--- title: "Hydropower requirements and components" subject: "Energy Environment and Society" chapter: 3 key: "semester_7/energy_environment_and_society:hydropower-requirements-components" source: https://www.bctengineer.com/q/semester_7/energy_environment_and_society/hydropower-requirements-components site: BCT Engineering --- # Hydropower requirements and components Energy Environment and Society · Chapter 3: Renewable Energy Sources - Asked in: 2070 Chaitra, 4 marks; year not given - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/energy_environment_and_society/hydropower-requirements-components - Whole chapter: https://www.bctengineer.com/md/semester_7/energy_environment_and_society/chapter-3 ## Question What are the minimum constructional requirements to develop a hydropower system? Describe the components of hydropower plants. ## Short answer Hydropower needs a water source with sufficient flow (Q), head (H), suitable topography, access to load/grid, and feasibility approvals. Components include weir/intake, settling basin, headrace canal, forebay, penstock, powerhouse with turbine/generator, tailrace, and switchyard. ## Answer #### Minimum requirements to develop a hydropower system 1. **Water source with sufficient discharge (flow, Q)** all year or at least a dependable flow, based on hydrological data (flow duration curve). 2. **Head (H):** a suitable height difference between intake and powerhouse. 3. **Suitable site:** stable geology and topography for the weir, canal, penstock and powerhouse. 4. **Access and load:** road or track access, and a market (load) or grid connection nearby. 5. **Technical, economic and environmental feasibility:** cost, tariff or PPA with NEA, EIA/IEE approval, licence from the Department of Electricity Development, and community acceptance. #### Components of a hydropower plant 1. **Dam / weir and intake:** raises and diverts the water; the intake has trash racks and gates. 2. **Settling basin (desander):** removes sand to protect turbines. 3. **Headrace canal or tunnel:** carries water to the forebay. 4. **Forebay / surge tank:** smooths flow changes and prevents water hammer. 5. **Penstock:** steel pipe carrying water at high pressure to the turbine. 6. **Powerhouse:** contains the turbine, generator, governor, valves, control panel and transformer. 7. **Turbine:** converts water energy to rotation (Pelton, Francis, Kaplan, cross-flow). 8. **Generator:** converts mechanical to electrical energy. 9. **Tailrace:** returns the water to the river. 10. **Switchyard, transformers and transmission line.** ```text Weir -> Intake -> Settling -> Headrace -> Forebay | Penstock (H) | Turbine+Generator -> Tailrace ``` ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which two physical quantities must a site have to develop hydropower? A. Wind speed and solar radiation B. Dependable discharge (flow) and suitable head C. Large population and high rainfall only D. Cold climate and high altitude Answer: B. Power depends on flow Q and head H, so both must be adequate, with flow dependable all year. (Key point: Basic physical requirements) 2. What is the purpose of the settling basin (desander)? A. To store water for peaking B. To remove sand and protect the turbine C. To increase head D. To step up the voltage Answer: B. Sand in water erodes turbine runners, so the desander removes it before the water goes to the penstock. (Key point: Settling basin) 3. What does the forebay or surge tank do? A. Smooths flow changes and prevents water hammer B. Generates electricity C. Returns water to the river D. Filters out trash at the intake Answer: A. It acts as a buffer between the headrace and penstock, absorbing flow changes and pressure surges. (Key point: Forebay / surge tank) 4. Which is the correct order of water flow in a hydropower plant? A. Penstock - headrace - turbine - forebay B. Intake - settling basin - headrace - forebay - penstock - turbine - tailrace C. Intake - penstock - settling basin - tailrace D. Weir - tailrace - turbine - penstock Answer: B. Water is diverted at the intake, desanded, carried by the headrace, held at the forebay, dropped through the penstock to the turbine, then released via the tailrace. 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