Wednesday, 6 November 2013


All energy conversion methods used to produce electricity have some environmental impact. The impact may have an active effect like the emission of airborne pollutants, or may have a passive effect like aesthetics or habitat modification. Even methods considered environmentally friendly, like wind, solar, and hydro, have some impact on the environment. Not only does the final production of electricity have an environmental impact but the transmission of electricity with concerns over electromagnetic fields, aesthetics, and land use, also impacts the environment.
The whole cycle of electricity generation must be considered when looking at the environmental impact. This includes the production and transportation of fuel for the conversion process. This is especially true of fossil fuel and nuclear power plants, which use large quantities of fuel taken from the earth. Energy system environmental impact consists of fuel recovery and production, fuel transportation, electricity transmission, and spent fuel emissions.
Fossil fuel power plants generally have the most widespread effect on the environment, as the combustion process produces airborne pollutants that spread over a wide area. Nuclear power plants have the most potentially dangerous effect. An operating accident at a nuclear station could allow a large release of radioactive particles to occur. Solar, hydro, and wind power plants generally have smaller effects on the environment.
Nonetheless, these renewable sources of energy provide substantial benefits for our climate, our health and our economy. Each source of renewable energy has unique benefits and costs like little to no global warming emissions, improved public health and environmental quality and a vast and inexhaustible energy supply etc.
Hydroelectric power includes both massive hydroelectric dams and small run-of-the-river plants. Large-scale hydroelectric dams continue to be built in many parts of the world leaving a lasting impact on the world. The amount of water usage is often of great concern for electricity generating systems as populations increase and droughts become a concern.
Still, hydroelectric power is the most energy efficient power generator. Currently, hydropower is capable of converting 90% of the available energy into electricity. This can be compared to the most efficient fossil fuel plants, which are only 60% efficient.
The size of the reservoir created by a hydroelectric project can vary widely, depending largely on the size of the hydroelectric generators and the topography of the land. Hydroelectric plants in flat areas tend to require much more land than those in hilly areas or canyons where deeper reservoirs can hold more volume of water in a smaller space. Flooding land for a hydroelectric reservoir has an extreme environmental impact: it destroys forest, wildlife habitat, agricultural land, and scenic lands. In many instances, such as the Three Gorges Dam in China, entire communities have also had to be relocated to make way for reservoirs.
Dammed reservoirs are used for multiple purposes, such as agricultural irrigation, flood control, and recreation, however  hydroelectric facilities can still have a major impact on aquatic ecosystems. For example, though there are a variety of methods to minimize the impact (including fish ladders and in-take screens), fish and other organisms can be injured and killed by turbine blades.

Yet, before a project can be developed, it must go through a rigorous process of screening that examines the impact the project would have on the environment and the local communities. Water flow, water quality, water shed management, fish passage, habitat protection as well as the welfare and lifestyle of the local communities are taken into consideration.
Although hydroelectric power can prove to be a challenge to the environment, it yet has a distinct advantage over fossil fueled generator plants: it is clean, green and renewable and has very low operating costs. It is renewable because it draws its essential energy from the sun that drives the hydrological cycle, which in turn provides a continuous renewable supply of water. Hydropower does not contribute to local air pollution.

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