---
title: "Advantages and limitations of hydropower"
subject: "Hydro Power"
chapter: 3
key: "semester_6/hydro_power:hydropower-advantages-limitations"
source: https://www.bctengineer.com/q/semester_6/hydro_power/hydropower-advantages-limitations
site: BCT Engineering
---

# Advantages and limitations of hydropower

Hydro Power · Chapter 3: Planning of Hydropower Projects

- Asked in: 2081 Chaitra, 6 marks
- Video: [Advantages and disadvantes of hydropower](https://www.youtube.com/watch?v=43ZCdBJwoDI) — Future Energy & Technology
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/hydro_power/hydropower-advantages-limitations
- Whole chapter: https://www.bctengineer.com/md/semester_6/hydro_power/chapter-3

## Question

Enumerate the advantages and limitations of hydro-electric power.

## Short answer

Advantges: renewable, zero fuel cost, clean, high efficiency (80–90%), long life, quick start for peak load, and multipurpose. Limitations: high initial cost, long construction, output depends on rainfall, site remote, submergence, sediment, and seismic risks.

## Answer

**Hydro-electric power** is electricity produced by using the potential energy of water falling through a head to drive turbines coupled to generators ($P = 9.81QH\eta$).

#### Advantages
1. **Renewable source:** water is renewed by the hydrological cycle and is not used up.
2. **No fuel cost:** running cost is very low; only operation and maintenance.
3. **Clean:** no smoke, ash or CO₂ during operation.
4. **High efficiency:** overall efficiency 80–90%, much higher than thermal plants (30–40%).
5. **Quick start and load following:** units can start and take load in a few minutes, so they are ideal for peak load and frequency control.
6. **Long life:** 50–100 years for civil works.
7. **Reliable and simple:** fewer moving parts, low breakdown rate.
8. **Multipurpose benefits:** storage projects also provide irrigation, flood control, water supply, fisheries and tourism.
9. **No import dependence:** for Nepal it uses local resources and saves foreign currency; surplus can be exported.

#### Limitations
1. **High initial cost:** dams, tunnels and access roads are costly.
2. **Long construction period:** usually 4–10 years.
3. **Dependent on rainfall/flow:** output falls in the dry season or drought years.
4. **Site specific:** plants are in remote hills, far from load centres, needing long transmission lines.
5. **Environmental and social effects:** submergence of land, displacement of people, effect on fish and the downstream river.
6. **Sedimentation:** reservoirs fill up and turbines are eroded, especially in Himalayan rivers.
7. **Geological and seismic risk:** landslides, weak rock and earthquakes can damage works.
8. **Risk of dam failure and GLOF:** large consequences downstream.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. How does hydro efficiency compare with thermal?
   A. Hydro 30-40%, thermal 80-90%
   B. Equal
   C. Hydro 80-90%, thermal 30-40%
   D. Hydro 50%, thermal 50%
   Answer: C. Hydro overall efficiency is 80-90% against 30-40% for thermal. (Key point: Efficiency)

2. Why is hydro suited to peak load and frequency control?
   A. It starts and takes load in a few minutes
   B. It needs fuel storage
   C. It has very low capital cost
   D. It is independent of rainfall
   Answer: A. Quick start allows load following. (Key point: Operational advantage)

3. Which is a limitation of hydropower?
   A. Fuel cost
   B. CO2 emission in operation
   C. Short life
   D. High initial cost, long construction and dependence on flow
   Answer: D. Dams and tunnels are costly, take 4-10 years, and output falls in the dry season. (Key point: Limitation)

## Related in Hydro Power

- [Power sources and hydro versus thermal](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Apower-sources-hydro-vs-thermal) — Hydro Power, chapter 3
- [Bernoulli's equation limitations and application](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Abernoulli-limitations-application) — Hydro Power, chapter 1
- [Stages of hydropower project study](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-study-stages) — Hydro Power, chapter 3, asked 3×
- [Layout of hydropower scheme components](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Ahydropower-scheme-layout) — Hydro Power, chapter 5
- [Firm power and plant load factors](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Afirm-power-load-factors) — Hydro Power, chapter 3
- [Flow and power duration curves](https://www.bctengineer.com/question.md?key=semester_6%2Fhydro_power%3Aflow-power-duration-curves) — Hydro Power, chapter 3

## Related in other subjects

- [Hydro and thermal power sources](https://www.bctengineer.com/question.md?key=semester_4%2Fpower_system_analysis_i%3Ahydro-thermal-sources) — Power System Analysis I, chapter 1
- [Micro hydro net head, power and energy](https://www.bctengineer.com/question.md?key=semester_6%2Fenergy_resources%3Amicro-hydro-power-output-numerical) — Energy Resources, chapter 5
- [Hydropower site power and turbine](https://www.bctengineer.com/question.md?key=semester_7%2Fenergy_environment_and_society%3Ahydro-site-power-numerical) — Energy Environment and Society, chapter 3
- [Characteristics of hydro turbines](https://www.bctengineer.com/question.md?key=semester_8%2Fpower_plant_design%3Aturbine-types-characteristics) — Power Plant Design, chapter 3