The use of hydropower can date back to 7th millennium BC, were ancient Egyptian communities used hydropower for irrigation. In the contemporary society, hydropower still remains influential in the operation of mechanical devices such as watermills as well as energy or specifically electricity production, but the use of hydropower had becoming highly controversial due to its impacts on several geographical aspects. In this essay, I will be using several case studies to demonstrate the socio-economic, environmental factors of which the use of hydropower will have an impact on, in order for me to discuss and evaluate the advantages and disadvantage of using hydropower.
The use of hydropower could lead to various types of socio- economical impacts in a region. For example, unlike fossil fuels, hydropower is a renewable energy source as it is not likely to run out, whilst un- renewable resources such as oil are predicted to run out between 2025 and 2070 (Senior, 2012). Hydropower enables a reliable supply of energy as long as the water supply remains stable. This is very important to maintain socio- economical stability as countries such as China uses up to 4692.8 TWh in 2011 according to the National Energy Commission. Without the contribution of hydropower, it would be more challenging for the Chinese to meets it demands for electricity. Since 48.6% of China's GDP is made up by industrial sector (Censky, 2011), the shortages of electricity supply could bring negative economic impacts across the region, as industrial sectors often requires electricity to produce products. Without sufficient electricity, the production of various products will be bought to a halt, thus reducing its income from manufacturing and trading. This could also affect the social aspect of the society, as trading decreases due to insufficient electricity, this could lead to negative multiplier effect as wages are likely to be reduced for workers, thus affecting people's quality of life as their income reduces. However, some would argue that the relative importance and the contribution of hydropower is low. This was supported by the fact that even when fully functional, the Three Gorges Dam can only support about 1.7% of electricity demand in China (Wikipedia, 2012). This shows that the infrastructure in placed were not capable to catching up the demand for electricity in China, as the dam was predicted to provide 10% of China's required electricity(Wikipedia, 2012). However, the demand for it has increased more rapidly than originally planned. This also help illustrates that political decisions and inaccurate prediction and planning also plays in part in affecting the number of advantages and disadvantages in the use of hydropower, as in this case, these factors lead to the reduction of effectiveness of hydropower.
Besides that, hydropower had also bought more social- economical benefits into China. Although the full cost of the dam was estimated to be US$22.5 billion, it is expected that after 10 years of full operation, the full cost of the dam could be recovered as the generation of electricity will be cheap after the dam has been constructed (I.W.P. D.C., 2007). Until July, 2008, the State Grid Corporation and China Southern Power Grid paid 250 Yuen per MWH. After the construction of the damn, the cost of electricity for some province were reduced to 228.7 Yuen (China Three Gorges Coroperation, 2008). This is a benefit in terms of the social aspect as electricity became more affordable for people within some areas of China, thus this makes it an advantage which hydropower brings as people are likely to have to spent less income on electricity for appliances like heating, thus allowing them to have more disposable income for recreational activities, which potentially improve people's quality of life.
When looking further into social impacts, it is clear that some negative impacts and disadvantages were the results of using hydropower. For example, due to construction of the dam, official estimated that at least 1.2 million (Yardley, 2007) will be displaced and relocated (Yardley, 2007). More than 100 towns are submerged as a consequence, including Fuling and Wanxian (Gleick, 2008). Fourteen thousand hectares of agricultural land, along with 100 or more archaeological sites will be submerged (Gleick, 2008). These are the disadvantage of using hydropower by installing large scale energy generation units like the dam. These disadvantage include severe cultural, historical and social impacts. For example, towns like Fuling and other archaeological being submerged means that archaeological researches will not be able to carried out in the area in the future. Although reparations were given out when people are relocated, some would argue that the sentimental value and emotional attachment of these historical locations as well as their home time could never be replaced. Furthermore, the fact that people had to be relocated means that families and friends are likely to be separated during the relocation process due to the scale of the population. And again, although these social impacts are hard to measure to the full extent, but it is clear that these impacts will decrease the quality of life for the residents in those areas, and possibly leading to depression. However, it should be noted that this example may not apply to every case study related to hydropower. Small scale hydropower projects like watermills in rural areas will have less social impact on the local area, both negative and positive. For example, when building small scale watermills, the number of people displaced within a small area will be limited. Therefore, in this case, the disadvantages mentioned when looking at the Three Gorges Dam may not apply to small scale projects.
Besides socio- economical impacts, the use of hydropower can also lead to environmental impacts. In comparison to burning fossil fuels, hydropower does not contribute directly to submission of greenhouse gases such as carbon dioxide while generating electricity. For example, in 1999, hydropower contributed 2659 TWh in global energy generation and this is 17.5 percent of the world's total electricity produced for 1999 (Koch 2002). That amount of electricity would normally require the burning of 1595 million tonnes of coal, in which about 2 631.75 tonnes of carbon dioxide would be released into the atmosphere, thus contributing directly to global warming via the emission of greenhouse gas. Another example is the Three Gorges Dam in China. According to the National Development and Reform Commission of China, the Three Gorges Dam could reduce annual coal consumption by 31 million tonnes in energy production, which potentially reduced the emission of one million tonnes of sulphur dioxide. This is a major advantage as reduced of sulphur dioxide production could reduce acid rain on a national scale. This means that impacts of acid rain on the natural environment, such as the creation of acidic lakes and the disruption to soil chemistry would decrease and helps maintain biodiversity in natural environments.
However, although various gas emissions has decreased potentially, the use of hydropower, particularly the use of dams and reservoirs can still create pollution and contribute to global warming. A study estimates that in 1990, the Curua-Una dam in Brazil generated more than three and a half times the amount of greenhouse gas by generating the same amount of electricity from oil (Fearnside, 2005). This was caused by the flooding of reservoirs, resulting in a build up of methane dissolved in water, as plant matters were left to rot and decay under water along with the sediments. Eventually, the methane would be released into the atmosphere when water passes through the dam after passing though the turbines. Since methane is a greenhouse gas which is also 21 times more heat trapping that carbon dioxide (Mark, 2012), the use of hydropower in terms of the use of dams and reservoir could be considered as a contributor to global warming and the generation of methane as a by-product of dams and reservoirs remains to be a disadvantage of using hydropower. Lastly, the construction of some infrastructure to utilise hydropower are known for causing negative impacts upon the environment as biodiversity is reduced as a result. For example, the percentage of forested area near the Three Gorges Dam decreased from twenty percent to less than ten percent between the years of 1950 and 2002 mainly due to deforestation when the dam was built (Chetham, 2004). Turbines used to generate electricity are also know for damaging fish and other freshwater animal species, further decreasing the biodiversity of the rivers (Xie, 2003). These impacts are strong evidence to demonstrate the disadvantage of using hydropower as a energy resource.
In conclusion, using hydropower has its advantage to some extent. For example, it can be used to produce electricity as a more sustainable manner as hydroelectricity is a form of renewable energy. This means unlike fossil fuels and other un-renewable energy sources, electricity supply is not likely to run out, thus being able to provide continuous support to meet the demand of electricity required in socio-economical activities. However, the use of hydropower has also got its disadvantage, limitations and it could even overshadow its initial benefits. The limitation was demonstrated by the high initial set-up costs for more technological advanced, as well as efficient infrastructures and equipments to extract the power or potential energy from water, meaning that the use of hydropower will be limited in some regions, particularly in less economically developed regions like the Republic of Zimbabwe. Furthermore, disadvantages like the Curua-Una dam in Brazil generating large amount of greenhouse gases could mean that the use of hydropower, particularly in electricity generation could be questionable. Different factors and limitation, such as geographical location also plays a part in affecting the performance, as well as the efficiency of hydropower. The impacts also varies according to the scale, as well as the method and the infrastructure used to extract the energy. Therefore, it is over-simplistic to say that hydropower is completely advantages or disadvantageous based on the facts above, as the use of hydropower has both advantages and disadvantages.