How it Works:
1. The generation of electricity by using the force of falling water is called hydro-electricity.
2. Water is a renewable resource and can be used year after year. Thus, making hydel power cheaper to produce than thermal or nuclear power.
3. Water from storage reservoirs is sent through pipes along a steep gradient to rotate the turbines, which convert this energy into electricity. This process is very clean and does not cause pollution of any kind.
4. The water used for generating hydro-electricity is not consumed or contaminated in any way and is still available and suitable for use. It may be used for irrigation, industries or domestic purposes.
5. After the initial cost of constructing dams, power stations and transmission lines, the production of hydro-electricity is inexpensive since there is no consumption of fuel as in thermal power stations.
6. In most cases in India, the production of hydro-electricity is linked with irrigation, flood control, navigation and therefore the cost of hydel power production is lower.
Development of Hydro-Electricity in India:
Our country is endowed with enormous economically exploitable and viable hydro potential assessed to be about 84000 MW-at 60% load factor (148701 MW installed capacity.
The first hydro generating unit in India was commissioned in Darjeeling (W.Bengal) in 1897. Many projects were taken up for execution after independence and at one time (1962-63), the capacity contribution from hydro schemes was equal to thermal schemes.
However, with the rapid increase in demand for power, higher priority was given to the pithead super thermal power stations as their gestation period was smaller than of the hydel schemes. About 30 new hydro projects are now under execution with an installed capacity of 5,600 mw. The more important among these are the Nathpa Jhakri Project, Sardar Sarovar Project, and Sri Sailam Project.
Although hydro electricity accounts for less than 1/4th of the total installed capacity of electricity in India, it is the single largest source of energy for some states, e.g. Kerala’s cent per cent dependence is on hydro-electricity.
The other states being Himachal Pradesh (99.3%), Meghalaya (96.4%) and Sikkim (90%). Hydroelectricity accounts for over 2/3rds of the total installed capacity in Karnataka (79%), Odisha (72.2%), Jammu and Kashmir (68.8%) and Arunachal Pradesh (67.8%) while some other areas like Andhra Pradesh, Punjab, Rajasthan etc. depend upon this source for more than half of their installed capacity of hydro electricity is concerned. Andhra Pradesh, Karnataka, Kerala, Maharashtra, Odisha, Punjab, Tamil Nadu and Uttar Pradesh are the outstanding states.
Hydro-Electric Power (HEP) generated from water is the cheapest amongst all the sources. Following are favourable conditions for the development of HEP in India.
(i) There should be perennial flow of large volume of water.
(ii)The water should fall from a sufficient height. This height may be in the form of a natural waterfall or obtained by constructing a dam across the river.
(iii) There should be no silting of water to save machinery.
(iv) A readily available market is an essential requirement for generating HEP as electricity cannot be stored.
(v) The generation of HEP requires huge capital investment as it is capital- intensive.
Thus heavy rainfall, rough topography to cause water to fall and a regular and continuous flow of water are the three important geographical requirements for developing hydro- electricity. Waterfalls exist mainly in the Cardamom hills, the Shillong plateau and the sea facing margins of the Western and Eastern Ghats.
Hydro- electricity is developed mainly in the Western Ghat, Kerala, Western UP, Himachal Pradesh and the Punjab because these areas are located far away from the coal mines and have sufficient water.
Due to heavy rainfall, deep and narrow river valleys and waterfalls, Western Ghats, the Nilgiri hills and the Cardamom hills have substantial share in the installed hydro-electricity capacity. The narrowness of river valleys reduce the cost of construction. India’s natural waterways are more or less evenly distributed over the entire country.
About 20 per cent of this capacity has been harnessed and 80 per cent still remains unharnessed. But there are some topographic limitations, as the regions possessing large hydro-power resources do not have enough demand for power to warrant development of the hydro power resources on a large scale.
Further the storage hydro power stations with large capacities have high initial capital requirements. Lastly, the performance of the hydro power stations has been seasonally variable. However, notwithstanding these limitations the country has a sizable quantum of untapped hydro resources.
Hydro-electricity Dominated Region:
It extends over Karnataka Kerala, Himachal, Jammu and Kashmir, Western Ghats, Meghalaya, Nagaland, Tripura and Sikkim. These are far away from coal fields but have optimum condition for the development of Hydro-electricity.
Potential and Developed Water Power:
Potential water power refers to the power that could be generated if all the water resources are harnessed. India is blessed with vast resources of water power. In potential water power, India comes after Republic of Zaire, Russia, Canada and the United States of America. India’s water power potential is estimated to be over 40 million kilowatts.
Nearly 60% of the potential water power resources lie in the Himalayas, while the remaining lie in Peninsular India. So far the areas richer in potential hydel power have practically not been developed.
The Himalayan region in Assam, Bihar and Uttar Pradesh has not been fully exploited. At present about 66% of the developed water power resources lies in the Western Ghats.
Factors Affecting H.E.P. Development:
The following are the factors which influence H E P. development.
(i) A Head of Water:
The hydro-turbines are driven by the force of the water against their blades. In natural streams and rivers, the force of the water is greatest where it flows most swiftly or where it falls rapidly as in the case of a waterfall or rapids. Even a smaH stream, when dropping from a great height has tremendous power and can be used to generate electricity.
Thus, many H.E.P. generating plants are located in mountainous districts where the rivers and streams have a steep gradient and waterfalls are common, e.g. the Swiss Alps, Scandinavia, the Rocky Mountains, Appalachians and the Japanese Alps. Rivers with a low gradient but a large volume of water can also be utilized, e.g. the River Shannon in Ireland or the Volta River in Ghana.
(ii) Large Volume of Water:
Generally speaking, although almost any river could be used to generate H.E.P., in practice, it is much more economic to harness large rivers such as the Indus, Nile or Zaire, than to use smaller rivers and streams.
(iii) Regular and Reliable Water supply:
It is important that rivers to be harnessed for power generation should not be subjected to great fluctuations in the volume of water, since this would make it difficult for plants to operate at a constant level of power production.
(iv) Presence of Lakes:
The presence of natural lakes along the course of a river is often a great advantage in H.E.P. development. There are many examples of this in Switzerland and Britain. In most cases, however, there are few natural lakes in suitable locations and dams are built to create large artificial lakes.
(v) Space for a Reservoir:
Another aspect of planning the construction of a dam for H.E.P. generation is that there must be a suitable location for creating a lake if this is necessary.
(vi) Large Market:
As electricity cannot be stored for long on a large scale, the demand for the power generated, by both domestic and industrial consumers, must be large and constant to warrant the initiation of H.E.P. stations.
(vii) Heavy Capital Outlay:
Modern large-scale H.E.P. projects are expensive undertakings. It is a common misconception, because H.E.P. is derived from water which is free, that it is always cheap. Once initial costs have been recouped, it may indeed be relatively cheap but this will necessarily take some time.
Because initial costs are so high H.E.P. undertakings are usually financed and operated by governments, which are concerned more with providing services than with profits. This is particularly true of multi-purpose projects.
Integrated Power Grid:
The production of electricity from hydel power stations in India varies from year to year depending on the variation of the monsoon rainfall. (In other parts of the world with cold winters, the freezing of lakes and rivers hinders power production).
This drawback of hydel power production can be overcome by the development of an integrated power grid. An integrated power grid is bringing into a common network power stations fed on different sources of power.
In this way thermal power stations can supplement hydel power during periods of low water supply or a breakdown on any kind. This helps to maintain a power supply on a regular basis free from marked fluctuations.