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Classification of Hydroelectric Power Plants

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Hydro Electric Power plants

Classification of Hydroelectric Power Plants

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Hydro energy is one of the renewable forms of energy. Hydro electric power plants have very high efficiency when compare to any other power plant. They have very long life, lesser impact over the environment, low production cost, lesser maintenance and flexibility in operation and control. The main drawbacks of these power plants are higher cost during construction and the land requirement for construction of reservoir.

Hydro electric power plants can be classified based on their location, the presence and absence of storage, range of operation, operational features etc.

Layout of Hydro electric power plants

classification-of-hydroelectric-power-plants
Conventional hydroelectric plant

Conventional hydroelectric plant

Pumped storage  hydroelectric plant

Pumped storage hydroelectric plant

Tidal power plant

Tidal power plant

Classification based on the hydraulic features

Based on the hydraulic features hydro electric power plants can be classified into the four types:

conventional hydro electric plants:

These plants utilize the hydraulic energy of the flowing water of the rivers. Dams are constructed to collect the water in the reservoir and is used to run the turbines.

Pumped storage plants

In this type of hydroelectric power plants the same water is utilized again and again by pumping back during the off peak hours. They are mainly used to meet the peak demand.

Tidal power plant

These power plant produces electric energy from the tides of the seas.

Depression power plants:

In this type of power plant water is diverted into a natural topological depression which provides head for the plant. Water is diverted from ample resources such as seas. It is a rare type of power plant. This type of power plants exists in Egypt.

Classification based on the operation

Base load plants

This type of plants involves in continuous power generation. Simply speaking conventional hydroelectric power plants are base load plants.

Peak load plants

If the power plant is operated only to meet the peak demand then it is called peak load plants. In general, pumped storage power plants are peak load plants. In this type of hydroelectric power plants the same water is utilized again and again by pumping back during the off peak hours.

Classification based on storage

By considering the availability of storage reservoirs, hydro electric power plants can be classified into power plants having storage reservoir and without storage reservoir. If the availability of the water is uneven over the year, storage reservoirs are essential. If there is a natural normal flow throughout they year then it is not essential to have a reservoir. Under such conditions a mini reservoir or pond that takes care of day to day fluctuations is enough.

Classification based on plant capacity

Typecapacity

Very low capacity hydro electric plants

Up to 0.1 MW

Low capacity hydro electric plants

Up to 1.0 MW

Medium capacity hydro electric plants

Up to 10 MW

High capacity hydro electric plants

More than 10 MW

They can also be classified as follows

TypeCapacity

Micro hydro electric plants

< 100 kW

Mini hydro electric plants

100kW to 1MW

Small hydro electric plants

1 MW to a few MW

Medium hydro electric plants

More than a few MW

Super hydro electric plants

More than 1000 MW

Classification based on head

Based on the available head hydro power plants are classified into the following:

TypeHead

Low head plants

< 15 m

Medium head plants

15 – 70 m

High head plants

70 – 250 m

Very high head plants

More than 250 m

High head power plants

classification-of-hydroelectric-power-plants

High head plants

Due to high head, small amount of water can produce large amount of power. Therefore these types of plants are very economical. The reservoir is found at the top of the mountain and the power house is found at the foot. For high head plants catchment area of small capacity is sufficient. If the water from one stream is not sufficient, more than water can be diverted from the neighboring streams. For heads above 500 m, Pelton turbine is used and for low heads Francis turbines are used.

Medium head plants

Larger volume of water is required in this type if power plant. The reservoir capacity will be large. In these power plant water is carried from the reservoir is carried to the penstock through the forebay. There is no need of surge tank as forebay itself acts as a surge tank. Francis, Kaplan and Propeller turbines are commonly used for the medium head plants.

Low head plants.

Low head plants require larger volume of water than high and medium head plants to produce same amount of power. The reservoir capacity will be large. Francis, Kaplan and Propeller turbines are commonly used for the low head plants.

Comments

LUZ CANAS from CALOOCAN CITY on July 06, 2019:

thank you for your explanation. now i understand it.

Abhishek S on May 31, 2017:

Nice explainations

Biki on April 18, 2016:

Thanks ...sir

kamlesh yadav on February 20, 2015:

good

OSBERT JOEL C (author) from CHENNAI on March 31, 2014:

You are welcome

gat on March 31, 2014:

Thank you

OSBERT JOEL C (author) from CHENNAI on January 16, 2014:

Thank you lesliebyars..

lesliebyars on January 16, 2014:

You explained things that I never knew about power plants. I used to live near a power plant. When we would go, to look at the water, we felt so small next to it's massiveness in size. It was amazing to think of the technology that is involved. I voted up, useful and interesting. Thank you for sharing.

OSBERT JOEL C (author) from CHENNAI on January 15, 2014:

Thank you both of you!

Adityapullagurla on January 15, 2014:

How amazing are these types of power plants .. really good hub

CJ Kelly from the PNW on January 15, 2014:

You really have a gift for explaining these technologies. Very interesting.

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