Water energy is one of the renewable forms of energy.

As the word says it is nothing but the energy which is generated from water. The water that flows or falls down produce energy. Water creates two types of energy they are Kinetic energy and potential energy. Kinetic energy is the one that gets released when the water moves and potential energy is the one in water that is not used immediately. The energy which is extracted from water is called as hydro power.

Hydro power plants are hence located at places that have heavy water flow such as dams. In industrial process water is made to flow through the pipes to turn the turbines that are connected to a generator which produces water energy.


Water Energy Definition

The hydroelectric plants are cost effective. The heat produced by these plants is very little and emission of harmful gases is also minimal when compared to other power plants.

The water in the dams and reservoirs after taking hydro energy from them are stored within it and used for irrigation and other purposes.

The usage of water energy was in its peak during the mid-20the century. But the idea of using water to generated power dates back 2,000 years ago.

The Greeks primarily used a water wheel for grinding wheat flour. Water is made to flow through the water wheels and it spins when the water with force hits its blades. The gears of the wheel are used to grind the wheat into flour. The water wheels are nothing but the oversized turbines we use today.



Water Energy Definition


The hydro power extracted from its resource can be evaluated in the following way.

Power – Function of hydraulic head and rate of flow of the fluid

Head - Energy per unit mass of water

Static Head – Proportional to the difference in height through the one the water falls.

Dynamic Head – depends on velocity of moving water.


Water Energy Definition

Hydro Power is calculated from

  1. Density of water

  2. Flow rate

  3. The height of fall

  4. Local acceleration due to gravity


P = ηρQgh


P – Power in watts

η – Dimensionless efficiency of the turbine

ρ – Water density in kilograms per cubic meter

Q – Water flow in cubic metres per sec

g – Acceleration due to gravity

h – Difference in height between inlet and the outlet.

Water Energy Definition

Types of power plants:

Water that is used widely to generate electricity and it is one of the very old techniques. There are so many ways from which power can be extracted from water. They are

Conventional Hydroelectric plants: this includes the basic method of extracting power from water. That is hydroelectric dams. This is the most common type used in power generation.

Run-of-the-river hydroelectricity: This method directly consumes the kinetic energy from the water in rivers and streams. This method does not depend on construction of dams.

Small hydroelectric plants: A very low amount of power generation takes place in these projects. Only more or less 10 megawatts power used to get generated and hence has no artificial reservoirs.


Water Energy Definition

Types of power plants (Continue):

Micro Hydro electric stations: this provides supplies to homes, small scale industries or villages. The power production here ranges from few kilowatts to some 100 kilowatts.

Conduit Hydroelectricity: these projects use the water that is being used for other purposes.

Pumped- storage hydroelectricity: In this method, water is stored when the need is low and when the need arise it pumps the stored water to produce power.


Water Energy Definition

Largest dams:




Three gorges Dam  


22,500 MW

Itapúa Dam

Brazil Paraguay

14,000 MW

Guri Dam


10,200 MW 

Tucurui Dam


8,370 MW


Water Energy Definition

Largest Producers:

China is the largest producer of hydroelectricity. Annual consumption of electricity in china is about 3,450 billion kwh. 22% contribution of the total electricity produced is from hydroelectric plants.

Canada is the second largest producer which has a contribution of about 60% of its total electricity production from hydroelectric plants, whose total power production is 620 billion kwh.

Brazil tops as the third producer. The total production of electricity in the country is about 438.8 billion kwh. 83 % of that is generated from hydroelectric plants.

USA ranks fourth with 5.50% contribution of the total power produced in the country. USA is the largest electricity producer that generates about 4,110 billion kwh.

Russia produces annually about 925 billion kwh and ranks fifth. The contribution by the hydroelectric plants is about 17% to the total electricity produced.


Water Energy Definition

Interesting Facts:

More than 24% of the world’s electricity is produced from the hydroelectric power plants supplying more than 1 billion people with electricity.

More than 2,000 hydro power plants are put up in the United States.

The total output of the world’s hydro electric power plants is 675,000 megawatts
Steam energy


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