Hydroelectricity Facts

Did You Know?Hydroelectricity currently provides one-fifth of the total amount of electricityconsumed by the world.

In this age of global warming and its numerous impending consequences, it is imperative for us to bevery careful with our choice of fuel, since the output of the energy source may directly contribute topollution and thus heighten the threats of global warming.

There are very few sources of energy that truly are environment friendly, and hydroelectricity is oneof them. Although there are some disadvantages to using hydroelectricity, they are nowhere near asplentiful compared to the disadvantages of other major sources of energy, and are overwhelmed byits advantages.

History

Waterwheels have been built by human civilizations since time immemorial. The Romans, theEgyptians and many other civilizations are known to have used it. These early waterwheels weremainly used for agricultural purposes, such as grinding grains. The first hydropower plant producingelectricity was built in 1882 in the United States of America. Hydroelectricity had so manyadvantages that soon, hydroelectric dams started springing up all over United States, including oneon the Niagara. In 1911, the construction of the Roosevelt dam was completed. This constructionwas the largest rock masonry in the world, and housed the largest artificial reservoir at the time.

Despite the boom in the number of dams, the technical know-how of blocking rivers was stillprimitive, and rivers maintained their seasonal flow. However, this obstruction was soon overcome,and hydroelectric power has since been a major source of electricity.

Mechanism

It is a commonly known fact that energy cannot be created, but can only be converted from one formto another. In thermal power plants, for instance, coal (or any other fossil fuel) is burnt, convertingthe chemical energy in the fuel into heat, which is used to convert water into steam, which is used toinduce the mechanical motion of turbines, and finally electric energy. In hydroelectric power plants,no fuel is burnt. What, then, is the source of energy in hydroelectric dams?

The answer to this question is kinetic energy -- the energy of motion. One of the ways to generate

energy is letting an object attain height against the force of gravity. The energy from the fallingobject can then be harnessed quite easily. In hydroelectric power plants, the kinetic energy of falling(or flowing) water is directed onto turbines, the movement of which generates electricity.

Pros and Cons

? Advantages ?

? The major advantage of hydroelectricity is that it is generated from a clean source, i.e., no harmfulbyproducts are produced in hydroelectric plants (except a relatively negligible amount of carbondioxide), as opposed to fossil fuels. In fact, ideally, a hydroelectric power plant generates no wasteat all!

? The economics involved are nearly immune to prices of crude oil. This renders hydroelectricityvery cheap.

? The reservoirs of hydroelectric dams can be used as major sources of running water, for purposessuch as agriculture.

? A great advantage hydroelectricity holds over other renewable forms of energy is that the flow ofrivers and annual rainfall is fairly reliable and can be calculated beforehand. This is not the casewith wind or solar power, which can fluctuate literally by the minute.

? Tourism and other water-based commercial avenues (aquatic sports etc.) can add to theeconomical benefits of hydroelectric dams.

? Disadvantages ?

? Dam failures have been some of the deadliest and costliest tragedies till date. Since dams have tosustain enormous pressure from the stored water, any minor fault in the construction can have muchlarger, more destructive consequences.

? Dams functioning on reservoirs rather than running water cause large-scale flooding (see image),forcing animal and human communities to relocate. The natural ecosystems of the area can beseverely damaged by the introduction of an artificial reservoir.

? Relocating human population in the vicinity of a proposed dam is a huge task, and not just due tothe sheer logistical effort required to actually 'move' all the people. New facilities, such as houses,schools etc. have to be constructed for these people from scratch, further increasing the economicsetback.

? Although hydroelectricity is said to be a clean source of energy, the reservoirs of the dams are saidto produce methane, a greenhouse gas. If running water (run-of-the-river power plants) is usedwithout storage, hydroelectricity is indeed a clean source. But a reservoir is a virtual must-have ifthe dam is to produce large amounts (a few hundred MW) of electricity.

Intriguing Facts About Hydroelectric Power

? Considering there's no structural weakness, hydropower dams provide flood control, since theycurb the flow of rivers and only permit a specified amount to pass through.

? Hydro-power is the world's largest renewable energy source.

? About 20% of the world's electricity needs are met through hydroelectric power generation. Thisfigure by far outstrips other renewable power sources.

? PR China is the leading producer of hydroelectricity (annual hydroelectric production), while theUS is fourth.

? The largest hydroelectric power plant in the world is the Three Gorges Dam in China.

? Of the 25 largest hydroelectric power plants in the world, PR China has 8 -- about 1 in 3. Russiaand Brazil have 5 each (although the latter shares one of them with Paraguay).

? The largest hydroelectric plant in the US is the Grand Coulee Dam.

? One other form of hydropower includes tidal energy -- harnessing the motion of tides to produceelectricity. This source of power doesn't contribute significantly to the world's energy charts.

? Very few countries use hydroelectricity as the major form of power. Among the ones that do,Norway draws a stunning 98% of its total power from hydroelectric plants, Brazil draws 85%,Venezuela 69%, Canada 61% and Sweden 44%.

? A notable omission in the above list is PR China. China has an installed capacity of production(maximum capacity of production under ideal conditions) of 196.8 gigawatts, which accounts for amere 22% of China's total energy consumption. To put the numbers in the proper context, China'sinstalled capacity of production is the highest in the world -- considerably more than that of the nexttwo candidates, Canada and the US, put together!

? Modern hydroelectric power stations tend to recover their construction cost in a matter of eight toten years.

With fossil fuels becoming more expensive by the hour, mankind needs to turn to other fuels toquench its insatiable thirst. Like all fuels, hydroelectricity has its own unique set of perks and quirks.But considering its pros and cons, it must be said that hydroelectricity looks like the most promisingcandidate.