ES210903 theoretical test

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POWER PRODUCTION FROM RENEWABLE ENERGY AY 2020-21 3rd September 2021 Prof. Silva Time: 1 hour 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. Considering a large scale three-bladed horizontal axis wind turbine, discuss the regulation strategies adopted by the control system in the range between the nominal and cut-off wind speed, explaining the main pros and cons of each of them. In particular highlight the velocity triangle modification introduced by a gust. 2. Debate the various benefits and negative aspects associated with the energy use of bio- mass. 3. Consider a binary ORC coupled to a geothermal source. Starting from the configuration based on a saturated cycle with one pressure level , discuss the possible modifications of the cycle that will lead to an increase in the net electric efficiency of the plant. 4a. For Energy Engineering students: Consider a high-head hydro power plant whose flow rate allows the adoption of either a Francis or a Pelton turbine. Explain the aspects that must be considered to choose the optimal type of turbine. 4b. For Mechanical and Management Engineering students: For some renewable sources, discuss the energy and environmental advantages related to cogenerative or even thermal only applications compared to those involving a fully electric configuration.