Question

3- Assume a pumped hydro energy storage arrangement that pumps up water from a low- level water reservoir to a higher-level reservoir to store energy. The water then is running back from the top reservoir down to the low reservoir through the pipe by passing a turbine. Assume a reasonable case of your choice and calculate the efficiency of this arrangement for storing energy (i.e. the electrical energy delivered by the turbine divided by the electrical energy used by the pump). • Assume reasonable material and size for the pipe carrying water (your credible references to support your assumptions) • Avoid complex pathways; however, the question has been designed such that different individuals would expectedly come up with different piping plan with different solutions. • Assume 150 m height difference between the lower and upper reservoirs and a horizontal distance of 400 meters between them. • Assume 5 parallel pumping lines working together to pump up the water • Use minimum 6 bends on each (i.e. a combination of 45 ̊ and 90° elbows) depending on the piping path that you are assuming • Place the pumps right next to the lower reservoir • Assume the five piping lines to be identical from the geometry and size as well as materials point of view. • Assume some limitations and geological barriers that prevents you from having a straight piping line from the lower reservoir to the upper reservoir • Provide the sources from which you extracted the performance characteristics of the pump (as per used in your calculations) • Choose a single turbine with the selected capacity. Try to assume a reasonable efficiency, pressure drop, and other specs of the turbine as required. You can extract such data from the suppliers’ websites or credible references. You may use a similar piping line (in terms of pathway and geometry) as those used for pumping. • Make any other assumptions as required with clear justification and supporting sources. • List all your assumptions and justifications in a table with any key notes and explanations in front of each of them. • You may use the Moody diagram attached if required. • Use any other information as required from the book (e.g. for minor losses)

Answer 1

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