1.1. Study area
The study was conducted in Asgede Tsimbla district, northern Ethiopia located at about 900-1800 m.a.s.l. with an estimated area of 2,358 km2 (Figure1). The rainfall of the area is bimodal with a short rainy season occurring between January and April, and a long rainy season from June to August. Average annual rainfall is about 550-900 mm. The mean maximum temperature ranges between 20°C (November and December) and 35°C (January and March). The district has a total of 29,874 households (23,618 males and 6,256 females) with a total livestock population of 135,661(33).
1.2. Sampling methods
To select the study villages, first discussion was done at regional and district energy offices. Two potential kebeles (Lemlem and Hitsats) using both improved and traditional biomass-based stoves from Asgede Tsimbla district was selected (Figure 1). Lemlem kebele were selected because most of the improved baking stoves locally called “Mirt” user is found in this village. This stove is distributed by the World Vision. The second Hitsats keble is selected because the use improved cook stove locally called “Tikikil“ which is distributed by Zoa Relief projects.
To select the study households (HH), we used both cross-sectional and longitudinal methods. In Lemlem keble because of the absence of both improved and traditional stove users, cross-sectional methods are taken. During the selection of households, both socioeconomic and environmental factors which can affect the sampling are considered. While in Hitsas households agreed to use both the improved and traditional cook stoves (TCS) were selected. In this study a total of 192 households were participated. The number of household covered on this study were more than the rule of thumb (10% of the total number of ICS users) suggested on KPT protocol [34]. Of which, 43 HHs each from improved baking stove (“Tikikil”) and traditional baking stove (TBS) users; and 53 were both improved and TCS users.
1.3. Description of both improved and traditional cookstoves
The improved stoves called Mirt and Tikili had specified materials and dimensions when first designed in Ministry of water and energy of Ethiopia and GIZ in 2011 [35]. Whereas, the traditional cooking stove were made up of stone and mud and have not fixed structure and design (Figure 2)
Mirt stove is produced with mortar using a mixture of scoria (red ash) or pumice or river sand with cement for the service more than five years. It is used for baking of the staple food items called “Injera” and/or bread. The stove has six parts that are joined together, four parts fit to make a cylindrically shaped enclosure and two other parts joined one on top of the other and are fitted with the cylindrical enclosure from behind (Figure 3). The two parts serve as smoke outlet and rest for the cooking pot. There is classic Mirt stove- with 6 cm and the slim mirt stove with 4 cm of wall thicknesses. Depending on the thickness of the parts as well as the raw materials used, the total weight of Mirt stove ranges from 45 kg – 65 kg. Mirt stove dimensions for cylindrical enclosure is: diameter: 64-70 cm, height: 22-24 cm, fuel/air inlet: 24 cm by 11cm, and smoke outlet: 19 cm by 7 cm and for rear parts is: 32 cm wide, 26 cm deep and 35 cm high.
“Tikikil” is basically a rocket stove, however adopted to suit the conditions in most Ethiopian households and local production techniques; meaning “Appropriate”. Tikikil” is adopted to replace the most inefficient but widely used traditional three-stone stove (Open Fire). The design parameters were considered the households’ pot sizes, ease of production, affordability, use of locally available raw materials and skills. It is designed to accommodate pot sizes of 25 cm (and smaller) in diameter. The stove has two main parts which include the ceramic liner and the metal part (Figure 3). The metal part contains of the sheet metal cladding and the wood support. This stove is used to prepare sauce (commonly known “Wot”), boiling water, making coffee and similar activities involve burning a fuel several times a day.
1.4. Fuelwood use measurement
Our KPT were based on three days of repeated fuel wood use measurements in a relatively enough sample size, thereby limiting the influence of inter-household variability. According to the experimental protocol, participants prepared three patches of wood enough for three days of cooking, based on their typical fuel requirement. The participants didn’t provide with wood as this can bias the test result [34]. On the 1st day of the tests, the three batches of wood were weighted using pocket balance and recorded. The wood moisture content was measured using pin-type electorophysics moisture meter (MT800). For moisture content, three pieces of wood samples from the stock were taken randomly and measured using moisture meter at the top, middle and bottom parts. On the 2nd day of the test, the wood that remained from the first day was weighted, and the difference recorded as the day’s fuel. The moisture content of the randomly selected three pieces of wood was also measured. The same procedure was repeated on the day three. The adult equivalent for meals in a household was also calculated for each baking days.
The probable impact of fuel savings by using ICS on carbon emission in the study area was calculated based on the clean development mechanism and United Nation’s Framework of Convention on Climate change [36]; Table1)
Where:
E= emissions; fNRB= fraction of non-renewable biomass; NCV= net calorific value (for wet wood); EF= default emission factor (per unit of energy)
1.5. Statistical analysis
An excel software based tool developed by Shell Foundation was used to calculate the daily fuel and energy consumption by a household. Here, daily refer to the sessional baking or cooking day, because the firewood consumption was not measured daily. Independent sample t test was used to compare the consumption rate of wood and energy when households were using improved cook stove and traditional ones. Analysis of variance was used to know whether there is significant difference in the consumption of wood, energy and emission reduction by using the two different cook stoves. The social data were encoded in SPSS software, and descriptive results were produced for interpretation and description.