Bio-Wastes as an Alternative Household Cooking Energy Source in Ethiopia

Abstract

Abstract:Up to the present day, wood has been used to supply the needs for cooking in rural Africa. Due to the ongoing deforestation, households need to change to other energy sources. To cover this need, a large amount of people are using residues from agriculture (straw, manure) instead. However, both straw and manure also have a function in agriculture for soil improvement. Using all the straw and manure will seriously affect the food production. In this paper we first determine the amount of energy that households need for cooking (about 7 GJ per year). Then we estimate the amount of residues that can be obtained from the agricultural system and the amount of energy for cooking that can be derived from this amount when different conversion techniques are used. The amount of residues needed is strongly affected by the technology used. The traditional three stone fires require at least two times as much resource than the more advanced technologies. Up to 4 ha of land or 15 cows are needed to provide enough straw and manure to cook on the traditional three stone fires. When more efficient techniques are used (briquetting, biogas) this can be reduced to 2 ha and six cows. Due to large variation in resource availability between households, about 80% of the households own less than 2 ha and 70% holds less than four cows. This means that even when modern, energy efficient techniques are used the largest share of the population is not able to generate enough energy for cooking from their own land and/or cattle. Most rural households in Sub-Saharan Africa may share similar resource holding characteristics for which the results from the current findings on Ethiopia can be relevant. OPEN ACCESSEnergies 2015, 8 9566

Alternative energy supply system to a rural village in Ethiopia

“…The annual energy required for both types of cooking is estimated to be equivalent to about 163 GJ of useful energy. This assumption is in line with the annual cooking demand estimation made in a previous study, which is 5-7 GJ of useful energy per household [11]. Overall, the village annually requires about 163 GJ of useful energy for cooking and 20 GJ of useful energy for lighting and appliances.…”

“…Availability of dung is also limited by feeding practices and the need for fertilizers. As a consequence, only about 30% of produced residues and 40% of produced dung are assumed to be available for energy based on [11].With these, we estimated about 22 t of residues and 30 t of dry dung per year from the average land and cattle resources of the village respectively (Table 1). Data on the quantity and composition of rural household wastes are not available for Ethiopia to include in this study.…”

“…Data on land resources and corresponding cereal crop yields and cattle population holdings are taken from Ethiopian CSA databases [25]. The quantities of bio-wastes produced from household resources and their availabilities are determined in a previous study [11] based on the average residue to product ratio (RPR) of cereal crops [26,27] and dry dung per animal [3,28,29]. Accordingly, households annually on average produce about 3 t (1 t = 10 3 kg) of residues and 3 t of dung from their land and cattle resources respectively.…”

“…Shortage of feedstock is attributed to the traditional use of only cow dung limited by the number of cows held at households. Only few households with a sufficient number of cows can produce enough biogas to meet their demand [11,12]. In addition, adoption and installation of household level biogas digesters are limited by the long payback period associated with the technology [13,14].…”

Problems with Biogas Implementation in Developing Countries from the Perspective of Labor Requirements

“…As a consequence, they look for closer resources (crop residues and cow dung) as alternatives to solve the time problem. Use of their own biomass depends on availability of land and livestock resources holdings, which are also very scarce [3]. In addition, crop residues and dung are an integral part of the agricultural system providing feed and fertilizers.…”