ES220725 test WHG

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Wind, Hydro and Geothermal Power Generation AY 2021-22 25st July 2022 Prof. Paolo Silva Time: 90 minutes Instructions for the examination: 1) Clearly indicate your name on all the sheets you will deliver. 2) Give a synthetic and clear answer to as many questions as possible. The final score will be normalized according to the average results. 3) Talk with colleagues and / or cheating will cause the cancellation of the exam. 1. Consider a three-bladed, horizontal-axis wind turbine whose regulation strategy is designed to operate at sea level according to the only measured value of undisturbed wind speed. How would the power curve change if the same turbine is installed at 4000 m asl respectively (i) with no adjustment of the regulation strategy and (ii) with adjustments? (5 points) 2. Provide a definition of the Levelized Cost of Electricity (LCOE) for renewable power plants. How is it affected by the availability of the renewable source? What are the other parameters affect- ing the LCOE? (5 points) 3. Consider a medium -head hydro power plant whose flowrate allows the adoption of either a Kaplan or a Francis turbine. Explain the aspects that must be considered to choose the optimal kind of turbine. (5 points) 4. Discuss the potential advantages of vertical axis wind turbine technology (VAWT) over the state of the art of three-bladed HAWT for off-shore wind farms and especially for floating applications. (5 points) Exercise (11 points) A geothermal source has the following characteristics at the outlet of the well: temperature 180°C, enthalpy 1050 kJ/kg. Consider a single flash direct steam cycle cogenerative plant, based on a cooling tower condenser with a condensation pressure of 0.075 bar. The flash pressure is 3.3 bar. Design the lay-out of the plant (i) with all…