What are the advantages and disadvantages of Hydroelectric energy?

Water energy is the most conventional renewable energy source and is obtained from water flow, water falling from height. The water under high pressure flows through the base of the dam and drives turbo-generators producing hydroelectric power. Hilly and highland areas are suitable for this purpose.

In the late 18th and early 19th century, most industries were located near waterfalls. Technology was also developed for use of steam energy.

Norway, Switzerland, Canada, Sweden and New Zealand harnessed their water resources for water energy. Japan, USA and former USSR are the leading countries in the production of hydropower.

In US about 300 large dams generate 9.5 per cent of its total electricity power production. According to the recently published report, only eight per cent of the total hydroelectric power is being used in the continents of Asia, Africa and Latin America.

In India, the generation of hydroelectric power was emphasized from the First Five Year Plan. A number of multipurpose river valley projects were launched, of which Bhakra Nangal project over Sutlej, Bokaro Panchet and Tilaiya in Damodar Valley, Hirakund, Rihand, Nagarjuna Sagar, Kosi and Koyana etc. are examples. A number of such projects including construction of large dams as Tehri dam on Bhagirathi River in Uttaranchal, Sardar Sarovar in Gujarat and Narmada Valley Project (NVP) are also under different stages of development.

The construction of these dams could generate at times many political and environmental controversies. There are hundreds of dams, big and small, capable of generating 4-5 kwts of electricity. The Rourkee University has designed a small dam with a power generation capacity of about 4-5 kwts costing Rs. 30,000.

Advantages

1. Hydropower is a clean, non-polluting source of energy.

2. Hydroelectric power is considered to be a renewable source of energy.

3. Emitting a very low level of greenhouse gases when compared to fossil fuel plants.

4. Hydropower has a low operating cost, once installed, and can be highly automated.

5. The power is generally available on demand since the flow of water can be controlled.

6. Reservoirs can also offer a variety of recreational opportunities, including fishing, boating, and swimming.

7. It can be transmitted to a long distance through wires and cables.

Disadvantages

1. This form of energy cannot be stored for the future.

2. Dams have drowned beautiful stretch of rivers, wildlife, habitat, forests, productive farmlands and areas of historic, archeological and geological significance. The construction of big dams has also rendered several farmers and tribals homeless and without any livelihood.

3. The reservoir behind the Aswan High Dam in Egypt has caused the spread of a parasitic worm, which caused a debilitating disease.

4. Since water flow from the dam is regulated as per the requirement of power, dams play havoc downstream because water levels may change from extremes of near flood levels to virtual dryness and back to flood even in a single day.

5. Devastating earthquakes, observed near Koyana in India, are attributed to the Koyana dam (Maharashtra) by some scientists.

6. Dams can block fish passage to spawning grounds or to the ocean.

7. The diversion of water can impact stream flow, or even cause a river channel to dry out, degrading both aquatic and streamside habitats.

8. Hydroelectric plants can also have an impact on water quality by lowering the amount of dissolved oxygen in the water.

9. In the reservoir, sediments and nutrients can be trapped and the lack of water flow can create a situation for undesirable growth and the spread of algae and aquatic weeds.