Hydroelectricity – The Solution for Energy Crisis or an outdated technology
After industrialization, the growth of human race was accelerated. Factories and skyscrapers become a common sight in 20th century. Energy became our fundamental need. Our average daily energy usage raised more than 100 times in the past century. The natural energy sources become insufficient for human needs. We start depending on Fossil fuel and nuclear energy which are the most efficient energy sources. Years past, and we are now facing an energy crisis. Fossil fuel is no longer an endless source. Nuclear power plants are causing great damage to environment. It is clear that non-renewable resources are not the way to future. It is the time to look back to the nature.
We have endless renewable energy sources in the nature. The most common and traditional energy source is hydroelectricity. We have a long history with hydropower. It starts from Mesopotamia and ancient Egypt since the 6th millennium BC. Water wheels, water mills, turbines, compressed air hydro etc were some popular methods to gain energy from water. There are lot of hydroelectric power generating methods. Dams, Run-of-the-river, pumped-storage etc are some examples. Even though there are many methods, dams and reservoirs are the most common and effective hydroelectric power generation method.
Hydroelectric plants are one of the first generation technologies. First-generation technologies are most competitive in locations with abundant resources. Among the renewable resources, hydroelectric plants are the oldest power source. Some plants are operating for more than 100 years. The first commercial plant was built near Niagara Falls in US in 1881. Then there were a huge growth in number of power plants. By 1889 there were 200 plants in the US alone. At the beginning of 20th century, there was a boom in hydro electricity. Commercial companies start building small power plants in mountains near to cities. By 1920, 40 percentage of US energy was from hydroelectricity. The scenario was almost same in the other developed countries. Relate to dams’ irrigation projects and flood control plans were started.
In 1930s and 1940s, some massive and effective dams were constructed around the globe. The most famous dam in the world, Hoover Dam was constructed in 1936 with an initial capacity of 1345 MW. Grand Coulee Dam overtook Hoover Dam in 1942 with 6809 MW capacity. There are three dams larger than 10 GW in the world now, the Three Gorges Dam in China with 22.5 GW, Itaipu Dam in Brazil with 14 GW and Guri Dam in Venezuela with 10 GW capacities. Three more are under construction, Xiluodu Dam in China with 12.6 GW, Belo Monte Dam in Brazil with 11.2 GW, Siang Upper HE Project in India with 11 GW.
The total energy production from hydroelectricity around the world is less than 10%. China is the major producer with 721 terawatt-hours of production per year, accounting 17% their total usage. Currently 150 countries are producing hydroelectricity. Countries like Brazil, Venezuela, Canada, Norway, Austria, New Zealand etc produce majority of their energy from hydropower. Paraguay produces 100% of its electricity from hydroelectric dams, and exports 90% of its production to Brazil and to Argentina. Norway produces 99% energy for their internal energy usage from hydroelectric sources.
|Three Gorges Dam, China
Hydroelectricity is not just about big dams and thousands of mega watts projects. There are small hydro electric projects which are considered sustainable and effective. In the rural regions where power transmission is very difficult, these plants are helpful. Energy is produced by installing turbines on river or collects water on small storages and flow it to the turbine. This is called Run-of-the-river hydroelectricity. The electricity produced is used to power the nearby localities.
Advantages over non-renewable sources
The main advantage of hydroelectric plants is low cost energy. Not like Fossil fuel sources the cost will not vary time by time. Once the plant is installed, the only cost is for maintenance. Since the source is non ending, there is no need of money wastage on source. The plants are generally long living; some plants are in good condition for more than 100 years. Even the construction cost is less comparing nuclear or coal power plants of same production capacity. The labour cost is low too considering the fact that the plans need only minimal attention.
Hydroelectric dams produce only very minimal amount of CO2. That also happens at the time of construction. It is very small comparing the emissions of fossil fuel plants. According to studies, hydroelectricity produces the least amount of green house gases than any other sources. Dams are not only used for energy production but also used for irrigation and agriculture. We can say that hydroelectric dams are the source which creates major social impacts.
Siltation and flow shortage issues
The river which brings water to the dam also brings heavier particles with it. This includes organic particles and sand. This will deposit on the dams and gradually reduce its capacity. This is called siltation. This can increase pressure in dams and cause its failure. Since energy production is proportional to the water level, it will seriously affect the power generation. Some plants are abandoned because of excessive siltation in the reservoir. Enloe Dam in America is an example.
Environmental issues related of dams are mainly due to the area which the dam floods. Since the dams needs large storage area, it has to flood a large region for functioning. Power generation capacity of the dam increases with increase in water storage and it will harm environment proportionally. To date, over 400,000 km2 of the earth have been flooded due to damming.
|Flood Plain of Itaipu dam, Brazil
In general dams are situated on mountain ranges which are surrounded by thick forest. When a dam is constructed in the area, it floods the whole forest region. In fact a normal dam floods 100 to 500 hectors of surrounding area. Which means a huge number of trees and animals goes under water. It will affect the ecosystem badly. Not only it will kill a large number of species but the anaerobic decay of the forest produce tremendous amount of methane which is a much stronger greenhouse gas than CO2. In some cases, the flooded basins are produce methane which has pollution potential 3.5 times more than an oil-fired power plant would for the same generation capacity.
A contemporary issue related to this is the issue related to the proposed Athirapally Dam. Athirapally is a major tourist place in Trissur district, Kerala. The proposed dam would have submerged more than 140 hectares of forest, dried up extensive riparian areas downstream and destroyed Athirapally Waterfall, one of several scenic waterfalls important to the local tourism industry. The dam also would have destroyed critical habitat of many important species, including the rare Cochin Forest Cane Turtle, the endangered Great Indian Hornbill, the Lion-Tailed Macaque and the Nilgiri Langur. Because of these reasons the dam failed to get the environmental clearance.
Another important issue was related to 11 GW Upper Siang Hydroelectric Project. Considering the fact that the project will give a great contribution to the grid, the Environment Ministry gave clearance to the dam. Narmada Bachao Andolan lead by Medha Patkar and Baba Amte against the height increasing of the Sardar Sarovar Dam was an important milestone in protest against environmental issues raised by dams.
Social issues raised by the dams including Diseases and Relocation. Reservoirs can become breeding grounds for disease vectors. This includes mosquitoes and snails which takes advantage of slow moving water. Dams require relocation of large number of population who leaves around the specified area. It is because of the flood plain issue.
The record for the largest population relocated belongs to the 22.5 GW Three Gorges Dam built in China. Its reservoir submerged a large area of land, forcing over a million people to relocate. Another example is the Indira Sagar (Polavaram) Project in Andra Pradesh. It is estimated that the project will affect 175,275 persons from Andhra Pradesh, 6,316 persons from Orissa and 11,766 from Chhattisgarh. Polavaram Project would displace about 73,000 Scheduled Tribe persons in 299 villages in the States of Andhra Pradesh, Orissa and Chhattisgarh.
Dams are considered “installations containing dangerous forces” under International Humanitarian Law due to the massive impact of a possible destruction on the civilian population and the environment. Dam failures are normally rare, but it can wipe out a large population in a very short time.
The Banqiao and Shimantan Dam failure (1975) in china is a classic example. It is the biggest of 61 known dam failures. The reason was extreme rainfall beyond the planned design capability of the dam. The dam failures killed an estimated 171,000 people; 11 million people lost their homes. The energy released was equivalent to 18 GW, equivalent to the power of 20 nuclear reactors.
|Mullaperiyar Dam, Kerala |
The famous Mullaperiyar Dam issue is related to dam failure threat. Mullaperiyar is a 100 year old Dam is situated in Idukki district, Kerala. After the 1979 Morvi Dam failure which killed up to 15,000 people in Gujarat, safety concerns of the aging Mullaperiyar dam’s were raised by the Kerala Government. The issue become fear to the people of Kerala after the report by IIT Roorkee in 2009 stated that the dam “was likely to face damage if an earthquake of the magnitude of 6.5 on the Richter scale struck its vicinity when the water level is at 136 feet”. It is estimated that the failure may affect 3.5 million people in Kerala. Since the water from the dam is extremely important for the farmers of Tamilnadu, the Tamilnadu government is not willing to demolish the dam. The issue is now under the Supreme Court.
Hydroelectricity is an effective and important form of renewable energy. It is a first generation sustainable energy technology. Generally speaking, hydroelectric plants produce much lower life-cycle emissions than other types of power generation. Some plants are still working for more than 100 years. But the dams constructed cause various environmental and social issues. To avoid those there should be better planning and environmental studies before every project. It is better to concentrate on second and third generation technologies like solar energy, biomass and ocean energy which cause minimal impact to earth.
Harikrishnan S G