32 Hydropower Projects and their Environmental Implications

Sunil Mittal

epgp books

 

 

1.      Introduction

 

2.      Definition and Principal of Hydropower Plant

 

3.      Types of Hydropower Plants

 

4.      Hydropower plants in India

 

5.      Advantages of Hydroelectric Plants

 

6.      Disadvantages of Hydro-Electric Plants

 

7.      Implications of Hydropower Plants

 

8.      Case studies Conclusion

 

 

1.  Introduction

 

Electricity is an important requirement for the whole world for running of electrical equipments. Our daily basic need of life depends upon electricity. Electricity is the bone of any nation and insufficient electricity supply is one of the main reasons of crushing economics. There are various ways to generate electricity by using heat energy of sun, Kinetic energy of water, coal and from nuclear energy. Now a days, hydropower is considered as one of the most economic and non-polluting source of energy. Hydroelectricity is the power produced by the use of gravitational force of falling or flowing water. This technology of power generation neither produces any waste matter directly nor is subjected to exhaustion. In these plants, kinetic energy of flowing water rotates the turbines contacted with magnets which produce electricity. Hydro power plant depends upon the water cycle of that area. Inadequate availability of water, reduce the electrical energy production capacity. In past some hydro power plants had been shut down due to lack of water availability in the dam. Hydropower plants produce 16% of total renewable energy of the world. China stands on first rank for the production of hydroelectricity in world. India also comes under the top ten producers of hydroelectricity. India produces approximately 4200MW by installing large, medium and small hydro power plants. The construction of hydropower plant in area has advantages like economic development but these may produce many ill effects on environment, ecology and localized people of that area. This module will discuss the definition of hydropower plants, their working, types, advantages, environmental implications and case studies.

 

 

2.  Definition and Principal of Hydropower Plant

 

A generating station which utilizes the potential energy of water from high head for the production of electricity is called hydro-electric power station. Water stored in dam contains potential energy because of the height of the dam. When water moves towards the turbine, the kinetic energy of moving water is converted into mechanical energy through turbines. Rotating turbine coupled with generator produces the electricity.

 

2.1 Working of Hydropower Plant

 

In nature, energy is neither destroyed nor produced but only transformed from one form to another form and similarly this phenomenon occurred in case of hydro power plants. In hydropower plants kinetic energy of water is converted into mechanical energy that generates electricity. No doubt, hydropower plants are constructed on the bank of rivers, streams and canals but dams are also needed because they act as batteries for storing the water that is released according to the requirement for generation of power. Dams create a head from the water flows and a pipe supplies the water from the reservoir to the turbine. This released fast water hits with turbine blades and rotates the turbine or rotor of turbine that moves part of electrical generator. Then, coil of wire on the rotor sweep past the generator’s stator or stationary coil and power is produced and stored in grids and further electricity is supplied in various sectors.

Scheme: 1- Represents the energy transformations in Hydropower plant.

Figure 1: Working of Hydropower Plant Source: http://slideplayer.com/slide/5840150/

 

2.2 Factors for Selection of Site

 

Availability of water: As the basic requirement of hydro-electric plant is water, the availability of huge quantity of water is the main consideration. The plant must be constructed where sufficient quantity of water is available at a good head.

 

Storage of water: The rainfall is not regular every year. Hence the available water should be stored. This makes it necessary to construct dams. The storage helps in equalizing the flow of water throughout the year.

 

Head of water: For getting sufficient head, dam should be constructed at a height in a hilly area. The availability of the head directly affects the cost and economy of the power generation.

 

Cost and type of land: The initial cost of the project includes the cost of the land, so the land must be available at a reasonable price. Similarly, the type of the land should withstand the weight of the heavy equipments to be installed.

 

Transportation facilities: For transporting the equipments, machinery and labor, site selected must be easily accessible by rail and road.

 

Distance from load centers: The load center is connected to the site by the transmission lines so that cost of the transmission lines should be minimum.

 

 

3. Types of Hydropower Plants

 

Classification of hydropower plants

 

a)      Quantity of water available

 

b)      Available head

 

c)      Nature of load

 

 

Scheme: 2- Represents the types of the Hydropower plants.

 

 

4. Hydropower plants in India

 

India holds 7th position among the whole world for the production of hydroelectricity by producing near about 4200 MW. India has a target of 5 GW renewable energy productions from the hydropower plants by 2022 and currently in India 25 plants are working.

 

Table 1: Represents the number of hydropower plants in India.

 

5.        Advantages of Hydroelectric Plants

  • The running, operation and maintenance cost of this kind of plants are low.
  • After the initial infrastructures are developed the energy is virtually free.
  • The plants are totally free of pollution as no conventional fuels are required.
  • The lifetime of generating plants are substantially long.
  • Reliability is much more than wind, solar or wave power due to its easy availability and convertibility.
  • Water can be stored even above the dam so that excess energy can be produced during the peak demand.
  • The uncertainties that arise due to unscheduled breakdowns are relatively infrequent and short in duration due to the simplicity and flexibility of the instruments.
  • Hydro-electric turbine generators can be started and put ‘‘on-line’’ very rapidly.
  • It is possible to produce electricity from hydro-electric power plant if flow is continuously available.

 

6. Disadvantages of Hydro-Electric Plants

  • The potential of hydro power depends on locations if the locations are not properly selected may cause lots of hostility and absurdity during operational stage of the power plant.
  • The dams are very expensive to build. However, many dams are also used for flood control or irrigation, so building costs can be shared.
  • The capital cost of electrical instruments along with civil engineering works to be installed and cost of laying transmission lines is generally high.
  • The impact on plant life due to the water quality and quantity downstream of hydro power plants are reported.
  • The impact on residents and the environment may be unacceptable environmental and social activities if location is not optimally selected.
  • Due to increase in water temperature and insertion of excess nitrogen into water at spillways, health and migration of fish as well as other aquatic plants get affected.
  • Due to the installation of reservoir in the flow paths the siltation rate gets altered.

 

7.        Implications of Hydropower Plants

 

i.Disrupts Aquatic Ecosystems: Hydropower dams are built in the middle of the rivers without taking into consideration the aquatic life so that fish and other river animals are obliged to swim against the water stream for multiple reasons and first one reason is that they need to breed and the second one to avoid being trapped and killed in turbines. In some occasions, dams are built in the middle of the fish migrating paths therefore there is drastic cut on the fish population.

 

ii. Dam size: When a dam is constructed, it won’t just be built in the river and it covers a huge part of the land that surrounds the river. It’s not that uncommon to see huge forests being destroyed just to build one dam. As you can imagine, this affects the natural ecosystems.

 

iii. Initial Costs: Cost of installation of hydropower plants is relatively higher compared to Coal/Gas bases thermal power generation systems. In most of the cases, dams are being constructed in some parts of the rivers that don’t have the necessary roads to allow the materials to get there so that new roads and new bridges are constructed. Water reservoir and availability of grid to transmit electrical energy also adds up the installation cost of the hydro power.

 

iv. Habitat destruction: Construction of hydro power stations require a huge amount of land are demanding the shifting of the leaving place for a large number of habitats of that area. This causes hardship to human beings and animals. One of such examples is the Sardar Sarovar project in India.

 

v. The Construction Materials Need To Be The Best: When a dam is being constructed, only the high-quality materials can be used. Otherwise, there can be a dam breakage, just like the one that happened in China, in the Banqiao Dam. Due to the massive flooding, 171,000 people died and millions lost their homes.

 

vi. Environmental Impacts: Construction of a hydropower plant has huge effects on the environment. When any dam is constructed it changes the natural course of river and dramatically also effects the flora and fauna. Forests are destructed and localities are forced to move out. Water reservoirs are responsible for the emission of greenhouse gases those effect the plant and animal lives.

 

vii. Wildlife Impacts: Dammed reservoirs are also used for multiple purposes, like agricultural irrigation, flood control, and recreation. However, hydroelectric facilities have a major impact on aquatic ecosystems. For example, though there are a variety of methods to minimize the impact including fish ladders and in-take screens for fish and other organisms those are injured and killed by turbine blades. Apart from this, there can also be wildlife impacts both within the dammed reservoirs and downstream from the facility.

 

viii. Life-cycle Global Warming Emissions: Global warming emissions are produced during the installation and dismantling of hydroelectric power plants. Such emissions depend on the size of the reservoir and the nature of the land that was flooded by the reservoir. Small run-of-the-river plant emits between 0.01 and 0.03 pounds of carbon dioxide equivalent per kilowatt-hour. Life -cycle global warming emissions also depends on type of land like hydroelectric plants built in tropical areas or temperate peat lands are much higher and after flooding vegetation and soil in these areas decomposes and releases both carbon dioxide and methane.

 

 

8. Case studies

 

i.  Banqiao Dam Project: This construction of a hydro power plant on the Ru River in Zhumadian city, Heavan province, China started in April 1951 and completed in June 1952. Total capacity of reservoir was 492 million m3 with 375 million m3 reserved for flood storage. Due to the massive flooding, 171,000 people died and millions lost their homes in 1975 and it was the biggest accident of hydrological project.

 

ii. Narmada Project: Sardar Sarovar project was conceived in mid-1960’s on Narmada River in Gujarat and largest westward flowing river but construction was postponed due to disagreement between 3 states Madhya Pradesh, Gujarat and Maharashtra impacted by the project. Sardar Sarover dam has capacity of production of 1450 MW of electricity, provide water to 40 million people residing in about 100 villages and towns and irrigate almost 1.8 million hectares in Gujarat and 73000 hectares of land in Rajasthan. In 1990, a large number of people protested for the closure of the plant. On Christmas day 1990, 3000 people walked 100km and once Medha Patkar and 6 other went on hunger strike and it lasted 22 days until they broke the fast and it became an international issue. Medha Patkar and Baba Amte were leading activists of the project. Finally Supreme Court of India ruled on Sardar Sarovar dam and in 1999 ordered work to continue. Then in October 18, 2000 they ruled in favor of building the Sardar Sarovar dam.

 

iii. Tehri Dam Project: This dam is located on Bhagirathi River and 200 miles of north east of Delhi at the height of 855 feet and it is 5th largest dam in the world with capacity of 2400 MW. In 1949 Tehri dam was conceived and chosen as tentative site for dam in 1961. Actual construction was started in 1978 under police protection and completed in 2003. Tehri bandh virodhi sangharsh samiti protested against dam and 74 day hunger strike was held by Sunderlal Bahuguna in 1996. He is environmental activist who led the anti tehri dam movement for years from 1980 till 2004.During 2001 main bridge leading to Tehri town and close areas were submerged and 1 lakh people were affected because there was no resettlement plan.

  1. Koyna Hydroelectric Project: This plant is India’s argest hydroelectric power plant, located at foothills of the Sayadri hill range in Maharastra. This plant consisted of four units, first two units completed in 1966, third & fourth in 1976 and 1990 respectively. Total production capacity of this plant is 1000 MW.
  2. Gangrel Hydro Electric Power Plant: This plant is located at Gangrel in left bank of Mahanadi River which is 90 km away from Raipur and 13 km from Dhamtari. Total capacity of this plant is 10 MW and consists of 4 units and each of 2.5 MW. After production of electricity water is supplied for the irrigation of fields.
  3. Salal Hydro Electric Power Plant: It is located at Udhampur in Jammu & Kashmir on the bank of Chenab River. Total capacity of this plant is 690 MW and 6 units and each of 115 MW. Major problem in this plant is clogging of tubes because solids level increases from 5000 PPM to 40000 PPM during monsoons.

 

Conclusion

 

Global electricity needs are rising rapidly. In order to satisfy these needs various types of power plants are being installed over the entire world. Hydropower may seem an understandable choice for the production of clean, low cost electricity, yet the negative environmental impacts of hydropower schemes are less in comparison to other types of power plants.

you can view video on Hydropower Projects and their Environmental Implications

References

 

  1. Majumder, M., & Ghosh, S. (2013). Hydropower Plants. In Decision Making Algorithms for Hydro-Power Plant Location(pp. 15-19). Springer Singapore.
  2. Panić, M., Urošev, M., Pešić, A. M., Brankov, J., & Bjeljac, Ž. (2013). Small hydropower plants in Serbia: Hydropower potential, current state and perspectives. Renewable and Sustainable Energy Reviews, 23, 341-349.
  3. Purohit, P. (2008). Small hydro power projects under clean development mechanism in India: A preliminary assessment. Energy Policy, 36(6), 2000-2015.
  4. Mishra, U. C. (2004). Environmental impact of coal industry and thermal power plants in India. Journal of environmental radioactivity, 72(1), 35-40.
  5. Bahadori, Z. Gholamrez, Z. Sohrab, An overview of Australia’s hydropower energy: Status and future prospects. Renew. Sust. Energ. Rev. 20, 565–569 (2013)
  6. Chen, X., Wang, Z., He, S., & Li, F. (2013). Programme management of world bank financed small hydropower development in Zhejiang Province in China. Renewable and Sustainable Energy Reviews, 24, 21-31.
  7. Castronuovo, E. D., & Lopes, J. P. (2004). On the optimization of the daily operation of a wind-hydro power plant. IEEE Transactions on Power Systems, 19(3), 1599-1606.
  8. Doolla, S., & Bhatti, T. S. (2006). Load frequency control of an isolated small-hydro power plant with reduced dump load. IEEE Transactions on Power Systems, 21(4), 1912-1919.
  9. Dos Santos, M. A., Rosa, L. P., Sikar, B., Sikar, E., & Dos Santos, E. O. (2006). Gross greenhouse gas fluxes from hydro-power reservoir compared to thermo-power plants. Energy Policy, 34(4), 481-488.