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\datereceived{2023-03-15}
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\dateposted{2023-07-12}
\begin{document}

\begin{noXML}

%\TopicEF{Materials and Clean Processes for Sustainable Energy and
%Environmental Applications}{Mat\'eriaux et proc\'ed\'es propres pour
%des applications \'energ\'etiques et environnementales}

\title{Comparative analysis of fuel wood consumption of improved mud
stove and three stone fire stove: a~case study}

\alttitle{Analyse comparative de la consommation de bois dans une
cuisini\`ere perfectionn\'ee et dans un fourneau traditionnel \`a trois
pierres : une \'etude de cas}

\author{\firstname{Awais} \lastname{Junejo}\CDRorcid{0000-0002-5395-2756}}
\address{Department of Mechanical Engineering, Mehran University of
Engineering and Technology, Shaheed Zulifqar Ali Bhutto Campus,
Khairpur Mir's-66020, Sindh, Pakistan}
\email[A. Junejo]{awaisjunejo@muetkhp.edu.pk}

\author{\firstname{Sanjay} \lastname{Kumar}\CDRorcid{0000-0003-0139-3179}\IsCorresp}
\addressSameAs{1}{Department of Mechanical Engineering, Mehran University of
Engineering and Technology, Shaheed Zulifqar Ali Bhutto Campus,
Khairpur Mir's-66020, Sindh, Pakistan}
\email[S. Kumar]{sanjaykumar@muetkhp.edu.pk}

\author{\firstname{Khanji} \lastname{Harijan}}
\address{Department of Mechanical Engineering, Mehran University of
Engineering and Technology, Jamshoro-76062, Sindh, Pakistan}
\email[K. Harijan]{Khanji.harijan@faculty.muet.edu.pk}

\author{\firstname{Mejdi} \lastname{Jeguirim}\CDRorcid{0000-0003-2401-5824}}
\address{Institut de Sciences des Materiaux de Mulhouse, UMR 7661 CNRS,
Mulhouse, 68093, France}
\email[M. Jeguirim]{mejdi.jeguirim@uha.fr}

\shortrunauthors

\keywords{\kwd{Fuel wood}
\kwd{Traditional cook stove (TCS)}
\kwd{Improved cook stove (ICS)}
\kwd{Kitchen performance test}
\kwd{Biomass}
\kwd{Fuel consumption}
\kwd{Emissions}}

\altkeywords{\kwd{Bois de chauffage}
\kwd{Fourneau traditionnel (TCS)}
\kwd{Fourneau am\'elior\'e (ICS)}
\kwd{Test de performance de la cuisine}
\kwd{Biomasse}\kwd{Consommation de carburant}\kwd{\'Emissions}}

\begin{abstract}
Energy crisis is a global issue in recent times. Meeting the energy
requirements for daily cooking and heating in rural population using
biomass as a fuel in traditional cookstoves (TCS) is an energy
consuming and inefficient method. Moreover, the use of biomass in TCS causes
serious health and environmental problems. TCS have very low efficiency
and high fuel consumption. A kitchen performance test (KPT) was
conducted in order to measure fuel wood 
consumption by TCS and improved cookstoves (ICS). Furthermore, the fuel
wood consumption of the study area is also estimated. The fuel wood
characteristics are determined by proximate and ultimate analysis. The
KPT results show that ICS reduces fuel consumption by 0.16 kg/person/day. The
ICS can also reduce 0.258 tonnes of CO$_{2}$ emissions per
ICS user annually. Stove performance index shows that ICS uses 6\% less
fuel as compared to TCS. ICS also emits significantly less CO and PM
emissions. The use of ICS would also possibly solve the environmental
impacts of fuel wood collection and combustion.
\end{abstract}

\begin{altabstract}
La majorit\'e de la population rurale des pays en d\'eveloppement satisfait
ses besoins quotidiens en \'energie pour la cuisson et le chauffage en
utilisant la biomasse comme combustible dans des fourneaux
traditionnels inefficaces (TCS). En outre, l'utilisation de la biomasse
dans les fourneaux traditionnels entra\^ine de graves probl\`emes
sanitaires et environnementaux. Les fourneaux traditionnels sont tr\`es
peu efficaces et consomment beaucoup de combustible. Un test de
performance de la cuisine (KPT) a \'et\'e r\'ealis\'e afin de mesurer la
consommation de bois de chauffage des fourneaux traditionnels (TCS) et
des cuisini\`eres perfectionn\'ees (ICS). De plus, la consommation de bois
de chauffage de la zone \'etudi\'ee est \'egalement estim\'ee. Les
caract\'eristiques du bois sont d\'etermin\'ees par l'analyse sommaire et
ultime. Les r\'esultats du KPT montrent que les ICS r\'eduisent la
consommation de combustible de 0,16~kg/personne/jour. L'ICS peut \'egalement
r\'eduire les \'emissions de CO$_2$ de 0,258 tonne par utilisateur chaque
ann\'ee. L'indice de performance de la cuisini\`ere biomasse montre que
l'ICS consomme 6~\% de combustible en moins que le TCS. L'ICS \'emet
\'egalement beaucoup moins d'\'emissions de CO et de particules.
L'utilisation de l'ICS pourrait \'egalement r\'esoudre les impacts
environnementaux de la collecte et de la combustion du bois.
\end{altabstract}

\maketitle
\pagebreak
\twocolumngrid

\end{noXML}

\section{Introduction}\label{sec1}

Biomass is one of the oldest energy sources available on earth.
Biomass has a major share in future energy supply of the world, it
may partially subside the fossil dependency~\cite{1}. Due to its
sustainability and environment friendly nature, the biomass is nowadays used
in different applications such as energy production and biomaterials
synthesis~\cite{2,3,4}. Currently, biomass has 14\% share in
world's primary energy reserves~\cite{5}. Around 62\% population of
Pakistan resides in rural areas and uses solid biomass fuel as a
primary source for cooking and heating in traditional cook stoves
(TCS)~\cite{6}. The traditional use of biomass for cooking and heating
in rural areas of Pakistan is inefficient and results in various
environmental and health problems~\cite{7}. The rural areas of Pakistan
such as Tharparkar region uses solid biomass fuel such as firewood,
crop waste and animal dung for cooking and heating purposes. However,
the combustion of solid biomass fuel in enclosed spaces results in
indoor air pollution. Additionally, the combustion of solid biomass
also emits particulate matter (PM), which causes pneumonia, stroke,
heart disease, chronic obstructive pulmonary disease, and lung
cancer~\cite{8}. Around 1.6 million people died prematurely in 2017 as
a result of indoor air pollution, accounting 3\% of global
deaths~\cite{9,10}.

The cookstove design significantly affects the cookstoves' performance
and fuel consumption rate. The cookstoves' designs were modified from
time to time and improved with technological advancement such as by
improving the design of stove and by performing mathematical modelling.
Some authors categorized cookstoves i.e., as traditional cookstoves,
improved cookstoves (ICS), advanced biomass cookstoves and effective improved
cookstoves~\cite{11}. Traditional cookstoves (TCS) are commonly
available in three types such as three-stone fire, mud stove and
traditional coal/charcoal stoves. These traditional
cookstoves are inefficient, have high fuel consumption, longer cooking
time and high pollutant emissions. ICS are actually
TCS-modified traditional stoves having closed combustion chambers with
chimneys. ICS includes Magan Chulha generally found in India~\cite{12},
Envirofit stove, Ugastove, Top-lit-updraft (TLUD) stove, Plancha stove,
Patsari stove and Centrafricain stove~\cite{11}. All these ICS produce
less harmful emissions, consume less fuel and reduce the cooking time
as compared to traditional ones ~\cite{13,14,15}. In addition, improved
cookstove not only mitigates the greenhouse gas (GHG) and particulate
matter (PM) emissions but also reduce the financial burden on a
household by improving the fuel consumption~\cite{16}. Advanced
cookstoves are designed at high standards, considering safety,
efficiency, emission, and durability due to which these stoves have
high cost and are unreachable for rural people. Improved cookstoves are
advanced cookstoves design with scientific principles as well as
technology and are user friendly~\cite{17}.

The TCS have an efficiency of about 9 to 13\%~\cite{18}. Ergo, to
mitigate the environmental and health issues caused by the use of TCS,
a lot of research is \mbox{being} carried out throughout the world on the
development and dissemination of ICS which have
lesser fuel consumption as well as harmful emissions~\cite{19}. In the
last few decades, various types of ICS have been introduced with the
modern scientific approach and are being disseminated in rural areas of
developing countries including Pakistan~\cite{20}. Many studies have
been performed on fuel conservation by ICS particularly in rural
areas~\cite{21,22}. The study performed by Harijan and
Uqaili~\cite{23} estimated that replacing ICS with TCS in Pakistan can
result in decreasing the demand for biomass fuel for cooking and
heating purposes up to 50\%. Furthermore, the dissemination of ICS in
rural areas of the country can also reduce the deforestation rate.
Still \etal~\cite{24} and Jetter and Kariher~\cite{25} discussed that
ICS have lesser fuel consumption compared to TCS. The study concluded
that the ICS not only reduces the fuel consumption, they could also
potentially mitigate the health and climate change impacts due to the
use of TCS~\cite{13,26,27,28}. Bluffstone \etal\ adopted ICS 
for biomass cooking in Ethiopia. They reported that ICS
reduced the cooking times by 18\% over traditional stove in
initial adoption of first 5 to 6 months. However, it further reduced by
7\% in next 6 months~\cite{29}.  

ICS dissemination programs mostly are successful in rural areas where
the main source of energy is fuel wood~\cite{30}. The performance of
ICS can be evaluated by fuel efficiency~\cite{31,32}. There are three
distinct methods to evaluate the performance of cook-stoves namely;
water boiling test (WBT), control cooking (CCT) and kitchen performance
test (KPT). WBT is conducted in controlled environment. This method is
mainly focused on simulation of cooking practices by water boiling
hence does not present the actual cooking conditions.  CCT is a field
test capable of providing reliable results as compared to WBT. This
method measures the fuel consumption and time of cooking. However, it
may not predict the outcomes of uncontrolled usage of the cook-stoves
in actual practice. KPT is a field base test that involves both
qualitative survey and quantitative measurements. This method is quite
useful than WBT and CCT since it involves pre-treatment surveys which
assess the situation of households before dissemination of stoves and
post treatment surveys which assess the impact of the cookstoves in
the households~\cite{33,34}. In order to evaluate the performance of
TCS and ICS, a field based Kitchen Performance Test (KPT) is used, in which
daily basis cooking is monitored and fuel consumption is
assessed~\cite{13,35,36}.  A study was conducted by Wallmo and
Jacobson~\cite{35} for five days using KPT to analyze the fuel use of
TCS and ICS. The results estimated that ICS could use 39\% less fuel
than TCS. Ochieng et al. compared the fuel consumption for TCS and ICS
in rural areas of Kenya by conducting a KPT for two days. They
concluded that TCS consumed more fuel than\break ICS~\cite{37}. 

Furthermore, a quantitative assessment using KPT was conducted of fuel
use in rural households and the impact of stoves on household energy
use with stove in developing countries like India, Nepal, and Peru.
These studies concluded that ICS utilizes 27--66\% less fuel as compared
to TCS~\cite{38}. Agurto Adrianz\'{e}n presented fuel consumption of
ICS in Northern Peruvian Andes by using KPT analysis. The authors
concluded that ICS could reduce fuel consumption by approximately 46\%
in the study area~\cite{39}. In addition, ICS could also significantly
decrease IAP in kitchens by decreasing the particulate matter emissions
up to 84\% and CO emissions up to 99\%~\cite{40}. Globally, a number of
ICS type exits which can significantly reduce the harmful emission by
40--75\%. Moreover, they also increase fuel efficiency by 30\% and have
the potential to reduce global warming up to 40--60\%~\cite{41,42}.

Moreover, improved cookstoves (ICS) can be applied for the electricity
production by retrofitting with low cost thermoelectric generator.
Adding a thermoelectric generator is a viable solution to fulfil the
basic needs such as light, phones and other electronic
devices~\cite{43}. Several researchers have designed a prototype, an
energy efficient cookstoves along with a thermoelectric power generator
as an advancement in cookstoves~\cite{44,45,46,47,48,49,50,51}.

From the above literature, it can be inferred that the use of ICS has
several benefits over TCS especially in rural areas of Pakistan in
Tharparkar district where there is no gas supply. The people in
Tharparkar mainly rely on combustion of fuel wood using TCS for their
cooking heating purpose. Previous studies have shown that TCS consumed
more fuel wood than ICS and due to increase in the cost of fuel wood 
along with various socio-economic problems, people in Tharparkar
district are facing severe social and economical problems. Therefore,
there is an urgent need for improved cooking technology which can be
economical for rural population, consumes less fuel and could be
environment friendly.  

This study aims to identify the fuel wood potential and consumption in
rural areas of Tharparkar district. The ICS and TCS cookstoves were
used to estimate the fuel wood consumption. The characteristics of fuel
wood were determined by ASTM method. A KPT was used to measure the
reduction in fuel consumption and reduction in CO$_{2}$ emissions.

\section{Material and methods}\label{sec2}

\subsection{Study design and sample size}\label{sec21}

The study was conducted in the Tharparkar district of Pakistan located
in the southern part of the country as shown in Figure~\ref{fig1}.
Tharparkar district was selected since it is to one of the highly
remote areas of Pakistan. 

\begin{figure*}
\includegraphics{fig01}
\caption{\label{fig1}Map of Tharparkar district Pakistan focusing study
area.}
\end{figure*}

The entire population in the district relies on biomass fuel (i.e. fuel
wood) for their basic cooking and heating energy requirements.
Tharparkar district is subdivided into 7 administrative talukas, Mithi,
Diplo, Islamkot, Chachro, Dahli, Nagarparkar and Kaloi. For this study,
Diplo taluka was selected. Diplo is located at 24\textdegree~35${''}$~N
69\textdegree~35${''}$~E, 40~km away from district headquarter Mithi,
having an area of 2673~km$^{2}$ and an estimated population of 147,978
in 2017~\cite{52}. The selected location is remote and rural having an
average household size of 5.6~\cite{53}. The households use fuel wood
mainly from Propis glaandulosa which is the most common tree found in
the study area. Majority of the population in the study area burns fuel
wood for their energy needs using TCS. TCS and ICS used in the current
study are shown in Figures~\ref{fig2} and~\ref{fig3}, respectively. 


\begin{figure}
\includegraphics{fig02}
\caption{\label{fig2}Traditional Cook Stove (TCS) used in Tharparkar
district, Pakistan.}
\end{figure}

\begin{figure}
\includegraphics{fig03}
\caption{\label{fig3}Improved Cook Stove (TCS) used in Tharparkar
district, Pakistan.}
{\vspace*{-1pt}}
\end{figure}

In Figure~\ref{fig3}, stoves' emission on the wall of the kitchen
represents incomplete combustion due to the usage of TCS for cooking
for several years. The use of forced draft ICS can improve combustion
by maintaining the required air to fuel ratio. However, the habitants
are poor and cannot afford to have force draft ICS that requires
electricity or batteries for their operation. Therefore, this study
focuses on natural draft ICS only, as they are easy to operate and do
not require any additional cost for operation. Although, the gaseous
emissions from natural draft ICS are higher than forced draft ICS, they
are still lower as compared to TCS due to exhaust chimney.

Figure~\ref{fig4} shows KPT survey approach that was used in present
study. The KPT was conducted in two stages: the first stage was
conducted before the distribution of selected ICS and at second stage
survey was conducted when they ICS were distributed in selected
community households. During both stages of the study, a survey covered
the consumption of fuel wood by ICS and TCS. The second stage of the
survey was conducted after a month and the selected ICS has similar
physical properties that were used in the literature~\cite{37}. The KPT
was performed during\unskip\break 3 months from December 2016 to February 2017.
During this period, the baseline information of study households,
qualitative features of the stoves and fuel use, number of family
members was obtained 
using interviewer administrated semi-structured questionnaires.
In order to find the fuel consumption of TCS and ICS,
the testing was carried out by finding the daily measurements as
families use the TCS for 3--7 days, followed by daily
measurements of the same families using selected ICS for the same
period of time. This kind of test makes an evaluation of the family's
daily fuel consumption with the traditional stove and with the improved
stove.

\begin{figure}
\includegraphics{fig04}
\caption{\label{fig4}Sampling approach flow chart of KPT survey.}
\end{figure}

\subsection{Fuel characterization}\label{sec22}

The main parameters affecting the wood fuel performance are its
chemical composition, heating value and the proximate analysis,
i.e. moisture volatile matter, fixed carbon and ash contents. The
moisture content is different in different parts of the tree and it
affects the energy content in the wood fuel~\cite{54}. Higher the
moisture content, lower the heating value~\cite{55}. Ash content is
the core parameter in fuel characteristics that directly affect the
heating value. Large ash content in the tree or plant part makes it
less desirable as fuel~\cite{56}. The fuel characteristics are
determined through proximate and ultimate analyses. The proximate,
ultimate analysis and gross caloric value of the fuel wood obtained
from Propis glandulosa was performed as per the American Society for
Testing and Materials (ASTM) standards ASTM E870-82 (2006).

\subsection{Fuel use measurement}\label{sec23}

The fuel use measurement is actually the extent to which how fuel wood is
consumed per day for \mbox{cooking,} and heating. The fuel wood consumption is
estimated by monitoring the quantity of fuel used 
before and after cooking and heating. The
estimation of per capita fuel wood consumption is presented as
``standard adult equivalent'' (SAE) per day. The SAE is utilized in the
KPT to normalize the caloric energy requirements by gender and age with
the following weights: child 0--14 years $=$ 0.5; female over 14 years
$=$ 0.8; male 15--59 years $=$ 1; and male over 59 years $=$
0.8~\cite{57}. In this study, three days of repeated fuel use
measurement in a relatively large sample size KPT is performed. The
participants prepared food with three batches of fuel enough for 3 days
of cooking, based on their typical daily basis requirements. The weight
of fuel for each batch was weighed on the calibrated digital scale
(Model SF-400A, ranges 0.1--10~kg) before starting the experiment at the
start of the day. On the second and third day of the tests, the fuel
that remained from the first day was weighed and the difference is
recorded as the day's fuel consumption.

\subsection{Fuel wood potential}\label{sec24}

The major sources of fuel wood in the Tharparkar district are forest
and agricultural land. Tharparkar has around 93 thousand hectares of
forest cover representing 7\% of the total land area of the district.
Agriculture land cover is around 1014 thousand hectares of representing
50\% of the total land area of the district~\cite{58}. The production
of agricultural crops completely depends on the rain during the monsoon
season and these are only cultivated once in a year. Therefore, the
main source of fuel for local inhabitants is only fuel wood for their
cooking and heating. This fuel  is usually obtained by cutting the
local trees in the vicinity of the region. The potential of fuel wood
production from the forest in the Tharparkar district can be estimated
using Equation~(\ref{eq2})~\cite{59} as: 
{\begin{equation}\label{eq2}
\mathrm{WP} = \sum (\mathrm{LA})_{i}\cdot (\mathrm{WP})_{i}\cdot 
(\mathrm{AF})_{i}
\end{equation}}\unskip
where WP is the fuel wood production (tonnes/year), LA is the land area
in (thousand/hectare), WP is the wood fuel productivity in
(tonnes/hectare/year) and AF is the availability factor (\%). The
annual yield of 1\% of biomass density (excluding leaves) is assumed
from forest land. However, not all of the fuel wood available from
forest and would be available as a fuel to meet cooking and heating
energy needs. Hence an assumption is made on the availability of fuel
on a percentage basis which is 80\% for the cases. 

\subsection{Emissions measurement}\label{sec25}

The share of ICS in diminishing CO$_{2}$ emission was evaluated by the
amount of fuel wood saving as per the SAE of the households using ICS.
The estimation of CO$_{2}$ reduction was carried out by using the 
Equation~(\ref{eq3}) as per clean development mechanism and the United Nation's
framework of Convention on Climate Change which is given as~\cite{60}:
{\begin{equation}\label{eq3}
E_{\mathrm{Ry}} = 
B_{\mathrm{y}\cdot \mathrm{Savings}} \times 
f_{\mathrm{NRBY}} \times  
NCV_{\mathrm{biomass}}\times  EF_{\mathrm{fuel wood}}
\end{equation}}\unskip
where;

$E_{\mathrm{Ry}} =$ Emission reduction during the year in tons of carbon
dioxide equivalent (tCO$_{2}$e)

$B_{\mathrm{y}\cdot\mathrm{Savings}}=$ Annual fuel wood saved per ICS in tons

$f_{\mathrm{NRBY}} =$ Fraction of non-renewable biomass

$NCV_{\mathrm{biomass}} =$ Net calorific value of the non-renewable
biomass

$EF_{\mathrm{fuel wood}}=$ Emission factor of fuel wood.

The values of the parameters used for estimating CO$_{2}$ reduction by
ICS are presented in Table~\ref{tab4}. Carbon Monoxide CO is considered
indirect greenhouse gas due to its close coupling to atmospheric
methane~\cite{61}. Therefore, it is necessary to measure the CO
emission for the evaluation of biomass improved cookstoves. In the
present study, the CO emission is measured by a portable CO analyser
(KANE-Model 100-1) and the concentration of particulate matter
PM$_{2.5}$ is measured by Aerosol Monitor~(Model DustTrak 8530, TSI
Inc.). Presented results are the average of the 3 repetitions of the
performance tests. 

\begin{table*}
\caption{\label{tab1}Fuel wood production of Tharparkar district}
\begin{tabular}{ccccc}
\thead
Fuel wood source & \parbox[t]{1.5cm}{\centering Area (``000'' ha)} & 
\parbox[t]{3.5cm}{\centering Fuel wood productivity (tonne/ha/year)}
& \parbox[t]{2cm}{\centering Availability factor (\%)} & 
\parbox[t]{3.5cm}{\centering Fuel wood production (thousand tonnes)}\vspace*{2pt} \\
\endthead
Forest & \093 & 1 & 80 & \074 \\
Agricultural land & 241 & 0.7 & 80 & 168 \\
{Total} &  &  &  & 242
\botline
\end{tabular}
\end{table*}

\section{Results and discussion}\label{sec3}

Tharparkar district is one of the arid region of the Pakistan and its
regional population is completely contingent on fuel wood for their
basic needs. The major source of fuel wood is natural forest and
agrarian land. The natural forest together with the agricultural land
could generate around 242 thousand tonnes of fuel wood per year in the
district Tharparkar as given in Table~\ref{tab1}. However, besides natural
forests and agricultural land, there are also few other major sources
of wood supply like other wooded lands, plantations beside homes and
scrap wood generated during the construction activities. These sources
of fuel wood are not counted in this estimation because no reliable
data source was available. The population of Tharparkar is around 1.65
million and almost 98\% of this population uses fuel wood as a source
of energy to meet their daily cooking and heating energy requirements.


Considering 0.87 kg of fuel wood consumption per person per day the
annual fuel wood consumption of the Tharparkar is estimated to 538
thousand tonnes per year. The consumption of wood in the Tharparkar is
almost 1.45 times its fuel wood potential. This higher and inefficient
consumption of the fuel wood, as well as the lack of availability of
modern energy sources for the daily energy needs, are the main reason
for the deforestation and degradation of the environment in the
district.

The characteristics of biomass fuel wood are determined and given in
Tables~\ref{tab2} and~\ref{tab3}. The carbon C and oxygen O content
percentage are found within the standard range of about 49.1\% and
42.4\%, respectively. One advantage of biomass fuel wood over fossil
fuel is its very low content of sulphur which was found to be around
0.02\%. Volatile matter in fuel wood was 74.47\%. The low moisture and
ash contents indicated the positive impact on the heating value of
biomass fuel wood. The moisture and ash content in the fuel wood were
2.85\% and 1.78\%, respectively. The low moisture content 
can be due to fuel type. Thus, the
higher heating value was calculated as 17.8~MJ/kg.

\begin{table}
\caption{\label{tab2}Ultimate analysis of the fuel wood}
\begin{tabular}{ccccc}
\thead
{C}  {(\%)} & {H}  {(\%)} & {N}  {(\%)} & {S}  {(\%)} & {O}  {(\%)} \\
\endthead
49.1 & 6.1 & 0.2 & 0.02 & 42.4
\botline
\end{tabular}
\end{table}

\begin{table}
\caption{\label{tab3}Proximate analysis of the fuel wood}
\tabcolsep=3pt
\begin{tabular}{ccccc}
\thead
\parbox[t]{1.3cm}{\centering Moisture  (\%)} & 
\parbox[t]{.5cm}{\centering Ash (\%)} & 
\parbox[t]{1.7cm}{\centering Volatile matter (\%)} & 
\parbox[t]{1.7cm}{\centering Fixed carbon (\%)} & 
\parbox[t]{1.2cm}{\centering HHV  (MJ/kg)}\vspace*{2pt} \\
\endthead
2.85 & 1.78 & 74.47 & 14.90 & 17.8
\botline
\end{tabular}
\end{table}

The fuel wood consumption was estimated as per kitchen performance test
KPT method by monitoring fuel consumption before and after cooking and
heating for the TCS and ICS. For the first day of the test, the fuel
consumption of TCS was about 0.880 kg of dry wood with the standard
deviation of 0.148, per person per day, while for the second and third
day fuel consumption was around 0.865 kg with SD of 0.1126 and 0.891 kg
with SD of 0.148 per person per day respectively. Consumption of fuel
wood for ICS was about 0.749 kg of dry wood with SD of 0.129 on the
first day, 0.705 kg with SD of 0.107 on the second day, and 0.7007 kg
with SD of 0.099 per person per day on the third day of the KPT
monitoring. A substantial reduction in fuel wood consumption was
observed with ICS as compared to TCS.

Figure~\ref{fig5} represents the fuel wood consumption of TCS and ICS.
The KPT results show that the TCS consumed fuel wood averagely of about
0.878 kg per day per person and ICS consumed averagely of about 0.718
kg per day per person. The consumption of fuel wood is apparently
reduced from 0.878 kg per day to 0.718 kg per day per person when ICS
has been successfully installed instead of TCS. Thus, ICS uses almost
0.16 kg/person/day less fuel wood as compared to TCS. Thus, the KPT analysis
reveals that there is a significant reduction in fuel consumption when
the households have switched to ICS. It is observed that change in fuel
use was related to the kind of stove used, with ICS consuming less fuel
as compared to the TCS. There have been very few studies \mbox{presenting}
household fuel use by conducting KPT. While the studies have shown that
a significant amount of fuel can be saved by changing TCS with
different types of ICS~\cite{19, 25}.

\begin{figure}
\includegraphics{fig05}
\caption{\label{fig5}Comparison of fuel wood consumption with TCS and ICS.}
\end{figure}

The performance of cookstove can be compared quantitatively using stove
performance index ($\eta _{\mathrm{SPI}}$), which is defined as $\eta
_{\mathrm{SPI}}=({{{F}}_{{s}}-{{F}_{{c}}}})/{{F}_{{s}}}$, 
where $F_c$ is stove fuel consumption in kg per person per day and $F_s$
is amount of initial wet wood fuel supplied in kg per day which is 12~kg.

\break
The higher values of the stove performance index indicate less fuel
consumption and better performance by the cookstove. Figure~\ref{fig6}
shows the cookstove performance index for TCS and ICS, respectively. It
can be observed from Figure~\ref{fig6} that the values of performance
index for TCS and ICS are 0.926 and 0.94 per person per day,
respectively. It is implying that the ICS consumed ${\approx}$2\% less
fuel per person per day as compared to TCS. Considering the household size
of 4.1 (According to SAEs), the ICS can consume approximately 6--8\% less
fuel per house as compared to TCS. Moreover, the performance of the ICS
can further be enhanced by adapting new scientific approach, designing
methods and suitable materials.

\begin{figure}
\includegraphics{fig06}
{\vspace*{-2pt}}
\caption{\label{fig6}Cookstove performance index.}
{\vspace*{2pt}}
\end{figure}

\begin{table*}
\caption{\label{tab4}Values of parameters used for estimating CO$_{2}$
reduction}
\begin{tabular}{cccc}
\thead
{Parameter} & {Values} & {Reference} \\
\endthead
Annual fuel wood saved per ICS & From KPT &  \\
The net calorific value of fuel wood (wet basis) & 15 MJ/kg & \cite{62} \\
Emission factor of fuel wood & 81.6 (CO$_{2}$/T) & \cite{60} \\
Fraction of non-renewable biomass & 88\% & \cite{62}
\botline
\end{tabular}
{\vspace*{6pt}}
\end{table*}

ICS dissemination programs has an important role in the implementation
of the policies and {\unskip\break} programs that aims to reduce the social and
environmental problems related to the use of fuel wood in traditional
inefficient cook stoves in rural areas of developing countries like
Tharparkar district of Pakistan. Thus, the ICS can be successfully
disseminated and implemented in different rural regions of the
Tharparkar district of Pakistan. Moreover, the current study has also
received positive response from the local inhabitants after the
dissemination of ICS. Their positive response implies that the ICS not
only reduce the fuel consumption but also improve the indoor air
quality. 

It is very difficult to minimize random errors in a field-based test
during the measurement of fuel wood consumption. However, careful
consideration was given to the techniques to decrease the errors by
following the testing protocols of KPT (for example the test
supervisors were from the test area and were given proper training; all
the instruments and scales used in the study were calibrated). The
participants of the test were also given the training to follow their
daily routine cooking style during the test tenure. The test
supervisors visited the test participants from time to time to make
sure they are following the test protocols correctly. It was also
observed in this study that the factors like rainy weather, guests,
unattended stove, and cooking by inexperienced cook such as children
may also cause some errors in the results. However, these factors are
unintentional and cannot always be avoided.

Forests are the main source of fuel wood around the world. The
extensive use of fuel wood, growth in the population, agricultural land
and poverty are the major threats to forests. The time spent \mbox{collecting}
fuel wood has a significant social and economic impact on the life of
women and children who spent hours collecting fuel wood. Hence, in this
scenario, the use of ICS in the areas where fuel wood is the main
source of energy can help in partial reduction of deforestation as well
as it will improve the socio-economic conditions of the people living
there. Additionally, the use of ICS can also be helpful in climate
change mitigation and the reduction in indoor pollution due to the
reduction in fuel consumption and reduction of carbon emissions.
Especially for Pakistan, who is already suffering from deforestation
and has one of the highest deforestation rates\break in the world. 

Table~\ref{tab4} present the estimated the CO$_{2}$ reduction by the
use of the ICS. The CO$_{2}$ reduction was estimated by applying
Equation~(\ref{eq3}). The CO$_{2}$ reduction due to the use of ICS was
estimated as 0.063 tons equivalent per ICS per person per year. This
estimation incorporates the average annual fuel wood saving by ICS of
around 58.4 kg per person. Hence, with the normal family size (measured
in SAEs) of about 4.1, ICS could decrease 0.259 tons of CO$_{2}$
equivalent per ICS user. 

Moreover, Figures~\ref{fig7} and~\ref{fig8} show the CO and PM$_{2.5}$
emissions for TCS and ICS. The CO emission were measured by a portable
CO emission analyser. The emissions were carefully monitored and
recorded throughout all three days of the field test. The measured
values were repeated and averaged for a single value. The CO and PM$_{2.5}$
emissions for TCS were recorded as 153 g/kg and 8.9 g/kg, respectively.
Similarly, the CO and PM$_{2.5}$ emissions for ICS were found to be around
96 g/kg (SD $=$ 3) and 5.7~g/kg (0.7) respectively.

\begin{figure}
\includegraphics{fig07}
{\vspace*{-3pt}}
\caption{\label{fig7}CO emissions for TCS and ICS.}
\end{figure}

\begin{figure}
\includegraphics{fig08}
{\vspace*{-3pt}}
\caption{\label{fig8}PM$_{2.5}$ emission for TCS and ICS.}
\end{figure}

Hence, the results in the current work are in good agreement with the
study conducted by Roden \etal~\cite{63}. ICS significantly reduce the
CO emission factor by 37.25\%. The reduction in CO and PM$_{2.5}$
emissions for ICS can be attributed to the improved design and
operation of ICS that promote proper combustion of the fuel wood. Thus,
ICS not only reduces fuel consumption, but it can also significantly
reduce carbon and PM emissions.

\section{Conclusions}\label{sec4}

The fuel wood consumption of cookstove is measured by employing a
field-based test (KPT) in the Tharparkar region of the Pakistan. The KPT
analysis were carried out for the TCS and ICS. The CO
and PM$_{2.5}$ emission analyses were also carried out. The following
conclusion are drawn from the present study;
\begin{enumerate}[(1)]
\item The fuel consumption estimation presented in this study shows
that in rural Pakistan the use of ICS can lead to a significant
reduction in fuel consumption from 0.878 kg per  person per day to
0.718 kg per person per day and can also reduce CO$_2$
emissions by 0.259 tons per ICS user annually.
\item The performance index represents that the ICS consumes
approximately 6\% less fuel as compared to TCS.
\item The CO emission and PM$_{2.5}$ concentration reduced nearly 37.25\%
and 36\%, respectively with the intervention of ICS over TCS. 
\item The dissemination of ICS in the rural areas of Pakistan as well
in the other developing countries can offer a short term solution to
the deforestation and physical burden on poor people due to the
collection of fuel wood. Thus, the ICS can be disseminated successfully in the
Tharparkar district of the \mbox{Pakistan}. 
\end{enumerate}

\section{Recommendations}\label{sec5}

\begin{itemize}
\item KPT is a field-based test conducted in an uncontrolled
environment. The result of the test may vary from area to area or
community to community. For further understanding of the fuel
consumption by ICS, the results obtained from KPT can be compared with
the results obtained from a controlled environment based test such as
water boiling test (WBT) and control cooking test (CCT).
\item Further estimation of fuel consumption by ICS can be performed
across a range of stove technologies and fuels such as wheat straw,
wood pellets, torrified pellets, and dung.
\item The economic, environmental and social impacts of ICS also need
further investigation.
\end{itemize}

\section*{Conflicts of interest}
No potential conflict of interest was reported by the authors.

\section*{Funding}

This study was not funded by any funding agency.  

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