What are the disadvantages and advantages of using hydroelectricity?

Answer 1

Advantages:

• Once a dam is constructed, electricity can be produced at a constant rate.
• If electricity is not needed, the sluice gates can be shut, stopping electricity generation. The water can be saved for use another time when electricity demand is high. The build up of water in the lake means that energy can be stored until needed, when the water is released to produce electricity.
• Dams are designed to last many decades and so can contribute to the generation of electricity for many years / decades.
• The lake that forms behind the dam can be used for water sports and leisure / pleasure activities. Often large dams become tourist attractions in their own right.
• The lake's water can be used for irrigation purposes.
• When in use, electricity produced by dam systems do not produce green house gases. They do not pollute the atmosphere.
• Hydro-power is a fueled by water, so it's a clean fuel source. Hydro-power doesn't pollute the air like power plants that burn fossil fuels, such as coal, oil or natural gas.
• Hydro-power is a domestic source of energy, produced locally near where it is needed.
• Hydropower relies on the water cycle, which is driven by the sun, thus it's a renewable power source so long as the rain keeps falling on the dam catchment area.
• Hydropower is generally available as needed; engineers can control the flow of water through the turbines to produce electricity on demand.
• Hydropower is not only a cleaner source of energy than oil but is it more cost effective as well. The most efficient coal burning plants are only able to convert around 50 percent of their energy into electricity, whereas modern day hydro power turbines convert up to 90 percent of their energy into electricity.
• Hydropower can cost less than a penny per kWh (Kilowatt Hour) compared to fossil fuel power plants at around 2 to 3 cents per kWh. That may not seem like a big difference, but when factored out over a year and the millions of kW hours Americans burn, it adds up to a huge savings.
• Hydropower plants also have an added bonus as they create recreational opportunities for people as well as electricity. Hydro power dams provide not only water-based activities, but since much of the surrounding land is public they also encourage numerous other outdoor activities aside from boating, skiing, fishing, and hunting.
• Hydropower plants provide benefits in addition to clean electricity. Hydro power plants create reservoirs that offer a variety of recreational opportunities, notably fishing, swimming, and boating. Most hydro power installations are required to provide some public access to the reservoir to allow the public to take advantage of these opportunities. Other benefits may include water supply and flood control.

Disadvantages:

• Dams are extremely expensive to build and must be built to a very high standard.
• The high cost of dam construction means that they must operate for many decades to become profitable.
• The flooding of large areas of land means that the natural environment is destroyed.
• People living in villages and towns that are in the valley to be flooded, must move out. This means that they lose their farms and businesses. In some countries, people are forcibly removed so that hydro-power schemes can go ahead.
• The building of large dams can cause serious geological damage. For example, the building of the Hoover Dam in the USA triggered a number of earth quakes and has depressed the earth's surface at its location.
• Although modern planning and design of dams is good, in the past old dams have been known to be breached (the dam gives under the weight of water in the lake). This has led to deaths and flooding.
• Dams built blocking the progress of a river in one country usually means that the water supply from the same river in the following country is out of their control. This can lead to serious problems between neighboring countries.
• Building a large dam alters the natural water table level. For example, the building of the Aswan Dam in Egypt has altered the level of the water table. This is slowly leading to damage of many of its ancient monuments as salts and destructive minerals are deposited in the stone work from 'rising damp' caused by the changing water table level.
• Hydro power dams can damage the surrounding environment and alter the quality of the water by creating low dissolved oxygen levels, which impacts fish and the surrounding ecosystems. They also take up a great deal of space and can impose on animal, plant, and even human environments.
• Fish populations can be impacted if fish cannot migrate upstream past impoundment dams to spawning grounds or if they cannot migrate downstream to the ocean. Upstream fish passage can be aided using fish ladders or elevators, or by trapping and hauling the fish upstream by truck. Downstream fish passage is aided by diverting fish from turbine intakes using screens or racks or even underwater lights and sounds, and by maintaining a minimum spill flow past the turbine.
• Hydro power can impact water quality and flow. Hydro power plants can cause low dissolved oxygen levels in the water, a problem that is harmful to riparian (riverbank) habitats and is addressed using various aeration techniques, which oxygenate the water. Maintaining minimum flows of water downstream of a hydro power installation is also critical for the survival of riparian habitats.
• Hydro power plants can be impacted by drought. When water is not available, the hydro power plants can't produce electricity.
• New hydro power facilities impact the local environment and may compete with other uses for the land. Those alternative uses may be more highly valued than electricity generation. Humans, flora, and fauna may lose their natural habitat. Local cultures and historical sites may be flooded. Some older hydro power facilities may have historic value, so renovations of these facilities must also be sensitive to such preservation concerns and to impacts on plant and animal life.
• By 2020, it is projected that the percentage of power obtained from hydro power dams will decrease to around four percent because no new plants are in the works, and because more money is being invested in other alternative energy sources such as solar power and wind power.