The need for Energy, mainly sustainable Energy led scientist to look for alternatives of fossil Fuels. The conventional way of generating electricity is to run steam through a turbine to make it rotate. So a logical line of thought would be if "Gases can Rotate a turbine so should flowing water(fluid)". And with this logic the quest for Hydro Energy began!!
Although the concepts of Hydro-Power generation have been laid long back, commercialization took place back in the 19th Century. It was popularized in the 20th century as a green carbon free source of Energy having high concentration of energy. Capturing the Energy of Water is possible from mainly three sources:-
> Waterfalls
> Sea Waves
> Running water
Utilising Wave Energy
The sea waves are a source of highly dense energy, denser than solar(1kW/m^2) and wind energy(1kW/m^2 at 12m/s) with a transformation efficiency of 40-70%. For example it has an energy density of 25kW/m^2 at San Francisco. Wave power is not as popularised as the other renewable source of energy. But recently the huge demand for clean energy has demanded the capture of wave Energy. the first commercial electricity generation wave energy plant was established in 2000 at Scotland with a power output of 500 kW. Later it was downsized to 250kW due to technical issues. This is based on a shore oscillating water column device. The construction has a cavity just submerged in water (as shown in fig) which is connected to a Wells turbine and an outlet on the other side. As the sea waves oscillates the air column inside the construction also oscillates, making the turbine move. The wells turbine has a speciality that it rotates in the same direction irrespective of the direction of flow of air. Even slight fluctuations are enough for rotating this turbine.
Another modern method is the use of submerged pressure differentials to extract energy. It uses flexible membrane (usually made up of rubber) to create a pressure difference which drives a flow inside causing the turbine to rotate, similar to the above technique.
R-O-R Hydro Energy and Hydro Power Plants
ROR or Run-of-river hydroelectricity is method of generating hydroelectricity from running water (river, waterfalls, creating small damps) where little or no water Storage is essential. Such methods are useful in generating energy for small scale uses.
The Hydro power plants are large industrial scale Power stations created by constructing dams and barrages and using the high energy falling water to rotate the turbine and generate electricity. The concept is to exploit the Gravitational Potential energy into fast down flowing Kinetic Energy which does mechanical work by spinning the wheel of a turbine. This rotating turbine creates large amount of clean electricity.
A global view on Hydro Energy
About 70% of the renewable energy comes from Hydro Power, China being one of the leading countries. It accounts for about 16% of the world's power need. The International Hydropower Association estimates that the total hydropower potential in India is 660,000 GWh/year, of which 540,000 GWh/year (79%) is still undeveloped. Hydropower is produced in 150 countries, with the Asia-Pacific region generating 33 percent of global hydropower in 2013. China is the largest hydroelectricity producer, with 920 TWh of production in 2013, representing 16.9% of domestic electricity use.
As per 2020 reports :-
- >Global hydropower installed capacity reached 1,308 gigawatts (GW) in 2019, as 50 countries completed greenfield and upgrade projects, including pumped storage.
- >A total of 15.6 GW in installed capacity was added in 2019, down on the 21.8 GW recorded in 2018. This represents a 2019 rise of 1.2 per cent.
- >India has overtaken Japan as the fifth largest world hydropower producer with its total installed capacity now standing at over 50 GW.
- >The countries with the highest increases in 2019 were Brazil (4.92 GW), China (4.17 GW) and Laos (1.89 GW).
- >The region to add the most capacity was East Asia and the Pacific, followed by South America and then South and Central Asia.
- >Hydro-power's flexibility services have been in high demand during the Covid-19 crisis, while plant operations have been less affected due to the degree of automation in modern facilities.
- >Hydro-power developments have not been immune to economic impacts however, with the industry facing widespread uncertainty and liquidity shortages which have put financing and refinancing of some projects at risk
- >Hydro-power developments have not been immune to economic impacts however, with the industry facing widespread uncertainty and liquidity shortages which have put financing and refinancing of some projects at risk
Hydro Energy Projects in India
India has the 5th largest Hydroelectricity power capacity in the world. As per 31st March, 2020 data, India produces 46 000 MW energy through Hydroelectricity which accounts for 12.3% of the net power production. Additionally smaller hydro power generators produces an energy output of 4683 MW, contributing 1.3% of the total power produced. There are hydro-electric power generator in Darjeeling(1898) and Shivanasamudram(1902), which are among the very first in Asia. Since then India has been a major investor in hydro power. India also imports a lot of hydro energy from Bhutan.
India's economically exploitable and viable hydroelectric potential is estimated to be 148,701 MW. Another 6,780 MW from smaller hydro schemes (with capacities of less than 25 MW) is estimated as exploitable. Some recent major projects will be developed in various rivers like Narmada, Godavari, Nagavali etc. The mountainous regions of the Himalayas are suitable for Hydro Power Generation. A lot of India Hydro energy potential is untapped. Globally India ranks 4th among the under developed Hydro energy potential after Russia, China and Canada.
India has huge scope for capturing Wave energy, since it has a long enough coastline of 7,516.6 km. Its wave energy potential is about 40-60 GW, with 5-15 MW/m estimate. Recent study showed that the Western coast is more windier than the east coast and thus have a higher Wave-Energy potential. But with the present technology the efficiency of wave power generation would be a lot lesser than the estimated value.
Disadvantage of Hydroelectric Power Generation :-
Despite being a green source of Energy and having tremendous potential there are some disadvantages of Hydro Energy. Some of these are as follows :-
- Environmental Effects :- Building of submerged wave energy producers often result in trapping wildlife in the machine (Blades of turbine). On shore large Wave Energy exploiter may cause shift in coastline and harm the marine life. Making dams often alter the flow of the river and prevent fishes to migrate upstream to spawn. The species of White sturgeon has become endangered due to this. Some modern method of Wave energy capture are fairly safe. Natural Waterfalls also serve as pretty safe alternatives to dams.
- Expensiveness :- Making of mega projects like dams is very cost extensive. But on the other hand these have low maintenance.
- Drought:- smaller reservoirs become non operational during the drought season in many places decreasing profit and efficiency drastically.
Facts
- Largest Dam and the Largest Hydro power generating Facility - Three Gorges Dam at the West of Shanghai in Yangtze River.
- Highest Dam - Jinping-I Dam of China
- Country with highest Hydro-power output:- China
- With a great 27 kilometres in length, Hirakud is the longest Earth dam in the world, located in the state of Odisha,India.
- The Bhakra Nangal Dam, located in the state of Himachal Pradesh and Punjab. It is the largest dam in India having a height of 225 metres and also in the second position in the largest dams in all over Asia.
- Largest Dam and the Largest Hydro power generating Facility - Three Gorges Dam at the West of Shanghai in Yangtze River.
- Highest Dam - Jinping-I Dam of China
- Country with highest Hydro-power output:- China
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