stoves. The following suggestions
will improve intermittently fed stoves that
are  designed to achieve more complete initial
combustion and improved heat transfer efficiency to
the pot or griddle.
1. A hotter fire burns cleaner. Insulating around
   a fire helps it burn hotter. Insulation should be
   made from lightweight materials, because heavy
   materials such as sand, clay or cement placed
   around a fire absorbs heat that could be used for
   cooking.
2. Burning too much wood at once creates
   smoke. Wood burns cleanly when It is fed
   slowly Into the fire. Wood  gets hot and makes
   gases that can be more completely burned if the
   gas and air are mixed into flame.
3. The right amount of incoming air helps the
   fire burn cleanly. Increasing the velocity of the
   right amount of air helps the fire burn hotter
   and helps to improve the mixing of fuel, air and
   spark.
4. A grate lifts wood above the floor of the
   combustion chamber. This allows air to .flow
   up through the fire. Air can enter the fire from
   underneath, which is beneficial.
5. Insulating the path of the hot flue
   (except around the pot or griddle) delivers
   more heat to the cooking surface. That is
   because the heat is not lost into the body of the
   stove.
6. Get more heat into the pot.  Most of the
   inefficiency in cooking occurs because heat
   is not effectively transferred to the pot. Heat
   transfer can be increased by directing the hot
   gases in a narrow channel parallel to the cooking
   surface. Gases should be kept as hot as possible
   and flowing at the highest  possible velocity
   without decreasing gas temperatures. More
   detailed information can be found in Design
   Principles for Wood Burning Cookstoves (EPA
   402-K-05-004) available at www.PCIAonline.
   org/resources.
7. Increasing the surface area of the cooking
   surface is helpful. On the other hand,
   decreasing the surface area of exposed water in
   pots helps to reduce steam production.
8. An insulated space above the fire improves
   the mixing of hot gases, air and flame. This
   significantly reduces emissions, especially if the
   gas is well mixed.
10

-------
Test Results of Cook Stove Performance
                                                  Stove Descriptions and Comparisons
Chapter 1
Stove  Descriptions  and  Performance
  Wood-burning stoves without chimneys
  Wood-burning stoves with chimneys
    Jufta, Stoift.
               Uganda, Z-pot
Patsari. Prototype.
OniiSton.
  Wood-burning stoves with
  electric fans
   Wood FUme.
                Wood QMS
           Charcoal stoves
  Liquid-fuel stoves
    Propane.
                Alcokoi - Clton, Cook.
                             Kerosme,
                       Solar cooker
                                                    Parabolic. Solar Ceok&r
                                                                  11

-------
Test Results of Cook Stove Performance
                                                                    Stove Descriptions and Comparisons
This chapter describes how the individual stoves
performed in three major categories:
•   Fuel Economy
•   Cost and Safety
•   Emissions
Included are the following:
•  Description of the stoves
•  Stove origins
•  Specifications
•  Comments on performance
•  Pictures and drawings of each stove
Use the following key to understand what the various numbers and the different categories
mean. More detailed information on each stove and the testing methods can be found in the
appendix.
          Fuel Economy
                 Time to Boil SLof water
          Energy Consumption compared to other stoves
             L
             E
             S
             T

             Fuel Used to Boil
         +   Fuel Used to Simmer
             5L of Water for 45 minutes

             TOTAL -
      Total amount of fuel used to bring 5L of water to a rolling boil and
      then to simmer the water for 45 minutes. The fuel is weighed before
      and after each test phase to determine the amount of fuel used for each
      task.
                     Time to Boil 5 L of
                     water (expressed in
                     minutes:seconds). The
                     total time is an average
                     of the cold and hot start
                     phases of the Water
                     Boiling Test.

                     Energy Consumption rating
                     is how much energy is used to
                     complete a cooking task. Dif-
                    ferent fuels can be compared
                     on the basis of energy used. A
                     rating of I would mean the
                     stove used less energy com-
                    pared to a stove that received a
                     higher rating.
12

-------
 Test Results of Cook Stove Performance
                                                                    Stove Descriptions and Comparisons
     Cost and  Safety
              Cost = $ 0.00
              Fuel Use =  100kg
              estimated per month
     Safety Rating
                                                           The Cost of buying or building the
                                                          stove is shown in U. S. dollars.
           Fuel Use is the amount of fuel used to
           bring 5 L of water to a rolling boil and
           simmer it for 45 minutes twice a day for
           one month (30 days). This number can
           be used to compare the monthly costs of
           operating the stoves based on local fuel
           costs.

          The Safety Rating is determined by
          evaluating the stove in multiple categories
          such as the likelihood of tipping, burns,
          fire spreading and sharp edges on a scale of
          zero to 40 points. Appendix C includes the
          detailed safety evaluation methods.
   Emissions
    Carbon Moruoxide (CO)
Particulate Matter (PM)
The Carbon Monoxide (CO) and Particulate Matter (PM) ratings show the average relation between stoves based
on pollution-level data collected from the test kitchen. The CO and PM averages are based on three tests done in the
test kitchen. Percentages were calculated relative to an open fire.
                                                                                          13

-------
Test Results of Cook Stove Performance
                                                                           Stove Descriptions and Comparisons
   3 Stone Fire
   Origin: Traditional

   Weight:  5.1  kilos

   Fuel Type: Wood
             The 3 stones or bricks (20 x 6.5x9.5 cm)
             hold the pot over the flames of an open fire.
                                                                      Description:

                                                                      Open fires are used every day by
                                                                      a large percentage of the world's
                                                                      population.The 3 Stone Fire can
                                                                      be used more or less successfully,
                                                                      depending on the care and skill of
                                                                      the operator. If the sticks of wood
                                                                      are burnt at the tips and pushed
                                                                      into the center as the wood is
                                                                      consumed, the fire can be hot
                                                                      and relatively clean burning. If too
                                                                      much of the stick is smoldering, a
                                                                      lot of smoke can be  made. If the
                                                                      pot is closer to the fire, more of the
                                                                      heat enters the pot.

                                                                      In this case, the pot was placed
                                                                      12 cm above the ground on three
                                                                      bricks. Dry wood was used.The
                                                                      fire was indoors and care was
                                                                      taken to make the fire as effective
                                                                      as possible.The 3 Stone Fires are
                                                                      usually made less carefully and
                                                                      can be expected to use more
                                                                      wood and make more smoke and
                                                                      harmful emissions than the fires in
                                                                      these tests.
14

-------
Test Results of Cook Stove Performance
                                                              Stove Descriptions and Comparisons
3 Stone  Fire

Performance:

It is difficult to keep the 3 Stone Fire burning.The sticks of wood are often
touching the ground, and the fire can die out fairly easily.The temptation is
to make a big fire, so it won't go out.

A lot of smoke was made when lighting the fire and when it wasn't burning
well. When the fire was large and hot,there was less smoke.

The 3 Stone Fire was hard to start. If it had been outside in the wind,
lighting the fire and cooking would have been much more difficult.
3 Stone Fire

Test Results

Fuel Economy ^^
• y£y~~2>
fy Time to Boils/, ofw/afer- 26:42
Energy Consumption compared to other stoves
L .* . M
E 1 0
A I S
s l| IT
5.2
Fuel Used to Boil 601 g
+ Fuel Used to Simmer 51 7 g
5L of Water for 45 minutes
TOTAL- 1,1 18 g
?
1

1 Emissions
Carbon Monoxide (CO)
Open fire
L . P» . M
M ?
I T
T 0% 100% 200%
100%
I
PC
L
E
A
T (

Cost and Safety /9\
JH Cost = $0.00
Fuel Use = 67 kg
estimated per month
Safety Rating
1 \\ M

s If ' T
r o 10 ' 30 40
1
1

irticulate Matter (PM) JTm
Open fire VJlili/
A i M MEm
?
1 n T
)% 100% 200%
100%
                                                                                  15

-------
Test Results of Cook Stove Performance
                                                                        Stove Descriptions and Comparisons
   Ghana Wood
   Origin: Ghana, Africa

   Weight: 8 Kilos

   Fuel Type: Wood
                                                   19cm
                                                                  Description:
The Ghana stove surrounds the fire
with a thick ceramic liner inside a
sturdy sheet metal body.The pot sits
on three supports about 20 cm above
the stove floor. Fuel is pushed into
the fire through a door that can be
closed.

This is a durable and safe stove.The
walls protect the fire from the wind,
and the opening is large enough to
freely feed the fire. Closing the door
helps leftover wood simmer food
efficiently.

Once the stove body is hot, the walls
surrounding the fire help keep the
fire from cooling. Radiant heat from
the fire directly contacts the pot.
Sturdy handles help the cook move
the stove as needed.
16

-------
Test Results of Cook Stove Performance
                                                      Stove Descriptions and Comparisons
Ghana Wood

Performance:
Although the Ghana stove uses slightly less fuel than the 3 Stone Fire, it
pollutes more. Enclosing a fire inside a cylinder of heavy ceramic and sheet
metal does not help the fire burn more cleanly. Instead, the walls may cool
the fire initially and cause the fire to smoke a bit more.
On the other hand, the stove is faster to boil than the 3 Stone Fire and
works better in windy conditions. As mentioned, closing the door helps
conserve wood, which is very useful when simmering food.
Test Results
 Fuel Economy
       Time to Boil siof water- 21:48
 Energy Consumption compared to other stoves
    L
    E
    A
    S
             4.1
   Fuel Used to Boil
+  Fuel Used to Simmer
    5L of Water for 45 minutes
    TOTAL -
                              10
                           422 g
                           574 g
                           996 g
                                                                      T
Cost  and Safety
                                                Cost = $ 5.00
                                                Fuel Use = 60 kg
                                                estimated per month
                                          Safety Rating
L
E
A
S
                                                   10
                                                         20
                                                                      40
  Emissions
   Carbon Monoxide (CO)
                                      Paniculate Matter (PM)
\\

Si i T
T 0% 100%
124%

' T
200%
                                                   Open fire
                                      E
                                      A
                                      S
                                      T 0%
                                                    100%
                                                                200%
                                                           178%
                                                                        17

-------
Test Results of Cook Stove Performance
                                                                        Stove Descriptions and Comparisons
  20 L Can  Rocket
   Origin: Prototype

   Weight: 6.6 kilos

   Fuel Type: Wood

   Contact:
   Aprovecho Research Center

   PO Box 1175
   Cottage Grove, OR 97424

   www.aprovecho.org
   tel: (541) 767-0287
   tel: (541) 895-5677
  12 cm
                                           36cm
                                                                  Description:
Relief agencies such as the World
Food Program distribute food in 20
L metal cans all around the world.
Rwandan refugees made stoves from
these cans in the Mgunga camps in
Tanzania.

A rocket-type combustion chamber
is inserted in the can.Three supports
made from folded metal hold up the
pot. Wood ash fills the space inside
the stove between the combustion
chamber and the stove body. A metal
cylinder (not shown) surrounds
the pot, increasing heat transfer
efficiency by forcing hot flue gasses
to scrape against the pot.

The high temperatures in the
combustion chamber deteriorate
the metal, which has to be replaced
in two to three months. Making the
combustion chamber from ceramic
or preferably lightweight firebrick
makes this stove much longer lasting.
Ligthweight ceramic weighs less than
0.8 grams/cubic centimeter.
18

-------
Test Results of Cook Stove Performance
                                                        Stove Descriptions and Comparisons
20 L Can Rocket

Performance:

The lightweight, well-insulated combustion chamber in the 20 L can stove
reduces both CO and PM compared to the 3 Stone Fire. Both heat transfer
and combustion efficiency are improved, which means that fuel use and
emissions are reduced.

The CO produced is about one-third of that made by the 3 Stone Fire, and
the PM is about half.The higher temperatures and improved mixing of
flame,gases and air above the fire result in more complete combustion.

Since metal does not last at the high temperatures in the combustion chamber, it is preferable to
replace it with insulative refractory ceramics when possible.
                                20 L COM. Rocket

Test  Results
  Fuel  Economy
       Time to Boil siofwater- 22:18
 Energy Consumption compared to other stoves
    L
    E
    A
    S
    5 L of Water for 45 minutes

    TOTAL -
  Emissions
   Carbon Monoxide (CO)
               Open fire
     tf
   T 0%
                 100%
      26%
     ill
     o
     S
     T
            3.4
    Fuel Used to Boil        361 g
 +  Fuel Used to Simmer   372 g
733 g
                                      1
               Cost and  Safety
                      Cost - $ 0.00*

                      Fuel Use = 44 kg
                      estimated per month
                                            Safety Rating
I








                                                    10
                                                           20
                                                                  30
                                       33
                                                                        40
*   *When cans and sheet metal are available for free.
           Particulate Matter (PM)
    M
    O
    S
    T
 200%
                                         o%
       *
                        Open fire
3
                   60%
                                                      100%
  0
  S
  T
200%
                                                                           19

-------
 Test Results of Cook Stove Performance
                                                                           Stove Descriptions and Comparisons
   Mud/Sawdust  Stove
   Origin: Africa

   Weight: 18 kilos

   Fuel Type: Wood
26 cm
                                                                     Description:
This stove is made from 60% sand
and 40% clay.Then equal amounts
of sawdust are added to the earthen
mixture.The sawdust lightens the
sand/clay material.

Eventually the sawdust nearest the
inside of the wall burns away, creat-
ing small pockets of air which help to
insulate the fire.

The gap between the earthen cylinder
and the pot was 12mm.The small
channel forces the hot flue gases to
scrape against the sides of the pot
after touching its bottom.The scrap-
ing of heat against the side of the
pot increases  heat transfer efficiency,
which decreases wood use compared
to the 3 Stone Fire.

Emissions are higher than an insulated
stove with a combustion chamber
that effectively increases the mixing
of the flame and smoke. However, this
type of stove can be built with found
materials and provides improved fuel
use and protection of the fire from
wind.The stove might be suitable
for refugees, especially when used in
well-ventilated areas.
 20

-------
Test Results of Cook Stove Performance
                                                               Stove Descriptions and Comparisons
Performance:

Just as with the 3 Stone Fire, it is difficult to keep the fire going in this stove.
A grate under the fire would be a big help. It is tempting to make an overly   )
large fire that will not easily die out.                                   I
                                                                (
                                                                s
The small channel is filled with flame at times, and it is easy to see           j
why more heat enters the pot through the sides. It is nice to see that a       !
potentially zero-cost wall of earth and sawdust can  boil water faster while
using less fuel than a 3 Stone Fire.

Unfortunately, the stove only works well with the pot for which it was designed.
                                                                  Mud/ Sawdust Stove
 IC>Ol  1 •Ii.iF'dtJI

        Time to Boils/,
 Energy Consumption compared to other stoves
    L
                                16:00
                                    m
   TO         ^s

   Fuel Used to Boil         386 g
+ Fuel Used to Simmer     406 g
   5L of Water for 45 minutes    	
   TOTAL
  Carbon Monoxide (CO)
                Open fire
   E
   A
   S
                               793 g
                                                 A
                                                 §
                                                 T 0
                                                          10
                                                                  20
                                            Particulate Matter (PM)
                                                          Open fire
1
0%
;,'i,'s=a
100% 20<
75%
                                              0%
                                                        J
                                                            100%
                                                        87%
                                                                         30
                                                                           33
                                                                                 T
                                                         and
Cost = $ 0.00
Fuel Use =  48 kg
estimated per month
                                                 Safety Rating
                            s
                            T
                                                                                 40
                                                                            m
                   1 T
                  200%
                                                                                   21

-------
   Test Results of Cook Stove Performance
                                                                              Stove Descriptions and Comparisons
      VITA Stove
      Origin: West Africa

      Weight: 2.2 kilos

      Fuel Type: Wood

      Contact:
      Relief International/
      EnterpriseWorks-VITA

      1100 H Street NW, Suite 1200
      Washington, DC 20005
      www.enterpriseworks.org

      info@enterpriseworks.org
      tel: (202) 639-8660
      fax: (202) 639-8664
                                 27 cm
28cm
Description:

The VITA stove was designed by
Dr. Sam Baldwin. It is the result of a
great deal of study to inexpensively
reduce the fuel used to cook food.

Dr. Baldwin's bookBiomass Stoves:
Engineering Design, Development, and
Dissemination is an important work
that describes practical methods to
improve heat transfer and decrease
the wood used for cooking.

The VITA stove is made from sheet
metal that creates an appropriately
sized gap between the pot and stove
body. A grate holds the wood up over
the floor, allowing air to pass through
the fire.The pot is held up by three
sturdy supports. Plans to build the
stove are included in Biomass Stoves.

Since the pot is contained within the
cylinder of sheet  metal, both it and
fire are protected from the wind.The
stove will work well only with the
intended pot.The stove is  durable,
lightweight and portable.
    22

-------
Test Results of Cook Stove Performance
                                                       Stove Descriptions and Comparisons
VITA Stove

Performance:
The simple VITA stove is one of the most fuel-efficient stoves tested.The fire
is close to the pot, and hot flue gases contact both the bottom and sides of
the pot. It can boil water quickly.

Since the stove does not have a combustion chamber, merely an open
space for the fire, and because the fire is close to the pot,emissions are
rather high.
The VITA stove features ease of construction, low cost and decreased fuel use.This type of stove seems
well-suited to emergencies and where cooking occurs outdoors in well-ventilated areas.
Test  Results
 Fuel Economy
       Time to Boils/,
 Energy Consumption compared to other stoves
                          14:00
i
s
T (
J
> f\ , !
?
r~ ^ T
; 10
    Fuel Used to Boil        352 g
 +  Fuel Used to Simmer    338 g
 5L of Water for 45 minutes

 TOTAL -
Emissions
 Carbon Monoxide (CO)
             Open fire
                            689 g
                                         L
                                         E
                                         A
                                           TO
                                                    10
                                                          20
                                       Particulate Matter (PM)
\\

Si i T
T 0% 100%
121%
                               M
                               0
                               S
                               T
                             200%
                                                    Open fire
                                         Cost and Safety
Cost = $ 2.00

Fuel Use = 41 kg
estimated per month
                                           Safety Rating
                                     E
                                     A
                                     S
                                     T 0%
           \
                                                     100%
                                                                 200%
                                                            165%
                     I;
                                                                 30     40
                                                                          23

-------
Test Results of Cook Stove Performance
                                                                            Stove Descriptions and Comparisons
   Origin: Central America

   Weight: 175  kilos

   Fuel Type: Wood

   Contact:
   Trees, Water & People

   633 Remington Street
   Fort Collins, CO 80524

   twp@treeswaterpeople.org

   tel: (970) 484-3678
   toll free: (877) 606-4897
                                           94 cm
                                            28 cm
Description:

The Justa stove body is constructed
from bricks enclosing a rocket-
type combustion chamber.The
combustion chamber is made from
"baldosa,"a widely available and
inexpensive ceramic floor tile.

Wood ash is deposited  between
the combustion chamber and the
stove body.The wood ash almost fills
the interior leaving a 2 cm channel
between the ash and the griddle. Hot
flue gases flow in this space to the
chimney.

A constant cross-sectional area is
maintained throughout the stove
from the fuel entrance, up the
combustion chamber, under the
griddle, to the chimney. Heat transfer
is increased because the hot gases
are forced to scrape against the
underside of the griddle.The wood
ash insulation helps to keep the
gases hot, while the constant cross-
sectional area of the spaces inside the
stove reduce friction that would slow
the gases. Heat has to pass through
the griddle to the pots on top of it.
24

-------
Test Results of Cook Stove Performance
                                                                 Stove Descriptions and Comparisons
                                                                      Jtwta-Stffve
Justa Stove

Performance:
The Justa stove can heat two or three pots of food at once. It is designed
for Central America, where the griddle is used for making tortillas. Since
heat has to pass through the griddle to the pots of food, the stove uses
more fuel than a single-pot stove to boil and simmer water.
However, the sea led stove body takes almost all pollution out of the room
through the chimney.This type of stove, with a functional chimney, can
solve the problem of indoor air pollution.The solid body also protects the
occupants from burns.
The griddle-type stove provides the cook with many advantages: clean pots, clean kitchen, greater
convenience, and potentially reduced fuel use for a variety of cooking tasks.ln field tests, the Justa stove
saved approximately 70% of the wood typically used for cooking.

Test Results

Fuel Economy <^Q
\P^~-3
fH) Time to Boils/, ofw/afer- 46:42
Energy Consumption compared to other stoves
L \ , M
A
i zn
s | IT
5 6.3
Fuel Used to Boil 662 g
+ Fuel Used to Simmer 704 g
5L of Water for 45 minutes
TOTAL -

1,367g

\
Cost and Safety /f\
j| Cost = $ 60.00
^^ Fuel Use = 82 kg
estimated per month
Safety Rating
* i M
E
A
S
TO 10 20
!
; 	

?
H- -jl T
30 40
38

   Emissions (in Test Kitchen)
   Carbon Monoxide (CO)
                                              Particulate Matter (PM)
   L
   E
   A
   5
   T
                  Open fire
                   100%
                                     M
                                     O
                                     S
                                     T
                                  200%
L
E
A
S
T
                                                             Open fire
                                                              100%
                                                                            200%
     0%                                      0%
  The Justa stove and Patsari Prototype were not tested in the test kitchen since they are stationary stoves. However, like the
  other stoves with chimneys, they can be expected to produce close to 0.0 CO and PM because the chimney removes
  pollution from the room.
  r                	-  - —                 _    —    	,«r*   -•	        _^v^.^
                                                                                       25

-------
Test Results of Cook Stove Performance
                                                                        Stove Descriptions and Comparisons
  Uganda 2-pot
   Origin: Uganda

   Weight: 36 kilos

   Fuel Type: Wood

   Contact:
   Aprovecho Research
   Center

   PO Box 1175
   Cottage Grove, Oregon 97424
   www.aprovecho.org
   tel: 541 767-0287
                 12 cm
                                                       96 cm
Description:

The Uganda 2-pot stove has a rocket-
type combustion chamber made
from lightweight insulative fire brick.
The hot gases made by the fire pass
through narrow, insulated channels
around the first pot, which is deeply
sunk into the stove.The gases then
pass through an insulated tunnel
and are forced into narrow channels
around the second pot before exiting
the chimney.The pots fit tightly
into holes in the sheet metal top,
preventing smoke from escaping into
the kitchen.

Like the VITA and Mud/Sawdust
stoves, this stove only works well with
the pots that come with it. Sinking
pots into cylinders that force hot
gases to scrape against the sides
of the pots increases efficiency
and decreases wood use. However,
this technique requires the use of
specified pots.
26

-------
Test Results of Cook Stove Performance
                                                                Stove Descriptions and Comparisons
Performance:
This stove is fast to boil and uses less wood than most stoves with
chimneys. Sunken pots help to dramatically improve fuel use and time to
boil in stoves with chimneys. Smoke exits the room up the chimney.

The first pot is 30 cm in diameter, which uses up most of the heat from the
fire.The smaller 23 cm pot will not boil but instead is designed to simmer
sauce while corn porridge is being prepared in the larger pot. For both pots
to boil, the first pot needs to be smaller than 25 cm, or the firepower has to
be increased.

The fire brick insulates the stove body, which does not get very hot, making this a safer stove.


1
(j-J Time to Boils/, ofw/afer- 16:12
Energy Consumption compared to other stoves
L % . M
E 1 •"' m °
TO 3 5
Fuel Used to Boil 262 g
+ Fuel Used to Simmer 459 g
5L of Water for 45 minutes
TOTAL - 720 g

»


and /T\
JH Cost - $ 40.00
Fuel Use = 43 kg
estimated per month
Safety Rating
1 L \ i M
«
:.;-'-*| o
s
* I ' T
T0 10 20 30 40
37
!


                    (in Test Kitchen)
   Carbon Monoxide (CO)
Particulate Matter (PM)
                 Open fire
E
A
T (

"j£ J
f
)% 100% 20(
2%
                                    M
                                    O
                                    S
               Open fire
                                                                              M
E
A
S
i
1

" ' ""-HI
''"""ill
i
T 0% 100% 20
3%
                                                                                     27

-------
Test Results of Cook Stove Performance
                                                                           Stove Descriptions and Comparisons
 Patsari  Prototype
   Origin: Patzcuaro,
   Michoacan, Mexico

   Weight: 280 kilos

   Fuel Type: Wood

   Contact:  GIRA

   Centra Comercial El Parian
   Interior 17, Col. Morelos, A.P.
   158, CP. 61609, Patzcuaro,
   Michoacan, Mexico

   giraac@gira.org.mx
   Tel: (+0052) (434) 342.32.16
                                      12cm
                                                          90 cm
Description:

The GIRA team developed the Patsari
stove with indigenous people in the
high-altitude, hilly regions of Mexico.
This version has two hollow cylinders
of insulative brick inside the spaces
under the two pots.The fire directly
hits the bottoms of both pots.

A second fire inside another
insulated combustion chamber
is used to cook tortillas on a large
circular comal or griddle.

The stove is made from a Lorena-type
earthen mixture of approximately
60% sand and 40% clay. Molds
are used to ensure uniformity.The
lightweight ceramic insulation
near the fire, with the Lorena mix
surrounding it, creates a composite
material which is  inexpensive and
beautiful.

A chimney stove made mostly from
sand and clay provides a family with
a clean, pleasant cooking stove that
removes harmful  pollution from the
kitchen.
28

-------
Test Results of Cook Stove Performance
                                                              Stove Descriptions and Comparisons
Patsari  Prototype
Performance:
The stove with chimney removes essentially all of the harmful emissions
from the room.The draft is sufficient to draw the smoke into the stove and
up the chimney.

Since the pots in this version are directly contacted by the fire, the Patsari is
more fuel efficient than other stoves with griddles.

This is a safe stove which keeps heat inside and does not overly warm the
exterior.

Test  Results

Fuel Economy <^Q
l^-^--3
(TH) Time to Boils/, of wafer- 34:48
Energy Consumption compared to other stoves
% J *"
E • 0
A I S
S f 1 T
55.7
r,,J-k|ii^.J-k^j4-^wD^wil c co ^m
huel Used to boil 558 g
+ Fuel Used to Simmer 720 g
5L of Water for 45 minutes
TOTAL- 1,277g










Cost and Safety /f\
j| Cost - $ 35.00
^^ Fuel Use = 77 kg
estimated per month

Safety Rating
1 M
i | S
5 1 ~ T
TO 10 20 30 40
Oft
ou
!
.__
  Emissions  (in Test Kitchen)
   Carbon Monoxide (CO)
                 Open fire
   E
   A
   S
   T 0%
H
              Particulate Matter (PM)
                            Open fire
^
                                                                            M
                  100%          200%
    0%                                     0%
  The Patsari Prototype and the Justa stoves were not tested in the test kitchen. However, like the other stoves with chimneys, they
  can be expected to produce close to 0.0 CO and PM because the chimney removes pollution from the room.
                                                                                   29

-------
Test Results of Cook Stove Performance
                                                                           Stove Descriptions and Comparisons
   Origin: Guatemala

   Weight: 280 kilos

   Fuel Type: Wood

   Contact:
   HELPS International

   15301 Dallas Pkwy. Suite 200
   Addison, TX 75001

   info@helpsinternational.com

   tel: (972) 386-2901
   toll free: (800) 414-3577
                      36 cm
                                       10 cm
                                                   71 cm
    15cm
Description:

Don O'Neal developed this molded-
cement griddle stove with the help of
indigenous women in Guatemala.The
three-part stove is made in a factory
using molds.

A rocket combustion chamber made
from ceramic floor tile material
(molded baldosa) is surrounded by
loose pumice used as insulation. The
pumice fills the stove within
2 cm of the griddle, creating a wide
channel that forces the hot flue gases
to scrape against the underside of
the griddle.

The griddle has removable inserts so
flame can contact the bottom of the
pots. A protected fence around the
chimney (not pictured) guards the
users from burns.

The Onil stove is made in a factory
and looks professionally made.The
molded-cement body is strong and
very long lasting.
30

-------
Test Results of Cook Stove Performance
                                                       Stove Descriptions and Comparisons
Onil Stove

Performance:
The Onil is a well-thought-out stove that can boil two pots of water
exposed to flame and hot gases.The removable inserts are well made and
fit large and small pots.
Fuel use is similar to the Justa. Smoke is removed from the kitchen through
the functional chimney.
                                                          OnU Stove

The Onil ranks high on safety and is a fine example of an improved griddle-
type stove. Field surveys found that the Onil stove uses approximately 70% less wood than traditional
cooking methods in Guatemala.
Test  Results
 Fuel Economy
       Time to Boils/,
 Energy Consumption compared to other stoves
                          28:00
i
S
T (

) !

1 n
> I- rt 10
    Fuel Used to Boil        584 g
 +  Fuel Used to Simmer    802 g
 S/. of l/l/afer for 45 minutes

 TOTAL -
                          1,386g
Emissions  (in Test Kitchen)
 Carbon Monoxide (CO)
                                       Particulate Matter (PM)
               Open fire
M

T 0% 100%
0%
                               M
                               0
                               S
                               T
                             200%
                                                 Open fire
                                         Cost and  Safety
Cost - $ 72.00

Fuel Use = 83 kg
estimated per month
                                           Safety Rating
i
S
T (




) 10 20 30 40
39
                                         1%
                                                     100%
                                                                         M
                                                                 M
                                                                 O
                                                                 S
                                                                 T
                                                                 200%
                                                                         31

-------
Test Results of Cook Stove Performance
                                                                         Stove Descriptions and Comparisons
   Ecostove
   Origin: Brazil, Nicaragua,
   Honduras

   Weight: 45 kilos

   Fuel Type: Wood

   Contact:  Brazil: ECOFOGAO
   Ltda, Rogerio Miranda ecofogao®
   ecofogao.com.br

   Nicaragua: PROLENA Marlyng
   Buitrago; mbprolena@hotmail.com

   Honduras: AHDESA, Ignacio Osorto
   Nunez; ignacio.osorto@ahdesa.org
   tel: (504) 226-4527
                        10 cm
                                                  82cm
Description:

The Ecostove was developed by
Rogerio Carneiro de Miranda in
Nicaragua and Brazil. PROLENA has
made thousands of stoves of this
type in Nicaragua.

The Brazilian Ecostove has a heavy
cast iron griddle that provides
an excellent cooking surface.
A handmade ceramic rocket
combustion chamber is surrounded
by lightweight cement insulation
made from Aerated Autoclaved
Cement. A channel under the griddle
ensures improved heat transfer.
Baffles direct hot flue gases to  more
evenly heat the griddle before exiting
the chimney.

The body of the Ecostove is made
from painted sheet metal and angle
iron.The cooking surface is at waist
height.The stove seems very well
suited for making tortillas or for any
type of grilling. Furthermore, it can be
equipped with a coil to heat piped-in
water.
32

-------
Test Results of Cook Stove Performance
                                                              Stove Descriptions and Comparisons

                                                                                  '"\

Performance:

Like other griddle stoves, the Ecostove is designed to cook tortillas. Large
amounts of grilled food can be prepared at the same time. Once the
griddle is warm,the stove can boil water in about 30 minutes. However,
it can use more fuel than an open fire to boil water from a cold start.This
stove was a favorite of cooks at Aprovecho since large amounts of fried
food can be prepared at the same time.

The heavy griddle takes time and fuel to heat initially, but once warm,the
stove had about the same fuel economy as other griddle stoves.

The Ecostove chimney removed almost all the smoke from the test kitchen,creating a much safer and
cleaner living space.


        Time to Boil siotwater-  38:36
 Energy Consumption compared to other stoves
1



\

	 '^
                                    w
                                    o
                                    s
                                 10
    Fuel Used to Boil       1,171 g
 +  Fuel Used to Simmer    843 g
    5L of Water for 45 minutes
    TOTAL -
2,014 g

                          Cost = $60.00

                          Fuel Use =  121 kg
                          estimated per month
                                                Safety Rating

I
s
T (



fe 	 1
) 10 20 30
34
i
40
                    (in Test Kitchen)
   Carbon Monoxide (CO)
              Particulate Matter (PM)
                 Open fire
                            Open fire

V&JB o
>1 i S
I ' T
0% 100% 200%
0%
                                             2%
                                                           100%
                                                                        H °
                                                                        I?
                                                                        200%
                                                                                  33

-------
   Test Results of Cook Stove Performance
                                                                          Stove Descriptions and Comparisons
     Wood  Flame
     Origin: Canada

     Weight: 6 kilos

     Fuel Type: Wood

     Contact: Woodflame

     6155 Des Grandes-Prairies
     Blvd. Montreal (Quebec),
     Canada H1P1A5

     info@woodflame.com

     tel: (514) 328-2929
     toll free: (888) 664-6966
                           • 29.5 cm
23.5 cm
a oa a a D a o a o o aaa
ana o a o D o a a a DO a
aoarj aanaao cinan
Description:

The Wood Flame stove uses a small,
externally powered electric fan to mix
wood gases, air and flame to clean
up combustion. In the bottom of the
metal combustion chamber are many
very small holes which send strong
jets of air up through the burning
wood.

A griddle used for grilling comes with
the stove.When tested, the griddle
was removed and supports were
made to hold up the pot.

The combustion chamber is filled
with small pieces of wood and lit. As
the fire grows larger, the speed of the
fan is increased manually,creating a
small blast furnace. Wood is added to
the combustion chamber by sliding it
under the pot.

Blowing air up into the fire causes the
fire to look very "jumpy" and frenzied.
Flames turn from yellow to reddish to
blue at various stages of burning.
   34

-------
Test Results of Cook Stove Performance
                                                         Stove Descriptions and Comparisons
Wood Flame

Performance:

The Wood Flame stove uses a batch of wood to grill foods. In these tests,
the grill is removed so a full Water Boiling Test can be performed.

This is an interesting stove to use, with nine fan speeds.The amount of
air is matched to the size of the fire.The stove is amazingly clean burning
and uses a reduced amount of fuel. Feeding the stove under the pot is
challenging, however.

The stove uses much less wood than the 3 Stone Fire and makes only 16% the CO and 2% of the PM
made by the 3 Stone Fire.
Test Results

Fuel Economy <^Q
l^-^--3
(TH) Time to Boils/, of wafer- 19:30
Energy Consumption compared to other stoves
L 1 J M
11 °
A 1 ^ S
s f H T
T° 2.8 5
^,,^1 1 lr-^r-vy-4 -l-^w D <^s. I 1 *""! ^1 ft .*••
huel Used to boil 249 g
+ Fuel Used to Simmer 377 g
5L of Water for 45 minutes
TOTAL - 626 g










Cost and Safety /f\
j| Cost - $ 229.00
^^ Fuel Use = 38 kg
estimated per month

Safety Rating
) M
E o
A I S
s i •n T
r 0 10 20 30 40
Vr*il
!
__.
Emissions
 Carbon Monoxide (CO)
             Open fire
                                        Paniculate Matter (PM)
    0%
       24%
                 100%
                                M
                                0
                                s
                                T
                              200%
                                                     Open fire
                                     E
                                     A
                                     S
                                     T 0%
                                         14%
                                                      100%
  M
  O
  S
  T
200%
                                                                            35

-------
Test Results of Cook Stove Performance
                                                                          Stove Descriptions and Comparisons
   Origin: Prototype

   Weight:  1 kilo

   Fuel Type: Wood

   Contact: Dr. Paul Anderson
   Biomass Energy Foundation

   227 South Orr Drive
   Normal, IL61761
   www. b iom assenergyfou ndat ion. org

   tombreed2009@gmail.com
   tel: (309) 452-7072
                    5 mm
   18cm
                                              10 mm
                                                                    Description:
Dr.Tom Reed has spent decades
studying and designing stoves in
which wood gases are burned in two
stages.This stove is started
by top-lighting a batch of fuel that
burns gases rising up into the fire
zone.

The Wood Gas stove is made from
sheet metal.The combustion
chamber has holes near the bottom
and larger holes near the top. A
fan powered by an external battery
blows jets of air into the fire.The fan
is located under the fire.

This very lightweight stove could fit
into a backpack.The handle makes
moving the stove easy, even when lit.
36

-------
Test Results of Cook Stove Performance
                                                          Stove Descriptions and Comparisons
Wood  Gas

Performance:
The Wood Gas stove is very clean burning and uses less fuel than other
stoves to boil and simmer water. Like the Wood Flame stove, it shows the
ability of a fan to dramatically lower emissions.
This isa small camping stove, so to complete the Water Boiling Test, fuel
must be added piece by piece to the fire under the pot.This manouver is a
bit difficult.

How the stove burns wood seems almost miraculous.There is no smoke after starting the fire;fan stoves
operate almost as cleanly as liquid-fueled stoves.
Test Results

Fuel Economy <^Q
\P^~-3
fH) Time to Boils/, ofw/afer- 23:42
Energy Consumption compared to other stoves
L 1 J M
E • 0
A I S
s f H T
T° 2.5 5
r,,J-k|||^-J-k^J4-^wD^wil *""! ^» C *•••
huel Used to boil 235 g
+ Fuel Used to Simmer 224 g
5L of Water for 45 minutes
TOTAL - 459 g










Cost and Safety /f\
j| Cost - $ 55.00
^^ Fuel Use = 28 kg
estimated per month

Safety Rating
% , M
I | V
S ^ T
r 0 10 20 30 40
oo
!
__.
Emissions
 Carbon Monoxide (CO)
             Open fire
                                         Paniculate Matter (PM)
 E
 A
 S
 T 0%
       22%
                 100%
                                 M
                                 O
                                 S
                                 T
                              200%
                                                      Open fire
                                          0%
                                                       100%
                                         15%
  M
  O
  S
  T
200%
                                                                             37

-------
Test Results of Cook Stove Performance
                                                                          Stove Descriptions and Comparisons
   Mali  Charcoal
   Origin: Mali

   Weight: 4.2 kilos

   Fuel Type:  Charcoal
                           22 cm
                                                          26 cm
Description:

The Mali charcoal stove is made from
silver-painted sheet metal. A door
controls the amount of air entering
underneath the charcoal.Controlling
the air saves charcoal,especially
during simmering, when less heat is
needed. A ring can be removed to
lower the pot when  smaller amounts
of charcoal are used.

An air gap between  the conical
combustion chamber and the
outside of the stove helps reduce
external temperatures.The conical
combustion chamber helps the
charcoal slide into the center as it is
consumed.

A draft is created that pulls air up
through the fire, increasing the heat
available for boiling.This increased
draft takes the place of blowing on
the charcoal to increase firepower.
38

-------
Test Results of Cook Stove Performance
                                                             Stove Descriptions and Comparisons
Performance:

Opening the door increases the draft, which speeds combustion. Closing
the door saves fuel and provides the reduced heat needed for efficient
simmering.

It's easy to see why people like charcoal. Once the fire is lit, cooking with
charcoal is almost as convenient as liquid fuel.

However, burning charcoal can emit high levels of CO. Especially at high
power, the levels of CO emitted were dangerous.

On the other hand,emissions of PM were lower than from most wood-burning stoves.
 I%7'C84 I ivrOUHO
                      I
        Time to Boils/,
 Energy Consumption compared to other stoves
    L
    E
    A
    S
                            38:36
                   5.3
    Fuel Used to Boil
    Fuel Used to Simmer
    5L of Water for 45 minutes

                           406 g
                           268 g
TOTAL
                               674 g
                                            T0
                                                     10
                                                            20
   Carbon Monoxide (CO)
                 Open fire
                                       Particulate Matter (PM)
                                                     Open fire

£•:
1 ' T
0% 100% 200%
194%
5
11!
» | IT
T 0% 100% 200%
56%
                                                                               T
                                                    and
Cost =  $ 5.00

Fuel Use = 40 kg
estimated per month
                                                Safety Rating
                    )__	 i  m

                           ?
                    ^A T
                                                                    30      40
                                                                     33
                                                                                  39

-------
Test Results of Cook Stove Performance
                                                                        Stove Descriptions and Comparisons
  Gyapa Charcoal
   Origin: Ghana

   Weight: 9 kilos

   Fuel Type: Charcoal

   Contact:
   Relief International/
   EnterpriseWorks-VITA

   1100 H Street NW, Suite 1200
   Washington, DC 20005
   www.enterpriseworks.org

   tel: (202) 639-8660
   fax: (202) 639-8664
                           32 cm
                                 24 cm
                                                       25cm
                                                                   Description:
The Gyapa charcoal-burning stove is
produced by Enterprise Works/VITA in
Ghana.The stove has a ceramic liner
bonded to the sheet metal body by
an insulative, cement-like adhesive.
The charcoal sits on a ceramic grate.

The door under the grate allows
varying amounts of air to pass up
into the fire, which raises and lowers
firepower. Having  a door on the
opening under the fire seems to be
an important feature in an improved
charcoal-burning  stove.

Three supports made from bent steel
bars hold the pot close to the fire.
Sturdy handles facilitate portability of
the stove.
40

-------
Test Results of Cook Stove Performance
                                                          Stove Descriptions and Comparisons
Gyapa  Charcoal
Performance:
The Gyapa is somewhat faster to boil than the Mali stove while using less
fuel. However,fuel use for both boiling and simmering is approximately the
same for the two stoves.

The ceramic liner in the Gyapa may help to lower the temperature of the
external stove body.
                     Qyapa. CkMrcoaJL

The stove boils water relatively quickly with the door open and simmers
nicely with the door closed or mostly shut. Again, the amount of CO emitted was high while PM was
reduced,compared to the 3 Stone Fire.

Closing the door lowers the firepower and reduces the emissions of CO. For this reason, charcoal stoves
seem to be safer when simmering.
Test Results

Fuel Economy <^Q
\P^~-3
fH) Time to Boils/, ofw/afer- 28:24
Energy Consumption compared to other stoves
L li J M
E • 0
A ! s
s \— "1T
4.8
Fuel Used to Boil 342 g
+ Fuel Used to Simmer 353 g
5L of Water for 45 minutes
TOTAL - 694 g

1


Cost and Safety ^\
j| Cost = $ 5.90
^^ Fuel Use = 42 kg
estimated per month
Safety Rating
-%
i
II

!\
M
O
S
1 1 T
I" 0 10 20 30 40
32
!



  Emissions
   Carbon Monoxide (CO)
                Open fire
Particulate Matter (PM)
              Open fire
   E
   A
   S
   T
                 100%
                              200%
E
A
S
T 0%
                               292%
        56%
                                                       100%
                                                                    200%
                                                                             41

-------
Test Results of Cook Stove Performance
                                                                            Stove Descriptions and Comparisons
   Origin: USA

   Weight: 1.8 kilos

   Fuel Type: Propane

   Contact:
   Century Tool & Manufacturing

   1462 US Route 20 Bypass
   P.O. Box 188
   Cherry Valley, Illinois 61016

   tel: (800) 435-4525
                            16 cm
       16 cm
         22cm
                           9cm
                                                  29 cm
                                                                      Description:
The stove consists of a single burner
that screws onto a propane cylinder.
A knob under the burner adjusts the
rate of burn. It is very pleasant to
go so easily from high to low power
with the twist of a knob.

The stove burns with a hot blue
flame,created by precise mixing
of gas, air and flame.The gas exits
under pressure, which aids the
superior mixing.The stove sits on top
of a wider stand that makes it more
stable.

A propane stove delivers controllable,
clean heat that is appreciated by
cooks around the world.
42

-------
Test Results of Cook Stove Performance
                                                        Stove Descriptions and Comparisons
Propane
Performance:

This camping-type stove is low powered. In Mexico,some propane stoves
are not hot enough to make tortillas,so the 3 Stone Fire is used.

Cooking on a propane stove is quite luxurious after operating a wood-
burning stove. It is pleasurable to turn on the stove and cook food without
having to even think about tending the fire.                         '

Propane can be somewhat dangerous as old storage cylinders and stoves
begin to leak.

Time to boil is slightly faster than the 3 Stone Fire. Emissions are close to zero compared to the other
stoves in these tests.
                                                          Propane
                                                                       ~.-J
Test  Results
 Fuel Economy
       Time to Boils/,
 Energy Consumption compared to other stoves
    E
    A
     °   1.8
    Fuel Used to Boil
    Fuel Used to Simmer
    5L of Water for 45 minutes
    TOTAL-
Emissions
 Carbon Monoxide (CO)
             Open fire
  1%
                100%
                           23:00
                              O
                              S
                              T

                           64 g
                           75 g
                          139g
               E
               A
                                          I" 0
                                                  10
                                                        20
                                       Particulate Matter (PM)
   M
   O
   S
   T
200%
                                                    Open fire
                                       E
                                       A
                                       S
                                       T
                                        0%
                                                     100%
                                                               30
                                         Cost and Safety
                     Cost - $ 1 8.00

                     Fuel Use = 8 kg
                     estimated per month
                                           Safety Rating
                                                                   33
                                                                  M
                                                                  O
                                                                  S
                                                                  T
                                                                  200%
H
M
O
S
                                                                      40
                                                                          43

-------
Test Results of Cook Stove Performance
                                                                            Stove Descriptions and Comparisons
  Alcohol - Clean Cook
  Prototype
   Origin: Nigeria

   Weight: 5.1  kilos

   Fuel Type: Alcohol

   Contact:
   Project Gaia, Inc.

   Mr. Harry Stokes
   22 Mummasburg Street,
   PO Box 4190
   Gettysburg, PA 17325

   hstokes@projectgaia.com
   www.projectgaia.com
   tel: (717) 334-5594
   fax:(717)334-7313
                             601
                                          19 cm
                                                                     Description:
The Clean Cook alcohol stove
prototype has two large fuel tanks
filled with an absorptive material
so the filled tank can be placed
under the burner without leaking.
Protective barriers placed over the
fuel canisters prevent filling the stove
while lit.

The stove body is stainless steel and
attractively made.Two levers open
and close the burners. By adjusting
the levers, which close a cover over
the fire, the power can be controlled.
Two sheet metal pot supports help  to
shield the fire.

The tanks are not pressurized,
allowing the fuel to burn in small,
open cylinders underneath the pots.
An unpressurized system is simple
and does not depend on air tightness
to work.
44

-------
Test Results of Cook Stove Performance
                                                       Stove Descriptions and Comparisons

Alcohol - Clean Cook Prototype

Performance:
Alcohol has been a popular fuel for many years. Like kerosene, it has been
used on boats when propane is considered too dangerous.
Alcohol stoves have a reputation for being somewhat low powered. In this
case, the pot used in the Water Boiling Test was covered, which helped
the water reach full boil but makes comparisons with other stoves using
uncovered pots problematic.The lid was removed for simmering.
                                          Alceturt- Clean Cook
                                                          J
The stove cooks food like other liquid-fueled stoves, without tending.The cook can work on other tasks
and gain hours once spent adjusting the fire.
Test  Results

Fuel Economy <^Q
l^-^--3
(TH) Time to Boils/, of wafer- 36:36
Energy Consumption compared to other stoves
1 J M
E • 0
A I S
S f 1T
T° 1.9
r,,J-k|ii^.J-k^j4-^wD^wil ^VIO^M
huel Used to boil 148 g
huel Used to bimmer 21 3 g
5L of Water for 45 minutes
TOTAL - 361 g










Cost and Safety /f\
j| Cost - $ 50.00
^^ Fuel Use = 22 kg
estimated per month

Safety Rating
% M
5 !
5 1 ^ T
TO 10 20 30 40
O7
O/
!
__.
  Emissions
   Carbon Monoxide (CO)
               Open fire
                       Particulate Matter (PM)
    3=
   T 0%
       14%
100%
               M
               0
               S
               T
            200%
                                   Open fire
E
A
S
T
                        0%
                                     100%
M
O
S
T
                                                 200%
                                                                          45

-------
 Test Results of Cook Stove Performance
                                                                           Stove Descriptions and Comparisons
    Kerosene
    Origin: Hong Kong

    Weight: 2.3 kilos

    Fuel Type: Kerosene

    Contact:
    Solar Stoves
    B/32 Shanker Tekari
    Jamnagar, Gujarat
    India 361004
              31 cm
                                             31 cm
22 cm
Description:

This kerosene stove uses wicks to
bring kerosene into a combustion
chamber where, with proper
adjustments such as trimming the
wicks and having the wicks at the
appropriate height, a blue flame is
created under the pot.

When correctly adjusted, the stove
can burn cleanly. However, as
received, the stove is somewhat
smoky.

An adjustable knob moves the
multiple wicks up and down. In
this way, higher and lower power
can be achieved.The wicks release
the correct amount of gases that
combust in a vertical chimney.The
evolution of this simple-but-effective
system has created a remarkable
technology that effectively burns the
unpressurizedfuel.

A large tank under the stove holds
the kerosene.The stove body is  made
of painted sheet metal.
  46

-------
Test Results of Cook Stove Performance
                                                      Stove Descriptions and Comparisons
Kerosene
Performance:

The short internal chimney helps the kerosene stove burn with a blue
flame when adjusted correctly.To operate the stove cleanly may take time
and practice,and the stove may need to be rebuilt. As received,the stove
was smoky and the stove tank leaked.

However,after the stove was set up properly, it ran well without much
tending.

Emissions, while low,are appreciably higher than with propane and alcohol.
Test Results
 Fuel Economy
       Time to Boils/,
 Energy Consumption compared to other stoves

    L
 41:54
s
T (
j
> f\ /* '•

; 10
                               M
    Fuel Used to Boil        115g
    Fuel Used to Simmer    132g
    5L of Water for 45 minutes
    TOTAL -
247 g
               TO
                       10
                              20
  Emissions
   Carbon Monoxide (CO)
           Particulate Matter (PM)
                                                  Open fire
         48%
              20%
                                    30
               Cost and  Safety
Cost =  $ 9.50

Fuel Use = 15 kg
estimated per month
                                          Safety Rating
i




                                                                        M
                                                                  35
                                          40
l\
S 1
T 0%

1!
I ' T
100% 200%
E
A
T (

1 ?
I ' T
)% 100% 200%
                                                                        47

-------
Test Results of Cook Stove Performance
                                                                           Stove Descriptions and Comparisons
 Parabolic Solar Cooker
   Origin: USA

   Weight: 103 kilos

   Fuel Type: Sunshine

   Contact:
   Aprovecho Research
   Center

   PO Box 1175
   Cottage Grove, Oregon 97424
   www.aprovecho.org
   tel: 541 767-0287
                             167 em
                                                                     Description:
The parabolic solar cooker was built
by students at Aprovecho. It was
made from a recycled fiberglass
satellite dish six feet in diameter.
One-inch by one-inch square mirrors
were glued to the surface with silicon
adhesive.

A metal support holds an insulated
box with a glass bottom at the focal
point. Reflected sunlight passes
through glass on the bottom of the
insulated box.The insulation helps
capture the heat and increase the
efficiency of heat transfer.The box
is placed around the pot and can be
removed by the cook.

The parabola is supported inside
a wooden frame on rollers so the
reflector can follow the moving sun.
The solar cooker needs to be
re-aimed at the sun about every half
hour.The stove can also be used with
a wok for grilling. One or two pounds
of food can be fried quite successfully.
48

-------
Test Results of Cook Stove Performance
                                                        Stove Descriptions and Comparisons
Parabolic Solar Cooker

Performance:
The solar cooker can generate over 2,000 watts of power, boiling 5 L of
water in an average of 70 minutes.
Solar cooking uses no fuel and makes no emissions.The solar cooker is the
only stove tested that does not use diminishing resources to cook food.The
fuel is free,as long as the sun is shining.
The cook can usually stand behind the reflector to stir food. However, the
glare when standing in front of the dish can be intense.
It is necessary to be careful, because the heat at the focal point is invisible and over 550° C.
Cooking with this parabolic dish is easy compared to using wood, because it only requires tracking the
sun once in awhile.

Test Results
 Fuel Economy
       Time to Boil siof water-  70:00
 Energy Consumption compared to other stoves
   il
    0.0
    Fuel Used to Boil
    Fuel Used to Simmer
    5L of Water for 45 minutes
    TOTAL -
  Emissions
   Carbon Monoxide (CO)
  O
  S
  T
                               10
Og
Og
Og
E
A
                     10
                            20
        Particulate Matter (PM)
L .
5
, M
Is
^ ' T
T 0% 100% 200%
                                                    Open fire
                                       E
                                       A
                                       S
                                       T
    0%
          0%
                                                     100%
                                   30
             Cost and Safety
                   Cost  - $ 55.00

                   Fuel Use = 0 kg
                   estimated per month
Safety Rating
M
O
S
                                                                     32
                                     M
                                     O
                                     S
                                     T
                                                                 200%
                                                                          49

-------
Test Results of Cook Stove Performance
                                                                                   Stove Rankings
Chapter 2

Stove  Rankings
This chapter contains lists and graphs showing
how each stove ranks in eight important
performance categories:
1. Time to Boil
Waiting for a pot to boil, or for tortillas to cook on
a slow stove, can be frustrating. Cooks and families
often appreciate a powerful, adjustable stove.

2. Fuel to Cook and 3. Energy to Cook
When looking at fuel consumption, it is
important to consider the amount of energy in
each type of fuel. For instance, propane has over
twice the amount of useful energy in each
gram compared to wood. When a particular stove
uses less fuel, it does not necessarily use less energy.

4. Carbon Monoxide and 5. Particulate
Matter Emissions
Carbon monoxide (CO) is a deadly odorless,
poisonous gas. Inhaling particulate matter (PM)
can cause acute respiratory infections and a
host of other diseases. To protect the health of a
family, high levels of indoor air pollution must be
prevented. Please note that measures of particulate
matter include total emissions produced by the
stoves, even chimney stoves, which protect the user
from these emissions. For this reason, while the
chimney took almost all of the pollution out of the
test kitchen, the PM results are higher, as measured
under the collection hood (see page 83) from the
chimney exit.


6. Safety Ratings
Using fire can be dangerous. Burns are often
horribly disfiguring. A stove should be as safe as
possible. Stoves were evaluated for safety using
safety evaluation methods developed by Nathan
Johnson at Iowa State University. Details on the
evaluation procedures can be found in Appendix C
on page 121.
7. Cost to Purchase and 8. Monthly Fuel
Use
The cost to build or purchase a stove and the
continual burden of fuel costs can be very impor-
tant factors in stove choice. A more expensive stove
that saves money by using less fuel can be a
worthwhile purchase. However, if the initial cost is
too high, the stove may never become popular. If
fuel is scarce in the area where the stove is being
used, fuel use may be the most important
factor.

What is the best stove for you?

Some people may think that the cost of the
stove is most important. Others might put
a higher value on time to boil, fuel use or safety.
Which categories are most important to your mar-
ket?

A total value for each stove can be determined by
adding the score in each of the categories that
are most important to you. The best stove in
each category can be given a score of 1, the next
2, and so on. In this way, the stove with the lowest
total score would be the "best" and might suit your
needs. As we've said, the choice of a best stove may
be based on preferences that are outside of these
categories. For example, griddle stoves  can make
tortillas and simmer multiple pots using one fire.
The griddle stove uses more energy to boil a single
pot, but it may cook food more successfully.

We strongly recommend that local cooks try the
proposed stove. Only cooks will know  if a stove is
suitable or not.
50

-------
Test Results of Cook Stove Performance
                                                           Stove Rankings
1. Time to Boil
5  L of water
  Shortest Time

  1.  Vita Stove
  2.  Mud/Sawdust
  3.  Uganda 2-pot
  4.  Wood Flame Fan
  5.  Ghana Wood
  6.  20 L Can Rocket
  7.  Propane
  8.  Wood Gas Fan
  9.  3 Stone Fire
  10. Onil
  11. Gyapa Charcoal
  12. Alcohol - Clean Cook
  13. Patsari Prototype
  14. Mali Charcoal
  15. Ecostove
  16. Kerosene
  17. Justa
  18. Parabolic Solar Cooker

  Longest Time
#1  Vita Stove
1 4.0
           minutes
#2  Mud/Sawdust
     16.0
      minutes
#3  Uganda 2-pot
     16.2
      minutes

VITA
Mud/ Sawdust
Uganda 2-pot
Wood Flame Fan
Ghana Wood
20 L Can Rocket
Propane
Wood Gas Fan
3 Stone Fire
Onil
Gyapa Charcoal
Alcohol
Patsari Prototype
Mall Charcoal
Ecostove
Kerosene
Justa
Solar
^^^^^^^•14.0
^^^^•^^•16.0
i i^ .>






































19.5





I ;>.



.0
3.4

i -<4 g








I -(




8.6
8.6

\4.h



70.0

0 10 20 30 40 50 60 70 80
Time to Boil 5 L (min)



chimneys I B itoves without chimneys
                                                                 51

-------
Test Results of Cook Stove Performance
                                                        Stove Rankings
2. Fuel to Cook
Boil and Simmer 5 L of water for 45 minutes
  Least Fuel Used

  1.  Parabolic Solar Cooker
  2.  Propane
  3.  Kerosene
  4.  Alcohol - Clean Cook
  5.  Wood Gas Fan
  6.  Wood Flame Fan
  7.  Mali Charcoal
  8.  VITA
  9.  Gyapa Charcoal
  10. Uganda 2-pot
  11. 20 L Can Rocket
  12. Mud/Sawdust
  13. Ghana Wood
  14. 3 Stone Fire
  15. Patsari Prototype
  16. Justa
  17. Onil
  18. Ecostove

!  Most Fuel Used
#1  Parabolic
     Solar Cooker
0.0
         grams
#2  Propane
     139
     grams
#3  Kerosene
     24/  grams

Solar
Propane
Kerosene
Alcohol
Wood Gas Fan
Wood Flame Fan
Mali Charcoal
VITA "
Gyapa Charcoal
Uganda 2-pot
20 L Can Rocket
Mud/Sawdust
Ghana Wood
3 Stone Fire
Patsari Prototype
Justa
Onil
Ecostove
0
^^139
^^^^•247
^^^^^•317
^^^^^^^4









59




1720




996
i i i IK






il j.h/

1 1 W



12,1114

0 500 1,000 1,500 2,000 2,500
Fuel to Cook 5 L (g)
^^•1 Stoves with chimneys ^^H Stoves without chimneys
52

-------
Test Results of Cook Stove Performance
                                                      Stove Rankings
3.  Energy to Cook
Boil and Simmer 5 L of water for 45 minutes
  Least Energy

  1.  Parabolic Solar Cooker
  2.  Propane
  3.  Alcohol - Clean Cook
  4.  Wood Gas Fan
  5.  Kerosene
  6.  Wood Flame Fan
  7.  Uganda 2-pot
  8.  VITA
  9.  20 L Can Rocket
  10. Mud/Sawdust
  11. Ghana Wood
  12. Gyapa Charcoal
  13. 3 Stone Fire
  14. Mali Charcoal
  15. Patsari Prototype
  16. Justa
  17. Onil
  18. Ecostove

  Most Energy
#1   Parabolic
     Solar Cooker
     0.0 kj
#2 Propane
    6,670 kj
#3 Alcohol -
    Clean Cook
    6,766 u

Solar
Propane
Alcohol ~
Wood Gas Fan
Kerosene
Wood Flame Fan
Uganda 2-pot
VITA
20 L Can Rocket
Mud/ Sawdust
Ghana Wood
Gyapa Charcoal
3 Stone Fire
Mali Charcoal
Patsari Prototype
Onil
Justa
Ecostove
0




















^m 6,670
^m 6,766













,434
>,623

I I I ^&(l









I
)7
L i c i on


1


3
9,496
19,801
1/1.1/4

1 7.1. S03




I/.1.

573


\y/,yyy
0 5,000 10,000 15,000 20,000 25,000 30,0
Energy To Cook 5 L (kJ)

• itoves witn c
DO 35,000 40
tiimneys ^^H Stoves without chimney
000
                                                            53

-------
Test Results of Cook Stove Performance
                                                                   Stove Rankings
4.  Carbon Monoxide  Emissions
Boil  and Simmer 5  L of water for 45 minutes
   Least CO Released

   1.  Parabolic Solar Cooker
   2.  Propane
   3.  Alcohol - Clean Cook
   4.  Wood Gas Fan
   5.  Kerosene
   6.  Wood Flame Fan
   7.  20 L Can Rocket
   8.  Patsari Prototype
   9.  Uganda 2-pot
   10. Justa
   11. Onil
   12. VITA
   13. Ecostove
   14. Mud/Sawdust
   15. Ghana Wood
   16. 3 Stone Fire
   17. Mali Charcoal
   18. Gyapa Charcoal

!   Most CO Released
  #1   Parabolic
        Solar Cooker
0.0
             grams
  #2   Propane
       0.5
     grams
  #3  Alcohol -
       Clean Cook
       5.3
     grams
Please note that these are measures of total emissions produced by the stove (including
emissions that would normally be exhausted from the house via a chimney), not emis-
sions to which the cook is exposed. Many chimney stoves that resulted in low emissions
in the test kitchen measure higher in the PM and CO emissions categories, which were
measured under the collection hood from the chimney exit.
        Solar
      Propane
      Alcohol
   Wood Gas Fan
      Kerosene
  Wood Flame Fan
  20 L Can Rocket
  Patsari Prototype
   Uganda 2-pot
        Justa
        Onil
       VITA
      Ecostove
   Mud/Sawdust
   Ghana Wood
    3 Stone Fire
   Mali Charcoal
   Gyapa Charcoal
0.0
10.5
"5.3
^m6.9
^"7.8
^^—15.
















3


i >4 [

31.5































































































.2
                  20       40      60      80      100
                                    CO to Cook 5 L (g)
                       120
                       140
160
                                                     l Stoves with chimneys ^^H Stoves without chimneys
54

-------
Test Results of Cook Stove Performance
                                                                    Stove Rankings
5.  Particulate Matter  Emissions
Boil  and Simmer 5 L of water for 45 minutes
   Least PM Released

   1.  Parabolic Solar Cooker
   2.  Alcohol - Clean Cook
   3.  Propane
   4.  Kerosene
   5.  Wood Gas Fan
   6.  Wood Flame Fan
   7.  Mali Charcoal
   8.  Gyapa Charcoal
   9.  Uganda 2-pot
   10. Justa
   11. Patsari
   12. 20 L Can Rocket
   13. Onil
   14. VITA
   15. Mud/Sawdust
   16. 3 Stone Fire
   17. Ghana Wood
   18. Ecostove

   Most PM Released
      #1  Parabolic
           Solar Cooker
0.0
                 mg
      #2  Alcohol -
           Clean Cook
4.4
                mg
     #3  Propane
           4.5 mg
    Please note that these are measures of total emissions produced by the stove (including
    emissions that would normally be exhausted from the house via a chimney), not emis-
    sions to which the cook is exposed. Many chimney stoves that resulted in low emissions
    in the test kitchen measure higher in the PM and CO emissions categories, which were
    measured under the collection hood from the chimney exit.
       Solar
      Alcohol
      Propane
     Kerosene
  Wood Gas Fan
 Wood Flame Fan
  Mall Charcoal
  Gyapa Charcoal
  Uganda 2-pot
       Justa
 Patsari Prototype
 20 L Can Rocket
       Onil
      VITA
  Mud/Sawdust
    3 Stone Fire
   Ghana Wood
     Ecostove
0
4
5
10
127
148


1792


















9


'







































































, — i ^,102
                   1,000
2,000        3,000        4,000
      PM to Cook 5 L (mg)
                     5,000
6,000
                                                       Stoves with chimneys ^^H Stoves without ch:
                                                                           55

-------
Test Results of Cook Stove Performance
                                                         Stove Rankings
6. Safety Ratings
Evaluated on  10 criteria (see Appendix)
  Most Safe
  1.  Onil
  2.  Justa
  3.  Alcohol - Clean Cook
  4.  Uganda 2-pot
  5.  Patsari Prototype
  6.  Kerosene
  7.  Wood Flame Fan
  8.  Eco stove
  9.  Propane
  10. Mali Charcoal
  11. Wood Gas Fan
  12. Mud/Sawdust
  13. 20 L Can Rocket
  14. Parabolic Solar Cooker
  15. Gyapa Charcoal
  16. Ghana Wood
  17. VITA
  18. 3 Stone Fire

!  Least Safe
#1  Onil
     39 out of 40
                ra
#2  Justa
     38 out of 40
#3 Alcohol &
    Uganda 2-pot
     37
out Of 40

Onil
Justa
Alcohol _
Uganda 2-pot
Patsari
Kerosene
Wood Flame
Ecostove
Propane
Mali Charcoal
Wood Gas "
Mud/Sawdust
20 LCan
Solar
Gyapa
Ghana Wood
VITA '_






















	 1 	 1 	 1 	 1 	 1 	 1 	 l^'
I 38














I -t /
























































=17.1

















1 \t.










35
35

0 5 10 15 20 25 30 35 40
Safety Score out of 40
^^•l Stoves with chimneys ^^H Stoves without chimneys
56

-------
Test Results of Cook Stove Performance
                                                         Stove Rankings
7. Cost to Purchase
lnUS$
  Least Expensive

  1.  3 Stone Fire
  2.  Mud/Sawdust
  3.  20 L Can Rocket
  4.  VITA
  5.  Mali Charcoal
  6.  Ghana Wood
  7.  Gyapa Charcoal
  8.  Kerosene
  9.  Propane
  10. Alcohol - Clean Cook
  11. Patsari Prototype
  12. Uganda 2-pot
  13. Solar Cooker
  14. Ecostove
  15. Onil
  16. Justa
  17. Wood Gas Fan
  18. Wood Flame Fan

  Most Expensive
#1  3 Stone Fire
     Free
#2  Mud/Sawdust
     Free
#3  20L Can Rocket
     Free
3 Stone Fire
Mud/ Sawdust
World Food
VITA
Mali ~_
Ghana Wood
Gyapa
Kerosene
Propane
Alcohol '_
Patsari
Uganda 2 Pot
Solar Cooker
Ecostove
Onil
Justa
Wood Gas
Wood Flame
$-

0
0
0
12
• 2.4
• 5
••5.9
••3.5
^Z-
1 -IS

140











If, 7







i / ;

i /•,









99
























$50 $100 $150 $200 $250
Cost to Purchase, US$
^•H Stoves with chimneys ^^H Stoves without chimneys
                                                              57

-------
Test Results of Cook Stove Performance
                                                      Stove Rankings
8. Monthly Fuel  Use
Wood Burning Stoves (kg / month)
  Least Fuel Used

  1.  Wood Gas Fan
  2.  Wood Flame Fan
  3.  VITA
  4.  Uganda 2-pot
  5.  20 L Can Rocket
  6.  Mud/Sawdust
  7.  Ghana Wood
  8.  3 Stone Fire
  9.  Patsari Prototype
  10. Justa
  11. Onil
  12. Ecostove

  Most Fuel Used
#1  Wood GaS Fan
    28 Kg /month
#2 Wood Flame Fan
    38 kg /month
..
                            #3  VITA Stove
                                 41 kg /month

Wood Gas
Wood Flame
VITA
Uganda 2 Pot
20L Can Rocket
Mud/Sawdust
Ghana Wood
3 Stone Fire
Patsari Prototype
Justa
Onil
Eco stove
^^^
















^^•^75










I 43. 2




59.8
167.1



I 76



6
I 82.0




I 83. 2






I 120.8

0 20 40 60 80 100 120 140
Fuel Use (kg)
^^B Stoves with chimneys ^^H Stoves without chimneys
58

-------
Test Results of Cook Stove Performance
                                                                 Learning From Improved Cook Stoves
Chapter 3
Learning  From Improved  Cook Stoves
                         3 Sttme fife
                            Time to Bml 5L- 26*2

                             Figure 1
j
Why do some wood-burning

cook stoves boil water faster?

The 3 Stone Fire (Figure 1) is often thought of as a
fast way to boil water. If an improved stove doesn't
boil water as quickly, people may switch back to
the 3 Stone Fire when
they are in a hurry.

An improved stove
designed to boil water
quickly must have
sufficient firepower. The
heat created in the stove
has to be high enough to
cook local foods in
acceptable times. To boil water quickly, as much
heat as possible has to get from the fire into the
pot. It is important to make sure the flame and hot
gases are directed right at the pot. Increasing the
temperature of the hot gases helps the stove boil
water faster than the 3 Stone Fire.

Eight stoves in these tests boiled 5 L of water faster
than the 3 Stone Fire (Figure 2). The three stoves
that boiled water the fastest in these tests were the
VITA, Mud/Sawdust, and Uganda 2-pot (Figure
3). They each have similar narrow channels around
the pot that force the hot gases to flow against the
bottom and sides of the pot.

If the channel around the pot is not narrow
enough, the hot gases will flow up the middle of
the channel, avoiding the surface of the pot. At the
same time, it is very important that the increased
friction in the narrow channel does not slow
the flow of gases and air through the stove too
much, otherwise the heat transfer to the pot will be
decreased.
The flow of hot gases is like a river of water. The
river of gases should not meet a restriction, such as
a dam, that would diminish its volume or speed.
If the river becomes half as wide, it needs to also
become twice as deep to continue flowing at the
same speed. In cleaner burning wood-fired stoves,
most of the heat is brought to the pot by the hot
gases. If the gases move slowly, less heat makes it
into the pot.

Gas has very little mass, so the few hot molecules
in the moving gases cannot transport much heat
energy per volume. It takes a lot of hot gas to
deliver the required heat to a pot or griddle. For
this reason, more heat is brought to the pot by
increasing both the amount and speed of the hot
gases without reducing their temperature.

Radiation from the fire can be important in
transferring heat, but to be effective, the radiant
surface has to be hot and close to the pot. In
wood-burning stoves, bringing the pot closer to the
fire can increase smoke and harmful pollution. In
cleaner burning stoves, the pot is farther away from
the fire and is therefore mostly warmed by hot flue
gases.
                                                                                       59

-------
Test Results of Cook Stove Performance
                                                                  Learning From Improved Cook Stoves
  Four techniques to boil water faster:


  1.  Create a large enough fire in the combustion chamber.

  2.  Force the gases to flow against the bottom and sides of the pot in narrow channels.

  3.  Make sure the gases are as hot as possible.

  4.  Increase the speed of the hot gases flowing over the surface of the pot.
Figure 2 - Stoves that boil 5 L of water faster than the 3 Stone Fire
VITA
Mud/Sawdust
Uganda 2 -pot
Wood Flame Fan
Ghana Wood
20 L Can Rocket
Propane
Wood Gas Fan
3 Stone Fire












1 16

























* Lighter bars that show stoves
equipped with a chimney that removes
most CO from the kitchen.






9





127




3 5 10 15
Time to Boil 5 L (min)



20 25 30
Figure 3  Fastest to Boil 5 L of Water
                      .
         VITA Stovt

          Time to Boii SL- 14:00
       \.  . 	
Tutu to BeUSL- 16:00
      	'
Uatuwa. 2-Mtt

   Time to BfilSL-16:12
60

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
Why do some wood stoves
use less fuel?

The 3 Stone Fire (Figure 4) can be fairly fuel ef-
ficient when operated carefully. In the Aprovecho
laboratory tests, expert operators tried to get
                     optimal results from each
                     stove. The 3 Stone Fire
                     consumed an average of
                     about 1,100 grams of
                     wood to bring to a boil
                     and then simmer 5 L of
                     water for 45 minutes. In
                     the field,  the 3  Stone Fire
                     usually consumes more
                   wood.
Figure 4
Six wood-burning stoves in these tests used less fuel
to complete the Water Boiling Test. The graph
below (Figure 7) details the performance of the
wood-burning stoves that used less energy than a
3 Stone Fire. Liquid-fueled stoves and charcoal-
burning stoves are included to place the results  in a
wider context.

The Wood Gas (Figure 5) and Wood Flame (Figure
6) stoves use electric fans to improve combustion
efficiency. The low-volume, high-velocity jets of
air increase the mixing of gas, air and fire in the
combustion chamber. At the same time, the veloc-
ity of hot gases contacting the pot is also increased.
Even though the hot gases contact only the bottom
of the pot, the two stoves consumed the least
wood in these tests. Fans seem to tremendously
help wood-burning stoves do well in all categories
of performance. Adding a fan to a wood-burning
stove seems like a great idea from what we have
seen in these tests.

The VITA, Uganda 2-pot, 20 L Can Rocket, and
Mud/Sawdust are natural-draft stoves. The velocity
of the flame and hot gases is determined by the
heat of the fire. In these stoves, the heat is forced to
contact the sides as well as the bottom of the pot,
so more of the heat from the fire gets into the pot.
Luckily for stove builders and designers, the four
techniques that help a cooking stove boil water
faster also help reduce fuel use.
       Fuel Us&i - 459 ()

      Figures
                                                                          fuel Ufeet - £26 a
                                                                                     J
                                                                        Figure 6
Figure 7 - Stoves that use less energy than the 3 Stone Fire

Solar
Propane
Alcohol
Wood Gas Fan
Kerosene
Wood Flame
Uganda 2-pot
VITA
20 L Can Rocket
Mud/Sawdust
Ghana Wood
Gyapa Charcoal
3 Stone Fire

















I A A7II

!6 V66


lc








434
,623









* Lighter bars indicate stoves that
do not burn wood or charcoal.
1 1 S 1 QO


i i
9,496

0 5,000 10,000 15,000 20,000 25,000
Energy to Cook 5 L (kJ)
                                                                                             61

-------
Test Results of Cook Stove Performance
                                                                       Learning From Improved Cook Stoves
Why do some stoves emit less

carbon monoxide?

Propane is a clean burning fuel that produces a
hot, blue flame. Propane is stored under pressure in
tanks. When released, the pressure causes mixing of
the gas, fire and air, resulting in very little pollu-
tion. The alcohol and kerosene stoves in this study
were not pressurized and were less successful at re-
ducing harmful carbon monoxide (CO) emissions.

As can be seen in the following graph (Figure 8),
two wood-burning stoves equipped with fans were
quite successful in reducing the amount of CO.
Adding a small electric fan to a wood-burning
stove helps in many ways. The jets of hot air create
improved mixing that forces the CO to interact
with air and flame, resulting in more complete
combustion and dramatically reduced emissions of
CO.

The Wood Gas stove shoots jets  of air into and
across the top of the fire, creating a zone
in which fuel, air and fire are so well mixed almost
complete combustion occurs. The Wood Flame
stove blows air up from under the bottom
of the fire. It is almost as successful as the Wood
Gas stove in reducing CO. Creating a zone of mix-
ing in or above the fire is an effective technique.
Please note that this page references total emissions (PM and CO) produced
by the stove, including PM and CO emissions that wouU normally be
exhausted from the house via a chimney not emissions to which the cook is
exposed. Many chimney stoves that resulted in very low emissions in the test
kitchen emitted high levels ofPM and CO as measured under the collection
hood from the chimney exit.

Figure 8 - Stoves that emit less CO than the 3 Stone Fire
 Adding an inexpensive fan to a wood-burning
 stove helps burn wood very cleanly. In many places
 where biomass fuel is used for cooking, electric
 power is available. In these locations, wood-burn-
 ing stoves with fans seem to have a great potential
 to reduce both fuel use and harmful emissions. The
 fuel savings and health benefits should far outweigh
 the cost of the electricity used.
The three T's
Carbon monoxide and participate matter always
form when fuel and air do not completely mix, and
complete mixing does not occur in stoves with natu-
ral draft. The orange color of a flame comes from
the radiation of particulate matter (soot) within the
flame. Blue flame results from  the reaction of carbon
monoxide to produce carbon dioxide. So, colored
flames indicate that PM and CO are reacting.

Emissions of these harmful pollutants can be re-
duced by burning them before the exhaust cools.
Wood stove  designers know that this burnout
requires the three T's: time, temperature and
turbulence.  Time indicates that the longer the
exhaust gas stays  hot, the longer pollutants have to
burn. Temperature  indicates that the gas needs to
stay as hot as possible; the reactions stop when the
gas gets too cool. Turbulence is an engineering term
for rough flow. If the air is turbulent, pollutants
have a greater chance of coming into contact with
oxygen so they can  burn out.

Propane _P 1
Wood Gas Fan _^^^^^^^^M 7
Kerosene _^^^^^^^^^^B 8
Wood Flame Fan ^^^^^^^^ i
20 L Can Rocket
Patsari Prototype
Uganda 2-pot
Justa
Onil
VITA
Ecostove
Mud/Sawdust
Ghana Wood
3 Stone Fire
















9

1 1&












* Lighter bars show stoves equipped
with a chimney that removes most CO
from the kitchen.




















1 56
0 10 20 30 40 50
Carbon Monoxide to Cook 5 L (g)


60
62

-------
Test Results of Cook Stove Performance
                                                                        Learning From Improved Cook Stoves
Which wood-burning stoves

produce less particulate matter?

Many factors can decrease the emissions of
unburned particles. The mixing of hot gases, air,
and flame in the Wood Gas and Wood Flame
fan stoves dramatically reduces particulate matter
(PM) emissions. If electricity is available, biomass
stoves with fans, such as propane, alcohol, and
kerosene stoves, seem to have a great potential for
protecting health by reducing indoor air pollution.

Charcoal-burning stoves made about one-quarter
of the PM emissions compared to the 3 Stone Fire
in these tests. Although charcoal can produce large
amounts of CO, PM emissions were relatively low.

The Uganda 2-pot, Justa, Patsari Prototype, 20 L
Can Rocket, and Onil stoves create approximately
one-third to one-half the PM made by an open
fire. These five stoves have low-mass rocket-style
combustion chambers (Figure 9). This type
of combustion chamber reduces PM and CO
emissions. The VITA and Mud/ Sawdust stoves,
on the other hand, are shielded-fire stoves without
insulated combustion chambers and do not
significantly reduce PM.

Again, adding a fan to a wood-burning stove is
shown to clean up combustion. Efficient mixing is
responsible for the reduction of PM in the fan and
to a lesser degree in the Rocket designs.
                                                    Figure 9 -nve stoves
                                                    with Rocket-style
                                                    combustion chambers
                                                      JiMta. Stovt
                                                       PM RffteM&t - 792 vug
                      Patsasi Prototype
                         PM ReUtMti - 879 wg
                                                                                              ;
Onii Stovt
 PM Refaated - 1,34-3 •ma
                                                                              ZOLCmitiocket
                                                                               PM. HeUased. -1,289 -mg
                                                    <^	
                                                    Please note that this page references total emissions (PM and CO) produced
                                                    by the stove, including PM and CO emissions that would normally be
                                                       usted from the house via a chimney not emissions to which the cook is
                                                    exposed. Many chimney stoves that resulted in very low emissions in the test
                                                    kitchen emitted high levels ofPM and CO as measured under the collection
                                                    hood from the chimney exit.
Figure 10 - Stoves that emit less PM than the 3 Stone Fire

Solar
Alcohol
Propane
Kerosene
Wood Gas Fan
Wood Flame Fan
Mali Charcoal
Gyapa Charcoal
Uganda 2-pot
Justa
Patsari Prototype
20 L Can Rocket
Onil
VITA
Mud/Sawdust
3 Stone Fire
0
4
5
10
• 27
• 48














1678


18 A)













* Lighter bars show stoves equipped
with a chimney that removes most PM
from the kitchen.
289
] 1,343










|3,;
0 500 1,000 1,500 2,000
Particulates to Cook 5 L (mg)
52
63

2,500
                                                                                                63

-------
Test Results of Cook Stove Performance
                                                                    Learning From Improved Cook Stoves
What was the average
firepower and turn-down ratio?

Firepower is a measure of how much energy is
released each second. More energy is required to
quickly boil water than to simmer water. The most
effective cooking stove should be fuel efficient at
both high and low power operation.

Figure  11 shows the average high firepower for
boiling and the low firepower for simmering for
each tested stove. It should be noted that in the
University of California, Berkeley Water Boiling
Test, the pot is uncovered, which increases the
energy  input needed to maintain the water at three
degrees below full boil. The ratio between
the high and low firepower (high firepower divided
by low  firepower) is called the turn-down ratio
(TDK). It is a measure of how well the stove can be
"turned down" from high to low power.
A TDK of 2 means that half the fuel
was consumed while maintaining a simmering
temperature, compared to the amount of fuel used
to bring the water to boil. Cooks usually appreciate
a stove that is capable of both high-and low-power
operation. Many foods will burn if the firepower
cannot be sufficiently decreased.

It is interesting to note that the liquid-fueled stoves
were generally low powered and used nearly the
same energy to boil  and simmer food. The Mud/
Sawdust (TDK 3.9) and VITA (TDK 3.8) stoves
had the highest TDR The average for the other
wood-burning stoves without chimneys was 2.4.
The average for stoves  with chimneys was 2.2. The
Gyapa charcoal stove (TDR 2.8) scored slightly
higher. While TDR seems to  be an important stove
characteristic, the graphs on the following page
(Figures 12 and 13)  indicate that TDR alone does
not predict fuel efficiency.
Figure 11- Firepower and turn-down ratio of stoves



10 -

I 8
1 6-
O_
£
2



CD O
r^ oo 0
1 i
1 1
m i i

1 £ £





o
CO
• 1
n
• o

^

CTi
i—l ^r

^
ft
•i D
Li ,1

4

CO
•

1
§ .2 « ^ 5 g S
R u
•* (-> X P. *4
! > g ii 3> ° co 8 ^
CO

=9 ro
= "E
2 co
13

o £

m <<
S. o
CO
>!
C3

3 o "

1 CO —
, O co
_i 2
o
CM


in Boil Firepower
D Simmer Firepower
03 •Turn-Down Ratio
-
LO
CO
r 1 • • •
^1,0 "^
- r-. •
CXI _A CXI
i — i cn °^o cxi
r> ^_ H "^ fe rr
imj l.mJTJrr

- 4.0
3 5
o
3.0 -si
8.
2.5 c
2.0 g
- 1.0
- 0.5
0)-oCC'oSn

g^^g-CDSgOO
2 co , -S
Q- 5
64

-------
Test Results of Cook Stove Performance
                                                          Learning From Improved Cook Stoves
Figure 12- Energy to cook vs. turn-down ratio
Figure 13- Firepower of stoves and energy to cook 5 L
                                                                             65

-------
Test Results of Cook Stove Performance
                                                                    Learning From Improved Cook Stoves
What is the effect of adding a

chimney to a wood-burning

cook stove?

Chimneys protect the cook and family from
smoke. The chimney has evolved over time to
be the primary solution to indoor air pollution.
If the stove and chimney do not leak, pollution
is removed from inside the house. In these
experiments, chimneys protected the testers
from the dangerous levels of indoor air pollution
made by fire. A functional chimney can remove
essentially all the emissions made inside a stove,  if
the smoke does not leak into the room.

Figures 16 and 17 compare the performance of
stoves with and without chimneys. Chimneys
removed all but  1% of the CO and PM from the
test kitchen. The pollutants that did enter the
kitchen escaped  through small leaks in the stove.

The stoves with  chimneys in this study were slower
to boil water and used more wood to boil and then
simmer water (Figure 14). However, these stoves
were mostly griddle stoves in which hot gases
transfer heat through a heavy metal surface to the
pots or food placed  directly on the griddle.  It was
the griddle that caused these differences, not the
chimney.

Figure 14-  Comparison of non-
chimney and chimney stoves

Time to Boil
Fuel to Cook
CO in Kitchen
PM in Kitchen
Average
No Chimney
19 min
870 g
340 ppm
1 8,000 u/m3
Average
Chimney
33 min
1,400g
3 ppm
280 u/m3
Griddle stoves such as the Justa, Onil and
Ecostove have a great advantage in that food can
be cooked directly on the hot surface. The griddle
stove is necessary and popular in places where flat
breads are cooked. In Central America tortillas are
a staple food. As the tortillas are made, a pot of
beans often simmers to completion at the back of
the griddle. The griddle stoves in this study all had
chimneys that removed essentially all emissions
out of the kitchen.

As can be seen in Figure 17, stoves without
chimneys often created dangerous levels of
pollution in the test kitchen.

The Uganda 2-pot stove (Figure 15) is the only
stove equipped with a chimney studied in which
pots are submerged into the stove body. It does not
have a griddle. Instead, the hot gases flow against
the bottom and sides of the two submerged pots,
which fit tightly in holes that prevent smoke from
escaping into the kitchen. As can be seen in Figure
16, the Uganda 2-pot chimney stove boils water as
quickly and uses about the same amount of fuel as
stoves without chimneys. Stoves without chimneys
are shown on the left side of the graph, while those
with chimneys are on the right.
Lacking a sealed griddle, the Uganda 2-pot stove
leaks more pollution into the room than do other
stoves equipped with chimneys. However, the
levels of indoorair pollution are greatly reduced
compared to a 3 Stone
Fire. If the stove had
better seals around the
pot, more of the smoke
would exit the chimney.
                                                                             	.	)
                                                                              Figure 15
66

-------
Test Results of Cook Stove Performance
                                                       Learning From Improved Cook Stoves
Figure 16-Chimney stoves: fuel to cook and time to boil
h
2,500
0)
~ 2,000
LO
•§ 1,500
O
0 1,000

1J 500
LL.

























DFuel




to
- No Chimney




Cook
• Time to Boil













<7l
















^B




?>







«f -/
-^


f
£
&

4?



















r>































^7*




















































A




















•







 <•£• ^ ^ £






















0.
'V







^

-------
Test Results of Cook Stove Performance
                                                                       Learning From Improved Cook Stoves
How does ventilation affect

pollution in a kitchen?

To make all the tests as similar as possible,
the test kitchen doors and windows were closed
when the stoves were being tested and testing was
done only on calm days. If the wind was blowing
one day and not the next, the levels of CO and
PM measured in the building would be affected,
making accurate comparisons difficult. Tests were
conducted to determine whether opening the door
or window, or making a small hole in the roof,
would  significantly reduce the indoor air pollution.
The tests described here explore this question.

In this  study, 20 Kingsford charcoal briquettes
were burned in the approximately 15-cubic-meter
test kitchen with approximately 3 air exchanges
per hour. The emissions-monitoring equipment
consisted of six HOBO carbon monoxide monitors
and two Airmetrics Minivols pump and filter
particulate meters. The Minivol draws 5 L of room
air per  minute though a filter that collects PM2.5
(particles less than 2.5 micrometers in aerodynamic
diameter).
Three tests were performed for each configuration:
1. The window, door and hole in the roof closed.

2. The 0.6 by 1.8 m door open.

3. A 20 by 25 cm hole in the roof open.

4. A 28 by 36 cm window,  along with the 20 by
   25 cm hole in the roof, open.

The kitchen diagram (Figure 18) shows the loca-
tion of openings as well as the placement of moni-
toring equipment.

The charcoal was left to burn vigorously for 30
minutes. It was then quickly removed through
a small opening, which was then closed. The  test
continued for another 30 minutes as levels of CO
and PM declined.

Figure 19 shows the peak concentration of
CO reached after the half hour of burning, the
average CO level throughout the test, and  the
average concentration of PM during the four levels
of ventilation. As Figure 19 shows, increasing
amounts of ventilation significantly  lowered levels
of both types of emissions.

Figure 20 summarizes the variability and potential
reduction in indoor air pollution resulting  from
the four configurations. The levels of both  CO
and PM with the door and window  closed were
elevated, as can be expected. Opening the door was
highly effective in this study, reducing emissions
by 96%.

Making a small hole in the roof also significantly
improved air quality. However, simultaneously
    Hobo Data Logger: 2 at 3 ft (1 m), 3 at 4.5 ft (1.4 m), 1 at 7.5 ft (2.3 m)
   i CO2 meter at 4.5 ft (1.4 m), All 4.3 ft (1.3 m) horizontally from stove
   'Particulate meter at 3 ft (1 m)

         Figure 18-Test kitchen diagram
 Kitchen Dimensions:
 10 ft (3 m) wide X 8 ft (2.4 m) deep X 6 ft (1.8 m) high X
 8 ft (2.4 m) peak
 Door: 2 ft (0.6 m) X 6 ft (1.8 m)
 Window: 11 in (0.28 m) X 14 in (0.36 m)
 Hole in Roof: 9.8 in (0.25  m) X 7.9 in (0.2 m)
 Stove height: 2 ft. (0.6 m)
68

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
 Figure 19 - CO and PM in the test kitchen with differing ventilation
160 -,
140

120

100
Q.
-S- 80
0
o
60



20
0
(All Instruments at 1m from Floor)
















f-








































Closed











t



>


















<















»


















Hole in Roof Window & Hole in Ro
n Average CO Level
• Peak CO Level
• Average PM Level












of Door Open















- 1,200

- 1,000

800

1
600 §>

Q_

400

200
0

opening a small window did little to further reduce
levels of pollution, possibly because the window
did not add much flow to the movement of CO
and PM through the smoke hole in the roof.

Increasing ventilation seems to be an effective
strategy for decreasing indoor air pollution in
houses in which biomass fuel is burned. Increasing
ventilation dramatically reduced both CO and
PM in the test kitchen. Opening the door was
especially effective. Cutting a small, covered hole in
the roof also removed most of the smoke from the
kitchen because the smoke collects near the ceiling
in a room.
Figure 20-CO and average PM level reduction  by ventilation

Closed Kitchen


Hole in Roof


Window and Hole in Roof


Door Open



CO Average (ppm)
CO Peak (ppm)
PM Average (ug/m3)
CO Average (ppm)
CO Peak (ppm)
PM Average (ug/m3)
CO Average (ppm)
CO Peak (ppm)
PM Average (ug/m3)
CO Average (ppm)
CO Peak (ppm)
PM Average (ug/m3)
Average
54
160
1,025
18
41
334
14
44
345
1
6
66
% Reduction
from Closed
Kitchen



67%
75%
67%
75%
73%
66%
97%
96%
94%
Expected ZAP
Reduction for
This Ventilation





70%


71%


96%
                                                                                            69

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
Natural ventilation is driven by air pressure
due to differences in air density. If indoor air is
warmer than outdoor air, the flow out of the hole
in the roof can be increased. To some extent,
this stack effect depends on winter and summer
temperatures.
Stratification of CO and PM in
the test kitchen (See Figure 21)
Three additional tests were run to study
stratification in the closed kitchen using six
HOBO CO data loggers and six Minivol PM
monitors at three different heights on opposite
sides of the room. The HOBOS  and Minivols
were located across from each other at 1 meter,
1.4 meters and 1.8 meters above the floor.

Both CO and PM stratified by height in the
test kitchen, collecting densely at the ceiling
and decreasing gradually towards the floor.
Levels were lowest nearest the floor, suggesting
that exposure could be reduced by sitting
instead of standing while cooking. Some
horizontal stratification was also  observed.
 Figure 21-CO and PM concentrations by height across the
 unventilated kitchen
               CO and PM Concentrations by Height Across the Unventilated
                                           Kitchen
                                                                                  T 4,000
             Bottom Left  Middle Left   Top Left  Ceiling Center  Top Right  Middle Right Bottom Right
                (1m)      (1.4m)     (1.8m)     (2.3m)     (1.8m)      (1.4m)       (1m)
70

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
How do fans improve wood-

burning cook stoves?

As can be seen in Figures 22 and 23, wood-burning
cook stoves equipped with fans have several
advantages. In natural-draft stoves, smoke, air and
flame are not forced to mix; smoke can go in one
direction and flame can go in another. The smoke can
easily escape combustion, so CO and PM emissions
are often high. The averages of CO and PM in
the test kitchen and under the emissions hood are
dramatically reduced when a fan is used.

In the Wood Gas fan stove (Figure 24), jets of air are
blown into and over the fire. The Wood Flame fan
stove  (Figure 25) blows jets of air only into the fire
from under the floor of the combustion chamber. The
two stoves used an average of 540 grams of wood to
boil and then simmer  5 L of water for 45 minutes.
The average stove without a fan used 870 grams of
wood to accomplish the same task. The velocity of
hot gases and possibly gas temperature are increased
by the jets of air. Radiation to  the pot can also be
increased in a fan stove because the distance between
the fire and the pot is usually reduced. For these
reasons, the heat transfer to the pot is increased and
less wood is needed for cooking.

Although the hot gases contact only the bottom of
the pot in the Wood Flame and Wood Gas stoves,
the fuel used to boil and simmer water is less than
the VITA, Mud/Sawdust and 20 L Can Rocket
stoves, even though these natural-draft stoves all force
the hot gases to flow against the sides of the pot after
contacting the bottom. The fan increases both heat
transfer and combustion efficiency.
Stoves with fans are remarkably clean
burning (see Figure 26). Even though
the 20 L Can Rocket stove is
considered a "clean-burning" wood
stove, the fan stoves are much cleaner
because the production of PM and
CO is considerably reduced. A stove
equipped with a chimney or a fan
can reduce emissions and exposure to
pollutants while cooking with wood.
               Figure 22 Fan stoves fuel to cook and time to
               boil 5 L
                             I Fuel to Cook 5 L • Time to Boil
  1,200-

@ 1,000--
«  800 --

8  600-
2  400 --

^  200 -

     0
                           1118
                                      626
                                                459
          T 30

          + 25|

          -- 20 -i
          f 15 o
              DQ
          + 10 S
              0
          + 5  I
                                                     -4- 0
                        3 Stone Fire Wood Flame Fan Wood Gas Fan
               Figure 23 Fan stoves CO and PM emissions to
               boil 5 L

60 T

50 -
B
^ 40 -
un
^
8 30 -
o
o
5 20-
O
10 -


1













• CO to Cook 5L

(2,363
56





















9

48



• PM to Cook 5L























7

mE

j 2,500













2,000
B
^
-1,500^
8
-1,000"
-
^
- 500

A
I I — • \J
3 Stone Fire Wood Flame Fan Wood Gas Fan
                   Figure 24
Figure 25
                                                        FutStovt
Figure 26 Comparison of stoves with and without a fan

Time to Boil (min)
Fuel to Cook (g)
CO in Kitchen (ppm)
CO under hood (ppm)
PM in Kitchen (ug/m3)
PM under hood (ug/m3)
Average of
No Fan Stove
19
870
340
43
18,000
2,500
Average of
Fan Stove
22
540
90
8
2,200
37
Fan/No Fan
1 1 7%
63%
27%
19%
12%
1%
                                                                                             71

-------
Test Results of Cook Stove Performance
                                                                      Learning From Improved Cook Stoves
How do wood- and charcoal-
burning stoves compare?

The charcoal used in this study was made in
Mexico from the trunks and branches of mesquite
trees. Two charcoal-
burning stoves were tested,
one from Mali (Figure
27) and one from Ghana
(Figure 28). In these tests
fuel use and emission
measurements began 10
minutes after the charcoal
was lit. The two stoves were
found to be more effective
than traditional  charcoal-
burning models studied in
previous tests.
                               Midi CkasaiaJ.
                               Figure 27
                                            j
                              Ciyapa Ctuurcoed
Charcoal is made by
heating wood or other
biomass fuel inside
a relatively air-tight
enclosure, such as an earth
covered pit in the ground.
Smoke escapes through holes in the covering
                                     	.j
                              Figure 28
                               and causes air pollution. In this case, wasted smoke
                               is fuel that could have been used to cook food.
                               However, there are more efficient methods of
                               producing charcoal that can avoid energy losses.
                               Examples include producing charcoal in stoves that
                               burn  the volatiles in biomass to produce heat for
                               cooking and producing charcoal from crop residues
                               that otherwise would be burned. Between 70%
                               and 80% of the energy in wood is used to produce
                               charcoal.5 "The charcoal thus produced retains the
                               same  shape of the original wood but is typically
                               just one-fifth the weight, one-half the volume, and
                               one-third the original energy content."6

                               Figure 29 compares the energy in charcoal and
                               wood fires. Since so much energy is lost when
                               making charcoal, wood stoves were much more fuel
                               efficient. Almost three times as much total energy
                               was used to cook food with the charcoal stoves in
                               these  tests.

                               As can be seen in Figure 30, the two charcoal stoves
                               boiled water slower than the 3 Stone Fire and the
                               average of all single-pot, wood-burning stoves.
                               Charcoal seems especially well suited to simmering,
                               but is somewhat low powered for rapid boiling.
 Aprovecho/GTZ. (1984). Charcoal: small scale production and use.
 Baldwin, S./VITA. Biomass stoves: engineering design, development and dissemination. Princeton University, 1986. PI3.

 Figure29 - Charcoal comparison: Energy used to cook 5 L
                    "70% to 80% of the energy in the wood was used to produce the charcoal.
                    (Charcoal: Small Scale Production and Use, Aprovecho/GTZ, 1984)
      in
      ^
       o
       o
      O
       o
      *J
       >1
       en
       o>
       c
      L±J
          70,000
          60,000
          50,000
          40,000
          30,000
          20,000
          10,000
              0
D Energy Lost to Making Charcoal
• Energy to Cook
                      3 Stone Fire
                                     Average of Wood
                                      Stoves Without
                                         Chimney
                                    Mali Charcoal      Gyapa Charcoal
72

-------
Test Results of Cook Stove Performance
                                                                   Learning From Improved Cook Stoves
The great advantage of charcoal is that it continues
burning at a steady rate, without the need to
constantly feed the fire, as in a wood-burning
stove. Reducing the air entering the fire prolongs
the useful cooking time and provides a gentle heat
suited to simmering.
               Charcoal is known to produce a large amount of
               CO. In these tests was certainly true. Charcoal
               stoves produced at least twice as much CO as
               any other stove. On the other hand, PM from
               charcoal-stove emissions was low, especially during
               simmering. The significant reduction in PM  when
               using charcoal could help reduce human health
               impacts, except that CO emissions are so high
               (Figure 31).
Figure 30 - Charcoal comparisomTime to boil 5 L


Gyapa Charcoal
-
Mali Charcoal
-
Average of Wood Stoves Without
3 Stone Fire
(







•
) !







•
5 1







M
0 1







•
5
Time







•
2
tc







•
0 2
> Boil 5







•
5
L(m








3
n)








0 3








5








4








0 4








5
Figure31 -Charcoal comparison:CO and PM emissions to cook 5 L
                 3 stone fire
Average of Wood
 Stoves Without
   Chimney
Mali Charcoal
Gyapa Charcoal
                                                                                         73

-------
Test Results of Cook Stove Performance
                                                                 Learning From Improved Cook Stoves
How does a retained heat
cooker help when cooking?

When food simmers, the fire replaces the
constantly lost heat from the pot. If the heat were
not lost but captured instead, then less fuel would
be needed for cooking. Placing the pot of boiling
food in an insulated container keeps the food hot
enough to simmer it to completion. In the same
way, a drafty and uninsulated house has to have
a big fire in the heating stove going all the time
to keep the house warm. Even if no fire is lit, the
super-insulated, almost airtight house can stay
warm for a long time.
After a pot of food boils, the contents are close to
100° C. When the hot pot is placed in a super-
insulated, almost airtight box, the food finishes
cooking, because the stored heat stays in the food.
Once the pot is in the box, food cooks without
further attention. The retained heat cooker (RHC)
or Haybox as it is called in some parts of the
world, saves time, effort, and fuel, freeing the cook
from long hours of watching the slow fire when
simmering food.

Figures 32 and 33 depict both time and fuel
savings when using a retained heat cooker to
simmer food. Approximately 50% savings in both
categories can be expected.
Figure 32 - Use of the RHC potentially saves time tending the stove
during simmering
Figure 33- Useofthe RHC potentially saves fuel during simmering
74

-------
Test Results of Cook Stove Performance
                                                                   Learning From Improved Cook Stoves
Because the fuel is initially used only for boiling
food, cooking with an RHC creates much less
pollution, helping to clean up the air in the
kitchen. In these tests, using an RHC reduced, on
average for all stoves, CO emissions by 56% and
PM emissions by 37% (Figures 34 and 35).

RHCs have been used for hundreds of years. They
can save time and effort which can be devoted to
                                           other tasks. The attraction of the RHC begins
                                           with its convenience. The fuel savings and
                                           decrease in harmful emissions add to the benefits
                                           of retained-heat cooking. More information on
                                           Retained Heat Cookers can be found in PCIA's
                                           Guide to Designing Retained Heat Cookers available
                                           at www.PCIAonline.org/resources.
  Important Note!
  Food should be boiled for at least 5 minutes to kill bacteria before being
  placed in a retained-heat cooker.
Figure 34- Potential  PM emission savings using an RHC during simmering
      6,000
                                                                 D PM Emissions During Simmering
                                                                  PM Produced to Boil 1 L
Figure 35 - Potential CO emissions savings using an RHC during simmering
   0)

   (7)
   •a
   8
   •n
   E
   Q.
   o
   o
160
140
120
100
 80
 60
] CO Emissions During Simmering
I CO Produced to Boil 1 L
                                                                                          75

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
What is efficiency?

People are naturally drawn to the word "efficiency"
and think that improved thermal efficiency
means decreased fuel use when cooking food.
Unfortunately, choosing a stove based on thermal
efficiency can result in the selection of a stove that
is not necessarily as fuel saving as possible.

Thermal efficiency is a  measure of how much
energy in the wood fuel is transferred into the
cooking pot. Because there is no good way to
measure this heat transfer, it  is often approximated
by measuring the amount of water evaporated; but
this technique does not indicate how much of
that energy is useful for cooking. Boiling off a lot
of extra steam can result in a higher "efficiency"
number, but it will not cook food any faster than a
more moderate rate of simmering.

A water-boiling test is usually used to determine
efficiency. There are many versions of water-boiling
tests. Varying test methods result in numbers for
efficiency which are not readily comparable. An
alternative approach called "specific consumption"
replaced efficiency in the  1985 VITA International
Testing Standard.
                                              Specific consumption is the fuel used per unit of
                                              product produced. The unit of product could be
                                              bowls of cooked food and or loaves of bread. In
                                              this case, liters of boiled and simmered water
                                              represent cooked food. Remember that we are
                                              talking about the weight of finished product
                                              (cooked food, or in this case, water remaining at
                                              the end of the test), not starting weight (uncooked
                                              food, or in this case, water at the beginning of the
                                              test).

                                              Figures 36 and 37 rank the energy and fuel used
                                              by different stoves to do the same task (producing
                                              a liter of boiling water, then simmering it for 45
                                              minutes). The efficiency of the stoves is represented
                                              by the line. It can be seen that the two measures of
                                              stove performance are not closely related. "Thermal
                                              efficiency" rewards the production of excess steam,
                                              while "specific consumption" penalizes it. Making
                                              excess steam results in less final product and is
                                              not needed for fuel-efficient cooking. The VITA
                                              1985 International Testing Standard recommends
                                              "Specific Consumption" as the more reliable
                                              indicator of stove performance.
Figure 36 - Comparison of specific energy consumption and thermal efficiency
to boil 1 L
o
•g.
    o
    o
    >l
    en
    te
    o
    1=
a.

-------
Test Results of Cook Stove Performance
                                                                      Learning From Improved Cook Stoves
Stove power must be sufficient to overcome heat
losses through the sides of the pot and to supply
the heat required for vaporization of water. As
the water approaches the boiling point, more
power is needed to offset heat losses from the
pot. This high-energy requirement is difficult for
low-powered stoves to meet, and they remain in
the pre-boiling state longer than high-powered
stoves. At near-boiling temperatures, a lot of water
evaporates. For this reason, low-powered stoves can
evaporate more water than high-powered stoves
before they reach a boil. However, this condition
may not be efficient because the stove is struggling
to reach the boiling point.

The  requirement for more energy as the boiling
point is approached creates an energy "hump"
which low-powered stoves take longer to overcome.
The  low-powered stove boils off a great deal of
water because the water remains in the high steam-
making condition longer than the higher powered
stove. This condition results in long times to boil
and large losses of water through vaporization.
Increased steam production can produce high
efficiency numbers even though fuel is being used
for a longer period.
Problems with efficiency become even more
evident when simmering water. Simmering
attempts to maintain hot water (or food) at just
under the boiling temperature, using the minimum
amount of fuel. The most effective methods for
simmering water (such as the use of pot lids,
insulation, retained-heat cookers, etc.) cannot be
measured by the method of estimating heat transfer
from steam loss.

Problems with thermal efficiency have been
recognized for decades. Thermal efficiency in
conjunction with power output (at high and low
power) can  be used to make accurate predictions
about stove performance. By using the two factors
together and defining a cooking process (cooking
rice, for example), one can calculate cooking time,
fuel use, water loss and so forth. However, thermal
efficiency by itself is not a reliable predictor of
performance and should only be used with other
measures, such as specific consumption, when
comparing cook stoves.
Figure 37 - Comparison of specific energy consumption and thermal efficiency
to simmer 1  L
5"
2
o
;3 3,000 -
Q.
| 2,500 -
(fl
g 2,000 -
^ 1,500 -
o5
0) 1,000 -
^ 500-
W




*









•








* / /
— « y^V
|s- x ^ y

M
ft
i



-












^




^ ////////
/////,///






—
^ ^
^
/






/
/




	
7



t
^
.6 2^
>>
n c O
~ 5
n d O
t
15
• £- C
-0,|
/
                                                                                             77

-------
Test Results of Cook Stove Performance
                                                                      Learning From Improved Cook Stoves
Does increasing heat transfer
efficiency have to decrease
combustion efficiency?
Dr. Grant Ballard-Tremeer7 and Dr. Kirk
Smith have pointed out that getting more of the
heat from a fire into the pot can also result in
more pollution. For example, lowering a
pot closer to the fire results  in lower fuel use but
also makes more smoke. Smith summarized
this observation as follows:

"Combustion efficiency (CE) may not be
worth pursuing from an overall efficiency (OE)
standpoint, but is very much worth pursuing from
a pollution standpoint because pollution emissions
are a direct function of (1-CE). Thus,  a relatively
slight lowering of CE, which may produce only
a slight change in OE, can produce substantial
increases in pollution, even  on a per meal basis."8

Smith lists examples from his studies where
small decreases in combustion efficiency, following
changes to increase heat transfer efficiency, resulted
in two to three times more pollution per
meal. Is it always true that getting more of the
heat from a fire into the pot results in  poorer
combustion and more smoke?
Dr. Larry Winiarski9 approached designing stoves
by separating functions along the same lines as
Ballard-Tremeer and Smith. His hope was that
if wood were burnt in an improved combustion
chamber, cleaner hot gases could be forced to
flow against the pot without making more smoke.
Winiarski hoped that if CE was close to  100%,
improving heat transfer efficiency (HTE) would
not decrease combustion efficiency.

Figure 38 shows examples where increasing HTE
does decrease CE. Emission factors are useful to
compare because emission  factors report the mass
of pollution per mass of wood burned, indicating
the cleanliness of combustion. As can be seen, the
Mud/Sawdust stove and especially the VITA stove
sacrifice clean burning for reduced fuel use and
quicker time to boil. However, neither of these
stoves has an improved combustion chamber.

In the VITA and Mud/Sawdust stoves, the fire is
surrounded by a metal or earthen wall and moved
closer to the pot. In both stoves, small
channels force the hot gasses to also flow against
the sides of the pot. This type of stove can make
more pollution per meal because it does  not
address combustion efficiency.
    Figure 38 - Comparison of specific energy consumption and thermal efficiency to simmer 1 L
3 Stone Fire Mud/Sawdust VITA
Time to Boil (min)
Fuel to Cook (g)
CO to Cook (g)
PM to Cook (g)
Emission Factor CO (g/kg)
Emission Factor PM (mg/kg)
27
1,100
56
2,400
51
3,500
16
780
49
2,400
43
5,100
14
690
43
2,200
93
8,300
20 L Can Rocket
22
730
15
1,300
14
2,000
7 Dr Ballard-Tremeer graduate thesis. (1997). See http://ecoharmony.com/thesis/PhDintro.htm.
8 REPP Stove List, May 2002
9 Dr. Winiarski Capturing Heat I fAprovecho Research Center, 1996).
78

-------
Test Results of Cook Stove Performance
                                                                       Learning From Improved Cook Stoves
Winiarski's 20 L Can Rocket stove, on the
other hand, has an insulated combustion chamber
that cleans up smoke before it can escape. This
feature can simultaneously improve combustion
efficiency and heat-transfer efficiency. Fuel use
and emissions are both reduced.
                                           As can be seen in Figure 39, emission factors in
                                           the 20 L Can Rocket stove are reduced, compared
                                           to a carefully made 3 Stone Fire. Well-engineered
                                           combustion chambers in cooking stoves create
                                           cleaner gases which can be forced to more
                                           effectively get heat into the pot. This type of stove
                                           can use less wood and make less smoke, while
                                           boiling water faster than the 3 Stone Fire.
Figure 39-Comparison of emission factors (EF)
     D)
     o
     o
     u_
     LU
100 T

 90

 80

 70

 60

 50

 40

 30

 20

 10

  0  -
                         9,000

                         8,000

                         7,000

                         6,000 •

                         5,000

                         4,000 j
                              i
                         3,000'

                         2,000

                         1,000
                         0
               3 Stone Fire
                    Mud/Sawdust
VITA
20 L Can Rocket
                                                                                              79

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
DoesCOpredictPM?

It might possible to use measured CO levels to
predict a general expected level of PM for a given
fuel. Generally, it is much easier to measure CO
than PM. If a correlation can be established, stove
researchers might be able to simplify measurements
in the field.

Some researchers report that CO and PM are
related. The levels in a house or in the streets
of a city may generally follow a similar pattern.
However, CO and PM do not rise and fall together
as combustion occurs.

CO is created by gases that are not burnt up in the
flame. Burning wood usually produces high levels
of CO when the fire is started. CO levels rise as
burning wood makes charcoal. Alternately, PM
is seen when the fire makes flame. Both CO and
PM tend to rise when fresh wood is added. Each
pollutant is produced by a different mechanism,
at various times during a cooking task. Figure 40
shows a typical record of CO and PM emissions
during a Water Boiling Test.
                 In the tests done at Aprovecho, charcoal- and
                 liquid-fuel stoves did not emit levels of CO and
                 PM like wood-burning stoves. Burning charcoal
                 makes high levels of CO, but relatively low levels of
                 PM. Liquid gas fuels produce almost no PM when
                 the stove is properly tuned.

                 As can be seen in Figure 41, in the test kitchen
                 the levels of CO and PM when water is brought
                 to a boil and simmered for 30 minutes do seem to
                 be related. Most stoves that emitted less CO also
                 produced less PM.

                 Figure 42 details the same comparison for stoves
                 tested under the emissions collection hood. It
                 should be noted that due to problems with the
                 data, only one Water Boiling Test for PM could
                 be used. The PM hood results show the average
                 of cold and hot starts to boil that are added to
                 the emissions for simmering for 45 minutes. The
                 levels of CO are the average of three Water Boiling
                 Tests. This analysis also shows a positive relation,
                 although the Ghana Wood and Ecostove PM levels
                 seem unexpectedly high.
Figure 40-Comparison of emission factors (EF) for improved heat transfer
    en
    O
    u
       1:57          12:27
            3 Stone Fire
   12:57
Mud/Sawdust
13:27
 VITA
 13:57
20 L Can Rocket
14:27
                                                          3
                                                          IQ
                                                          7s-
                                                          10
80

-------
Test Results of Cook Stove Performance
                                                                 Learning From Improved Cook Stoves
In this study, the levels of CO and PM do seem
to be related for stoves burning the same type of
fuel. Clean-burning stoves remove most of the PM
and CO, and polluting stoves emit high levels of
PM and CO. Stoves with chimneys remove both
PM and CO from the kitchen. However, some
stoves reduce CO while increasing PM. Of course,
charcoal stoves emit much more CO than PM.
It may not be safe to assume that clean-burning
stoves reduce both PM and CO in proportional
amounts, because this assumption does not hold
true for all stoves. Further studies would be
required for a particular application.
Figure 41 - Relation of CO and PM for a cooking task in the test kitchen
Q.

£ 1,200-

8
•E 600 -
3
"O 400
•33
g 200 -
o o -
O)
<§


" A A

nnYn\
II, ,H, ,r
¥ o 3 £ £ 1
u- O T3 > ^ L
tu > S — ' 5
C m ro °
2 c sc ^
LO J5 T3
00 5 •§
i 	 Chimney 	




\ 	
0 ~ cu ™ = g;
£• 3 £ 3 o I
fU Q "^ d
fU Q- ^j O
™ ^ m ;
ID


^m CO to Cook
N— •— PM to Cook

A A
/' \
_* \ w
1*1 1 1*1 1 | ^_ | ijf^ri^^
i pili! | 1 i 1
D
O
i
1
30,000 • — •
- 25,000 £

- 20,000 g
- 15,000 c
- 10,000 |
5,000 |
g
Q.
O)
Figure 42 - Relation of CO and PM for a cooking task under the emissions
collection hood
                                 • Chimney
                                                                               1,200
                                                                                       81

-------
Test Results of Cook Stove Performance
                                                                  Learning From Improved Cook Stoves
How do hydrocarbon emissions

compare?

Hydrocarbons are unburned gases with hydrogen-
carbon bonds such as propane, methane, butane
and hexane. Like other pollutants, hydrocarbons
are harmful to human health and contribute to
global warming. The Enerac 3000E (Figure 43),
used in the Aprovecho emissions hood, uses non-
dispersive infrared (NDIR) to count the number
of carbon bonds to determine the concentration
of hydrocarbons, reporting them as propane. Since
the Enerac is designed for higher concentrations
of hydrocarbons and counts all as propane, the
results presented in Figure 44 may not be accurate
in magnitude.  However, it is possible to compare
the relative amounts of hydrocarbons emitted by
stoves.

As measured by the Enerac 3000E, the two
charcoal stoves emitted about twice as  much
unburnt hydrocarbons as the wood-burning
stoves. As with CO and PM emissions, the wood-
burning stoves that produced the least amount
of hydrocarbons used either rocket combustion
chambers or fans. Because there is significant
difference in measured hydrocarbon emissions,
further study seems warranted.
        Figure 43 - Enerac 3000E
Figure 44- Hydrocarbon emissions to cook 1 L
 3
 ^
  o
  o
 o
  o
 *-»
 o
 I
82

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
How does emission testing with
a  hood or in a test kitchen
compare?
Two different methods were used in this study to
measure the emissions from different stoves when
performing a standard task: boiling and simmering
water in the same pot.

The exhaust collection hood (Figure 45) creates
a constant flow of air which is carefully measured
so  that the amount of pollutants is known. The
amount of air leaving the test kitchen (Figure 46)
also has to be controlled. Tests cannot be done on
windy days and all windows and doors must be
closed as the stove burns fuel. The  intent of both
methods is to reduce the factors that affect stove
performance measurements.
        Figure 45 - Testing hood

The hood collects all the smoke and draws it past
measuring devices; monitoring equipment
in the test kitchen is immersed in the smoky air.
One of the big differences between testing with
a hood or in a kitchen is the cost. The
equipment used in the hood (Enerac 3000E,
Radiance M903 Nephelometer, etc.) cost more
than $20,000. The instruments for the hood were
chosen to provide real-time information about
emissions so that designers could understand
stoves better. It also provides specific emissions
in pollutant per cooking task or per kilogram of
fuel burned. The portable equipment used in the
test kitchen (AP Buck filter system, HOBO CO
monitor) cost less than $2,000. However, it cannot
provide such detailed information.

It took more than a year to build the hood and
calibrate it so that the results were usable. The
portable equipment used in the test kitchen is
made to be used by field personnel with little
training. One reason for the long development
time for the hood was that few stove developers had
used this kind of system before. New procedures
and instruments had to be developed. On the other
hand, many researchers had already been using in-
field indoor air pollution (IAP) monitors which were
placed in the test kitchen to assess air quality.

How did the data from the hood and the test
kitchen compare?
Three Water Boiling Tests (WBTs)were performed
under the hood and three shortened WBTs were
performed in the test kitchen. The average results
for each stove are shown in Figures 47 and 48. The
stoves equipped with chimneys removed almost
all pollutants from the test kitchen. The emissions
of the stoves with chimneys were measured under
the hood from the chimney exit. For this reason,
the results from the hood and in the test kitchen
  It should be noted that testing stoves in
  a test kitchen exposes the tester to high
  levels of smoke and carbon monoxide. In
  these tests, the stove operator always wore
  a respirator that directly provided fresh air
  for breathing.
                                                            Figure 46 - Test kitchen
                                                                                             83

-------
Test Results of Cook Stove Performance
                                                                     Learning From Improved Cook Stoves
for stoves with chimneys cannot be compared. The
kitchen test shows the levels of pollutants in the
room. The hood tests show total emissions that
affect the environment.

In most cases, for stoves without chimneys, the
levels of CO measured under the hood and in the
test kitchen were quite similar.

Figure 48 compares the PM data from the hood
and test kitchen. Unfortunately, the PM data
from two of the three tests done under the hood
could not be used because of technical problems.
However, there is general  agreement (for stoves
without chimneys) between the results for PM
from the test kitchen and the hood. Again, the
chimney stoves on the right side of the graphs were
measured differently and cannot be compared.

When stove prototypes are being developed,
emission data are important. Measuring how cleanly
stoves operate is necessary for the evaluation of
stoves that are to be distributed.

Using an emission hood or a standardized test
kitchen are two ways to provide data on pollution
made by stoves. The test kitchen has the advantage
of lower cost and easier to use equipment.
The hood is more accurate and provides more
reliable information that answers a wider variety
of questions. Either, when used carefully and
systematically, can be used to compare cook stoves.
Figure 47 - CO to cook 5 L under emissions hood and average CO Level in
test kitchen
        Note: Gray bars indicate chimney stoves.
Figure 48 - PM to cook 5 L under emissions hood and average PM Level in
test kitchen
     6,000
                                   30,000
                                 -  25,000
                                   20,000
                                   15,000
                                 -  10,000
       Note: Gray bars indicate chimney stoves.
84

-------
Test Results of Cook Stove Performance
                                                                    Learning From Improved Cook Stoves
What is an "improved"cook
stove?

The eighteen stoves in this study were tested
under an emission hood and in a test kitchen,
using various monitoring devices. Capturing  the
emissions in the hood makes it possible to estimate
the mass of CO and PM made during a cooking
task. In the test kitchen, the parts per million
(ppm) of CO and the micrograms per cubic meter
(|ag/m3) of PM in the room air are monitored,
using portable equipment. Assuming that the air
exchanges in the test kitchen are relatively constant,
higher readings of pollution in the air are caused by
stoves that  are burning less cleanly.

The CO/CO2 ratio has been suggested as another
method for determining how cleanly a stove is
burning.  It is calculated by dividing the amount of
CO by the amount of CO2.  A lower ratio means
that more CO2 and less CO were produced during
the Water Boiling Test. If biomass fuel is burned
cleanly, more CO2 is made and less CO is emitted.
The CO is combusted and changed into CO2.
A stove that is operating at 100% combustion
efficiency would emit only CO2 and water.

It may be possible to use the CO/CO2 ratio as a
benchmark for stove combustion efficiency. The
South African Bureau of Standards suggests that
the CO/CO2 ratio from paraffin (kerosene) stoves
should be 2% or less. Both CO and CO2 are
relatively simple to measure with equipment that
has a combined cost of about $600.

The following graph (Figure 49) shows the average
results of three Water Boiling Tests of each stove
Figure 49-Comparison of C0/C02 ratio and CO produced per liter to cook
                                                                                          85

-------
Test Results of Cook Stove Performance
                                                                        Learning From Improved Cook Stoves
conducted under the emissions hood. The propane,
kerosene, fan stoves and the rocket stoves meet the
suggested benchmark of 2% of CO/CO2. The CO/
CO2 ratio also seems to be correlated to another
measure of CO generated from the Aprovecho
emissions hood: the amount of CO produced to
boil and simmer 1 L of water. The emissions hood
results are presented as the mass of CO produced
per liter of water boiled and then simmered during
the Water Boiling Test.

Benchmarks for emissions can also be created using
the data from the hood or test kitchen. Fuel use is
also comparable. Figure 50 shows two lines drawn
across the  graph that could establish a proposed
level of acceptable performance.

The Shell  Foundation asked Aprovecho Research
Center to  use the data from these tests to create
proposed benchmarks to encourage the production
of improved cooking stoves (ICS) that save fuel
and reduce indoor air pollution. The lines that
cross Figures 50, 51 and 52 are for stoves with and
without chimneys.  Both fuel used and energy used
to cook 5 L are included.
A suggested benchmark for fuel and energy use is
(Figure 50):

1. Fuel use: Using the International Testing Pot, a
cooking stove without a chimney should use less
than 850 grams of wood or less than 15,000 kj of
energy to bring to boil 5 L of 25° C water and then
simmer it for 45  minutes during the University of
California, Berkeley revised Water Boiling Test.
Stoves equipped  with chimneys should accomplish
the same task, consuming less than 1,500 grams of
wood or 25,000  kj of energy.

A suggested benchmark for CO produced is
(Figure 51):

2. Emissions: A cooking stove without a chimney
should produce less than 20 grams of carbon
monoxide to boil 5 L of 25° C water and then
simmer it for 45  minutes during the University of
California, Berkeley revised Water Boiling Test.
Wood-burning stoves equipped with chimneys are
exempt from the above standard if the stove  does
not allow more than 50 ppm of CO to pollute the
air within 30 cm of the stove in the standard test
kitchen with a controlled air exchange.
Figure 50 - Fuel and energy to cook 5 L vs. benchmark
                              Fuel and Energy to Cook 5 L vs. Benchmark
                            "Lighter colored bars show stoves equipped with chimney
    2,500
                                                                      ^H Fuel to Cook 5 L
                                                                      —Q— Energy to Cook 5 L
                  mney Stove Benchmark = 1500g/25000kJ
                                                      Non-ChimneyStove Benchmark = 850g/15000kJ
                                                                   ^
                                      45,000 _
                                    -  40,000 3
                                      35,000 -i
                                      30,000 ^
                                      25,000 g
                                      20,000 °
                                    -  15,000-
                                      10,000 g)
                                      5,000
                                      0
                                                                                               LJJ
86

-------
Test Results of Cook Stove Performance
                                                                        Learning From Improved Cook Stoves
A suggested benchmark for PM is (Figure 52):

3. Emissions: A wood-burning stove without a
chimney should produce less than 1,500 milligrams
of PM (with a total size of2.5 micrometers in
aerodynamic diameter or smaller) to boil 5 L of 25°
C water and then simmer it for 45 minutes during
the University of California, Berkeley revised Water
Boiling Test.

These preliminary suggestions show how
performance benchmarks can be created from data
generated from  various methods. Benchmarks can
be developed using the CO/CO2 ratio or from test
kitchen or emission hood results. Each method has
advantages and disadvantages. CO/CO2 and test
kitchen results are obtained using less expensive
but less accurate equipment. The emission hood
data are probably the most accurate, but a hood
system is complicated and more expensive. Before
a set of performance benchmarks is generally
adopted,  more research and development are
needed. The suggested fuel use and emission levels
can be adjusted up or down. Benchmark levels can
be determined using various emission monitoring
systems.
Figure 51 - CO to cook 5 L and average CO level in test kitchen vs. benchmark
                             "Lighter colored bars show stoves equipped with chimney
      160
                                                                                          1,400
                                         CO Benchmark = 20g or 200ppm
                                                                                          200  8
Figure 52 - PM to cook 5 L and average PM level in test kitchen vs. benchmark
                            "Lighter colored bars show stoves equipped with chimney
                                                                                          40,000
                             PM Benchmark = 1500 mg or 10000 ug/m
                                                                                                87

-------
Test Results of Cook Stove Performance
                                                                   Learning From Improved Cook Stoves
How can wood-burning cook
stoves  be improved?

The success of some of the groups of stoves in this
study point out a few simple techniques that help
to improve performance.

         Functional chimneys can address
         the problem of indoor air pollution.
         Chimneys are the practical solution that
evolved in all developed or industrialized countries
to remove harmful pollution from the indoor
environment. The Onil stove, the Ecostove, and
the Uganda 2-pot stove (Figure 53) have chimneys
that removed most emissions from the test kitchen.
The test kitchen is a 15 m3 building in which a
door and a window are closed to simulate the
worst conditions when fire is used inside in a
cold climate. Even in this mostly unventilated
structure, stoves with chimneys removed most
of the pollution. It is important to use a cooking
stove with good draft, however. If smoke can flow
out of the fuel entrance, or leak in other ways into
the room, harmful emission levels will rise.

Chimney stoves dramatically reduced the emissions
of PM and CO, as can be seen in Figure 54. The
use of chimneys is probably the most cost-effective
technique to address the problem of indoor air
pollution.
 Figure 53 - Chimney Stoves
                      . ,
Figure 54 - Concentration of CO and PM in the test kitchen generated by stoves with chimneys
500
400
*§ ,
Q. 300
^Q.
CD 200
O
100





C




pen Fir




e



— • — i • i •
Uganda 2-pot Onil Ecos

• CO
• PM
i
tove





16,000
14,000
12,000^
1 n nnn P
I U,UUU ^
8,000 %
6,000 J
4,000 °-
2,000

88

-------
Test Results of Cook Stove Performance
                                                                    Learning From Improved Cook Stoves
         Providing an insulated combustion
         chamber around and above the fire
         creates better mixing of gases,
flame and air, which helps to boil water faster,
reduces fuel use, and decreases CO and PM. The
20 L Can Rocket, the Uganda 2-pot, Justa,  and
the Patsari Prototype stoves have "rocket type"
insulated combustion chambers (meaning L-shaped
insulated combustion chambers) (Figure 55). The
higher temperatures and improved mixing in
an insulated enclosed space above the fire reduces
harmful emissions (Figure 56).
Figure 55 - Five stoves with rocket-
type combustion chambers
   ZOL COJH. Rffckefr
                           JtwbiStovt
                                                    OnttStovt

Figure 56- Insulated combustion chamber CO and PM emissions to cook 5 L
           60 T
                                                                               2,500
                                                                             - 2,000
                                                                                   _
                                                                                   8
                                                                             - 1,000o
                                                                             -- 500
               3 Stone Fire    20 L Can   Uganda 2-pot    Patsari
                            Rocket                Prototype
            Justa
Onil
                                                                                           89

-------
Test Results of Cook Stove Performance
                                                                          Learning From Improved Cook Stoves
          Forcing the hot gases to
          flow against as much of the
          pot or griddle as possible
          improves heat transfer.
This is an effective method to reduce
the fuel needed for cooking. The
20 L Can Stove, the VITA stove, the
Uganda 2-pot stove and the Mud/
Sawdust stove use small channels that
direct the hot gases to contact the
sides and bottom of the cooking pot.
Baldwin and Winiarski  have shown
that improving heat transfer significantly decreases
fuel use.

The VITA (Figure 59) and Mud/Sawdust (Figure
58) stoves are cylinders  surrounding the pot,
creating a small gap between the pot and stove
body. This simple technique dramatically reduces
fuel use (Figure 57). In  outdoor cooking situations
where fuel efficiency, not reduction of emissions, is
most important, this approach provides a low-cost
method for decreased fuel consumption.
Cylinders Surrounding the Pot — Fuel to Cook 5 L
  3 Stone Fire
Mud/Sawdust
                                                  VITA
              Figures?
                                 VITA Stove
                                     Fuetto Cavk -
         Figure 58
                Figure 59
          Stoves can be designed with small fans that create high-velocity, low-volume jets of air that mix
          fuel, air and flame. This mixing is mostly missing in stoves without fans. Mixing dramatically
          reduces  pollution (Figure 61). The Wood Flame and Wood Gas stoves burn wood much more
cleanly. Adding low-cost fans to stoves could provide another low-cost solution to cleaner,  more efficient
cooking with biomass (Figure 60 & 61).
      Fan Stoves — Fuel to Cook and Time to Boil 5 L
               I Fuel to Cook 5 L • Time to Boil
                                  24
                                  •
                                  459
T 30

-- 25 l"

-- 20 ^J
          3 Stone Fire  Wood Flame Fan Wood Gas Fan
                 Figure 60
          60 --

          50 --

          40 --

          30 --

          20 --
            Fan Stoves — CO and PM Emissions to Boil 5 L

                                          T 2,500
                                                                     I CO to Cook 5L • PMtoCookSL
                                                                   »2363
                         2,000
                            1
                            j
                       -  1,500;
                       -- 1,0000
                             o

                             Q.
                                                                                            -- 500
                                                                3 Stone Fire Wood Flame Fan Wood Gas Fan
                        Figure 61
90

-------
Test Results of Cook Stove Performance
                                                                        Appendix A - Glossary of Terms
Appendix A
Glossary
Benchmarks: Suggested measures of performance
that, in this case, seek to define an improved cook
stove.

Boundary layer: The very thin layer of slowly
moving air immediately adjacent to a pot surface
that insulates the pot from the hot flue gases and
decreases the amount of heat that enters the pot.

Carbon monoxide: An odorless, colorless gas that
is harmful to health produced by the incomplete
combustion of fuel.

Convection: The heat transfer in a gas or liquid by
movement of the air or water.

Combustion chamber: The area of a stove where
the fuel is burned.

Combustion efficiency: The percentage of energy
in fuel that is turned into heat.

Constant Cross Sectional Area: Maintaining
spaces with the same volume measured at right
angles to the flow throughout a stove.

Draft: The movement of air through a stove and up
the chimney.

Emissions: Byproducts from the combustion of
fuel that are discharged into the air.

Emissions Hood: An instrument that captures and
measures the mass of emissions from burning fuels.

Excess Air: Air used for combustion that exceeds
the theoretical (stochiometric)  amount needed.

Firepower: A measure of how much energy is
released from burning fuel per unit of time.

Flue Gas: The hot gas  from burning fuel that flows
up from the combustion chamber.
Grate: A framework used to hold the fuel above the
combustion chamber floor.

Heat Transfer Efficiency: The percentage of
available energy released from the fuel that entered
the pot.

High Mass Stove: A stove made from dense
materials such as earth,  clay and sand that absorb
heat  from a fire more readily than lighter, more
insulative materials.

Hydrocarbons: A mixture of gases including
propane,  methane and butane released from wood
fuel but that remain unburnt and exit the stove due
to incomplete combustion.

Mixing: The combining of air, hot gases and flame
to reduce emissions. Biomass stoves do not mix
air, hot gases and flame very well, so smoke and
unburnt gases are often not fully combusted.

ug/m3: Micrograms per cubic meter, the measure of
concentration of particulate matter in air.

Overall Efficiency: The combination of heat
transfer efficiency and combustion efficiency
expressed as a percentage.

Particulate Matter: The fine particles that make
up smoke. They can vary in size and composition
and are harmful to health when breathed. The
smaller the particle, the more deeply into the body
it can travel.

Pot Skirt: A cylinder, usually made from sheet
metal, that creates a narrow channel around the
sides of a pot to increase heat transfer efficiency.

ppm: Parts per million, a measure of the
concentration of a gas in air.
                                                                                           91

-------
Test Results of Cook Stove Performance
                                                                            Appendix A - Glossary of Terms
Retained Heat Cooker: A relatively air-tight, well-
insulated box that uses captured heat to simmer a
hot pot of food to completion.

Specific Consumption: The fuel used per unit of
product produced, e.g., how much wood was used
to cook a liter of beans.

Stratification: The levels of smoke and other
pollutants that rise and can be more highly
concentrated near the ceiling of a room.

Test Kitchen: A kitchen used for testing emissions
in which the air exchanges are controlled to reduce
the effect of ventilation on the measured levels of
emissions.
Turn Down Ratio: The ratio between high and low
power in a stove. The high firepower is divided by
the low firepower.

Ventilation: The exchange of air from the outside
to the inside of a building.

Water Boiling Test (WBT): A standardized test
in which water is boiled and simmered. Fuel use
and other parameters, including emissions, are
measured. The WBT is designed to investigate the
heat transfer and combustion characteristics of a
stove under controlled operating procedures.
92

-------
Test Results of Cook Stove Performance
                                                                         Appendix B - Testing Methods
Appendix B
Testing  Methods
How were the tests  performed
and analyzed?

Many variables affect the performance of a cook
stove. Whether the stove was cold or hot when
started, the difference in performance when slowly
simmering and rapidly boiling,  and the skill of the
operator all affect the test results.

A standard method for determining stove perfor-
mance is the UCB 2003 Revised Water Boiling Test.
This test has three phases:

1.   Bringing 5 L of water to a boil at high power
    with the stove starting cold, or "cold start."

2.   Bringing 5 L of water to a boil at high power
    with the stove starting hot, or "hot start."

3.   Simmering 5 L of water for 45 minutes at low
    power (3° to 6° C below full-boiling tempera-
    ture).

The international standard 7 L stainless steel testing
pot with no lid was used for each test for each stove
except the alcohol stove.

Kiln-dried Douglas fir cut into sticks  1 cm x 1.5 cm
x 30 cm was used for fuel. The fan stoves were fueled
by 5 cm x 3 cm x 1.5 cm pieces of the same wood.
The fuel was carefully metered into the fire in an
effort to operate each stove as effectively as possible.

The levels of emissions released during a Water
Boiling Test (WBT) varied depending on how and
where they are measured. Two approaches involve 1)
collecting all the smoke under a hood and 2) moni-
toring the amount of smoke dispersed in the air of a
test kitchen.
Emission testing provides information about how
cleanly the stove changes fuel into useable heat.
Emission testing can also shed light on how much
carbon monoxide (CO), particulate matter (PM)
and other pollutants are found in room air.

Three series of tests were performed on each stove:

1.  WBT Series (three full WBTs per stove) - moni-
   toring only fuel use, not emissions:

   a. 5 L of water brought to a boil with stove at
      cold start.

   b. 5 L of water brought to a boil with stove at
      hot start.

   c. 5 L of water boiled again and then simmered
      for 45 minutes.

2.  Test Kitchen Series (three per stove) - monitor-
   ing fuel use and emission concentration within
   an approximately 15m3 kitchen:

   a. 5 L of water brought to a boil with stove at
      cold start.

   b. 5 L of water simmered for 30 minutes.

3.  Emissions  Hood Test Series (three full WBTs per
   stove) monitoring fuel use and collecting/record-
   ing total emissions released from each stove:

   a. 5 L of water brought to a boil from a cold
      start.

   b. 5 L of water brought to boil from  a hot start.

   c. 5 L of water simmered for 45 minutes.

(Due to technical problems, the PM data were not
usable from two of the three WBTs performed under
the emissions hood.)
                                                                                            93

-------
Test Results of Cook Stove Performance
                                                                           Appendix B - Testing Methods
Emissions testing hood

The emissions testing hood at Aprovecho collects
all of the smoke created by a fire and records the
amount of pollutants created each second.

The emissions collection hood includes the follow-
ing:

Hood. Aim2 bell with fire-resistant adjustable
welder's fabric hanging from three sides. The hood
may be raised or lowered depending on the size of
the stove.

Exhaust System and Flow Measurements. The
smoke is drawn up through the hood by using a
large fan. The flow is adjusted so that the smoke is
collected without inducing extra draft in the stove.
Flow is measured with a manometer by pressure
drop across a 1.5" diameter orifice and a type K
thermocouple.

Gas Concentration Measurement. Concentrations
of CO, CO2 and hydrocarbons are measured after
the orifice by an Enerac 3000E NDIR (infrared)
stack meter.
Paniculate Measurement. A sample of smoke is
drawn from the exhaust, diluted and cooled with
clean, dry air then metered using a Radiance Re-
search Nephelometer with light-scattering analysis.
The CO and CO2 are then measured again, using
sensors provided by Tami Bond and Chris Roden
of UIUC, to determine the level of dilution of the
smoke sample.

Data Acquisition and Analysis. Analog signals from
the sensors are read by a data acquisition board con-
nected to a computer. Concentration data are dis-
played in real time on a computer monitor.  Data are
analyzed in conjunction with WBT data entered,
using an Excel spreadsheet with a Visual Basic macro
developed by Tami Bond and Nordica MacCarty.
The concentration of each of the emission compo-
nents times the mass flow through the hood can be
integrated over time to calculate how much of each
pollutant was produced during a given time period.
When a standard WBT (representing a cooking task)
is done under the hood, it is possible to determine
how much wood is consumed and how much pollu-
tion is generated in performing the task.
                               Exhaust to
                               Outsld
                                        Emissions Testing Hood
                                        Schematic
                                        Aprovecho Research Center, ASAT Lab
                                        June 2005

                                                     Dilution Air

                                                     Diluted Sample
                                                     to Nephelometer
                    CO&C02
                   " Meter to PC
                                                     HC, CO. CO2 to Enerac, to PC

                                                     StackTemperatureThermocouple to PC
94

-------
Test Results of Cook Stove Performance
                                                                              Appendix B - Testing Methods
Test kitchen

The Aprovecho test kitchen is a building measuring
8 x 10 x 8 ft designed to replicate common kitchens
around the world. It has been calculated to have
about three air exchanges per hour. The stove tester
sitting inside the kitchen wears a forced-air respi-
rator so that he or she can breathe fresh air from
outside.
Emissions monitors consist of the following:

AP Buck Personal Air Sampler measuring PM.
A common method for measuring PM is a pump
and filter system that draws in air at a constant
rate through a pre-weighed filter. The particles
collect on the filter during the test. The filter is post
weighed after the test on a very sensitive scale. The
mass of the particles, factored by the rate of air
flow through the filter and the  amount of run time,
gives the average concentration of PM entering the
intake during the test. The flow rate of the pump is
calibrated using an AP Buck  bubble calibrator.

HOBO CO Loggers measuring CO. A common
method for measuring concentrations of CO is the
HOBO data logger. The HOBO uses an electro-
chemical cell, which puts off an electrical signal
proportional to the concentration of CO in the air.
The signal is recorded by an  on-board data logger.
The unit is launched and provides results on a per-
sonal  computer, providing a  moment-by-moment
graph of the CO levels in the room.
Three HOBOs were used in the test kitchen: one
logger 1.3 meters away from the stove, one at 1 me-
ter off the floor and one 2.5 meters above the stove.
CO tends to stratify, collecting near the ceiling. In
this report, only the average readout of the HOBO
1.3 meters from the stove is reported.

In the test kitchen tests, 5 L of water were brought
to a boil and then simmered for 30 minutes.

This report presents stove performance based on  10
measures of key importance. The final results were
calculated as an average of the 18 total applicable
test phases completed for each stove.

1. Time to Boil 5 L of water - Corrected to reflect
   a beginning temperature of 25 ° C. Average of
   the following (11)  tests:

   a. One cold and three hot starts in
      the WBT

   b. Three cold starts in the test kitchen.

   c. One cold and three hot starts in the emis-
      sions hood tests.

2. Fuel to Boil 1 L - Temperature-corrected spe-
   cific consumption  is a measure of fuel used per
   liter of boiling water produced, starting from a
   corrected temperature of 25 ° C. Average of the
   following (11) tests:

   a. One cold and three hot starts in the WBT.

   b. Three cold starts in the test kitchen.

   c. One cold and three hot starts in the emis-
      sions hood test.

3. Fuel to Simmer 1 L - Temperature-corrected
   specific consumption to produce 1 L of sim-
   mering water for 45 minutes, average from the
   following tests:

   a. Three WBT.

   b. Three emissions tests.

4. Fuel/Energy to Cook 5 L - found by adding
   the average fuel to  boil 1 L to the  average fuel
   to simmer 1 L for 45 minutes, a typical cooking
                                                                                                 95

-------
Test Results of Cook Stove Performance
                                                                             Appendix B - Testing Methods
5.
situation. This is multiplied by 5 L.  When mul-
tiplied by the effective calorific value of the fuel
used, a comparison of energy used is possible to
compare stoves burning different fuels.

CO Emissions to Cook 5 L - Separate reporting
from both methods of measuring.
Emissions:

    a. Emissions Hood - Monitoring the quantity
    of CO produced each second to find the grams
    of CO produced during each test phase. To find
    CO emissions to cook 5 L, the average grams of
    CO produced to boil  1 L in cold and hot starts
    is added to the CO produced to simmer 1 L for
    45 minutes, averaged  across three tests under the
    emissions hood.

    b. Test Kitchen -The average of three tests
    reporting the average of the CO concentration
    recorded by a HOBO CO sensor at breathing
    level in the test kitchen for the duration of a
    cooking situation (boil 5 L and then simmer for
    30 minutes).

6.  Particulate Emissions  to Cook 5 L - Separate
    reporting from both methods of measuring emis-
    sions:

    a. Emissions Hood - Data from one WBT data
    monitoring the micrograms of PM emissions
    each second to find the specific milligrams of
    PM produced during  each test phase. The aver-
    age milligrams of PM produced to boil 1 L in
    cold and hot starts is added to the PM produced
    to simmer 1 L for 45 minutes under the emis-
    sions hood.

    b. Test kitchen - Average of three tests of the
    average PM concentration recorded by an AP
    Buck Pump and Filter system at breathing level
    in the test kitchen  during the duration of a cook-
    ing situation (boil  5 L and then simmer for 30
    minutes).
7. Thermal Efficiency - Energy transferred into
   the water expressed as heating and vaporization
   divided by energy consumed from the wood.
   Average of all tests.

8. Firepower - Energy in the fuel consumed divid-
   ed by the time of burning in seconds. Average of
   all tests.

9. CO/CO2 Ratio - Grams of CO converted to
   moles divided by grams of CO2 converted to
   moles produced during each phase of testing.
   Average of all emissions hood tests.

10. Emission Factors - Mass of pollutant divided by
   mass of dry fuel consumed during the test phase.
   Average of all emissions hood tests.

11. Turn Down Ratio - High-power firepower di-
   vided by Low-power firepower.

The following pages contain the full testing data and
information on variation between tests.
96

-------
Test Results of Cook Stove Performance                                             Appendix C - Testing Data
Appendix C
Testing  Data
Calculations and Theory for the UCB 2003 Revised Water Boiling Test
Variables that are directly measured
fh;    Weight of fuel before test (grams)
Ph;    Weight of pot with water before test (grams)
Th;    Water temperature before test (°C)
th;    Time at start of test (min)
fhf    Weight of wood after test (grams)
ch    Weight of charcoal and container after test (grams)
Phf    Weight of pot with water after test (grams)
Thf    Water temperature after test (°C)
thf    Time at end of test (min)

Variables that are calculated
f     Wood consumed, moist (grams)            f  = f c- f.
 hm                        vo                 hm   hf   hi
•ch    Net change in char during test phase (grams) »ch = ch - k
fhd    Equivalent dry wood consumed (grams)     fhd = fhm *(!-(!.12*m))-1.5*Ach
why    Water vaporized (grams)                  why = Ph; - Phf
whr    Water remaining at end of test (grams)      whr = Phf - P
•th    Duration of phase (min)                  »th = thf- th;
                                                4.186 * (P.. - P) * (T.f-T..) + 2260 * (W. )
                                                      ^ hi   '  v  hf  hr       v  hvy
h     Thermal efficiency
                                                            fhd * LHV
rhb    Burning rate (grams/min)                rhb =  	

                                                     fhd
SCh   Specific fuel consumption                SCh = —-—-—
      (grams wood/grams water)                         hf

SCTh  Temp-corrected specific consumption       SCTh =	—	* —;———
      (grams wood/grams water)                         hf         M   hi

                                                    £ . * LHV
FP,    Firepower (W)                         FP, =	
                                                   60 * (t -1 1
                                                     FP
TDK  Turn down ratio                        TDK =	
                                                     FP
                                                                                     97

-------
Test Results of Cook Stove Performance                                                        Appendix C - Testing Data
     Explanations of Calculations
     fcm - Wood consumed (moist): This is the mass of wood that was used to bring the water to a
     boil found by taking the difference of the pre-weighed bundle of wood and the wood
     remaining at the end of the test phase:
     •cc - Net change in char during test phase: This is the mass of char created during the test
     found by removing the char from the stove at the end of the test phase. Because it is very
     hot, the char will be placed in an empty pre-weighed container of mass k (to be supplied by
     testers) and weighing the char with the container, then subtracting the two masses.

                                          •cc = cc - k

     fcd - Equivalent dry wood consumed: This is a calculation that adjusts the amount of wood
     that was burned in order to account for two factors: (1) the energy that was needed to
     remove the moisture in the wood and (2) the amount of char remaining unburned. The
     calculation is done in the following way:

                                fcd=fcm*(l-(l.12*m))-1.5*Acc

     The factor of 1 - (l .12 * m) adjusts the mass of wood burned by the amount of wood required
     to heat and evaporate m* fcm grams of water. It takes roughly 2,260 kj to evaporate a
     kilogram of water, which is roughly 12% of the calorific value of dry wood. Thus if wood
     consists of m% moisture, the mass of wood that can effectively heat the pot of water is
     reduced by roughly 1 - (l .12 * m)  because the water must be boiled away (see Baldwin, 1986
     for further discussion).

     The factor of 1 .5 * Acc accounts for the wood converted into unburned char. Char has
     roughly 150%  the calorific content of wood, thus the amount of wood heating the pot of
     water should be adjusted by 1.5* Acc to account for the remaining char. Note, in the
     simmer phase it is possible that there will be a net loss in the amount of char before and after
     the test, in which case »c is negative and the equivalent dry wood increases rather than
     decreases.

     w^ - Water vaporized: This is a measure  of the amount of water lost through evaporation
     during the test. It is calculated by subtracting the final weight of pot and water from the initial
     weight of pot and water.

                                        wcv=Pci-Pcf
     wcr - Water remaining at end of test: This is a measure of the amount of water heated to
     boiling. It  is calculated by subtracting the weight of the pot from the final weight of the pot and water.
                                         wcr=Pc/-P
98

-------
Test Results of Cook Stove Performance                                                   Appendix C - Testing Data
    •t. - Duration of phase: This is simply the time taken to perform the test. It is a simple clock
    difference:
    hc - Thermal efficiency: This is a ratio of the work done by heating and evaporating water to
    the energy consumed by burning wood. It is calculated in the following way.

                           h  ^4.186*(Pci-P)*(Tcf-Tci) + 2260*(wcv)
                                            fcd*LHV

    In this calculation, the work done by heating water is determined by adding two quantities:
    (1) the product of the mass of water in the pot, (Pd - P), the specific heat of water (4.186
    J/g°C), and the change in water temperature (Trf- Td) and (2) the product of the amount of
    water evaporated from the pot and the latent heat of evaporation of water (2,260 J/g). The
    denominator (bottom of the ratio) is determined by taking the product of the drywood
    equivalent consumed during this phase of the test and the lower heat value (LHV).

    rcb - Burning rate: This is a measure of the rate of wood consumption while bringing water to
    a boil. It is calculated by dividing the equivalent dry wood consumed by the time of the test.
    SCc - Specific fuel consumption: Specific consumption can be defined for any number of
    cooking tasks and should be considered "the fuelwood required to produce a unit output"
    whether the output is boiled water, cooked beans, or loaves of bread. In the case of the cold-
    start high-power WBT, it is a measure of the amount of wood required to produce one liter
    (or kilo) of boiling water starting with cold stove. It is calculated in this way:
                                        SC =_k.
    SCTc - Temperature corrected specific fuel consumption: This corrects specific consumption
    to account for differences in initial water temperatures. This facilitates comparison of stoves
    tested on different days or in different environmental conditions. The correction is a simple
    factor that "normalizes" the temperature change observed in test conditions to a "standard"
    temperature change of 75 °C (from 25 to 100). It is calculated in the following way.
                                                    75
                                                  Tcf-Tci
    FPc - Firepower: This is a ratio of the wood energy consumed by the stove per unit time. It
    tells the average power output of the stove (in watts) during the high-power test.
                                      Fp     f* LHV
                                           60*(tci-td)

    Note, by using f d in this calculation, we have accounted for both the remaining char and the
    wood moisture content.
                                                                                               99

-------
Test Results of Cook Stove Performance
                                                                               Appendix C - Testing Data

                                                       3 stone Ghana 20 LCan  Mud/
                                                        fire   wood  Rocket Sawdust VITA
1 . HIGH POWER TEST (COLD START) units
Time to boil Pot # 1 min
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Temp-corrected specific consumption g/L
Firepower watts
Equivalent dry wood consumed g
2. HIGH POWER TEST (HOT START) units
Time to boil Pot # 1 min
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Temp-corrected specific consumption g/L
Firepower watts
Equivalent dry wood consumed g
3. LOW POWER (SIMMER) units
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Firepower watts
Turn down ratio
Equivalent dry wood consumed g
4. ENERGY & MOISTURE CONTENT OF FUEL units
Net calorific value (dry) kJ/kg
Moisture content %
Effective calorific fuel value kJ/kg
5. COLD START ADDITIONAL MEASURES units
Temp-Corrected time to boil min
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ
6. HOT START ADDITIONAL MEASURES units
Temp-Corrected time to boil min
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ
7. SIMMER ADDITIONAL units
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ

28
24.08
19%
136.02
118.44
7,761
511

30
25.61
20%
136.87
121.92
8,243
567.6

9.49
26%
103.38
3,130
2.77
419.4

19,260
11%
17,302

23.8
408
2,024
11,282

29.6
431
2,160
11,766

161
1,807
7,625

25
21.03
24%
106.38
92.13
6,774
387.4

22
19.32
27%
86.67
76.54
6,207
310.0

9.91
23%
114.89
3,298
1.99
279.1

19,260
11%
17,332

24
327
1,619
8,968

19.7
318
1,298
7,173

143
1,580
6,455

22
17.13
37%
76.70
68.06
5,532
395.3

23
18.03
31%
85.99
76.18
5,809
416.0

6.68
26%
74.41
2,235
2.64
192.8

19,260
11%
17,332

22.7
261
1,262
6,853

21.9
296
1,337
7,220

111
1,216
4,977

20
24.15
28%
94.28
82.02
7,801
412.5

16
24.86
31%
83.30
72.58
8,004
390.9

6.28
44%
81.28
2,078
3.92
221.5

19,260
11%
17,334

18.1
343
1,293
7,152

13.9
428
1,223
6,784

114
1,364
5,137

16
25.18
29%
83.71
72.91
8,129
269.6

15
24.66
31%
74.97
67.82
7,944
273.6

7.15
34%
67.52
2,385
3.85
208.8

19,260
11%
17,281

14.1
393
1,122
6,213

13.9
412
1,149
6,314

107
1,175
4,813
100

-------
Test Results of Cook Stove Performance
                                                                                   Appendix C - Testing Data

                                                                  Uganda  Pnatsari
                                                           Justa   2-pot   Pr0t°-
                                                                            type
Onil
 Eco-
Stove
1 . HIGH POWER TEST (COLD START) units
Time to boil Pot f 1 min
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Temp-corrected specific consumption g/L
Firepower watts
Equivalent dry wood consumed g
2. HIGH POWER TEST (HOT START) units
Time to boil Pot f 1 min
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Temp-corrected specific consumption g/L
Firepower watts
Equivalent dry wood consumed g
3. LOW POWER (SIMMER) units
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Firepower watts
Turn down ratio
Equivalent dry wood consumed g
4. ENERGY & MOISTURE CONTENT OF FUEL units
Net calorific value (dry) kJ/kg
Moisture content %
Effective calorific fuel value kJ/kg
5. COLD START ADDITIONAL MEASURES units
Temp-Corrected time to boil min
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ
6, HOT START ADDITIONAL units
Temp-Corrected time to boil min
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ
7. SIMMER ADDITIONAL MEASURES units
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ

52
25.41
17%
150.86
130.11
8,203
884.5

39
29.62
21%
151.80
134.75
8,685
703.2

12.70
14%
140.90
4,180
2.03
392.5

19,260
11%
17,384

54.5
363
2,437
23,080

38.9
420
2,006
18,322

228
2,493
10,239

20
20.38
40%
60.84
52.41
6,577
265.6

15
23.50
45%
58.63
52.29
7,580
231.3

7.71
33%
91.71
2,550
3.11
214.9

19,260
11%
17,384

18.7
310
843
6,914

13.6
377
759
6,021

124
1,475
5,609

42
25.57
20%
123.31
108.29
8,212
709.2

33
26.27
24%
129.78
114.79
8,439
529.6

12.96
14%
143.93
4,253
1.99
401.3

19,260
11%
17,384

40.1
397
1,869
18,530

29.6
413
1,463
13,811

233
2,599
10,490

35
33.58
18%
139.95
118.98
10,829
743.3

28
32.53
22%
131.72
114.77
10,489
551.8

14.50
13%
160.32
4,796
2.24
409

19,260
11%
17,345

30.4
541
1,942
19,356

25.6
489
1,474
14,369

237
2,592
10,648

53
29.87
13%
296.04
260.29
8,998
1074.4

34
31.84
16%
234.21
208.16
9,626
735.6

14.67
16%
168.50
4,531
2.04
448.8

19,260
11%
17,284

47.8
521
5,338
28,032

29.5
571
3,642
19,245

261
2,989
11,734
                                                                                                   101

-------
Test Results of Cook Stove Performance
                                                                             Appendix C - Testing Data

                                                      Wood   Wood
                                                      Flame    Gas
                                                       Fan     Fan
 Mall    Gyapa
Char-   Char-   Pro-
 coal     coal    pane
1 . HIGH POWER TEST (COLD START) units
Time to boil Pot # 1 min
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Temp-corrected specific consumption g/L
Firepower watts
Equivalent dry wood consumed g
2. HIGH POWER TEST (HOT START) units
Time to boil Pot # 1 min
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Temp-corrected specific consumption g/L
Firepower watts
Equivalent dry wood consumed g
3. LOW POWER (SIMMER) units
Burning rate g/min
Thermal efficiency %
Specific fuel consumption g/L
Firepower watts
Turn down ratio
Equivalent dry wood consumed g
4. ENERGY & MOISTURE CONTENT OF FUEL units
Net calorific value (dry) kJ/kg
Moisture content %
Effective calorific fuel value kJ/kg
5. COLD START ADDITIONAL MEASURES units
Temp-Corrected time to boil min
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ
6. HOT START ADDITIONAL MEASURES units
Temp-Corrected time to boil min
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ
7. SIMMER ADDITIONAL units
Energy consumption rate kJ/min
Temp-Corrected specific energy consumption kJ/L
Total energy consumed kJ

23
12.68
42%
59.37
49.85
4,093
265.9

23
12.43
42%
58.65
49.66
4,003
278.8

6.21
42%
75.4
2,059
1.88
276.5

19,260
12%
17,258

19.6
200
816
4,587

19.4
214
856
4,809

106
1,266
4,773

29
8.2
45%
53.46
47.22
2,656
206.9

29
8.5
46%
51.05
46.60
2,761
0.0

4.20
46%
44.85
1,400
1.97
0.0

19,260
12%
17,196

23.7
124
755
3,558

23.7
124
755
3,558

124
1,132
5,337

38
11.10
17%
88.55
78.31
5,859
253.2

47
10.31
18%
93.34
83.97
5,443
272.9

4.84
27%
53.64
2,586
2.10
157.9

31,680
6%
29,983

34.5
291
2,081
11,370

42.7
297
2,321
12,191

161
1,759
7,259

37
10.97
18%
81.28
70.65
5,790
256.8

29
12.76
19%
75.02
65.95
6,735
230.9

5.89
34%
70.54
3,174
2.82
137.6

31,680
6%
29,983

34.0
289
2,035
11,540

22.7
392
1,821
10,357

141
1,674
6,332

32
2.43
69%
14.94
12.70
1,946
66

30
2.40
66%
14.86
12.94
1,915
67

1.32
61%
15.00
1,072
1.89
41.3

47,490
0%
47,490

20.9
136
589
1,606

25.0
114
593
1,631

65
743
2,949
102

-------
Test Results of Cook Stove Performance
                                                                                      Appendix C - Testing Data

                                                            Alcohol
                                                             Clean   Kero-
                                                             Cook
Solar
1 . HIGH POWER TEST (COLD START)
Time to boil Pott 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
Equivalent dry wood consumed
2. HIGH POWER TEST (HOT START)
Time to boil Pott 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
Equivalent dry wood consumed
3. LOW POWER (SIMMER)
Burning rate
Thermal efficiency
Specific fuel consumption
Firepower
Turn down ratio
Equivalent dry wood consumed
4. ENERGY & MOISTURE CONTENT OF FUEL
Net calorific value (dry)
Moisture content
Effective calorific fuel value
5. COLD START ADDITIONAL MEASURES
Temp-Corrected time to boil
Energy consumption rate
Temp-Corrected specific energy consumption
Total energy consumed
6. HOT START ADDITIONAL
Temp-Corrected time to boil
Energy consumption rate
Temp-Corrected specific energy consumption
Total energy consumed
7. SIMMER ADDITIONAL MEASURES
Energy consumption rate
Temp-Corrected specific energy consumption
Total energy consumed
units
min
g/min
%
g/L
g/L
watts
g
units
min
g/min
%
g/L
g/L
watts
g
units
g/min
%
g/L
watts
g
units
kJ/kg
%
kJ/kg
units
min
kJ/min
kJ/L
kJ
units
min
kJ/min
kJ/L
kJ
units
kJ/min
kJ/L
kJ

38
4.33
66%
34.44
28.68
1,544
165.0

38
4.33
66%
34.44
28.68
1,544
165.0

3.09
59%
34.64
1,100
1.40
139.0

21,370
0%
21,370

31.6
93
613
3,526

31.6
93
613
3,526

66
740
2,970

46
2.73
52%
25.82
22.25
1,859
114.0

51
2.56
51%
27.67
23.75
1,859
113.0

2.40
40%
26.37
1,799
110
96.0

43,500

43,500

40.7
104
916
4,959

43.1
105
911
5,307

93
1,011
4,176

76

28%


2,386


77

23%


2,386





1,383







69.9




70.0







                                                                                                       103

-------
Test Results of Cook Stove Performance
                                                                                  Appendix C - Testing Data

                                                    3 stone    Ghana   20 L Can    Mud/
                                                     fire     Wood    Rocket   Sawdust
                                                 VITA
Totals
CO
C02
HC (propane)
appx PM
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/C02 ratio
Flame temp
grams
grams
grams (prop)
mg
degrees C
grams
grams
grams (prop)
mg
degrees C
grams
grams
grams (prop)
grams

26.50
818
1 .7405
1793
0.0572
485


28.91
934
2.3698
2004
0.0533
300


31.43
815
3.6547
281
0.0694
207

29.25
737
2.0569
5294
0.0648
159


20.22
669
2.0739
3751
0.0479
155


24.71
682
3.8498
948
0.0594
77

5.27
836
0.5386
997
0.0101
226


6.50
784
0.7755
594
0.0137
177


9.95
830
2.6255
MISS
0.0188
121

18.01
628
1 .5064
1847
0.0478
155


16.39
523
1
2255
0.0523
164


29.90
735
4.1328
663
0.0645
62

24.59
515
1.5081
1887
0.0752
282


26.19
523
1 .9752
2642
0.0804
301


21.88
661
3.4533
421
0.0525
70
 (Corrected for water temp and Moisture)
 Correction Factor
0.1408
CO
CO2
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
3.6351
112.0006
0.2385
238.2039
3.7049
94.4812
0.2604
652.9593
0.8044
126.7232
0.0800
162.3765
2.3990
82.3402
0.1990
265.2436
3.3932
71.3697
0.2090
283.4517
 Correction Factor
0.1446
CO
C02
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
4.0321
130.2379
0.3298
277.0760
2.4414
82.4174
0.2511
414.9405
0.9921
119.2356
0.1155
95.4476
2.2284
69.2491
0.2118
324.7657
3.6219
72.3851
0.2757
392.1768
 Correction Factor
0.2274
CO
CO2
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
7.3046
185.1880
0.8474
214.9977
7.0095
185.2308
1.0770
323.4849
2.1654
180.5102
0.5715
128.9121
7.3922
178.7203
0.9864
175.4471
5.0520
154.5302
0.8090
92.2347
104

-------
Test Results of Cook Stove Performance
                                                                                         Appendix C - Testing Data
Uganda 2- Proto-
Justa pot type Onil Eco- stove
Totals
CO
CO2
HC (propane)
appx PM
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/CO2 ratio
Flame temp
grams
grams
grams (prop)
rng
degrees C
grams
grams
grams (prop)
mg
degrees C
grams
grams
grams (prop)
grams

26.93
1983
5.1406
983
0.0200
11


17.40
1726
5.1970
933
0.0148
13


12.80
1254
5.8437
340
0.0168
13

13.03
372
1.4423
662
0.0539
12


12.46
369
2.0540
813
0.0529
13


12.87
654
4.8623
264
0.0304
14

16.47
1700
2.6841
903
0.0147
12


13.18
1549
3.1776
835
0.0146
13


11.96
1010
4.1460
446
0.0205
12

32.89
1730
2.4597
1437
0.0286
396


17.19
1361
3.1035
1483
0.0193
442


18.10
1141
4.2688
671
0.0247
277

52.83
2382
4.1091
5535
0.0349
13


27.41
1442
3.1484
4343
0.0302
13


14.06
1077
4.3466
1044
0.0201
13
 (Corrected for water temp and moisture)
Correction Factor
CO
C02
HC (propane)
appx PM mg
0.1408
g/L
g/L
g/L
mg/L

2.3540
172.6200
0.4454
83.1819
1.1894
33.9872
0.1327
62.6387
1.2863
132.9404
0.2106
71.8650
2.6733
139.3402
0.1952
111.7469
8.1161
365.8552
0.6313
851.8434
Correction Factor
CO
CO2
HC (propane)
appx PM mg

0.1446
g/L
g/L
g/L
mg/L

1.5561
153.5459
0.4603
78.5652
1.1529
34.0263
0.1871
72.2213
1 .0826
127.0328
0.2610
69.3188
1.3988
109.4260
0.2401
112.0330
4.0083
211.2221
0.4607
642.2649

 Correction Factor
0.2274
CO
CO2
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
2.8703
280.5839
1.3105
77.6056
3.2840
166.6359
1.2417
68.1982
2.7024
224.6289
0.9257
105.3058
4.2671
269.0215
1 .0003
156.6180
3.5458
266.7382
1.0712
273.3383
                                                                                                          105

-------
Test Results of Cook Stove Performance
                                                                                       Appendix C - Testing Data

                                                                                       Gyapa
Wood Wood Gas Mali Char Char- Pro-
Flame Fan Fan coal coal pane
Totals
CO
CO2
HC (propane)
appx PM
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/CO2 ratio
Flame temp
grams
grams
grams (prop)
mg
degrees C
grams
grams
grams (prop)
mg
degrees C
grams
grams
grams (prop)
grams

6.49
510
1.2411
6
0.0201
228


5.14
504
1 .5259
48
0.0182
251


4.52
664
3.5576
25
0.0117
180

3.64
525
2.3581
14
0.0109
366


3.64
525
2.3581
14
0.0109
366


5.46
788
3.5372
22
0.0109


73.97
524
8.0845
1026
0.2219
181


75.57
577
10.8352
1149
0.2279
214


43.41
359
7.8860
162
0.2251
187

105.09
665
7.7670
1155
0.2522
312


85.79
630
18.7060
1656
0.1579
360


56.89
522
10.9529
169
0.1726
202

0.64
281
0.9349
2
0.0043
13


0.50
323
1 .5905
1
0.0025
13


0.02
341
4.3930
2
0.0001
11
 (Corrected for water temp and moisture)
 Correction Factor
0.1408
CO
C02
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
0.9190
71.9071
0.1759
0.8663
0.5488
79.2075
0.3557
2.1627
12.7035
90.0783
1 .3648
50.2483
15.5781
98.5886
1.1513
102.5396
0.1164
50.3029
0.1661
0.2854
 Correction Factor
0.1446
CO
CO2
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
0.7203
71.3950
0.2141
6.7223
0.5488
79.2075
0.3557
2.1627
13.2394
102.0851
1.8575
38.6633
12.7283
93.3947
2.7752
96.6982
0.0907
58.1523
0.2848
0.2511
 Correction Factor
0.2274
CO
C02
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
1
152.4690
0.8266
5.7257
0.8232
118.8113
0.5335
3.2441
9.5875
82.6742
1.7700
7.5531
12.8843
118.2473
2.4806
17.7353
0.0046
85.7806
1.1048
0.6331
106

-------
Test Results of Cook Stove Performance
                                                                                       Appendix C - Testing Data

                                                     Alcohol-
                                                       Clean
                                                       Cook
                    Kero-
                    sene
Solar
Totals
CO
CO2
HC (propane)
appx PM
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/CO2 ratio
Flame temp

Totals
CO
CO2
HC (propane)
appx PM gr
CO/CO2 ratio
Flame temp
grams
grams
grams (prop)
mg
degrees C
grams
grams
grams (prop)
mg
degrees C
grams
grams
grams (prop)
grams
(cold start)
2.71
306
0.6992
2
0.0138
6

(hot start)
2.71
306
0.6992
2
0.0138
6

(simmer)
2.35
350
1.3251
2
0.0106
6

5.43
409
0.7374
2
0.0208
479


5.06
434
1.6961
3
0.0185
341


3.11
403
2.0206
5
0.0119
317























 (Corrected for water temp and moisture)
 Correction Factor
0.1408
CO
CO2
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
0.4722
53.0953
0.1195
0.3072
0.8918
68.2801
0.1157
0.4546
 Correction Factor
0.1446
CO
CO2
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
0.4722
53.0953
0.1195
0.3072
0.8347
71.1966
0.2874
0.5829
 Correction Factor
0.2274
CO
CO2
HC (propane)
appx PM mg
g/L
g/L
g/L
mg/L
0.5850
87.0337
0.3294
0.5663
0.7004
94.5210
0.4944
1.3829
                                                                                                       107

-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
HOOD Results
3 stone Ghana 20 L Can Mud/
fire Wood Rocket Sawdust VITA
Time to Boil (temp-corrected) min
Temp-Corrected Specific Consumption g/L
Temp-Corr Specific Energy Consumption kJ/L
Firepower W
Thermal Efficiency %
COOKING TASKS
CO TO Boil g/L
CO To Simmer g/L
CO TO Cook g/L
PM To Boil mg/L
PM to Simmer mg/L
PM to Cook mg/L
CO2 to Boil g/L
CO2 to Simmer g/L
CO2 to Cook g/L
HC to Boil g/L
HC to Simmer g/L
HC to Cook g/L
Average CO/CO2 Ratio for Boil
CO/CO2 Ratio for Simmer
Boiling
EF CO g/kg
EF C02 g/kg
EF PM mg/kg
EF HC g/kg
26.69
120.18
2,091.87
8,001.96
0.20
21.84
84.33
1 ,458.46
6,490.30
0.25
22.29
72.12
1,299.32
5,670.31
0.34
15.99
77.30
1,257.74
7,902.64
0.29
14.00
70.37
1,135.57
8,036.66
0.30


3.83
7.30
11.14
0.00
257.64
215.00
472.64

121.12
185.19
306.31

0.28
0.85
1.13


0.0552
0.0694

51.40
1,623.05
3,519.59
3.79
3.07
7.01
10.08
0.00
533.95
323.48
857.43

88.45
185.23
273.68

0.26
1.08
1.33


0.0564
0.0594

70.37
2,031.03
12,884.23
6.00
0.90
2.17
3.06
0.00
128.91
128.91
257.82

122.98
180.51
303.49

0.10
0.57
0.67


0.0119
0.0188

14.48
2,000.21
1,976.11
1.61
2.31
7.39
9.71
0.00
295.00
175.45
470.45

75.79
178.72
254.51

0.21
0.99
1.19


0.0501
0.0645

42.78
1,429.53
5,123.86
3.85
3.51
5.05
8.56
0.00
337.81
92.23
430.05

71.88
154.53
226.41

0.24
0.81
1.05


0.0778
0.0525

93.47
1,910.97
8,327.68
6.41
108

-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
HOOD ReSUltS Patsan
Uganda 2- Proto-
Justa pot type Onil Eco- stove
Time to Boil (temp-corrected) min
Temp-Corrected Specific Consumption g/L
Temp-Corr Specific Energy Consumption kJ/L
Firepower W
Thermal Efficiency %
COOKING TASKS
CO TO Boil g/L
CO To Simmer g/L
CO TO Cook g/L
PM To Boil mg/L
PM to Simmer mg/L
PM to Cook mg/L
CO2 to Boil g/L
CO2 to Simmer g/L
CO2 to Cook g/L
HC to Boil g/L
HC to Simmer g/L
HC to Cook g/L
Average CO/CO2 Ratio for Boil
CO/CO2 Ratio for Simmer
Boiling
EF CO g/kg
EF CO2 g/kg
EF PM mg/kg
EF HC g/kg
46.73
132.43
2,221.74
8,444.21
0.19
16.17
52.35
800.88
7,078.41
0.43
34.82
1 1 1 .54
1,666.19
8,325.55
0.22
28.00
116.87
1,708.19
10,663.36
0.20
38.63
234.23
4,490.09
9,312.02
0.15


1.96
2.87
4.83
0.00
80.87
77.61
158.48

163.08
280.58
443.67

0.45
1.31
1.76


0.0174
0.0168

27.60
2,348.28
1,219.54
6.60
1.17
3.28
4.46
0.00
67.43
68.20
135.63

34.01
166.64
200.64

0.16
1.24
1.40


0.0534
0.0304

51.47
1,497.56
3,005.25
7.16
1.18
2.70
3.89
0.00
70.59
105.31
175.90

129.99
224.63
354.62

0.24
0.93
1.16


0.0147
0.0205

24.06
2,660.75
1,425.69
4.89
2.04
4.27
6.30
0.00
111.89
156.62
268.51

124.38
269.02
393.40

0.22
1.00
1.22


0.0239
0.0247

37.70
2,397.11
2,310.11
4.47
6.06
3.55
9.61
0.00
747.05
273.34
1,020.39

288.54
266.74
555.28

0.55
1.07
1.62


0.0325
0.0201

43.21
2,088.72
5,527.62
4.05
                                                                                                                    109

-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
HOOD Results Gyapa
Wood Wood Gas Mali Char Char- Pro-
Flame Fan Fan coal coal pane
Time to Boil (temp-corrected) min 19.50
Temp-Corrected Specific Consumption g/L 49.76
Temp-Corr Specific Energy Consumption kJ/L 836.17
Firepower W 4,047.99
Thermal Efficiency % 0.42
COOKING TASKS
CO TO Boil g/L 0.82
CO To Simmer g/L 1 .02
CO TO Cook g/L 1 .84
0.00
PM To Boil mg/L 3.79
PM to Simmer mg/L 5.73
PM to Cook mg/L 9.52
C02 to Boil g/L 71 .65
CO2 to Simmer g/L 152.47
C02toCook g/L 224.12
HC to Boil g/L 0.19
HC to Simmer g/L 0.83
HC to Cook g/L 1 .02
Average CO/CO2 Ratio for Boil 0.01 92
CO/CO2 Ratio for Simmer 0.01 1 7
Boiling
EF CO g/kg 21 .42
EF C02 g/kg 1 ,863.01
EF PM mg/kg 98.36
EF HC g/kg 5.07
23.75
46.91
754.73
2,708.92
0.45
38.62
81.14
2,200.86
5,650.63
0.18
28.35
68.30
1,928.27
6,262.64
0.18
22.98
12.82
590.92
1,930.36
0.68


0.55
0.82
1.37
0.00
2.16
3.24
5.41

79.21
118.81
198.02

0.36
0.53
0.89


0.0109
0.0109

17.59
2,538.40
69.31
11.40
12.97
9.59
22.56
0.00
44.46
7.55
52.01

96.08
82.67
178.76

1.61
1.77
3.38


0.2249
0.2251

284.53
2,091.55
4,131.65
35.82
14.15
12.88
27.04
0.00
99.62
17.74
117.35

95.99
118.25
214.24

1.96
2.48
4.44


0.2050
0.1726

390.40
2,658.17
5,834.94
55.63
0.10
0.00
0.11
0.00
0.27
0.63
0.90

54.23
85.78
140.01

0.23
1.10
1.33


0.0034
0.0001

8.62
4,542.56
21.85
18.95
110

-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
HOOD Results
Time to Boil (temp-corrected)
Temp-Corrected Specific Consumption
Temp-Corr Specific Energy Consumption
Firepower
Thermal Efficiency
COOKING TASKS
CO TO Boil
CO To Simmer
CO TO Cook
PM To Boil
PM to Simmer
PM to Cook
CO2 to Boil
CO2 to Simmer
CO2 to Cook
HC to Boil
HC to Simmer
HC to Cook
Average CO/CO2 Ratio for Boil
CO/CO2 Ratio for Simmer
Boiling
EFCO
EFCO2
EFPM
EFHC
Alcohol-
Clean Kero-
Cook sene Solar
min
g/L
kJ/L
W
%
g/L
g/L
g/L
mg/L
mg/L
mg/L
g/L
g/L
g/L
g/L
g/L
g/L
g/kg
g/kg
mg/kg
g/kg
31.62
28.68
612.83
1,543.64
0.66
41.89
23.00
913.49
1,917.90
0.52
69.95


2,236.41
0.25


0.47
0.59
1.06

0.31
0.57
0.87

53.10
87.03
140.13

0.12
0.33
0.45


0.0138
0.0106

16.41
1,852.21
10.87
4.24
0.86
0.70
1.56
0.00
0.52
1.38
1.90

69.74
94.52
164.26

0.20
0.49
0.70


0.0197
0.0119

46.24
3,714.77
24.81
10.74
0.00
0.00
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00
0.00










                                                                                                                     111

-------
Test Results of Cook Stove Performance
                                                                              Appendix C - Testing Data
   WBT Results
                                                                                      Chimney
  1. HIGH POWER TEST (COLD START)
    Time to boil Pot # 1
    Burning rate
    Thermal efficiency
    Specific fuel consumption
    Temp-corrected specific consumption
    Firepower
  2. HIGH POWER TEST (HOT START)
    Time to boil Pot # 1
    Burning rate
    Thermal efficiency
    Specific fuel consumption
    Temp-corrected specific consumption
    Firepower
  3. LOW POWER (SIMMER)
    Burning rate
    Thermal efficiency
    Specific fuel consumption
    Firepower
    Turn down ratio
3 stone
fire
Average
21.03
33.10
0.16
145.98
139.13
10,756
Average
19.67
28.78
0.21
117.14
110.62
9,354
Average
8.83
0.22
99.59
3,062
3.15
Ghana
Wood
Average
20.45
22.03
0.24
93.11
84.94
7,086
Average
19.33
22.38
0.25
89.50
81.82
7,199
Average
16.86
0.12
186.47
5,793
1.27
20L Can
Rocket
Average
17.10
19.23
0.54
65.22
57.17
6,248
Average
18.49
20.88
0.35
84.31
73.78
6,784
Average
7.28
0.24
81.88
2,525
2.71
Mud/
Sawdust
Average
18.46
28.35
0.25
102.94
91.67
9,211
Average
17.42
25.51
0.31
89.11
78.93
8,289
Average
7.00
0.47
90.03
2,427
4.07

VITA
Average
14.33
25.96
0.29
76.31
71.16
8,435
Average
13.20
27.26
0.29
73.37
72.11
8,857
Average
5.95
0.34
66.16
2,063
4.28

Justa
Average
28.30
34.57
0.19
123.75
109.99
1,1232
Average
28.03
32.48
0.25
190.05
173.15
10,554
Average
11.94
0.17
136.05
4,141
2.55
                                                                                     Chimney
 1. HIGH POWER TEST (COLD START)
   Time to boil Pot # 1
   Burning rate
   Thermal efficiency
   Specific fuel consumption
   Temp-corrected specific consumption
   Firepower
 2. HIGH POWER TEST (HOT START)
   Time to boil Pot # 1
   Burning rate
   Thermal efficiency
   Specific fuel consumption
   Temp-corrected specific consumption
   Firepower
 3. LOW POWER (SIMMER)
   Burning rate
   Thermal efficiency
   Specific fuel consumption
   Firepower
   Turn down ratio
3 stone
fire
StDev
2.25
1.37
0.02
21.25
18.17
447
StDev
2.25
7.05
0.03
22.22
21.71
2,290
StDev
1.16
0.01
15.53
402
1.09
Ghana
Wood
StDev
0.83
1.25
0.02
6.90
4.45
408
StDev
1.46
2.01
0.01
8.38
6.36
653
StDev
2.60
0.02
27.86
882
0.25
20L Can
Rocket
StDev
3.53
10.39
0.50
32.46
28.10
3,377
StDev
3.43
5.12
0.10
35.43
31.63
1,662
StDev
1.59
0.03
21.46
552
0.44
Mud/Saw
dust
StDev
4.72
10.15
0.06
11.98
16.26
3,297
StDev
3.76
8.99
0.09
18.70
20.05
2,921
StDev
3.09
0.16
48.05
1,071
2.03

VITA
StDev
1.53
5.11
0.03
13.42
10.70
1,660
StDev
1.51
6.93
0.03
12.46
8.24
2,252
StDev
0.28
0.06
5.01
98
0.99

Justa
StDev
3.57
0.82
0.02
14.78
11.57
268
StDev
2.93
2.96
0.09
9.72
11.20
962
StDev
0.72
0.00
8.95
250
0.24
112

-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
WBT Results



1






2






3








. HIGH POWER TEST (COLD START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
. HIGH POWER TEST (HOT START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
. LOW POWER (SIMMER)
Burning rate
Thermal efficiency
Specific fuel consumption
Firepower
Turn down ratio
Chimney Stoves

Uganda 2-
pot
Average
15.00
25.51
0.36
64.62
60.15
8,288
Average
12.83
27.06
0.39
71.52
69.46
8,794
Average
8.79
0.31
105.59
3,050
2.93
Patsari
Proto-
type
Average
30.93
31.15
0.20
118.89
110.16
10,018
Average
29.33
31.36
0.21
191.81
176.12
10,087
Average
12.14
0.14
133.44
4,170
2.46


Onil
Average
33.17
38.28
0.16
149.06
133.10
12,439
Average
22.53
41.09
0.19
192.76
174.32
13,354
Average
16.24
0.12
182.16
5,635
2.37


Ecostove
Average
52.23
29.59
0.21
193.44
167.23
7,733
Average
36.77
29.96
0.24
235.03
206.79
7,830
Average
14.08
0.19
162.54
3,988
2.03
Chimney Stoves



1






2






3








. HIGH POWER TEST (COLD START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
. HIGH POWER TEST (HOT START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
. LOW POWER (SIMMER)
Burning rate
Thermal efficiency
Specific fuel consumption
Firepower
Turn down ratio

Uganda 2
Pot
StDev
1.00
2.73
0.05
5.59
5.01
887
StDev
1.89
4.32
0.03
3.97
5.74
1,403
StDev
0.86
0.02
12.24
297
0.74

Patsari
Prototype
StDev
1.44
2.35
0.01
6.25
8.74
750
StDev
4.35
3.03
0.01
13.87
16.42
979
StDev
1.45
0.01
15.97
502
0.50


Onil
StDev
2.02
1.37
0.00
2.48
4.92
444
StDev
0.46
2.39
0.01
6.76
6.36
775
StDev
0.47
0.02
2.16
162
0.07


Ecostove
StDev
5.35
3.33
0.01
8.42
4.52
870
StDev
2.12
2.34
0.02
6.87
14.08
611
StDev
2.84
0.04
32.33
804
0.53
Electric Fan
Wood
Flame
Fan
Average
22.33
13.96
0.40
63.83
52.01
4,535
Average
23.50
12.51
0.41
60.68
49.83
4,065
Average
6.84
0.39
81.66
2,372
1.72

Wood
Gas Fan
Average
31.50
8.24
0.44
53.68
48.74
2,678
Average
28.90
8.50
0.46
51.05
46.60
2,761
Average
4.03
0.46
44.85
1,400
1.97
Electric Fan
Wood
Flame
Fan
StDev
1.53
3.93
0.09
14.47
12.27
1,276
StDev
1.80
1.23
0.01
1.90
2.47
400
StDev
0.36
0.03
3.83
127
0.23

Wood
GasFan
StDev
4.86
0.90
0.05
6.84
5.82
294
StDev
2.62
0.37
0.01
2.79
2.62
121
StDev
0.12
0.02
1.73
43
0.10
                                                                                                                    113

-------
Test Results of Cook Stove Performance
                                                                                                    Appendix C - Testing Data
WBT Results




1. HIGH POWER TEST (COLD START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
2. HIGH POWER TEST (HOT START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
3. LOW POWER (SIMMER)
Burning rate
Thermal efficiency
Specific fuel consumption
Firepower
Turn down ratio
* Initial WBT tests of the Alcohol- Clean Cook stove




1. HIGH POWER TEST (COLD START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
2. HIGH POWER TEST (HOT START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
3. LOW POWER (SIMMER)
Burning rate
Thermal efficiency
Specific fuel consumption
Firepower
Turn down ratio
* Initial WBT tests of the Alcohol- Clean Cook stove
114

Charcoal Other Fuels
Alcohol -
Mali Gyapa Clean
Charcoal Charcoal Propane Cook*
Average Average Average Average
36.70 29.77 30.58
13.76 13.58 2.45
0.15 0.17 0.66
107.43 83.75 14.57
96.31 76.32 12.61
7,267 7,169 1,986
Average Average Average Average
42.93 33.40 32.00
11.49 11.97 2.38
0.16 0.18 0.62
104.58 82.83 15.89
96.17 76.21 13.84
6,066 6,323 1,934
Average Average Average Average
4.00 8.50 1.23
0.28 0.18 0.61
46.04 102.49 13.75
2,200 4,677 1,028
2.78 1.53 1.93
were dismissed after receiving an improved model in Dec,
Charcoal Other Fuels
Alcohol -
Mali Gyapa Clean
Charcoal Charcoal Propane Cook*
St Dev St Dev St Dev St Dev
2.29 2.36 9.36
0.23 1.13 0.69
0.01 0.01 0.02
6.27 7.29 0.90
5.35 7.02 0.43
120 599 561
St Dev St Dev St Dev St Dev
5.29 3.86 3.00
0.94 1.52 0.13
0.01 0.02 0.06
3.82 4.61 0.75
5.31 7.81 1.15
494 803 107
St Dev St Dev St Dev St Dev
0.50 2.96 0.25
0.04 0.03 0.10
5.99 40.39 2.84
275 1627 208
0.31 0.80 0.36
were dismissed after receiving an improved model in Dec.





Kerosene
Average
51.57
2.65
0.59
31.90
28.05
1,920
Average
50.67
3.05
0.52
36.77
32.16
2,209
Average
2.91
0.37
35.74
2,256
0.98
2006



Kerosene
St Dev
4.99
0.12
0.22
1.79
1.70
84
St Dev
3.62
0.65
0.11
11.58
10.76
471
St Dev
0.15
0.05
1.83
113
0.19
2006


-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
TEST KITCHEN Results
3 stone

1






3






. HIGH POWER TEST (COLD START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
. LOW POWER (SIMMER)
Burning rate
Thermal efficiency
Specific fuel consumption
Firepower
Turn down ratio
fire

Average
36
17
0
125
103
5,
.00
.08
.22
.76
.04
549
Average
10
0
82
3,

.81
.27
.22
752

3 stone

1





3

. HIGH POWER TEST (COLD START)
Time to boil Pot # 1
Burning rate
Thermal efficiency
Specific fuel consumption
Temp-corrected specific consumption
Firepower
. LOW POWER (SIMMER)
Burning rate
Thermal efficiency
Specific fuel consumption
Firepower
Turn down ratio
fire

St Dev
9
4
0
3
1
.17
.55
.01
.52
.24
1,479
St Dev
0.33
0.03
3.13
114
Ghana
Wood
20 L Can
Rocket
Average
20.99
26.58
0.21
114.76
95.98
8,
637
Average
7.88
0.37
58.99
2,

Ghana
Wood
St Dev
734

Average
16
21
0
70
64
6,
.27
.33
.31
.57
.85
930
Average
6
0
45
2,

.59
.25
.15
288

20 L Can
Rocket

1.86
5.13
0.04
13.98
15.00
1,668
St Dev
3.56
0.08
30.53
1235
St Dev
1
4
0
5
4

.96
.32
.02
.34
.52
1,404
StDev
1.19
0.02
8.49
413
Mud/Saw-
dust

Average
15
33
0
107
94
10,
.97
.10
.22
.80
.82
755
Average
4
0
34
1,

.73
.57
.03
640

VITA
Average
18
31
0
118
98
10,
Average
11
0
96
3,



.33
.82
.20
.80
.73
339

.25
.45
.28
902

Mud/Saw-
dust
StDev
2
12
0
31
24


.76
.24
.05
.25
.36
3,977
StDev
0.99
0.28
6.65
344
VITA
StDev
3
6
0
6
9
2,
StDev
1
0
20


.21
.91
.02
.81
.97
244
.76
.04
.60
612
                                                                                                                    115

-------
Test Results of Cook Stove Performance
                                                                           Appendix C - Testing Data
  TEST KITCHEN Results
                                             Electric Fan
Other Fuels
  1. HIGH POWER TEST (COLD START)
    Time to boil Pot # 1
    Burning rate
    Thermal efficiency
    Specific fuel consumption
    Temp-corrected specific consumption
    Firepower
  3. LOW POWER (SIMMER)
    Burning rate
    Thermal efficiency
    Specific fuel consumption
    Firepower
    Turn down ratio
  1. HIGH POWER TEST (COLD START)
    Time to boil Pot # 1
    Burning rate
    Thermal efficiency
    Specific fuel consumption
    Temp-corrected specific consumption
    Firepower
  3. LOW POWER (SIMMER)
    Burning rate
    Thermal efficiency
    Specific fuel consumption
    Firepower
    Turn down ratio
Wood
Flame
Fan
Average
22.00
14.65
0.37
67.64
55.30
4,759
Average
5.73
0.50
42.47
1,988

Wood
Gas Fan
Average
27.94
9.17
0.45
53.61
49.04
2,979
Average
4.37
0.45
30.98
1,518
Electric Fan
Wood
Flame
Fan
St Dev
2.83
0.01
0.04
8.90
7.03
2
St Dev
0.21
0.00
1.45
74

Wood
Gas Fan
St Dev
0.92
0.44
0.05
1.92
3.07
143
St Dev
0.60
0.02
4.55
209


Propane
Average
47.50
1.56
0.76
16.60
13.38
1,265
Average
1.30
0.63
9.36
1,084
Alcohol -
Clean
Cook
Average
59.33
3.67
0.55
49.66
41.43
1,218
Average
4.00
0.53
29.06
1,513


Kerosene
Average
35.38
3.33
0.47
22.99
20.24
2,415
Average
2.71
0.27
17.27
2,097
Other Fuels


Propane
St Dev
9.19
0.41
0.30
7.67
6.37
335
St Dev
0.05
0.02
0.52
39
Alcohol -
Clean
Cook
St Dev
10.07
0.27
0.00
7.79
3.67
88
St Dev
-
0.04
0.10
0


Kerosene
St Dev
12.90
1.22
0.01
0.10
0.11
881
St Dev
0.06
0.12
2.38
43
116

-------
Test Results of Cook Stove Performance
                                                                                Appendix C - Testing Data
   Overall Variations
# of 3 stone Ghana 20 L Can Mud/
Average Maximum Tests fire Wood Rocket Sawdust
VITA

Cold Temp Corr Time to Boil
Hot Temp Corr Time to Boil
15%
22%
30%
54%
9
9
21%
54%
15%
2%
16%
34%
14%
13%
18%
20%

Cold Firepower
Hot Firepower
Simmer Firepower
22%
21%
25%
33%
49%
51%
9
9
9
28%
49%
34%
23%
16%
43%
22%
12%
10%
28%
17%
33%
20%
23%
36%

Cold Specific Consumption
Hot Specific Consumption
Simmer Specific Consumption
17%
23%
24%
32%
46%
50%
9
9
9
29%
36%
37%
18%
15%
43%
27%
26%
9%
14%
15%
39%
20%
14%
11%

Cold CO perl
HotCOperL
Simmer CO per L
33%
36%
36%
73%
87%
87%
3
3
3
23%
47%
34%
45%
23%
36%
25%
45%
18%
18%
51%
37%
9%
31%
25%
   Coefficient of Variation = Standard Deviation /Average
   Includes different testers, different times of year.
   Most of the CO variability is in the chimney stoves
   Due to problems in test phases of the Wood Gas and Alcohol Stoves, variation are not reported
Patsari
Uganda proto-
Justa 2-pot type
Wood Wood Mali
Eco- Flame Gas Char-
Onil stove Fan Fan coal

Cold Temp Corr Time to Boil
Hot Temp Corr Time to Boil
5%
26%
30%
12%
2%
25%
30%
35%
17%
13%
9%
14%
18%
54%

Cold Firepower
Hot Firepower
Simmer Firepower
33%
22%
5%
24%
24%
19%
26%
25%
22%
16%
27%
16%
14%
29%
28%
14%
8%
12%
23%
32%
44%

Cold Specific Consumption
Hot Specific Consumption
Simmer Specific Consumption
14%
27%
6%
16%
30%
16%
16%
46%
20%
11%
45%
13%
32%
30%
24%
14%
4%
13%
20%
16%
43%

Cold CO per L
Hot CO per L
Simmer CO per L
73%
79%
25%
49%
23%
37%
52%
36%
12%
65%
56%
44%
2%
3%
60%
26%
87%
87%
22%
13%
63%
    Coefficient of Variation = Standard Deviation /Average
    Includes different testers, different times of year.
    Most of the CO variability is in the chimney stoves
    Due to problems in test phases of the Wood Gas and Alcohol Stoves, variation are not reported
                                                                                               117

-------
Test Results of Cook Stove Performance
                                                                            Appendix C - Testing Data
   Overall Variations
Gyapa
Char-
coal
Cold Temp Corrected Time to Boil
Hot Temp Corrected Time to Boil
Cold Firepower
Hot Firepower
Simmer Firepower
Cold Specific Consumption
Hot Specific Consumption
Simmer Specific Consumption
Cold CO per L
Hot CO per L
Simmer CO per L
12%
12%
21%
12%
51%
7%
14%
50%
17%
8%
7%
Alcohol-
Pro- Clean Kero-
pane Cook sene
3%
10%
24%
5%
8%
4%
6%
11%
41%
5%
22%
12%
1%
14%
14%
21%
17%
24%
24%
10%
0%
62%
   Coefficient of Variation = Standard Deviation /Average
   Includes different testers, different times of year.
   Most of the CO variability is in the chimney stoves
   Due to problems in test phases of the Wood Gas and Alcohol Stoves, variation are not reported
118

-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
Solar Cooker Tests




Average Record
Solar Energy
Testl
Cold start

Hot start

Simmer

Test 2

Cold start

Hot start1

Simmer

Tests

Cold start

Hot start'

Simmer

8/22/2004
start
12:30
17.4
5,840
1:47
18.1
5,840.0
3:10

8/23/2004
start
12:40
18.1
5,840
2:05
15.9
5,840
3:18

8/24/2004
start
12:12
16.1
5,840
1:52
15.4
5,840
3:07

Time
1 2 to 1 :00

1 to 2:00 2 to 3:00 3 to 4:00
843 860 806 702 Watthr/m2
multiplied by 1 .477 m2 (area of solar cooker)
1244 1271 1190 1037 Watthour

end
1:27
99.2
5,610
3:10
99.2
5,582.0
3:55


end
1:52
99.2
5,607
3:18
99.2
5,684
4:03


end
1:52
99.2
5,614
3:07
99.2
5,690
3:52


Minutes 30 27
Temp
g water
Firepower 2,489 2,824
Minutes 13 60
Temp
g water
Firepower 5,865 1190
Minutes
Firepower


Minutes 20 52
Temp
g water
Firepower 3,733 1,466
Minutes 55
Temp
g water
Firepower 1,298
Minutes
Firepower


Minutes 48 52
Temp
g water
Firepower 1,556 1,466
Minutes 8 60
Temp
g water
Firepower 9,530 1,190
Minutes
Firepower


1.477 m2

Average
10
6,223 Average
45
1,383 Average



Average
18
3,457 Average
45
1,383 Average



Average
7
8,890 Average
45
1,383 Average
                                                                                                                    119

-------
Test Results of Cook Stove Performance
                                                                                                  Appendix C - Testing Data
Test

Cold



1 8/22/2004
start
start 12:30
17.4
5,840


end
1:27
99.2
5,610



Minutes
Temp
g water
Firepower

Firepower



2,656 W hot start





57 min
28% Efficiency cold start
Hot start 1 :47



18.1
5,840.0

3:10
99.2
5,582.0

Minutes
Temp
g water
Firepower



2,528 W cold star



83 min
20% Efficiency hot start
Simmer 3:10

Test

Cold




2 8/23/2004
start
start 12:40
18.1
5,840

3:55


end
1:52
99.2
5,607

Minutes
Firepower


Minutes
Temp
g water
Firepower

1,383 W simmer





2,096 W hot start

45 min





72 min
28% Efficiency cold start
Hot start 2:05



15.9
5,840

3:18
99.2
5,684

Minutes
Temp
g water
Firepower



1 ,830 W cold star



73 min
30% Efficiency hot start
Simmer 3:18

Test

Cold




3 8/24/2004
start
start 12:12
16.1
5,840

4:03


end
1:52
99.2
5,614

Minutes
Firepower


Minutes
Temp
g water
Firepower

1,383 W simmer





1 ,509 W hot start

45 min





100 min
28% Efficiency cold start
Hot start 1:52



15.4
5,840

3:07
99.2
5,690

Minutes
Temp
g water
Firepower



2,798 W cold star



75 min
1 9% Efficiency hot start
Simmer 3:07



Average cold start
3:52

firepower
Minutes
Firepower

1,383 W simmer

45 min
2,087 W 76 min
Average hot start firepower
Average simmer firepower

Average cold start
Efficiency

Average hot start efficiency
[Average boil firepower
Average boil efficiency
2,386 W 77 min
1,383 W 45 min
21%
23%
2,236 Watts
22%




120

-------
Test Results of Cook Stove Performance
                                                                                        Appendix C - Testing Data
A method for evaluating safety, proposed by Nathan Johnson10 of Iowa State University, was used to evaluate
safety in these stoves, in this case without the weighted rankings his system suggests. Each of the following
criteria were rated as excellent (4 points), good (3 points), fair (2 points) or poor (1 point) for safety
evaluation.

         of
   No.
1 Sharp Edges/Points
2 Cookstove Tipping
3 Containment of Combustion
4 Expulsion of Fuel
5 Obstructions Near Cooking Surface
6 Surface Temperature
7 Heat Transfer to Surroundings
8 Cookstove Handle Temperature
9 Flames/Heat Surrounding Cookpot
10 Flames/Head Exiting
StO¥6
Onil
Patsari Prototype
Justa
Ecostove
Uganda 2-pot
Wood Flame
Propane
Kerosene
Alcohol
Mali Charcoal
Wood Gas
Mud/Sawdust
20L Can Rocket
Ghana Wood
Ghana Charcoal
VITA
3 Stone fire
Solar Cooker*
(*) Even though no
1
4
2
4
2
4
4
4
4
4
4
4
4
2
4
4
2
4
2
flames are
spontaneous combustion may
Fuel Chanber
2
4
4
4
3
3
2
1
2
3
2
1
2
2
2
2
2
1
4
3
4
4
4
4
4
3
4
3
4
3
3
2
3
2
2
3
2
4
present,
occur
•if
4
4
4
4
4
4
4
4
4
4
4
4
3
4
3
3
3
1
4
focal
5
4
2
2
3
4
4
4
3
4
3
4
4
4
4
4
4
4
4
point
6
3
4
4
2
2
3
4
3
4
2
3
3
2
2
2
1
1
2
solar
7
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
2
1
cooker
8
4
4
4
4
4
4
4
4
4
3
2
4
4
4
3
4
4
4
9
4
4
4
4
4
3
2
4
3
4
4
3
4
3
4
3
1
4
is extremely
10
4
4
4
4
4
4
2
4
3
4
4
4
4
4
4
4
1
3
hot
Total
39
36
38
34
37
35
33
35
37
33
33
33
33
32
32
29
21
32
when un
not careful.
10
  Nathan Johnson graduate thesis (Iowa State University 2005). See http://www.vrac.iastatc.edu/-atlas/safcty.htm.
                                                                                                         121

-------
Test Results of Cook Stove Performance
                                                                                       Appendix C - Testing Data
 For further details on this safety evaluation method go to http://www.vrac.iastate.edu/-atlas/safety.htm.
     Stove __
     Tester
Location.
Date
 1.                   AND
Equipment: Cloth, rag, or loose clothing

Procedure:
a) Rub cloth along exterior surfaces.
b) Note number of times cloth catches / tears.

Rating
Poor (1)
Fair (2)
Good (3)
Best (4)

No. of catches
four or more j^
three
one or two „ , , !
Result 1 j
none 	 ° 	

2.                 TIPPING
Equipment: Fuel, ruler / tape measure, calculator
          (immobile cook stoves get Best rati
Procedure:
a.) Set stove on flat surface and load with fuel but do not ignite.
b) Pick a side to tip towards and measure the height of its tallest point, place value into Table A.
c) Slowly tip cookstove in the outward direction from the side chosen until the stove begins to tip on its own.
d) Hold stove tilted where it can overturn and measure new height of the point chosen in part 'b', place value into
   Table A.
e) Using a calculator, divide the tipped height by the standing height to find the ratio R, place into Table A.
J) Repeat process as many times as there are legs on the stove (or four times for a circular base).
g) Use the largest ratio in Table A with the metric in Table B to find the most deficient rating for the result.
Run
1
7
3
4
5
6
Starting
Height


	
	
Tipped
Height


	
	
Ratio


	
	
                                                                       Rating
                                                                       Poor (1)
                                                                       Fair (2)
                                                                       Good (3)
                                                                       Best (4)


                                                                      Result 2
                        No. of catches
                          R > 0,978
                       0.961 
-------
Test Results of Cook Stove Performance
                                                                                    Appendix C - Testing Data
3. CONTAINMENT OF FUEL

Equipment: Fuel, ruler / tape measure, cookpot

Procedure:
a.) The cookstove should be stocked with fuel but not ignited.
b) Place cookpot onto burner.
c) Sum approximate areas through which fuel can be seen.
d) Use the summation of area, A, to find the rating.


Notes:
       (solar stoves receive Best rating)
 Rating
  Poor
  Fair
  Good
  Best


Area
                                                                      Result 3
No. of catches
   A > 250
 1504
 2.5
-------
Test Results of Cook Stove Performance
                                                                                   Appendix C - Testing Data
                                       SURFACE TEMPERATURE
Rating
5A
5B
Poor
Fail-
Good
Best
Pool-
Fair
Good
Best
Max/Rating
Below child-i
Metallic
T>50
44 < T < 50
38_
_58
52>T<58
46_
_66
60 > T < 66
54_
_74
68>T< 74
62 < T < 68
T<62
T>__
_ 65
55_
_80
70_
_32
26_
_44
38_
_ < T < _
^ 150
                                                   50
-------
Test Results of Cook Stove Performance
                                                                                   Appendix C - Testing Data
9. FLAMES
Equipment: Cookpot
                                                  (solar stoves receive Best rating)
Procedure:
a.) Keep cookstove fully ablaze from previous tests.
b) Place cook pot into cooking position.
c) Observe the amount of uncovered flames surrounding the cookpot and record a description.
d) Compare description with table to find rating.
e) Remove cook pot.
              Rating
               Poor
               Fair
              Good
               Best
Amount of Uncovered Flames Touching Cookpot
         entire cook pot and/or handles
         most of cook pot, not handles
     less than 4 cm up the sides, not handles
                    none
Description

Notes:
                                                      Result 9
10.                     FUEL                           OR
Equipment: None
                                                              (solar stoves = Best)
Procedure:
a) Keep cookstove fully ablaze from previous tests, b) Visually inspect the amount, if any, of flames coming
out of the fuel chamber, canister or pipes and record if flames do or do  not protrude, c) Consult table to find rating.
Rating
Pool-
Best
Occurrence of Fire
Flames protrude
Flames are contained
                                                                              Result 10
Description

Notes:
                                                                                                   125

-------
Test Results of Cook Stove Performance
                                                                                    Appendix C - Testing Data
To calculate the overall cookstove safety rating, place the point value of each individual rating in the "Value"
column. Next multiply the individual ratings by their respective weights and place result in "Total" column.
Sum these values and place that number in the box SUM. This value is applied to the overall rating metric to
provide the overall safety rating of the stove.
         Test
Value
          1
          2
          3
          4
          5
          6
          7
          8
          9
          10


       SUM
Individual
Rating
Best
Good
Fair
Poor
Overall
Rating
Best
Good
Fair
Poor
Value
4
3
2
1
Value
35-40
28-34
20-27
10- 19
Notes:
                                         Overall Raring
126

-------

-------
Atovccho Research Center
SHELL
FOUNDATION
c/EPA
             United States
             Environmental Protection
            iAgency
Office of Air & Radiation
EPA 402-K-11-001
November 2011

-------