--- title: "Hydropower source and plant types" subject: "Energy Environment and Society" chapter: 3 key: "semester_7/energy_environment_and_society:hydropower-plant-classification" source: https://www.bctengineer.com/q/semester_7/energy_environment_and_society/hydropower-plant-classification site: BCT Engineering --- # Hydropower source and plant types Energy Environment and Society · Chapter 3: Renewable Energy Sources - Asked in: 2070 Asar, 1+2 marks; 2070 Asar, 2 marks; year not given - Video: [Hydropower - The Source of Sustainable Power – [Hindi] – Quick Support](https://www.youtube.com/watch?v=s_mkhnGiUwo) — Quick Support - 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-plant-classification - Whole chapter: https://www.bctengineer.com/md/semester_7/energy_environment_and_society/chapter-3 ## Question What is a source of hydropower? How can you categorize the hydropower plants? Describe the types of hydropower plants. ## Short answer Hydropower comes from the water cycle, with elevated water energy converted by turbines and generators. Plants are categorized by capacity, head, storage and water use, and load. Main types are run-of-river, peaking run-of-river, storage, pumped storage, and micro-hydro; Nepal's storage example is Kulekhani. ## Answer The **source of hydropower** is the water cycle: the sun evaporates water, which falls as rain or snow at a height and runs back to the sea. Water stored or flowing at a height (head) has potential energy, which is converted into kinetic energy and then into mechanical and electrical energy by a turbine and generator. Power: P = ρ g Q H η. #### Classification of hydropower plants 1. **By capacity (Nepal):** pico (< 1 kW), micro (1–100 kW), mini (100 kW–1 MW), small (1–10 MW), medium (10–100 MW), large (> 100 MW). (Limits differ by country.) 2. **By head:** low (< 15 m), medium (15–70 m), high (> 70 m). 3. **By storage / water use:** run-of-river (ROR), peaking run-of-river (PROR), storage (reservoir), pumped storage. 4. **By load:** base load, peak load. #### Types - **Run-of-river (ROR):** uses the natural flow of the river, with a small weir to divert water; no or very little storage. Output varies with river flow. Most Nepali plants are of this kind, for example Khimti and Upper Bhotekoshi. - **Peaking run-of-river (PROR):** has a small daily pondage so it can generate more in peak hours, for example Kali Gandaki A, Middle Marsyangdi and Upper Tamakoshi. - **Storage (reservoir) plant:** a dam stores water in the monsoon and releases it when needed, so output can be controlled; for example Kulekhani I (60 MW), Nepal's main storage plant, whose water is reused by Kulekhani II (32 MW) downstream. - **Pumped storage plant:** water is pumped to an upper reservoir using surplus electricity and released through turbines at peak time. It works as a large battery. - **Micro/pico hydro:** small plants of a few kW for villages. ```text Intake -> Canal -> Forebay -> Penstock -> Turbine -> Tailrace (weir) (head H) + Generator ``` ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What is the source of hydropower? A. Nuclear fission in rivers B. The water cycle driven by the sun C. Wind over water D. Geothermal heat of the earth Answer: B. The sun evaporates water, which falls at a height as rain or snow; its head gives potential energy. (Key point: Source of hydropower) 2. Which formula gives hydropower? A. P = rho g Q H eta B. P = rho Q H / g C. P = g Q H / rho eta D. P = rho g H / Q Answer: A. Power equals density x gravity x flow x head x efficiency. (Key point: Power formula) 3. What is a feature of a run-of-river plant? A. A large dam to store monsoon water B. Pumps water to an upper reservoir C. Constant output regardless of flow D. Little or no storage, so output varies with river flow Answer: D. ROR plants use natural flow with a small weir, so output follows the river. (Key point: Run-of-river) 4. How does a pumped storage plant work like a battery? A. It stores electricity directly in chemical form B. It pumps water at peak time and generates off-peak C. Surplus power pumps water up; it is released through turbines at peak time D. It uses no turbines Answer: C. Water is pumped uphill with surplus electricity and released for generation at peak demand. 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