Integrating Hydropower and Wind Power in Ethiopia
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The importance of electricity in enhancing the daily activities of human life is a basis for the development of any nation. The developmental activity requires huge electricity supply and qualitatively the sustainability of the supply is also another big concern in planning the economic growth of a country.The potential availability of energy supply resources are not only ample but also variety of alternative renewable resource for energy exploitations are widely promising for implementation in Ethiopia. The recent study has indentified that around 1.3mill.MW wind potential and 45000MW hydropower potential are available among which only 171MW of wind and about 2000MW of hydropower potential have implemented. These existing power plants are insignificant compared to the available potential for exploitation and compared to the number of the consumers in need of the electricity.Recently the government has focused largely towards the development of hydropower and wind farms. Preferably the principles of hybrid electricity supply system is on its virtue of wide spread in sustaining the energy supply under any critical hydrological inflows and/or very low wind speeds. Hence, in this thesis, the study of the possibility of the integrating hydropower and wind power in Ethiopia was undertaken as a major concern. The challenges in the combined hydro-wind power system was also discussed and the possible best combination alternative was suggested. The effective way of managing the hydro-wind integrated power supply system is the use of back-pumped reservoirs to complement the critical times of the hydrological inflows and the periods of low wind speeds.In Ethiopia, it is common that the hydrology and wind availability varies temporally and spatially. The variability of these electricity sources ranges from short time variation, seasonal variation to yearly variation. However, the complementarities of these climate variables were checked in this study and concluded that during the time of critical inflow into the reservoirs there is high wind potential due to high temperature for heating the air system of the ground surface which creates the pressure difference and wind density. This results in wind blow during dry periods than during the wet periods. On the other hand, the hydro dominated power system with storage reservoirs in the country helps to store water inflow during high rainfall time in particular during the rainy season to secure the dry time power supply and environmental flow conditions.The data for this study were collected from the Ethiopian Electric Power Corporation EEPCO, the Ethiopian Ministry of Water and Energy MoWE, the Ethiopian National Meteorology Agency NMA, and the National Centers for Environmental Prediction NCEP and various websites and many literatures reviews. The data for hydropower production was collected directly from the Generation Department, EEPCO whereas the data for wind power was difficult to get from the generation department, instead the raw wind speed data were collected from the wind mast records, meteorology stations and NCEP.The raw wind speed data were used through different steps of analysis to approximate the actual wind power that can most probably be generated at both existing wind farms namely Adama I Wind Farm and Ashegoda Wind Farm. The computation of the wind power was undertaken using spreadsheet and the final result was used as an input for modelling combined hydro-wind power system for the present and the future. In this study, two major tasks were undertaken as the main objectives of the thesis work. The first one was the complementarities between hydropower and wind power under different circumstances in relation to the climate variables which are sources of electricity i.e., the hydrology and wind speeds. The second major task was to study the validity of the existing combined hydro-wind power system in meeting the balance between demand and supply system and also to check for the future possibility of the wind penetration into the hydropower system; assuming the future interconnected system of power supply only contains hydropower and wind power.In conclusion, the hydropower and wind integration system in Ethiopia shows a perfect match and the combined system should be beneficiary if developed further. The existing combined supply system was analyzed and indentified as there is insignificant average daily power shortage which was estimated to be 0.799GWh and the future possibility of the hydro-wind integration in the country, Ethiopia, is moreover promising as far as the share of wind penetration into the hydro dominating system is very low.