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Hydroelectric Power
Introduction
Hydroelectric power refers to the turning of a turbine or waterwheel, which is caused by the flow of water over it. In modern times, this rotating turbine is used to produce electricity which powers all kinds of machinery and equipment, however, hydroelectric power has in fact been utilised by mankind for many centuries. The ancient Greeks used water to turn wheels for grinding wheat into flour, whilst in the 18th century mechanical hydropower was used extensively for milling and pumping (Source: www.usbr.gov)
Today's hydroelectric power plants function by water which is stored and held back by a dam, and then forced down by gravity through a large pipe known as a "penstock". As it falls it spins a turbine which is connected to an electric generator, from where the electricity created is transported through wiring to the Grid or to where it is required. The water which has passed over the turbine is released out into a river or ocean. A nice diagram of the whole process can be found here.
Advantages of Hydroelectric Power
A hydroelectric power plant has a number of environmental benefits over other forms of power generation, as it will produce no harmful emissions and should not pollute the water, providing the machinery parts are well-maintained and are not leaking a harmful substance such as oil or hydraulic fluid.
As well as the benefits for the environment, hydroelectric power generation is much better at adjusting to the peaks and troughs of energy demand at different times of the day and night. Whereas other sources of power such as fossil fuel burning power stations take a long time to start up or shut down, hydroelectric power can be switched on or off relatively quickly. Some plants also have the ability to pump water back up to the reservoir above during off-peak times, so that a source of water is then available for use during peak electricity requirements.
It will depend on the size and scale of the respective project, but typically a hydroelectric power plant will generate a much greater quantity of electricity than having to generate it through other renewable means such as wind power or from solar panels. This means less land is taken up, and less habitats and ecosystems disturbed, to generate a specific amount of electricity.
Another advantage is that because hydroelectric plants do not burn fuel, there will be little risk of fires or explosions affecting nearby residents. All of the stored coal or gas at a fossil fuel power station can result in a major incident if it were to accidentally catch fire. Of course, there is a small danger that the dam could burst in a hydroelectric plant, which would cause devastating flooding in the valley below. This is rare, although accidents and near misses do occur occasionally. Whilst not a dam used in relation to hydroelectric power, the Whaley Bridge near-miss highlighted the dangers a broken dam might pose.
Not having to buy any fuel makes a hydroelectric plant relatively inexpensive to operate. It will also not be affected by any fluctuations in the price of fuel as would, say, a power station that burns coal or natural gas that is imported from overseas. This will be particularly advantageous during times of global crises which affects the financial and commodities markets.
Disadvantages of Hydroelectric Power
The most obvious disadvantage, as it is with most other forms of energy creation facilities, is the initial cost. Generating large amounts of electricity requires significant investment, and this may prevent a project even getting past the initial idea stage. Even though it will still cost a lot of money, it is highly likely to be a significantly lower outlay than would be required for constructing a fossil fuel power station.
Along with the high initial financial outlay, the drawbacks of hydroelectric power are primarily of an environmental nature. The dams associated with hydroelectric power facilities can be visually intrusive upon the natural landscape, whilst the requirement for a reservoir at the top can mean that houses and wildlife habitat in the area needs to be relocated or destroyed to make way for this large body of water.
Constantly altering the flow of water can cause issues for fish and other aquatic creatures and plant life that live in the water downstream, making it difficult or impossible to make a home there.
Whilst the water powering the whole thing will be there just about all of the time, there is the possibility of drought conditions caused by an extremely hot summer and a lack of rainfall. If the level of the reservoir falls significantly, or a river temporarily dries up, the lack of water flowing over the turbines could force the hydroelectric plant to close down until the water returns. Power stations utilising other methods of electricity generation may be able to take up the slack, but if the local community relies upon the hydroelectric plant for its electricity generation, there could be power cuts.
Conclusion
Despite the high costs involved in constructing them - with a need for the turbine and dam construction - hydroelectric plants normally have a long life span, so will justify the initial cost spent over their existence.
They can provide a great deal of electricity, such as the Hoover Dam in Nevada supplying power for much of Las Vegas, and do so without emitting harmful gases into the atmosphere.
Like all forms of power generation, there are inevitably some downsides. As well as the usual high initial costs of construction, there is an impact upon the environment in the form of variable water flow, and the probable need to flood some existing habitat to create a large reservoir above the dam.
Despite these drawbacks, generating electricity using water in a hydroelectric plant is one of the greenest ways to produce a large amount of electricity, without emitting large quantities of greenhouse gases into the atmosphere and contributing towards global warming. Despite its extensive use, there is still an enormous amount of unutilised potential for hydroelectric power, particularly in Latin America, Central Africa, India and China (Source: www.manufacturing.net).
