Notion of Hydropower 1. 1. Definition of hydroelectricity The main focus of this paper is hydroelectricity, which can be briefly defined as electricity produced by hydropower. This is a quite potential source of electricity in the contemporary world, which now provides round 715,000 MWe, which constitute about 19% of world electricity . Im mainly concerned with the advantages and disadvantages of the hydroelectricity, which are the main factors determining the future development of this source of energy. First, let us determine the main advantages of hydroelectricity.
1. 2. Historic facts about the oldest hydropower stations Hydropower can be considered as one of the oldest and one of the most powerful and perspective means of electric power generation. Among the most famous oldest hydro-electric power stations the following can be listed: Cragside, located in Rothbury, England, which was constructed in 1870, Appleton, situated in Wisconsin, USA built in 1882, Niagara Falls in New York completed in 1895, Duck Reach, located in Launceston, Tasmania, operating since 1895, Decew Falls 1, situated in St.
Catharines, Ontario, Canada, which began its work in 1898 . 1. 3. Advantages of hydroelectricity This first aspect to be discussed in this section is the connection between hydroelectricity and economics. Among the main advantages of hydroelectricity is that it eliminates of the cost of fuel. Thus, the cost of the operation of hydroelectric plants is quite low if compared with other means of electricity production. This is particularly important now when the price of fossil fuels such as oil, natural gas or coal constantly grows.
Hydropower plants do not require the use of fuel . The other economic value of the hydroelectric plants is that they tend to operate much longer than fuel-fired plants. Thus, the usual operation time of the hydroelectric plants is 50 or even up to 100 years ago. Besides, hydroelectric power plants involve fewer personnel due to the fact that they are highly automated. This leads to the reduction of the expenses associated with the high labor cost . Construction of the hydropower plant is particularly justified in the places where a dam has multiple purposes.
For example, it was estimated that the construction costs of the Three Gorges Dam will be covered by the electricity sold in just 5 7 years of full generation . The other possible economic benefit of hydroelectric plants is that they can create other activities. For example, well-considered hydroelectric schemes can create picturesque water sports, which draw attention of tourists and become the additional source of revenue. Quite many countries resort to the use of reservoirs for fish farming . Besides, some dams can be used for many purposes.
Thus, dams used primarily for irrigation may also serve the source of the constant water supply, which is beneficial for fish farming. The other positive moment of large hydro dams is their ability to control floods. Thus, they are beneficial for the people living downstream of the project. In some cases dams are proved to improve transportation through creation of large reservoirs and elimination of rapids . Further, I would like to discuss the connection between the operation of the hydropower plants and greenhouse gas emissions.
On the one hand there is no obvious emission of the carbon dioxide from the hydropower station due to the fact that is doesnt use fossil fuel, which eliminates this gas in the process of burning. To be fair enough it should be mentioned that still some amount of carbon dioxide, which is eliminated in the process of construction of the hydropower plant, but this is quite unessential amount if compared with the fossil-fuel electricity generation . Still hydropower plants cannot be counted completely safe to the environment and further I will discuss the possible sources of emissions and threats. 1. 4.
Disadvantages of hydroelectricity First possible threat of the hydropower plant is that it can have a disruptive effect on the aquatic ecosystems. There are several examples of such harmful influence. Thus, dams at the Atlantic and Pacific coasts of North America are proven to be the main cause of the reduction of the population of salmon due to the fact that these dams serve a barrier on the salmon way to the spawning grounds upstream. Even construction of fish ladders in salmon habitat seems not to improve the situation . Dams also prevent salmon to migrate to the sea as the fish has to pass through numerous turbines on its way.
One of the possible ways out of this situation is the transportation of smolt downstream with the help of by barges. There are still many researches, which focus on the elimination of the harmful effect of the hydropower plants on the aquatic life . The other negative influence of the hydropower plants is their ability to change the downstream river environment. Hydropower plants can have a disruptive effect on the river beds and even lead to the loss of riverbanks due to fact that water exiting a turbine for the most part has a very little suspended sediment.
As an example we can view the influence of Glen Canyon Dam, which is proven to contribute to the erosion of sand bars of the Grand Canyon through constant cyclic flow variation . Hydropower plant can also affect the surrounding aquatic live through changing the usual amount of dissolved oxygen in the river. Other possible threats may be attributed to the lower temperature of water exiting from turbines. This can be fatal to some aquatic faunal species. One of the most disruptive effects can be produced by the hydropower projects, which make use of the canals in order to divert a river at a shallower level to increase the head of the scheme.
Sometimes this may lead to the complete change of the flow of the river and drying of the old riverbed, like in case of the Tekapo and Pukaki Rivers . However, it should be mentioned that dams of the hydropower plants can affect not only aquatic life. They can also produce a harmful effect on birds. As the possible example of this I can name the influence of dams of the Platte River in Nebraska on the Piping Plover and Sandhill Crane, which are now seriously endangered . As it was discussed above hydropower plants do not typically serve a main contributor of the greenhouse effect.
However, it should be mentioned that sometimes reservoirs of hydropower plants particularly in tropical regions may be a source of methane and carbon dioxide emission. This happens because of the decay of the plant material, which involves the creation of methane, one of the main producers of the greenhouse effect. A research conducted by the World Commission on Dams, showed that in cases when the reservoir is large in comparison with the generating capacity of the plant and when there was no prior clearing of the forests, methane emission may be even higher than that of the oil-fired thermal generation plant .
However, it should be mentioned that this is true only for the tropical climate. In moderate climate conditions of Canada and Northern Europe the emission of greenhouse gas is not essential and typically constitutes not more than 2 to 8 % of emissions of conventional thermal generation. Numerous contemporary researches focus on the mitigation of the forest decay effect through underwater logging operation . One more disadvantage of hydropower plants operating on large dams is associated with the relocation of the population living on the areas, where the reservoirs are constructed.
Although for the most part people get compensation for this forceful relocation, no one can actually estimate spiritual and moral damage caused to the people, who have to leave the places, where their ancestors lived. In extreme cases unwise planning may lead to the loss of the valuable cultural and historic sites as this happened during the construction of the Three Gorges Dam in China, the Clyde Dam in New Zealand and the Il? su Dam in Southeastern Turkey . Finally, Id like to discuss one of the most serious potential threats of the hydropower plants operating on large dams.
Although quite rare, dam failures can be considered very dangerous and can be compared with the natural disasters. Let us only take a look at the case of the Banqiao Dam failure in China, with caused the death of 171,000 people. Millions of people became homeless. Large dams can be viewed as a weak point in war times as they quite often become a target of enemy bombardment, sabotage and terrorist actions . Besides it should be mentioned that construction of the dam should be carefully considered from the geological point of view.
Otherwise it can possibly lead to such disasters as the one happened in case of the Vajont Dam in Italy in 1963, which lead to deaths of 2000 people . Hydroelectric power is one of the oldest and one of the most popular sources of energy, which is considered to have a great future. This is partially due to the fact that it is viewed as a source of renewable energy and it is very valuable in the places with an adequate water source. The main advantage of the hydropower plants is that they give relatively cheap electricity without any visible threat to environment such as waste byproducts and air emissions.
Furthermore, hydropower plants are considered as an alternative to other electric plans due to the fact that its product water is not consumed in the process of electricity production and is subjected to reuse, which is not possible in many other electricity production processes such as ones using for example fossil fuels . On the other side hydropower has not only positive sides. Among its disadvantages many researchers list negative impact of the hydropower plants on the surrounding area.
Hydropower plants operate on the reservoir, which are quite often artificially-made by flooding valleys. Quite often this process involves flooding of places, which used to have towns, farmland or places of interests. Besides, new reservoirs tend to destroy the natural habitats of aquatic life and fish places . But on the other side the same reservoirs create the new conditions, which can be a new habitat for a new aquatic life. Other possible threat is that hydropower operations using run-of-the-river dams are sure to impede the natural process if fish mitigation.
This is particularly dangerous to salmon. One of the possible examples of this is problems of Pacific salmon mitigation created by the numerous large dams in the Columbia River Basin . Because of all this concerns the United States do not make emphasis on the hydropower as its main source of electricity production even due to the fact that its natural resources are quite favorable for its development. Thus, we can see that only some 2,400 of the 80,000 dams in the country are used for production of hydroelectric power.
Authorities claim that construction of a new hydroelectric power plant is quit costly, but the main fact is that such construction needs much water and land, which could be used for other purposes . Besides, development of the hydropower plants in the USA is impeded by the raising environmental concerns of the public. However, this doesnt mean that the USA will completely refuse to use hydropower as the possible source of energy. Among the possible future trends, named by the U. S. Geological Survey is the development of the small-scale hydropower plants, which can be used by single communities to generate electricity .
1. 5. Hydropower in comparison with other methods of power generation In order to realize the strengths and weaknesses of the hydropower it is very valuable to compare it with other methods of power generation. As compared with fossil-fuel generated power plants, hydroelectricity eliminates the flue gas emissions. These emissions include such environmental dangerous components as dust, carbon monoxide, sulfur dioxide, nitric oxide and mercury . In comparison with the nuclear power plants, hydroelectric plants are not that powerful.
However, they do not present such danger to people and do not serve the source of the nuclear waste. Besides, hydroelectric plants produce electric power with the help of water, which is a renewable energy source, in contrast with uranium . Hydroelectric power plans are also seem an advantage if compared with wind farms. This is mainly due to the fact that they are more reliable and predictable. Wind is a natural factor, which can be subjected to changes, while hydropower plants with a storage reservoir are completely reliable and able to generate power when needed even in case of low water level and rainfalls.
Besides, unlike wind farms hydroelectric plants are more easily operated and regulated corresponding to changes in power demand . On the other hand hydropower plants have also some disadvantages if compared with other ways of power production. Thus, we can see that construction of fossil-fueled combustion turbines does not require any specific preliminary studies, while in order to construct an environmentally-friendly hydroelectric plant researchers should carefully conduct site, hydrological studies, and environmental and social impact assessment. In the majority of cases these studies require deep analysis of data up to 50 years old .
One more disadvantage of the hydropower plants is their dependence on the level of water. Thus, in case of low rainfall or snowmelt generation of hydroelectricity can be significantly lower. However, as it was mentioned before there exist numerous ways to ensure sufficient power production even in low water years . 1. 6. Hydroelectric power production in the world In order to realize the capacity and the potential of hydroelectric power plants, lets compare the data of the following table, representing the characteristics of hydroelectric power production in the countries with the most hydro-electric capacity.
Country Annual Hydroelectric Energy Production(TWh) Installed Capacity (GW) Load Factor Peoples Republic of China  416. 7 128. 57 0. 37 Canada 350. 3 68. 974 0. 59 Brazil 349. 9 69. 080 0. 56 USA 291. 2 79. 511 0. 42 Russia 157. 1 45. 000 0. 42 Norway 119. 8 27. 528 0. 49 India 112. 4 33. 600 0. 43 Japan 95. 0 27. 229 0. 37 Sweden 61. 8 France 61. 5 25. 335 0. 25 Sources: BP Annual Report, 2006.