If you've visited the Victoria Falls in Zimbabwe, the Iguazu Falls in Argentina, or the Niagara Falls in USA, you would have marveled at the colossal amounts of water thundering down from high up above, and the immense power with which it hits the lake below. If you're a critical thinker, you may have thought that this power could be somehow used to generate useful energy for us. And, indeed, you are right. Welcome to hydroelectricity.

Both hydroelectricity and wind power generates energy from more or less the same principle – the movement (or flow) of a fluid over a certain distance. In wind power this fluid is air particles moving by temperature difference, and in hydroelectricity this fluid is water moving by gravity – usually a stream of flowing water.

The History of the Human Use of Water (Water Power)

As a rule, humans require water to survive, and consequentially human settlements developed around bodies of water. Gradually, our ancestors came to realize that water was not only a necessity for survival, but a potential source of accessible energy. The most common way of harnessing 'water power' was watermills in a principle more or less similar to wind power, the flow of water turned a turbine, the rotation of which could be used to do useful agricultural work. Watermills have been used from very early times, probably since more than 3,000 years ago.

The flow of rivers also enabled ships and boats to 'swim with the current' without having to use human power. This made transport and trade much easier, and as a consequence the major trading cities (and ultimately the largest cities of the world) have developed near rivers. Amsterdam, New York, Paris, Seoul, Rome, and London are all such examples.  

How does Water Produce Electricity?

A wind turbine uses multiple wings connected to a central axle to catch the wind, in a way very much similar to the way windmills run. Likewise, a water turbine uses the same principle to achieve a rotational moment. Typically, the greater the speed of water, the greater the speed of rotation attained hence, most hydropower plants are located right in the middle of waterfalls, in order to maximize the momentum of the falling water (obviously so just stand right below a significant waterfall and you will feel the immense blast). As the water falls it hits the turbine and the gravitational attractions pulls it down, turning the turbine in the process. 

Advantages & Disadvantages

Like wind energy, hydroelectricity is completely renewable and sustainable. As long as water keeps flowing in rivers and falling in waterfalls, the hydroelectric power stations will keep running. Likewise, it is a clean form of energy, with no emissions whatsoever. Moreover, hydroelectricity has two significant advantages over wind power: a) it has no time restrictions (rivers and waterfalls flow all year long as long as they don't freeze or dry up) and b) it is versatile worldwide (there are rivers and waterfalls all over the world, right?). Finally, hydroelectricity has a potentially large output, and thus we don't need to get picky and all that with scrounging up whatever energy we can draw out, as is in the case of wind power.

Then there are the disadvantages. Unlike wind turbines, hydroelectric power stations are not only costly, but take a long time to build (sometimes more than 10 years). Besides, while the power station itself takes over enormous amounts of space, the construction of a dam creates a lake of water above the waterfall (this is called a reservoir). This excess water will flood the riverbanks - a potentially bad score for the environment and the people. For example, the reservoir formed by the Three Gorges Dam, finished in 2003 on the Yangtze River, China, flooded at least 1,600 abandoned factories, mines, dumps, and potential toxic waste sites. The trash and toxic material were swept into the river because the dam prevented the material from flowing into the sea, the entire river estuary soon became heavily polluted. While this alone was a huge impact on the environment, the fishing economy formed around the Yangtze River received a huge blow, forcing many fisherman to turn to illegal poaching of endangered species for a living.

Finally, the largest waterfalls existing in the water – the potentially the best candidacy for building hydroelectric power plants – are already treasured by us as National Parks or wonders (all the names of waterfalls listed at the beginning of this article are such examples). The governments simply won't give up their valuable tourist attractions (which obviously makes far more money than building a power plant and pocketing that energy), while the people won't give up their nation's pride – even if it means paying a few more dollars of taxes for energy efficiency. It's highly unlikely that we'll be seeing a hydroelectric power plant sitting on the top of the Niagara Falls – at least for the foreseeable future.

Case Study

An important fact to consider is that in most countries, building hydroelectric power stations is nearly impossible, or requires significant sacrifices. In the greater part of the developed countries, major cities and towns have already settled on the riverbanks, meaning that they will be inundated if hydroelectric power stations are constructed nearby (most of the MEDCs, including UK, France, and USA, fall under this category). On the other hand, in less developed countries, there are no significant bodies of water to run the generators, either because they are dried up by the heat (most LEDCs are located near the equator), or because they are too insignificant volume-wise. Furthermore, LEDCs generally do not have sufficient budget to construct the power plants. Thus, building hydroelectric power plants is a choice available for only a limited number of countries – countries that are economically developed but have yet preserved their river and waterfall estuaries.

The nations that fall under this category are predominantly those in the Scandinavian Region (Europe), such as Norway, Sweden and Finland. These nations do not have a long history of industrialization, and have not settled too many cities in the rural areas, leaving their environment yet undamaged. Besides, they have sufficient technology and material to not have to rely on cheap fossil fuel for energy hence, they are in the perfect conditions for embracing wide usage of hydroelectricity. Norway, for example, relies on hydroelectricity for more than 90 % of her electrical energy demands – even though she is one of the top fossil fuel exporting countries in Europe, and annually pockets more than 30 million dollars from exporting petroleum.

Areas of Research in the Future

Hydroelectricity is already one of the cleanest and most efficient forms of energy in the world, and further research as to increase the efficiency and output probably won't make an enormous difference. What we really need to solve is the environmental impact hydroelectric power plants can wreak (the energy itself is clean, but the power plant itself can harm the surrounding habitat). Although hydroelectricity is a good alternate energy resource, our current mode of building the power plants can only have a worse and worse impact on the environment (remember the example of the Three Gorges Dam) our future goals of research, then, is to research means of minimizing environmental impact caused by constructing power plants, and ensure that they will be a true assistance to not only energy shortages, but equally to all ecological aspects as well.

Citation of Images

Niagara Waterfall Canada Wallpaper. Digital image. Niagara Waterfall Canada Wallpaper. Wallpaper Downloader, n.d. Web. 27 July 2014. <http://wallpaper-download.net/travel-wallpapers/niagara-waterfall-canada-wallpaper>.

Old Watermill. Digital image. Old Watermill. Lovethispic, n.d. Web. 27 July 2014. <http://www.lovethispic.com/image/41499/old-watermill>.

HYDROELECTRIC HYDROELECTRIC. Atlantica Centre for Energy, 2014. Web. 27 July 2014. <http://www.atlanticaenergy.org/hydroelectric>.

Garbage Floods the Three Gorges Dam. Digital image. Photos: Garbage Floods the Three Gorges Dam. China Digital Times, 2011. Web. 27 July 2014. <http://chinadigitaltimes.net/2010/08/photos-garbages-in-three-gorges-dam/>.