Fuelwood consumption patterns in Chumriey Mountain, Kampong Chhnang Province, Cambodia

Energy 44 (2012) 335e346

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Fuelwood consumption patterns in Chumriey Mountain, Kampong Chhnang Province, Cambodia Vibol San a, *, Vin Spoann a, Dalin Ly b, Ngov Veng Chheng a a b

Department of Environmental Science, Royal University of Phnom Penh, Russian Federation Blvd., Tuk Laak 2 Commune, Toul Kork District, Phnom Penh 12157, Cambodia Faculty of Agro-Industry, Royal University of Agriculture, Phnom Penh, Cambodia

a r t i c l e i n f o

a b s t r a c t

Article history: Received 8 December 2011 Received in revised form 6 May 2012 Accepted 11 June 2012 Available online 18 July 2012

The study was carried out to explore fuelwood consumption rate for different activities, such as cooking, boiling water, preparing animal feed and burning to protect cattle against insects; species preference; and to examine the characteristics of cook stoves. Approximately 96% of sampled households depend on fuelwood as a primary source for cooking, boiling water, preparing animal feed and protecting cattle against insects. Average fuelwood consumption for cooking and boiling water in very large families is significantly higher than that with very small families. Overall average fuelwood consumption for cooking and boiling water per family per day is 5.21
0.11 kg and 2.82
0.11 kg. Households with a high number of cattle or pigs consume a higher amount of fuelwood for producing smoke to protect cattle against insects or preparing pig feed. The average fuelwood consumption rate is approximately 5.60
0.11 kg day1 family1 for repelling insects to protect animals and 3.90
0.19 kg day1 family1 for preparing pig feed. The most preferred species is Shorea obtusa followed by Dipterocarpus obtusifolius, Xylia xylocarpa, Cratoxylon prunifolium, and Dipterocarpus tuberculatus. Two models of improved cooking stoves (the New Lao Stove and the Korng Rey Stove) are the most frequently used stove type in the study area. Ó 2012 Elsevier Ltd. All rights reserved.

Keywords: Fuelwood consumption rate Chumriey Mountain Cooking stove Species preference Fuelwood sources Cambodia

1. Introduction In 2004, about 2.5 billion people in developing countries, especially in rural areas, relied on biomass, such as fuelwood, charcoal, agricultural waste and animal dung, as their primary fuel for cooking. Without strong new policies, the number of people relying on the traditional use of biomass is projected to rise from 2.5 billion in 2004 to 2.6 in 2015 and to 2.7 billion in 2030 [1]. People in Asia and Africa depend mainly on fuelwood as a primary energy source for cooking and heating, which accounts for 75% of global wood production and consumption [2]. In rural areas of developing countries in particular, when wood is harvested in an unsustainable way to meet people’s energy demands and inefficient conversion technologies are used, there are a series of problems associated with health, the environment and economic development. The World Health Organization [3] reported that more than 1.45 million people e mostly women and children under five years old e die prematurely each year from household air pollution due to inefficient biomass combustion. Using WHO

* Corresponding author. Tel.: þ855 16 254 348; fax: þ855 23 880 116. E-mail addresses: [email protected], [email protected] (V. San). 0360-5442/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.energy.2012.06.025

estimates in 2004 [4], linked to IEA estimates in 2006 [1] on biomass use, it is estimated that household air pollution from the use of biomass in inefficient stoves will lead to over 1.5 million premature deaths per year (over 4000 per day) in 2030. This is greater than estimates of premature deaths from malaria, tuberculosis, or HIV/Aids. Not only does fuelwood consumption increase the direct payments of rural households, but valuable time and effort is devoted to fuelwood collection, resulting in loss of the opportunity for collectors to improve their education and engage in income-generating activities [5]. Unsustainable fuelwood collection and inefficient conversion technology have serious implications for the environment, such as forest and grass vegetation degradation and localized deforestation, accelerated soil erosion and changed ecosystem substance cycle [6,7]. The rapid growth of population as well as decreasing forest areas have led to depletion of fuelwood resources around localities, causing fuelwood shortage which has a direct impact on the poor, such as extending fuelwood collection time, increasing fuelwood prices, and putting into risk a basic human need [1,8]. Burning fuelwood and charcoal produces large amounts of CO2 (carbon dioxide) but the emissions from fuelwood consumption are considered as carbon neutral if fuelwood is harvested sustainably. Due to incomplete and inefficient combustion, fuelwood use may not be carbon neutral because

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carbon is released in other forms, including methane, nitrous oxide, carbon monoxide and non-methane hydrocarbons, which have more GWP (global warming potential) than CO2 [9]. In Cambodia, around 80.5% of total population lives in rural areas in 2.3 million households (81.7%) and 19.5% in urban areas in 0.5 million households (18.3%). The average household size of normal or regular households is 4.7 persons [10]. Fuelwood is the most common source of energy for the majority of the population in the Kingdom of Cambodia. Fuelwood and charcoal are often referred to as traditional fuels, yet they remain the dominant source of energy for cooking, boiling water, preparing animal feed and protecting cattle against insects within the domestic sector, and are used extensively by industry and services. The Statistical Yearbook 2008 published by the National Institute of Statistics [10] reported that fuelwood stood as far the most commonly used as fuel for cooking purposes, in 85.0% of Cambodian households in 2007. Charcoal was used in 6.0% of households, followed by LPG (liquefied petroleum gas) (5.2%), publicly-provided electricity/city power (0.2 percent) and kerosene (0.02 percent). Around 98.2 percent of rural households used fuelwood and charcoal. Approximately 31.2 percent and 87.0 percent used fuelwood and charcoal in Phnom Penh and other urban areas respectively. Usually, fuelwood is collected from forest; this makes forests an important resource for sustainable development in Cambodia. Forest cover in Cambodia has declined from 11.3 million ha or 61% in 2002 to 10.9 million ha or 59% in 2006; the net annual rate of deforestation is estimated as 0.5% [11]. The changes in forest cover in Cambodia are related to the population growth. The rapid increase of population has continuously led to an increase in demand for fuelwood and agricultural land [12]. Poffenberger et al. [13] identified fuelwood collection and consumption as one of the main deforestation drivers in Oddar Meanchey Province, Cambodia. In contrast, Top et al. [14] reported that there does not appear to be any evidence that fuelwood consumption is causing deforestation. However, wood removal for fuel only at a low but constant rate may have negative impact on the structure of natural forests [15]. Therefore, understanding fuelwood consumption patterns is expected to be useful for energy planning and improving fuelwood energy consumption pattern in rural Cambodia for long-term forest management. Studies on fuelwood use and flow have been conducted in different parts of Cambodia. FAO [16] studied the fuelwood consumption rate and fuelwood distribution system in Phnom Penh. In the same year, Gorse [17] conducted research on fuelwood energy supply, trading and demand in the whole province of Kampong Chhnang, Cambodia. Top et al. [18] studied fuelwood consumption rates and flow in Kampong Thom Province, Cambodia and Top et al. [14] conducted further research on variation in fuelwood consumption patterns in response to forest availability in the same province. Kong [19] investigated fuelwood and charcoal demand in Kampong Speu Province and flow in Phnom Penh. Mansvelt et al. [20] conducted a survey to estimate the total fuelwood use for cooking by households in Phnom Penh and to examine supply characteristics at the main production area in Kompong Speu Province. UNDP [21] released a report about residential energy demand in rural areas in Kampong Speu and Svay Rieng Province, Cambodia. However, there has been no recent study on fuelwood consumption for cooking, boiling water, preparing animal feed and protecting cattle against insects in the Chumriey Mountain area in Sameakki Mean Chey district. Therefore, the objective of this study was to explore in detail the fuelwood consumption patterns of households in Chumriey Mountain area in Sameakki Meanchey district. We examined the fuelwood consumption rate for cooking, boiling water, preparing animal feed and burning to protect cattle against insects, procurement methods, fuelwood species, and stove characteristics.

2. Methodology 2.1. Site description Chumriey Mountain area was selected as the study site (Fig. 1). Phnom Chumriey is located in Sameakki Mean Chey District in south western Kampong Chhnang Province at 11400 and 11520 North latitude and 104 400 and 104 430 East longitude and covers over 125 km2. The elevation is about 660 m. The study area is under a tropical climate with bi-annual change of monsoonal wind systems; the rainy season extends from May to October and the dry season from November to April. The Chumriey Mountain area has 40,496 ha of forest cover and is dominated by two forest types: mixed/semi-deciduous (on the top of the mountain) and deciduous [22]. It also serves as a buffer zone for the Aural Wildlife Sanctuary. Chumriey Mountain is one of the main fuelwood and charcoal sources for Phnom Penh city. Therefore, fuelwood and charcoal production are the main income of the people in the area as well as the main sources for daily consumption. According to our rapid survey, there are approximately 12,000 households living in the Chumriey Mountain area in 80 villages. Most are farmers and palm sugar producers, woodfuel sellers and charcoal producers. About 50% of households living around the Mountain have fuelwood-based jobs, collecting fuelwood for selling to brick making factories, making charcoal and producing palm sugar.

Fig. 1. Map of study location.

V. San et al. / Energy 44 (2012) 335e346

2.2. Data collection and analysis A reconnaissance survey was carried out before starting precise data collection to understand family size, number of households in a village, cooking stove patterns, and other variables referred to this study. This survey contributed to modifying the questionnaires and to selecting the numbers of samples. For the purpose of this study, four zones around Chumriey Mountain were selected. For each zone, a number of households were selected a using multi-stage sampling procedure. Since each zone was composed of different communes, a number of communes were selected using a simple random sampling method. After the selection of the communes, villages were selected in each commune. The number of households was used as the weight in determining the number of respondents. The household census was used as the sampling frame and the respondents were chosen through a systematic random sampling method. The sequence of selection was from zone to commune, from commune to village and then to households with different family sizes: very small (2e3), small (4e5), medium (6e7), large (8e9), and very large (>10). The quantity of fuelwood consumption for various purposes, such as cooking, boiling water, preparing animal feed and protecting animals against insects was estimated from user statements and direct measurement, as recommended by FAO [23]. The respondents were asked to gather the exact quantity of fuelwood used for these activities and then enumerators weighted the quantity during interviews. Direct measurement was conducted in some villages in order to compare results with the reporting of users, but there was no significant difference between the direct measurement and the reporting at both 0.05 and 0.01 levels. A review of secondary data was used in the preparation of the instruments for the study. The questionnaire comprised 4 broad headings: survey form, background information, socio-economic data, household energy consumption which consisted of energy sources for cooking, water boiling and appliances used, energy source for preparing animal feed, energy sources for animal protection, fuelwood species and so on. The questionnaire consisted of a mix of open-ended and confined questions which were administrated in face-to-face interviews in August 2010. All of the informants were presented with questions of a socio-economic nature (age, number of people living in the household, occupation). They were also asked questions at that time related to the plants used for fuelwood, the type of fuel used in the residence, the best species for use as fuelwood and their qualities, and so on. Additional questions were presented, such as what species were used as fuelwood, where the collections were made and who did the collecting, and which plant parts were collected. The respondents of the study were the main cook and the heads of household who presented at the time of the visit, regardless of their sex or age, where the women were between the ages of 20 and 85, and men were between the ages of 21 and 82. Generally, the male is the head of household in Cambodia and they usually collect the fuelwood and chip the fuelwood for air drying. Most women in Cambodia are the main cooks but they are not the head of household. Accordingly, males were asked about fuelwood collection, species use, quantity and so on, and the cook was asked about the stove, amount cooked, time of cooking, and health effects due to fuelwood burning. Although the empirical parts of this research were drawn mainly from primary data collection from sample households, embracing multiple perspectives, key informant interviews and indepth interviews were also applied. Concerned stakeholders including heads of households, fuelwood collectors, fuelwood and charcoal sellers, government officials, and local expatriates were included. These methods were used to validate and cross-check the information provided by respondents.

337

Sample size was not determined by using a specific equation. Samples were collected as much as possible to reduce bias. To select the samples, randomization was strictly maintained to avoid the bias. Fifty villages around the study area were selected for conducting the household interviews based on information on the number of households in each village (Fig. 2) and 767 households were selected for face-to-face interviews. The data on quantity of fuelwood used was collected in local units. Domestic consumption units of fuelwood are stere, cartload and head load. In Kampong Chhnang Province, one stere (1 m3 of stacked fuelwood) is equal to 360 kg of air dry wood [17]. An amount of green wood per cartload varies in different places and depends on cartload capacity and wood availability. Households were asked to estimate the amount of wood per cartload and head load in kg or m3 (600 kg of air dry wood). One tonne of charcoal comes from 5 tonnes or 11 steres or 6.6 m3 of wood [17]. The primary data on wood consumption recorded on a daily basis was converted to annual consumption. The consumption of biomass measured in local units during the field survey was converted into units of mass (tonne of dry matter) to standardize the data. Fuelwood consumption per capita per day was calculated using the equation PCFC ¼ FC/p, where PCFC ¼ Per capita fuelwood consumption, FC ¼ Total fuelwood consumption by sample household, and p ¼ Total number of family members in adult equivalents. Before calculating fuelwood consumption per capita, the members of each household were converted to the adult equivalent of the number of household members, using standard adult equivalent conversion factors [24]. 3. Results and discussion 3.1. Socio-economic conditions of households Table 1 shows the socio-economic conditions of households in the study area by household size. The household samples were categorized into five different family sizes: very small (2e3 persons), small (4e5 persons), medium (6e7 persons), large (8e9 persons) and very large (>10 persons). Family size and education status play an important role in planning and proper utilization of fuelwood. Nearly 40% (295 households) belonged to the small household category, while only 3% were in the very large category. The illiteracy rate in very small households was lower than that in very large households. The overall illiteracy rate was recorded as 31.6%. Approximately 70% of the households had formal education, e.g., primary, secondary or above. It is necessary to note that average annual income and agricultural land vary with the household size. The lowest average annual income (862.53
75.68 USD) was found in very small households, as compared to that of the other household size groups, whereas the highest value for annual income was estimated as 1187.28
154.26 USD for very large households. According to the statistical analysis, there was no significant difference among the household size groups (p > 0.05). The overall annual income was recorded as 969.42
35.90 USD. Agricultural land is one of the main household asset endowments. The overall average size of agricultural landholding was 1.08
0.34 ha. Very small households held approximately 0.80
0.66 ha of agricultural land, while small, medium, large and very large households occupied 1.10
0.58 ha, 1.14
0.63 ha, 1.20
0.97 and 1.44
0.22 ha, respectively. The statistical analysis of agricultural land showed that no significant difference was found between small, medium, large and very households (p > 0.05) but there was significant difference between very small households and the rest (p < 0.05) (Table 1). The average household size was 5.37
0.072 (Mode ¼ 5). In terms of household age composition, 38% of the sample population

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V. San et al. / Energy 44 (2012) 335e346

Fig. 2. Sample villages in study area.

was in the 0e14 years bracket, 49% in the 15e50 years e or working age e bracket, and 13% in the 51 þ years bracket. People within the low and high age brackets do, however, contribute labour, although not equal to the full adult equivalent. Family labour is a basis for both on- and off-farm employment activities. Labour is often shared reciprocally among neighbours and relatives to offset labour bottlenecks during peak seasons in agricultural production. 3.2. Fuelwood consumption According to the results of the study, most sampled households depend mainly on fuelwood for daily consumption. The results show that the main purpose of using fuelwood is for preparing everyday food. Other activities such as boiling water, preparing animal feed and protecting animals against insects during the rainy season are performed everyday using fuelwood as well, and boiling water is very often associated with food preparation. Families which raise animals, especially pigs, always prepare food for their

animals by using fuelwood as the main energy source. There are approximately 96% of sampled households using fuelwood for daily consumption. The proportion of fuelwood consumption in the study area is similar to the case in India reported by Balachandra [25]. Some people in the study area use fuelwood in their cooking along with other energy types such as charcoal, animal dung, crop residue, LPG, kerosene, and biogas. Only 12.4% of families use charcoal in addition to fuelwood. Charcoal is expensive, so it is only occasionally used, when the cook wants to grill meat or fish. Crop residue is being used by 6.6% of families, while only 0.3% of the families have installed a bio-digester in their home associated with charcoal for smoking fish and animal meat. Approximately 544 (74%) of the total sampled households prefer to prepare their food three times a day for breakfast, lunch, and dinner, while only 191 (26%) out of total sampled households prefer to cook their meals twice per day. Families cooking twice per day usually do not prepare food for breakfast because they have the food that remained from dinner the day before. Some families

Table 1 Socio-economic conditions of households in study area by household size (Mean
SE). Family size

Very small Small Medium Large Very large Total/Mean

Number of families

135 (18%) 295 (39%) 226 (30%) 87 (11%) 24 (3%) 767 (100%)

Education (%)

Average annual income (USD)

Illiterate

School Primary

Junior

Senior

26.7 30.2 34.5 33.3 41.7 31.6

58.5 59.3 54 57.5 50 57.1

10.4 8.1 8.8 6.9 4.2 8.5

4.4 2.4 2.7 2.3 4.2 2.9

862.53 926.79 985.14 1177.20 1187.28 969.42









75.68a 58.94a 56.09a 151.58a 154.26a 35.90

Agricultural land (ha)

0.80 1.10 1.14 1.20 1.44 1.08









0.66a 0.58b 0.63b 0.97b 0.22b 0.34

The letters a, b and c are used to show the significant difference (p ¼ 0.05) between/among the values within a column according to the Contrast test in the one-way ANOVA. Values in the same column followed by the same letters are not significantly different.

V. San et al. / Energy 44 (2012) 335e346

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Table 2 Fuelwood consumption for cooking and boiling water by income groups (Mean
SE). Income category (USD year1)

Number of families (cooking)

Number of families (boiling water)

Average daily consumption rate for cooking (kg day1 family1)

G1: <500 G2: 500e1000 G3: 1000e1500 G4: 1500e2000 G5: 2000e2500 G6: 2500e3000 G7: >3000 Total/Mean

275 219 122 59 28 15 19 737

217 168 97 49 22 13 14 580

5.18 5.29 5.20 5.19 5.11 4.81 4.70 5.21











0.19a 0.20a 0.24a 0.52a 0.52a 0.90a 0.70a 0.11

Average daily consumption rate for boiling water (kg day1 family1) 2.76 2.92 3.28 2.60 2.48 2.38 1.89 2.82











0.20a 0.18a 0.26a 0.25a 0.45a 0.53a 0.24a 0.11

The letters a, b and c are used to show the significant difference (p ¼ 0.05) between/among the values within a column according to the Contrast test in the one-way ANOVA. Values in the same column followed by the same letters are not significantly different.

prepare the food for breakfast and the rest of the food is brought to the rice field for lunch during rice cultivation period because their rice field is far from their village. Among 580 families using fuelwood for boiling drinking water, only 44% spend two times a day for boiling drinking water for everyday consumption and approximately 82% and 97% of the families which raise pigs and cattle use fuelwood only once a day for preparing animal food and burning to produce smoke to protect their animals from insects at night respectively. 3.3. Fuelwood consumption rate for cooking and boiling water Song et al. [26], Rosas-Flores and Gálvez [27], Rao and Reddy [28] and Pachauri [29] indicate that household energy consumption is influenced by several factors, such as family size, income, household land ownership, educational level, local availability and so on. Energy consumption in different localities and different parts of the world has a variable relationship with these socio-economic factors. In this section, the relationship of those socio-economic factors with energy consumption is discussed. Seven income groups (US$) were formed as group 1 (G1): <500; group 2 (G2): 500e1000; group 3 (G3): 1000e1500; group 4 (G4): 1500e2000; group 5 (G5): 2000e2500; group 6 (G6): 2500e3000 and group 7 (G7): >3000. It was found that about 37% of total sampled households were in income group 1 (G1) while 30% of total sampled households were in group 2 (G2) followed by G3, G4, G5, G6 and G7. It is clear that only a few sampled households were in the groups with higher incomes. Variation of fuelwood consumption is due to different income groups. Overall average fuelwood consumption for cooking is 5.21
0.11 kg day1 family1 with higher average consumption 5.29
0.20 kg day1 family1 in the lower income group G1 (<500) and lower average consumption of 4.70
0.70 kg day1 family1 in the higher income group G7 (Table 2). According to a one-way ANOVA analysis, average fuelwood consumption in income groups G1, G2, G3, G4, G5, G6, and G7

is not significantly different (p > 0.05). Fuelwood consumption status for boiling water is similar to that for cooking. Households with higher incomes consume less fuelwood for cooking than households with lower income level. Overall average fuelwood consumption for boiling water for households per day is 2.82
0.11 kg day1 family1. According to the statistical analysis, average fuelwood consumption in all income groups is not significantly different (Table 2). Pachauri et al. [29] report that households with low incomes use more non-commercial energy than households with high income level. In the study area, households with high incomes still consume fuelwood as their primary energy source because they cannot access the electricity grid and other commercial energy and also, they cannot afford the price of commercial energy. Although the results show that households with very large family size earn more money than households with small family size, the households cannot afford commercial energy because they have more mouths to feed. The results of the study reveal that lower average consumption (4.12
0.24 kg day1 family1) is found in very small families while the highest average consumption (7.84
0.77 kg day1 family1) is found in very large families. Statistical analysis of fuelwood consumption shows a significant difference between very small families and medium, large and very large families while there is no significant difference between very small and small families (p > 0.05). The average consumption rate of very large families is significantly different from that of other household sizes at 0.05. However, fuelwood consumption rates in small, medium, and large families are not significantly different (p < 0.05) (Table 3). Table 3 shows the amount of fuelwood consumption for boiling water by household size. It is necessary to note that with an increase in the number of household members, fuelwood consumption rates for boiling water are also increased. There is no significant difference between very small, small, medium and large families in terms of fuelwood consumption for boiling water while a significant

Table 3 Fuelwood consumption for cooking by household size (Mean
SE). Household size

Number of families (cooking)

Number of families (boiling water)

Average daily consumption rate for cooking (kg day1 family1)

Very small (2e3) Small (4e5) Medium (6e7) Large (8e9) Very large (>10) Total/Mean

124 283 223 82 23 737

97 227 176 63 17 580

4.12 4.92 5.65 5.86 7.84 5.21









0.24a 0.17ab 0.21b 0.33b 0.77c 0.11

Average daily consumption rate for boiling water (kg day1 family1) 2.34 2.55 3.25 3.86 4.08 2.82









0.22a 0.14a 0.24ab 0.33ab 0.65b 0.11

The letters a, b and c are used to show the significant difference (p ¼ 0.05) between/among the values within a column according to the Contrast test in the one-way ANOVA. Values in the same column followed by the same letters are not significantly different.

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V. San et al. / Energy 44 (2012) 335e346

Table 4 Fuelwood consumption rate for animal protection by number of cattle (Mean
SE). Number of cattle

Number of families

Average fuelwood consumption (kg day1 family1)

G1: 1e5 G2: 6e10 G3: 11e15 G4: 16e20 Total/Mean

232 69 10 2 313

5.06 6.77 8.70 11.50 5.60








0.11a 0.20b 0.30c 1.50c 0.11

Average fuelwood consumption (kg family1 month1) 151.91 203.04 261.00 345.00 167.9








3.39a 5.95b 9.00c 45.00c 3.34

Average fuelwood consumption (tonne family1 year1) 0.91 1.22 1.57 2.07 1.01








0.02a 0.04b 0.05c 0.27c 0.02

The letters a, b and c are used to show the significant difference (p ¼ 0.05) between/among the values within a column according to the Contrast test in the one-way ANOVA. Values in the same column followed by the same letters are not significantly different.

difference was found between very large families and very small, as well as small families (p < 0.05). Fuelwood consumption rates are not different among medium, large and very large household size at the 0.05 (Table 3). This is consistent with the study conducted by Song et al. [26] in U.S., Rosas-Flores and Gálvez [27] in Mexico and Miah et al. [30] in Bangladesh who state that family size has a significant impact on the amount of fuelwood consumption per family. Large families consume more fuelwood both because they have more workers to collect fuelwood and because they have more mouths to feed. 3.4. Fuelwood consumption rate for protecting animals Livestock plays an important role in Cambodian people’s lives. Cattle and buffalo are raised as draught power as an integral part of the rice cultivation and for cash income. Cattle and buffalo are predominantly kept to provide draught power, to prepare agricultural soil for rice growing and to provide manure rather than for meat production. They can be sold to a slaughterhouse or to a neighbour who wants to raise them for draught power. Burning fuelwood to produce smoke to protect the animals against insects is always conducted at night time during the rainy season. Therefore, the consumption load is six months in the rainy season. The number of cattle was categorized into four groups, group 1: 1e5; group 2: 6e10; group 3: 11e15; and group 4: 16e20 (Table 4). Approximately 74% of total sampled households belonged to group 1 followed by groups 2, 3 and 4. Families with a higher number of cattle consume more fuelwood to protect animals against insects than families with a smaller number of cattle. Lower consumption of 5.06
0.11 kg day1 family1 was found in group 1 and a higher rate 11.50
1.50 kg day1 family1 was found in group 4. The overall average fuelwood consumption rate was approximately 5.60
0.11 kg day1 family1. It is necessary to note that most households prefer to collect tree stumps rather than branches from the forest because they believe that a tree stump can produce smoke overnight to protect their animals from insects. One-way ANOVA analysis of fuelwood consumption for animal protection showed that there was no significant difference between groups 3

and 4 while consumption rates of group 3 and 4 were significantly different from groups 1 and 2 (p < 0.05). 3.5. Fuelwood consumption rate for preparing animal feed Pig raising is a common business for rural people. Pigs are raised for cash income and occasional home consumption. Fuelwood is used everyday to prepare pig feed. Therefore, the correlation between the number of pigs and fuelwood consumption rates was conducted as shown in Table 5. The number of pigs was classified into 5 groups. It was found that fuelwood consumption rates increase when the number of pigs increases. The highest average consumption rate of 9.90
0.50 kg day1 family1 was found in group 5 while the lowest average consumption rate 3.30
0.16 kg day1 family1 is found in group 1. Overall average fuelwood consumption per year was 1.40
0.07 tonne family1 year1. Statistical analysis shows that the fuelwood consumption rate in group 1 was significantly different from other groups at 0.05 while there was no significant difference between groups 2, 3, 4 and 5. 3.6. Fuelwood consumption rate per capita Based on the sample average as described in Table 6, average consumption per capita for cooking in the study area is 491.28
12.15 kg year1 with an average minimum of 354.26
38.95 kg year1 in very large families and average maximum of 663.62
40.67 kg year1 in very small families. Per capita fuelwood consumption for boiling water in the study area ranges from 188.83
31.52 kg year1 in very large families to 373.83
39.58 kg year1 in very small families. Overall average fuelwood consumption per capita for boiling water is 267.97
10.96 kg year1, while overall average fuelwood consumption for preparing pig feed and protecting cattle against insects is approximately 0.65
0.04 tonne head1 year1 and 0.31
0.01 tonne head1 year1, respectively. It is necessary to note that according to the statistical analysis, household size influences per capita fuelwood consumption for cooking and boiling water

Table 5 Fuelwood consumption rate for preparing pig feed by number of pigs (Mean
SE). Number of pig

Number of families

Average fuelwood consumption (kg day1 family1)

G1: 1e5 G2: 6e10 G3: 11e15 G4: 16e20 G5: 21e25 Total/Mean

181 19 10 5 2 217

3.30 6.53 6.95 7.20 9.90 3.90









0.16a 0.95b 0.63b 0.92b 0.50b 0.19

Average fuelwood consumption (kg family1 month1) 99.13 195.79 208.50 216.00 285.00 117.04









4.87a 28.50b 19.03b 27.50b 15.00b 5.59

Average fuelwood consumption (tonne family1 year1) 1.19 2.35 2.50 2.59 3.42 1.40









0.06a 0.34b 0.23b 0.33b 0.18b 0.07

The letters a, b and c are used to show the significant difference (p ¼ 0.05) between/among the values within a column according to the Contrast test in the one-way ANOVA. Values in the same column followed by the same letters are not significantly different.

V. San et al. / Energy 44 (2012) 335e346

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Table 6 Annual fuelwood consumption rate per capita by household size (Mean
SE). Household size

Annual fuelwood consumption rate per capita

Very small Small Medium Large Very large Total/Mean

663.62 521.27 429.86 334.71 354.26 491.28

Cooking (kg capita1 year1)







40.67a 19.98ab 16.01bc 18.07c 38.95c 12.15

Boiling water (kg capita1 year1) 373.83 267.00 252.69 174.17 188.83 267.97









39.58a 13.88ab 20.41ab 17.45b 31.52b 10.96

Preparing pig feed (tonne head1 year1) 0.69 0.61 0.62 0.74 0.78 0.65









0.10a 0.06a 0.06a 0.10a 0.13a 0.04

Cattle protection (tonne head1 year1) 0.36 0.33 0.30 0.26 0.23 0.31









0.03a 0.02a 0.02a 0.14a 0.11a 0.01

The letters a, b and c are used to show the significant difference (p ¼ 0.05) between/among the values within a column according to the Contrast test in the one-way ANOVA. Values in the same column followed by the same letters are not significantly different.

while household size has no influence on fuelwood consumption for preparing pig food and protecting cattle from insects. This clearly indicates that fuelwood consumption rates per capita decrease when household size increases. Therefore, households of larger family sizes tend to consume less fuelwood per capita compared with smaller families. Khuman et al. [31] in Uttarakhand in India report that the household size is inversely proportional to per capita fuelwood consumption at micro level. The result of this study is also consistent with the results of research conducted by Top et al. [18], Kituyi et al. [32], Hosier [33] in Kenya, Marufu et al. [34] in Zimbabwe, Mahapatra and Mitchell [35] in India, Kumar and Sharma [36] in Garhwal Himalaya in India and Kersten et al. [37] in Nigeria. Households of larger family sizes have more mouths to feed, so they spend more time earning money and preparing food. This means that larger family households consume fuelwood more efficiently than smaller ones. Top et al. [18] conclude that collective cooking for several individuals tends to require less fuel. Total average fuelwood consumption for cooking and boiling water, of 759 kg per capita, is higher than the consumption rate per capital (183 kg) of the study conducted by Top et al. [18] in Kampong Thom Province in Cambodia. Good infrastructure may be one of the main factors causing the higher consumption rate in this study area. The current roads in the study area as well as in whole country are better than those in 2003. Therefore, households in the study area have easy access to forest areas to collect fuelwood and access to local markets or local sellers to buy fuelwood, and fuelwood sellers can distribute fuelwood easily. The Chumriey Mountain area is one of the main fuelwood suppliers in the province and this fuelwood is transported to Phnom Penh. Fuelwood availability may be another factor affecting the rate of fuelwood consumption per capita in the study area. The study by Top et al. [18] reports that availability of forest may cause a different rate of fuelwood consumption. Angelsen and Kaimowitz [38] also conclude that greater access to forests and markets may often accelerate forest extraction. The average fuelwood consumption rate per capita in the study area is slightly different from the results of the study by Kumar and Sharma [36] in Garhwal Himalaya, Kituyi et al. [32] in Kenya and Amoo-Gottfried and Hall [39] in Sierra Leone, but lower than the consumption rate per capita in Zimbabwe [34]. In Zimbabwe, fuelwood is used not only for cooking and boiling but also for space heating. This factor causes the lower consumption rate in this area. Number of meals per day, stove types, fuelwood species, per capita food consumption, fuel substitutes, and measurement procedures can be explained as factors causing different fuelwood consumption rates per capita in different countries and regions. 3.7. Fuelwood sources and collection for cooking and boiling water Ninety-seven percent of the sampled households reported that they obtained fuelwood by collection from various sources

while only 3% of the sampled households said that they purchased fuelwood from fuelwood sellers in their village. The lower proportion of fuelwood purchased is due to high availability in forests of free and collected fuelwood for commercial is transported directly to Phnom Penh. The proportion of fuelwood purchased from fuelwood sellers revealed by the current study (3%) is lower than the 12% and 17% assumed by Top et al. [14,18] in Kampong Thom Province, Cambodia. Top et al. [14] report that in areas of high forest availability, less fuelwood is purchased from market than in areas of lower forest availability and people in areas with high forest availability are not likely to purchase fuelwood when they can easily collect it for free from nearby forests. Seventy-nine percent of fuelwood collectors are males and only 21% are females. Males are identified as the predominant collectors of fuelwood from natural forest and scrubland, and then chipping for air drying, followed by females and children. Females are reported to be predominant collectors of biomass fuel from agricultural plantations, hedges and homesteads, followed by children and males. The age of the head of household may be positively related to fuelwood collection until a peak of physical strength is reached and children move away. The results are consistent with the research carried out by Miah et al. [40]. Six different sources of fuelwood for daily consumption are identified in the study area e natural forest, scrublands, wastelands, agricultural plantations, hedges and homesteads (Fig. 3). The study revealed that 49% of families obtain fuelwood from natural forest and 18% obtain from scrubland. Top et al. [18] estimate that 51% of fuelwood originated from forested areas and 32% from nonforest sources and his study in 2004 [14] shows that these figures were 49% and 39%, respectively.

Wasteland 4%

Hedge 2%

Homestead 13%

Scrubland 18%

Natural forest 49%

Agricultural plantation 14%

Fig. 3. Sources of fuelwood collection for daily consumption.

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V. San et al. / Energy 44 (2012) 335e346

Fig. 4 shows the preferences for fuelwood collection for daily consumption. Most fuelwood collectors were found to cut green stems and dry stems (dead wood) for daily consumption and then transport the wood by power tiller with cart, oxcart, bicycle, cattle cart or manually. Actually, collectors prefer to gather dead wood but green wood is more available. On the other hand, households with better asset endowments exploit more dead or green stems for a long period of consumption. Local people prefer to collect fuelwood for daily consumption from forest areas near their village rather than to travel a longer distance to cut wood and they may be not permitted to cut wood in forest areas in other villages because of access rights of local people for fuelwood collection. Because of no restrictions on fuelwood collection for self-consumption, local people prefer to cut and collect all parts and kinds of trees available in the collection area rather than spending more time on searching for dead wood. The proportion of green wood and branches is high in the study area as well as in other areas in Cambodia. Top et al. [41] reveal that seventy-one percent of the total fuelwood was green wood while the remaining 29% reports was wood. This means that the proportion of green wood and branches is higher than that found in other studies. The study carried out by Nagothu [42] in Rajasthan, India, showed that on average only 26% of fuelwood collected from forests was green wood. Tabuti et al. [43] indicate that fuelwood for domestic consumption in Bulamogi County, Uganda, was largely comprised of dead wood. 3.8. Plant species for fuelwood for cooking and boiling water Almost all households reported some plant species preferences for fuelwood use for daily consumption (Table 7). The results of the survey indicate that a total of 41 species are being used for daily consumption throughout the study area. Eight species are the most preferred by the respondents. Ptchoek (Shorea obtusa) is the most preferred species, followed by Tbaeng (Dipterocarpus obtusifolius),

Sok Kram (Xylia xylocarpa), Lngieng (Cratoxylon prunifolium), Khlong (Dipterocarpus tuberculatus), Krorkoh (Sindora cochinchinensis), Pngeas (Memecylon floribundum), and Reang (Baringtonia acantagula). Approximately 46% of the sampled households use Ptchoek (S. obtusa) followed by Tbaeng (D. obtusifolius) at 40%, Sok Kram (X. xylocarpa) at 29%, Lngieng (C. prunifolium) at 21%, Khlong (D. tuberculatus) at 19%, Krorkoh (S. cochinchinensis) at 14%, Pngeas (M. floribundum) at 12%, and Reang (B. acantagula) at 11%. Most respondents said that they never select tree species for fuel. They collect all species of trees which are available in their collection area. This may be the reason why there is a larger number of tree species used for fuel in the study area. Top et al. [14] found that most people have never selected plant species for fuel in the area with the lower forest availability. Usually, the tree species used for cooking and boiling water in this study area are similar to those in other studies. Top et al. [14] found more or less the same tree species composition in this study area. The results of our study show Ptchoek (S. obtusa) to be used by most households, but Top et al. [14] found Kray (Xylopia pierrei) as the major fuelwood species. However, the results of this study are consistent with the research at the provincial level conducted by Gorse [17] in Kompong Chhnang Province, Cambodia. 3.9. Characteristics of stoves for cooking and boiling water Fig. 5 shows the percentage of households which own one to four stoves. The average frequency is two stoves. The study revealed eight types of stoves used for cooking and boiling water throughout the study area. The New Lao stove, known as Cambodian improved stove, is the most frequently used stove type in the study area (33%), followed by the Three Stone stove (18%), the Siam and Lao Kompong Chhnang stove (13%), the Traditional Lao stove (10%), the Korng Rey stove (9%), the self made or clay stove (2%) and the Samaki stove (2%) (Fig. 6). The New Lao Stove was designed by

Fig. 4. Preferences for fuelwood collection in study area.

V. San et al. / Energy 44 (2012) 335e346 Table 7 Fuelwood species for daily consumption.

343

3Stoves 4.3%

Scientific name (species)

Number of families using species

Ptchoek Tbaeng Sok Kram Lngieng Khlong Krorkoh Pngeas Reang Kray Trosek Puoch Chhlik Korntuot Prey Thlork Pring Ta lat Kreul Tromeng Sangker Chambak Krak Ling Pongrorphnom Kankon Svay Ampil Svay Chanty Trapaek prey Chhrao Porpel Preich Bangkong Angkot Khmav Khmear Tamakclar Cloot Haisan Knong Krorsang Jroolub Phlour

Shorea obtusa Dipterocarpus obtusifolius Xylia xylocarpa Cratoxylon prunifolium Dipterocarpus tuberculatus Sindora cochinchinensis Memecylon floribundum Baringtonia acantagula Kayea eugenicefolia Peltophorum ferrugineum Rhodomyrtus tomentosa Terminalia alata Phyllanthus emblica Parinarium spp. Eugenia spp. Canarium album Gluta laccifera Carallia lucida Combretum quadrangulare Irvingia malayana Rubus alceifolius N/A Guioa pleuropteris N/A Mangifera indica Tamarindus indica Anacardium occidentale Lagerstroemia floribunda Ficus rumphii Hopea recopei N/A Aglaia cambodiana Diospyros bejaudii Acacia intsia Gardenia angkoriensis Gnetum gnemon Cassia garretiana Pterocarpus indicus Polygonum odoratum N/A Dillenia indica

340 293 211 153 142 107 90 82 45 26 24 20 19 18 13 10 8 8 7 6 3 3 3 3 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1

N/A ¼ not available.

GERES (Groupe Energies Renouvelables, Environnement et Solidarités) e Cambodia, which can save up to 21.2% on charcoal and 20.89% on wood compared to traditional Lao stove [44]. Up to now more than one million New Lao stove have been made and sent to market. This is the reason why the proportion of New Lao stoves in the study area is higher than these of the study carried out by Top et al. [14], which found that the traditional Three Stone stoves were the most frequently used stove type (61%). The traditional Three Stone stove is still commonly used in some parts of the study area. There are some reasons behind the use of the Three Stone stove. Some poor families cannot afford new, energy-efficient stoves even though these stoves can save up to 60 percent on fuel. The Three Stone stove is made by combining three stones or bricks which can be collected in the village and around the houses. Most families raising pigs prefer the Three Stone stove to prepare pig feed because it can be resized as they prefer. Many researchers have reported that the Three Stone stove consumes more fuelwood than other cooking stoves [32,45e47]. Therefore, improved cooking stoves should be introduced throughout the study area and the rural areas in Cambodia at an affordable price so that the rural poor can easily access them. The national program to subsidize the cost of improved cooking stoves should be also expanded. Table 8 shows the characteristics, efficiency and cost of stoves produced by GERES in 2008 [48].

1Stove 39.4% 2Stoves 56.2%

Fig. 5. Stoves ownership in survey area.

3.10. Human health and social impacts of fuelwood use and collection During the interview, respondents who use fuelwood for cooking, animal food preparation, protection of animals against insects were asked about the health impact from using fuelwood but they said that fuelwood had been consumed for many years, so they had got used to it. However, the household reported that the large amount of smoke emitted from their cooking stoves was harmful to women and children in the area. As the health effects of the biomass burning in the traditional cooking stoves in the study area have not been medically diagnosed and there is no such study for Cambodia available, the results of these kinds of health effects reported in different developing countries have been summarized here from an extensive literature review. The impacts of burning fuelwood on human health have been reported by many researchers in the world. Health effects have been reported for some developing countries such as China, Mexico, Kenya, India, Nepal, Papua New Guinea, Guatemala, Turkey and Zimbabwe [49e63]. Those effects are acute respiratory infections, asthma. Blindness, cancer, chronic obstructive pulmonary disease, eye discomfort, headache, back pain, reduced birth weight, stillbirth, and tuberculosis. Women and children who mostly stay indoors are particularly susceptible to those health effects [64]. Bruce et al. [65] report that ARI (acute respiratory infection) is a major threat to women and children in developing countries. ALRIs (Acute lower respiratory infections), a specific type of ARI, are the leading cause of death among children younger than five, and

350 300 Stove Preference

Local name

4Stoves 0.1%

250 200 150 100 50 0

Stove Type Fig. 6. Preferred cooking stoves by rural households in the study area.

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V. San et al. / Energy 44 (2012) 335e346

Table 8 Characteristics, efficiency and cost of stoves [44]. Type of stove

Weight (kg)

Height (cm)

Width (cm)

Length (cm)

Efficiency (%)

Cost (Riels)

Improved Lao Kg. Chhnang New Lao Bucket Twin Samaki Three Stones Siam Lao Kompong Chhnang Traditional Lao

5

2.6

21.7

21.7

22

3000

12 9 e nil 1.5e4 2 to 4

30 20 55 nil Multi Multi

25.4 24 45 nil Multi Multi

25.4 70 100 nil Multi Multi

29 20e30 30e40 10 15 16

8000 5000e8000 3000 nil 800e3000 500e2000

3 to 8

Multi

Multi

Multi

24

2000e8000

chronic obstructive pulmonary disease and lung cancer increase mortality among adults [65]. The health impacts in the study area will not be exactly the same as impacts in other countries because of the differences in the types of biomass, the cooking stoves and kitchen location and design. In Cambodia, to make better inventions to reduce the health effects from biomass consumption, better understanding of the epidemiology and assessment of exposure are needed. ‘Tuberculosis and cardiovascular disease under casecontrol studies in women and randomized intervention trials acute respiratory diseases in childhood and adverse pregnancy outcomes’ can be useful for investigating the epidemiological implications of incomplete combustion of biomass in the traditional cooking stove. The PIC from different woody species needs to be identified. Due to deforestation and forest degradation in the study area, the task of collecting fuelwood has become increasingly onerous and the distances to be travelled to obtain sufficient supply of fuelwood have increased. Overall average amount of distance travelled and time spent in fuelwood collection is 6.67
0.35 km and 2.15
0.09 h (Mean
SE) respectively. The amount of time spent and distance travelled vary between villages depending on forest availability. This indicates that local people lose their opportunity to earn extra income and children lose time to attend school. 3.11. Deforestation effects of fuelwood consumption Although extraction of fuelwood for residential purposes such as cooking, boiling water, animal protection against insects, and animal feed preparation is not a major cause of deforestation throughout the whole country, it may be a major cause in particular areas and the constant rate of wood removal may have a negative effect on the structure of natural forest. Moreover, due to the significant reduction of forest cover at the national level, the people of the country no longer have access to a supply of forest products. In the study area, the forest area is covered by deciduous forest. Therefore, commercial timber extraction is not a major cause of deforestation in the study area because the area is covered by small trees. This is the reason why extraction of fuelwood for residential purposes, palm sugar producing, charcoal producing and pole is a major activity in the area. Fuelwood collection for use in cooking, boiling water and animal feed preparation in itself would not be the cause of deforestation in the study area. However, incomplete combustion of fuelwood in low efficiency traditional stoves is resulting in high consumption of fuelwood, which is leading to more collection of fuelwood from the forests. Top et al. [14] indicate that fuelwood consumption does not cause deforestation but they suggest that accessibility for fuelwood collection should be considered to give a more accurate assessment

of localized variation in the relationship between biomass and fuelwood consumption. Due to the rapid pace of population growth, more fuelwood is needed to meet demand from local people and people in the city as well. Therefore, fuelwood is harvested in an unsustainable way. Also, in terms of greenhouse gas emission, using traditional cooling stoves has some serious implications. Smith et al. [66] confirm that even if renewably harvested, biomass fuel cycles are often not GHG neutral because of their substantial production of PIC. Improved forest protection should be needed to complement improvements in forest management. Improvement management and protection of the natural forest will offer only long-term benefits. Plantations of fast-growing fuelwood species should be expanded in the gaps of village groves. Alternative renewable energy sources may be accessible to rural areas, which may reduce the dependency on wood. These may include solar energy and biogas, for which low-cost efficient cookers should be introduced throughout the rural areas. 4. Conclusion This study was conducted on fuelwood consumption patterns for different purposes of Chumriey Mountain area during 2010. The survey was done on the fuelwood consumption rate, wood species used for fuelwood, fuelwood sources and collection, and characteristics of stoves. Rural households in the study area depend mainly on fuelwood as the primary energy source for different purposes such as cooking, boiling water, burning to protect cattle against insects, and preparing pig feed. Approximately 96% of sampled households are using fuelwood for daily activities. Overall average fuelwood consumption for cooking and boiling water is 5.21
0.11 kg day1 family1 and 2.82
0.11 kg day1 family1, respectively. A significant difference in fuelwood consumption per family was found when comparing households of very large and small family sizes. The results clearly show that households of larger family sizes consume less fuelwood per capita in their cooking and boiling water, in comparison with those of smaller family size. Overall average fuelwood consumption per capita for cooking and boiling water in the study area is 491.28
12.15 kg year1 and 267.97
10.96 kg year1, respectively. Fuelwood is used not only for cooking and boiling water, but also for burning to protect cattle against insects during the rainy season and preparing pig feed. Households with a higher number of cattle and pigs consume more fuelwood than those with lower number of cattle and pigs. The average fuelwood consumption rate for burning to protect cattle and preparing pig feed is 1.01
0.02 tonne family1 year1 and 1.40
0.07 tonne family1 year1, respectively. Overall average fuelwood consumption per animal for preparing pig feed and protecting cattle against insects is approximately

V. San et al. / Energy 44 (2012) 335e346

0.65
0.04 tonne year1 and 0.31
0.01 tonne year1, respectively. We observed that improved stoves have been introduced to the study area but traditional cooking stoves are still used by local people in the study area. Ninety-seven percent of the sampled households obtain fuelwood by collection from various sources, of which natural forest is the main source. Males are identified as predominant collectors of fuelwood. The most preferred species is S. obtusa followed by D. obtusifolius, X. xylocarpa, C. prunifolium, D. tuberculatus, M. floribundum, and B. acantagula. An extensive literature review shows that using fuelwood poses severe epidemiological consequences to human health and contributes to deforestation caused fuelwood shortage and global warming. Therefore, this clearly indicates that human health damage is caused not only by burning fuelwood for cooking and boiling water, but also by burning fuelwood to produce smoke to protect cattle against insects and to prepare pig feed.

Acknowledgements The authors would like to express their gratitude to The Economy and Environment Program for Southeast Asia (EEPSEA) for providing financial support. We are also greatly indebted to Dr. David James and Dr. Herminia Francisco for their priceless support to achieve the results that we were looking for. It should be noted that their professional as well as moral assistance was the key for the successful accomplishment of this research work.

References [1] International Energy Agency. Energy for cooking in developing countries. World energy outlook 2006. Paris, France: International Energy Agency; 2006. [2] Food and Agriculture Organization. What woodfuel can do to mitigate climate change. Rome: Food and Agriculture Organization; 2010. [3] World Health Organization. The global burden of disease: 2004 update. Geneva, Switzerland: World Health Organization; 2008. [4] World Health Organization. Indoor smoke from solid fuel use: assessing the environmental burden of disease. Geneva, Switzerland: World Health Organization; 2004. Report No.: No. 4. [5] Kanagawa M, Nakata T. Analysis of the energy access improvement and its socio-economic impacts in rural areas of developing countries. Ecological Economics 2007 Apr 20;62(2):319e29. [6] Arnold M, Köhlin G, Persson R, Shepherd G. Fuelwood revisited: what has changed in the last decade? Bogor Barat, Indonesia: Center for International Forestry Research (CIFOR); 2003 May. Report No.: Occasional Paper No. 39. [7] Chen L, Heerink N, Berg MVD. Energy consumption in rural China: a household model for three villages in Jiangxi Province. Ecological Economics 2006; 58(2):407e20. [8] Arnold JEM, Köhlin G, Persson R. Woodfuels, livelihoods, and policy interventions: changing perspectives. World Development 2006 Mar;34(3): 596e611. [9] Smith K, Uma R, Kishore VVN, Lata K, Joshi V, Zhang J. Greenhouse gases from small-scale combustion devices: household stoves in India. Annual Review of Energy and the Environment 2000;25:741e63. [10] National Institute of Statistics. Statistical yearbook 2008: general population census of Cambodia 2008. Phnom Penh: National Institute of Statistics, Ministry of Planning; 2008. [11] Technical Working Group Forestry & Environment. Forest cover changes in Cambodia: 2002e2006. Cambodia: TWG Forestry & Environment for the Cambodia Development Cooperation Forum; 2007. [12] Kim Phat N, Ouk S, Uozumi Y, Ueki T. An outline of the causes of deforestation in Cambodia. Forest 1998. [13] Poffenberger M, Gryze SD, Durschinger L. Designing collaborative REDD projects: a case study from Oddar Meanchey Province, Cambodia. Community Forestry International 2008. [14] Top N, Mizoue N, Kai S, Nakao T. Variation in woodfuel consumption patterns in response to forest availability in Kampong Thom Province, Cambodia. Biomass and Bioenergy 2004 Jul;27(1):57e68. [15] Rüdger N. Dynamics and sustainable use of species-rich moist forest. A processbased modeling approach. Thesis Centre for Environmental Research e UFZ, Helmholtz; 2006. [16] Food and Agriculture Organization. Woodfuel flow study of Phnom Penh, Cambodia. Bangkok, Thailand: Regional Wood Energy Development Programme in Asia; 1998. Report No.: 54.

345

[17] Gorse V. Fuelwood flows in the province of Kompong Chhnang (Cambodia): wood energy supply, trading and demand. Kompong Chhnang Province. Cambodia: Cambodia Fuelwood Saving Project, Kompong Chhnang Environmental Service; 1998. Report No.: CFSP/98/E/03. [18] Top N, Mizoue N, Kai S. Woodfuel consumption rates and flow in Kampong Thom Province, Cambodia. Journal of Forest Planning 2003;9:17e24. [19] Kong P. Wood & charcoal supply study for rural energy balance in Kampong Speu Province. Phnom Penh, Cambodia: Ministry of Industry Mines and Energy; 2007. [20] Mansvelt ERV, Quan MCL, Im S, Buysman E, Rosa RKA, Guidal A. Wood energy baseline study for clean development mechanism in Cambodia: household woodfuel use and supply in Phnom Penh. Phnom Penh, Cambodia: Ministry of Environment; 2008. [21] United Nations Development Programme. Residential energy demand in rural Cambodia: an empirical study for Kampong Speu and Svay Rieng. Cambodia: United Nations Development Programme; 2008. [22] The National Committee for Sub-National Democratic Development. Commune database online 2010. Phnom Penh, Cambodia: NCDD, http://db. ncdd.gov.kh/cdbonline/home/index.castle; 2011. [23] Food and Agriculture Organization. A guild for woodfuel survey. Forest Department, Food and Agriculture Organization; 2002. [24] Ramachandra TV, Subramania DK, Joshi NV, Gunaga SV, Harikantra RB. Domestic energy consumption patterns in Uttara Kannada District, Karnataka State, India. Energy Conversion and Management 2000;41:775e831. [25] Balachandra P. Dynamics of rural energy access in India: an assessment. Energy 2011;36:5556e67. [26] Song N, Aguilar F,X, Shifley SR, Goerndt ME. Factors affecting wood energy consumption by U.S. households. Energy Economics 2012;34(2):389e97. [27] Rosas-Flores JA, Gálvez DM. What goes up: recent trends in Mexican residential energy use. Energy 2010;35:2596e602. [28] Rao MN, Reddy BS. Variations in energy use by Indian households: an analysis of micro level data. Energy 2007;32(2):143e53. [29] Pachauri S, Mueller A, Kemmler A, Spreng D. On measuring energy Poverty in Indian households. World Development 2004 Dec;32(12):2083e104. [30] Miah MD, Al Rashid H, Shin MY. Wood fuel use in the traditional cooking stoves in the rural floodplain areas of Bangladesh: a socio-environmental perspective. Biomass and Bioenergy 2009 Jan;33(1):70e8. [31] Khuman YSC, Pandey R, Rao KS. Fuelwood consumption patterns in Fakot watershed, Garhwal Himalaya, Uttarakhand. Energy 2011;36:4769e76. [32] Kituyi E, Marufu L, Huber B, Wandiga SO, Jumba IO, Andreae MO, et al. Biofuel consumption rates and patterns in Kenya. Biomass and Bioenergy 2001;20: 83e99. [33] Hosier R. Household energy consumption in Kenya. Ambio 1985;14:255e7. [34] Marufu L, Ludwig J, Andreae MO, Lelieveld J, Helas G. Spatial and temporal variation in domestic biofuel consumption rates and pattern in Zimbabwe: implication for atmospheric trace gas emission. Biomass and Bioenergy 1999; 16:311e32. [35] Mahapatra AK, Mitchell CP. Biofuel consumption, deforestation, and farm level tree growing in rural India. Biomass and Bioenergy 1999;17:291e303. [36] Kumar M, Sharma CM. Fuelwood consumption pattern at different altitudes in rural areas of Garhwal Himalaya. Biomass and Bioenergy 2009;33:1413e8. [37] Kersten I, Baumbach G, Oluwole AF, Obioh IB, Ogunsola OJ. Urban and rural fuelwood situation in the tropical rain-forest area of south-west Nigeria. Energy 1998;23:887e98. [38] Angelsen A, Kaimowitz D. Rethinking the causes of deforestation: lessons from economic models. The World Bank Research Observer 1999;14:73e98. [39] Amoo-Gottfried K, Hall DO. A biomass energy flow chart for Sierra Leone. Biomass and Bioenergy 1999;16:361e76. [40] Miah D, Ahmed R, Uddin MB. Biomass fuel use by the rural households in Chittagong region, Bangladesh. Biomass and Bioenergy 2003;24(4e5):277e83. [41] Top N, Mizoue N, Ito S, Kai S. Spatial analysis of woodfuel supply and demand in Kampong Thom Province, Cambodia. Forest Ecology and Management 2004 Jun 14;194(1e3):369e78. [42] Nagothu US. Firewood and fodder extraction and deforestation: mainstream views in India discussed on the basis of data from the semi-arid region of Rajasthan. Geoforum 2001;32(319):332. [43] Tabuti JRS, Dhillion SS, Lye KA. Firewood use in Bulamogi County, Uganda: species selection, harvesting and consumption patterns. Biomass and Bioenergy 2003;25:581e96. [44] Groupe Energies Renouvelables Environnement et Solidarités. Efficient cookstoves to mitigate global warming and contribute to poverty alleviation in Cambodia. Phnom Penh, Cambodia: Groupe Energies Renouvelables Environnement et Solidarités; 2007. [45] Batchelor SJ. Testing woodfuel stoves available in the market in Cambodia. RERIC International Energy Journal 1997;19:45e54. [46] Türker MF, Kaygusuz K. Investigation of the variables effects on fuelwood consumption as an energy source in forest villages of Turkey. Energy Conversion and Management 2001;42(10):1215e27. [47] Bank World. Improved energy technologies for rural Cambodia. Cambodia: World Bank; 2009. [48] Groupe Energies Renouvelables Environnement et Solidarités. Formal energy access project plan 2008. Energy Access 2008. [49] Bhargava A, Khanna RN, Bhargava SK, Kumar S. Exposure risk to carcinogenic PAHs in indoor-air during biomass combustion whilst cooking in rural India. Atmospheric Environment 2004;38(28):4761e7.

346

V. San et al. / Energy 44 (2012) 335e346

[50] Díaz E, Smith-Sivertsen T, Pope D, Lie RT, Diaz A, McCracken J, et al. Eye Discomfort, headache and back pain among Mayan Guatemalan women taking part in a randomised stove intervention trial. Journal of Epidemiology and Community Health 2007;61(1):74e9. [51] Ekici A, Ekici M, Kurtipek E, Akin A, Arsian M, Kara T, et al. Obstructive airway diseases in women exposed to biomass smoke. Environmental Research 2005; 99(1):93e8. [52] Ezzati M, Kammen DM. Indoor air pollution from biomass combustion and acute respiratory infections in Kenya: an exposure-response study. Lancet (British Edition) 2001;358(9282):619e24. [53] Mishra V, Dai X, Smith KR, Kika L. Maternal exposure to biomass smoke and reduced birth weight in Zimbabwe. Annals of Epidemiology 2004;14(10):740e7. [54] Mishra V, Retherford RD, Smith KR. Cooking smoke and tobacco smoke as risk factors for stillbirth. International Journal of Environmental Heath Research 2005;15(6):397e410. [55] Mishra VK, Retherford RD, Smith KR. Biomass cooking fuels and prevalence of tuberculosis in India. International Journal of Infectious Diseases 1999;3(3): 119e29. [56] Mishra VK, Retherford RD, Smith KR. Biomass cooking fuels and prevalence of blindness in India. Journal of Environmental Medicine 1999;1(4):189e99. [57] Ramirez-Venegas A, Sansores RH, Perez-Padilla R, Regalado J, Velazquez A, Sanchez C, et al. Survival of patients with chronic obstructive pulmonary disease due to biomass smoke and tobacco. American Journal of Respiratory and Critical Care Medicine 2006;173:393e7. [58] Regalado J, Perez-Padilla R, Sansores RH, Paramo Ramirez J,I, Brauer M, Pare P, et al. The effect of biomass burning on respiratory symptoms and lung

[59]

[60]

[61]

[62]

[63]

[64] [65]

[66]

function in rural Mexican women. American Journal of Respiratory and Critical Care Medicine 2006;174:901e5. Schei MA, Hessen JO, Smith KR, Bruce N, McCrachen J, Lopez V. Childhood asthma and indoor woodsmoke from cooking in Guatemala. Journal of Exposure Analysis and Environmental Epidemiology 2004;14(S1): S110e7. Smith KR, Samet JM, Romieu I, Bruce N. Indoor air pollution in developing countries and acute lower respiratory infections in children. Thorax 2000; 55(6):518e32. Vinod M, Kirk RS, Robert DR. Effects of cooking smoke and environmental tobacco smoke on acute respirations in young Indian children. Population & Environment 2005;26(5):375e96. Zhang JJ, Smith KR. Household air pollution from coal and biomass fuels in China: measurements, health impacts, and interventions. Environmental Health Perspectives 2007;115:848e55. Zhao Y, Wang S, Aunan K, Seip HM, Hao J. Air pollution and lung cancer risks in Chinaea meta-analysis. The Science of the Total Environment 2006;366: 500e13. Wang Y. The analysis of the impact of energy consumption on environment and public health in China. Energy 2010;35:4473e9. Bruce N, Perez-Padilla R, Albalak R. The health effects of indoor air pollution exposure in developing countries. Geneva, Switzerland: World Health Organization; 2002. Smith KR, Uma R, Kishore VVN, Zhang J, Joshi V, Khalil MAK. Greenhouse implications of household stoves: an analysis for India. Annual Review of Energy and the Environment 2000 Nov 1;25(1):741e63.