Hydroelectric Power: The World's Established Renewable Energy Resource

Hydroelectric power: The World's Established Renewable Energy Resource

For over a century, hydroelectric power has been used to generate electricity from falling water. The capacity to produce this energy is dependent on both the available flow and the height from which it falls. Hydroelectric dams create height for the water to fall and provide storage. In general, the higher the dam, the more potential energy is available. Building up behind a high dam, water accumulates potential energy. The potential energy is then converted to kinetic energy where it can perform work to power a generator. Hydroelectric power can come in many forms, such as utilizing oceanic waves and currents, shoreline waves, and tidal energy. However, I would like to focus on utilizing fresh water sources, in particular dammed rivers. Hydroelectric power utilizes the water in flowing rivers, a renewable resource, to conduct electricity. Humans have harnessed water for performing work for centuries. Now, it is our most important and widely used renewable resource. Despite being a renewable, no-emission power source, it is not without its environmental impacts.

Currently the most widely used type of renewable energy, hydroelectricity accounts for over 20% of the world's electricity. In Canada it constitutes for over 60 per cent of its power. Canada is the world leader of hydroelectricity production producing 353,000 GWh in 2002. This is followed by the U.S., which produced 300,000 GWh, followed by Brazil, China, Russia, and then Norway. However the energy produced is not representative of the countries total energy consumption. For example, Norway is sixth on the list of hydroelectric energy production, yet nearly 100 per cent of its energy comes from hydroelectric power. Although the U.S. is number two in hydroelectric energy production only about 7 per cent of its energy consumption comes from hydroelectric energy (1 Environment Canada).

In Brazil the Itaipu Dam is currently the largest dam in production in the world. It supplied 93 per cent of the energy consumed by Paraguay and 20% of that consumed by Brazil in 2002. China currently derives 40% of its energy from hydropower, and that number is soon to increase (1). China has just finished construction on the world's largest hydroelectricity project, which will be up-and-running within the next three years (3 Chao). Quebec, Canada still has one of the largest hydroelectric developments in the world, called La Grand complex, located on James Bay. Good revenue for Quebec's economy comes from selling excess electricity to American cities such as New York. British Columbia, Canada, home of BC Hydro serves more that 1.7 million customers in an area containing over 94 per cent of British Columbia's population. BC Hydro is the third largest electric utility in Canada. Hydroelectric power accounts for about 80 percent of the province's electricity and is produced by 61 dams at 43 locations. The remainder is generated by 32 hydroelectric facilities and only three natural gas-fuelled thermal power plants. Canada produces a surplus or power that is exported to the United States. The United States has an enormous hydroelectric potential. Only about 30 per cent of the potential has been utilized. Currently there are about 80,000 dams in the Untied States and only 2,400 are used for hydroelectric power (6 BC Hydro).

Reservoirs are perhaps the most environmentally detrimental part of the hydroelectric dam. Unfortunately reservoirs are also the reason that they are so efficient and reliable. Hydroelectric power is one of the most flexible and reliable sources of all renewable and non-renewable energy. The flexibility comes from the ability to be able to be stopped and started in minutes and always having a source of potential energy from the reservoir.

The flows in most rivers vary greatly with the seasons and the weather. Reservoirs allow the high flows to be stored for later use during times of high demand or draught. Reservoirs not only provide for water storage for future hydropower need, but as well as agriculture, irrigation, and a steady supply of water for nearby communities. Industries and product processing are able to utilize the water stored by reservoirs. Reservoirs alls provide for recreational activities, which can boost local economies. Dams can minimize the risk of flooding by reducing the peak flows and providing more time for downstream notification. Conversely, the storage of water in reservoirs can also pose a great risk to nearby communities in the event that the dam integrity fails.

The most environmentally damaging aspect of reservoirs is habitat loss. A river habitat is very different from a reservoir habitat. The flooding of a river system to create a reservoir destroys forests, human habitat, spawning routes, and animal habitats. Suspended soils, logs and debris may settle out of the water as it slows down. Shoreline erosion can increase the sediment load and increase turbidity of the water. Sedimentation, if left unchecked, can leave a dam rendered useless.

Sedimentation and habitat loss are not nearly the worst result of reservoir production. Methyl mercury levels in aquatic life can be an important potential impact of reservoirs. When soil and vegetation are submerged they decompose. Inorganic mercury may then be converted to methyl mercury where it is more likely to be consumed by organisms where it may concentrate as it moves up the food chain. This affect is not permanent however, and is only due to the initial flooding of the reservoir. However, depending on the species studied, mercury concentration returns to levels comparable to mean concentrations observed in fish in natural lakes approximately 30 years following dam construction.

Hydroelectric reservoirs can often cause significant damage