1. Biggest hydroelectric power plants in world
Three Gorges Dam, China
The Three Gorges Dam that spans the Yangtze River in Hubei province, China, is the world's largest power station in terms of installed capacity (22,500 MW).

2. II. Itaipu Dam, Brazil and Paraguay The Itaipu Dam is located on the Paraná River on the border between Brazil and Paraguay. Although the dam has a capacity of 14,000 MW, lower than that of the Three Gorges Dam, it has a higher annual yield generating an average of 91 ~ 95 TWh in. The plant supplies 90% of the electricity consumed by Paraguay and 19% of that consumed by Brazil.

3. ADVANTAGES
Water is a renewable energy source and It is a clean and safe source of energy.
Maintenance and operation charges are very low.
The efficiency of the plant does not change with age, They are the most efficient energy source running from 90-95% efficiency.
Useful for flood control, irrigation purposes, fishery and recreation.
Have a longer life(100 to 125 years) .
Can increase or decrease the plant’s production whenever there is high or low demand respectively

4. Disadvantages The initial cost of the power plant is very high.
Takes long time for construction of the dam.
Wildlife habitats can be changed or destroyed.
Power generation by hydro power plant is only dependent on natural phenomenon of rain .Therefore at the time of drought or summer session the Hydro Power Plant will not work.

5. CONCLUSION
Hydro-electric power is an important part of the world's electricity supply, providing reliable, cost effective electricity, and is expected to continue to do so in the future.
Hydro power has less negative environmental impacts which are very different from those of fossil fuel power plants.