Hydro Power

MAY, 2013

HYDROPOWER Mayadhar Swain

1.

Introduction

Hydropower is one of the renewable sources of energy. It uses the thread of the falling water to rotate a turbine and generator to generate electricity. In other words, the kinetic energy of the falling water is converted to mechanical energy by the turbine and the generator converts this mechanical energy into electrical energy.

2.

cycle. In the water cycle: z

Water on thesurface of the Earth is heated by solar energy causing it to evaporate.

z

This water vapour condenses into clouds and falls back onto the surface of the Earth as precipitation (rain, snow etc.).

z

The water flows through rivers back into

History

the oceans, where it again evaporates and

The use of falling water as a source of

the cycle continues.

energy is known since a long time. In the ancient times waterwheels were used for different purposes such as grinding grain. At the beginning of the nineteenth century, hydro turbine was invented to use hydropower. In the second half of nineteenth century electricity was generated from hydropower. The first hydropower plant in the world was established in 1882 on the Fox River in Appleton, Wisc on si n, USA. As th e so urc e of hydroelectric power is water, the hydroelectric plants must be located on a water source especially where the water head is available i.e. river falls from a higher region to lower region. Hence it was not developed until the technology to transmit electricity over long distances was developed.

3.

hydroelectric power. It relies on the water

How Hydropower Works

The amountof energyavailable in moving water is determined by its rate of flow and fall. In a hydropower plant a dam is built across the river. The water is allowed to flow through a pipe (in technical language it is called penstock). The water pushes against and turns blades in a turbine. Agenerator is coupled with the turbine. As it rotates, electricity is generated as per Faraday's law of electromagnetic induction.

4.

Calculation of Power Power potential of water in a river

depends on the flow in the river and the available head. The flow through unit is the amount of water which passes in a certain time cross section of the river. Flows are normally

When flowing water is captured and turned

expressed in cubic meters per second (m3/s)

into electricity, it is called hydropower or

or in liters per second (l/s)

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MAY, 2013

Head is the vertical difference in level (meters) through which the water falls down.

material but only uses water and after its use water is available for other purposes.

In a hydropower plant it is the difference of

Because the water cycle is an endless,

reservoir level and tail base level (see Fig-1).

co ns ta ntl y

rec har ging

sy ste m,

hydropower is considered a renewable energy. 2.

There is no fuel consumption and also needs limited maintenance. So running cost is low.

Fig-1

3.

The energy available is predictable.

4.

It is a clean source of energy. There is no pollution of air or water.

5.

Given a reasonable head, it is a

The theoretical power (P) available is in exact proportion to the head (H) and flow (Q).

concentrated energy source.

P=Q x H x c The constant c is the product of density

6.

Power is usually continually available on demand.

7.

Power can be generated from the unit

of water and the acceleration due to gravity (g). If P is measured in watts, Q in m3/S and H in meter, the gross power of the flow of water

within a few minutes. Due to this

is, P= 1000 x 9.8 x Q x H

advantage, it can be used as a base-load power plant.

This available power is converted by the turbine to mechanical power which is further

8.

It is a long lasting and robust technology and systems can last for 50 years or

converted to electrical power by generator. As there are some losses in turbine and generator,

more without major new breakdowns or

the net power is:

investments.

P = 1000 x 9.8 x Q x H x Where

K = efficiency of turbine and generator

(it is less than 1)

9.

Hydroelectricity is a fundamental system for sustainable development. (Sustainable development is the "development that meets the needs of the present without

5.

Advantages of Hydropower

1.

Hydropower is a renewable source of

generations to meet their own needs."

energy. It does not consume any raw

- Brundtland Commission)

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compromising the ability of future

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MAY, 2013

6.

Disadvantages

b)

1.

For a large power station, area of reservoir becomes large and hence there is

the plant mainly produces energy from the available flow of the river, taking advantage of

submergence of land, forest, villages etc.

the natural elevation drop of a river. Therefore, it is suitable for streams or rivers that have a

2. 3.

Rehabilitation of displaced people is a cause of discontentment. In most large power stations, power generation depends on monsoon.

4.

It is site specific. It can be built only where reasonable head is available in the river. It is often found in inaccessible areas where cost of infrastructure development becomes large.

5.

Construction time is more.

7.

Types of Hydropower Plants

There are three hydropower schemes, namely reservoir type, run-of-river scheme and pumped-storage type. a) Reservoir scheme : In this scheme a big dam is built across the river and water is stored in the reservoir. The water is released though turbines in a controlled manner thoughout the year. Generally all large power stations are of this type.

Run of river scheme : In this scheme

minimum flow all year round. A small barrage is constructed across the river and water is diverted through the power plant. Water is diverted into a penstockor pipe and channelled to the turbine and then returned to the river. These plants have either no storage or shortterm storage (Water required to run the power plant for two to three days only). In this scheme there is no submergence of land. c) Pumped-storage scheme : In this scheme there are two reservoirs. The upper reservoir stores the river water and the lower reservoir stores the water discharged from the power plant. When the demand for electricity is low such as during night time, the pumpedstorage facility stores energy by pumping water from the lower reservoir to the upper reservoir. During periods of high electrical demand, the water is released back through turbine to the lower reservoir to generate electricity. The reservoir acts much like a battery, storing power in the form of water when demands are low and producing maximum power during daily and seasonal peak periods.

8.

Sizes of Hydroelectric Power Plant Consideringsizes, hydropower plants can

be classified as large, small, mini and micro. Typical Hydroelectric Dam 22

In our country all hydropower plants with Science Horizon

MAY, 2013

installed capacity of more than 25 MW are

10. Hydropower Development inOdisha

classified as large power plant. Similarly plants

Odisha has ten important river systems

of capacity from 1 MW to 25 MW are small,

with potential of hydro power. Mahanadi, the

from 100 KW to 1 MW are mini and less than 100 KW are called micro power plant. Micro,

fifth largest river in the country in terms of flood discharge (45000 cusecs), flows in the

mini and small power plant can be installed

centre of the State from west to east. To the

even in small streams and irrigation canals.

Hydropower Development in India

north of Mahanadi are Brahmani, Baitarani, Salandi, Budhabalanga and Subarnarekha

Sidrapong Hydel Power Station with 2

flowing from west to east. To the south of

units of 65 kW each and located 12 km from Darjeeling is the first hydropower plant in the

Mahanadi is Rushikulya flowing from west to east. Indravati, Kolab (Saberi), Machhkunda

country. It was established in 1897 and is still

(Sileru) lie on the southern part of the State

operating. Central Electricity Authority have

flowing fromeast tosouth-west tojoin Godavari.

9.

estimated India's hydropower potential as 148701 MW and out of these only 39416 MW (26.5%) have been developed. Table - 1 shows basinwise hydropower potential in our country. Table - 1 Basin

Hydropower Potential (Megawatt) 33832 20711 4152

Indus Ganges Rivers of Central India Rivers of South India flowing westwards 9430 Rivers of South India flowing eastwards 14511 Brahmaputra 66065 Total 148701 Source: Central Electricity Authority

As on 31.01.2013, the total installed hydropower capacity in India is 39416 MW and it is 18.61 % of the total electricity generated from all sources. Science Horizon

Balimela Power House

The first hydropower station in Odisha had been established in 1898 in the erstwhile princely state of Bamra on the river Karadkot, a tributary of Brahmani (incidentally it was the second hydro power plant in India after the one established near Darjeeling in 1897). Its capacity was15 KW and it was generating power till 1915. The next hydel plant was established at Machhkund in South Odisha on 23

MAY, 2013

the river Machhkund in collaboration with

resistance from local people on the issue of

Andhra Pradesh. Then came the multi-purpose

subme rgence. Some other hydropower

mega river project Hirakud, in which

projects identified are Middle Kolab Hydro

generation of electricity is one of the main

Electric Project (285 MW), Bhimkund

purposes along with flood control and

hydro project (160 MW), Salki Hydro

irrigation. The list of hydropower plants in

Electric Project (96 MW) and Barmul

Odisha is given in Table - 2.

Hydro Electric Project (60MW).

Table - 2 Sl. Name of Power Station No. 1.

2. 3. 4. 5. 6.

Hirakud Power Station a) Burla b) Chiplina Balimela Power House Rangoli Power House Upper Kolab Power House Indravati Power House Machhkund Power house

Installed Capacity (MW) 275.5 72 510 250 320 600 45.25 (Odisha share)

Total

2072.75

Source: Odisha Hydro Power Corporation The hydro power potential of Odisha has been estimated as 2850 MW at 60% load factor (equivalent to an annual generation of

Indravati Power House

11. Conclusion For an ideal grid, the ratio of thermal power to hydropower should be 60: 40 to maintain grid stability and also to have low tariff. In India, Hydropower share has dropped from 45.5% in 1969 to 18% in 2013. Efforts should be taken to harness the hydropower

15000 MU) out of which 68% have been

potential of the country. But simultaneously

developed. The Government of Odisha signed

the resettlement and rehabilitation issues should

an MOU with National Hydro Power

be considered sympathetically. Government of

Corporation (NHPC) in July 2011 for

India has taken initiative to establish hydro

installation of three power stations of total

power plants of 50,000 MW capacity during

capacity of 320 MW on the downstream of

twelfth and thirteenth five year plans.

Hirakud reservoir on the river Mahanadi. But the project could not be taken up due to 24

„ Deputy General Manager, PP & EE Section, MECON Limited, Ranchi - 834002 Phone : 09470193755

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