ES221108 theoretical test

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POWER PRODUCTION FROM RENEWABLE ENERGY AY 2021-22 8th November 2022 Prof. Paolo 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 the drive train of a modern large scale wind turbine with three blades and horizontal axis, discuss the advantages and disadvantages of a direct drive configuration with a permanent magnet generator with respect to a doubly fed induction generator (DFIG) scheme. Discuss the opportunity to adopt these configurations in different sites, both by an energy and economic point of view. 2. Considering a liquid-dominant geothermal source, discuss advantages and disadvantages of a system based on a direct cycle with steam flash and separation, compared to a binary ORC cycle. 3. Classify biomass for energy applications and explain advantages and disadvantages in their exploitation, with particular reference to primary energy saving, avoided CO2 emissions and socio-economic aspects. 4a: ENERGY ENGINEERING STUDENTS (8 CFU): Discuss the effect of partial load operation on different kinds of hydraulic turbines. Which types of hydro power plants are mostly affected by part-load operation? 4b. MECHANICAL ENGINEERING STUDENTS (6 CFU): Draw the electrical layout of a multi-string PV plant and explain what happens when a single module is completely shadowed. 4c. MANAGEMENT ENGINEERING STUDENTS (5 CFU): Explain the concepts of ‘energy payback time’ and ‘energy return on investment’ for a renewable energy plant and identify the main items that have to be…