Ex 6 SIZING AND DESIGN OF A SMALL HYDRO PLANT Text

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SIZING AND DESIGN OF A SMALL HYDRO PLANT POWER PRODUCTION FROM RENEWABLE ENRGY - AY 2021/22 Prof. Paolo Silva – Prof. Nicola Fergnani A company wants to assess the feasibility of a small run -of-river hydroelectric plant to exploit the water potential of a weir located on the Chiese river with a gross hydraulic head of 3 m. For the water availability assessment, a daily surveys of discharged flow-rate is available over a period of 3 years (see attached Excel sheet). a) Identify the optimal kind of turbine for the exploitation of the hydraulic potential of the weir. For this purpose consider the gross hydraulic head, the discharged flow -rate trend over the year and the boundary conditions which affect the construction of the plant on the river (see photo below). b) Knowing that the regional legislation on environmental impact requires the construction a fish ladder with a feeding flow -rate of 0.3 m 3/s, find the optimal size of the turbine (nominal flow rate) to achieve the lowest PBP of the investment. Also consider the following assumptions:  Average annual electric efficiency of the plant = 0.78  Ratio of minimum flow-rate over nominal flow-rate of the turbine α = 0.15  Feed-in tariff as depicted in the actual regulation frame  Specific construction cost of the plant C [€/KWN] evaluated as follows (with P in kW): 𝐶 = 20′000 𝑃 + 15′000 ∙ 𝑃−0.3 c) determine the net hydraulic head in nominal conditions k nowing that the concentrated head loss coefficient is ε1 = 2.0 for the intake screen , ε 2 = 0.6 for the feeding channel and ε 3 = 0.9 for the tailrace channel. The wet cross-section is A1 = 10 m2, A2 = 3 m2 and A3 = 5 m2 respectively. Evaluate the actual energy yield of the plant considering the net hydraul ic head and the real hydraulic efficiency of the turbine…