Wind Resource Data Analysis : The case of MYDERHU project site, Tigray regional state, Ethiopia

Ethiopia is a developing country and its major primary energy consumption is largely covered by biomass and imported fossil fuels. Reliability of electricity supply varies widely across Ethiopia. Currently 65% of the population does not have access to electricity; 30 % of those without electricity live in village centers and 70% live in remote rural areas. However, the country is endowed with different renewable energy resources such as, hydro, wind, solar, geothermal and bioenergy. Wind energy is applicable for both power generation & water pumping applications for rural societies. The purpose of this study it to analyze the wind energy resource potential at Myderhu, to model the wind data with different statistical methods and software, selecting wind turbine class, forecast site wind energy & power density, develop site wind resource map, preliminary wind turbine micro siting, estimating farm annual energy production (AEP) and the expected cost of electricity. Based on the analysis and site survey, the site roughness and power exponent factors are classified as class I. Detailed wind resource data analysis is performed for the proposed site by using Excel, MatLab and WAsP software, based on a wind mast of 50m with an average wind speed of 7 m/s & mean power density of about 287 W/m2, this is categorized as a class-III wind resource (fair potential). Finally, wind resource mapping of 10km x 10km land area for a proposed wind farm is attempted at four different turbine hub heights of 30m, 50m, 80m and 100m. A supposed wind farm having 72 turbines with 82m rotor diameter at 80m hub height has been subjected to a simplified economy analysis by assuming investment costs of 1600 €/kW [38,400 birr/kW] and 1750 €/kW [42,000 birr/kW] and cost of energy estimated as 230.4 million € [5.53 billion birr], 0.028 €/kWhr [0.676 birr/kWhr] and 252 million € [6.05 billion birr], 0.031 €/kWhr [0.74 birr/kWhr] respectively. However, the Ethiopian FIT draft proclamation secure 0.073 €/kWhr [0.1 USD/kWhr] [1.75 birr/kWhr]. The calculation was done strictly by considering the power density at the site, and it didn’t address the issues of transportation and other installation related concerns and costs. Therefore, it is only applicable as a benchmark for future investigation work. As per this preliminary analysis the farm installed capacity is 144 MW, gross AEP is estimated about 593 GWhr, considering a wake loss of average 4.4% the net AEP is 567 GWhr and the average power density at the wind farm is estimated at 446 W/m2. The average capacity factor is estimated at 45%. The mean wind speed at hub height is 8.07 m/s. The Weibull shape factor (k) ranges from 2.8 to 3.3 with total average of 3.17