Hydroelectricity and the "Big Dam Era"

views updated

Hydroelectricity and the "Big Dam Era"

Overview

Dams have been used to control river flow since the time of the ancient Egyptians, but it was not until the twentieth century that the full potential of harnessing this natural resource was realized. Hydroelectric power has garnered a great deal of attention since the early 1900s as a clean and renewable source of energy. Traditional fossil fuels are expensive, have a finite supply, and produce a great deal of pollution. The extraction of substances like oil and coal is often damaging to the environment. During the early to mid-1900s hydro projects provided as much as 40% of the electricity consumed in the United States. Today, waterpower supplies about one-tenth of the electricity consumed in the U.S. and about onequarter of the world's electricity. The leading producers of hydroelectricity are Canada, United States, and Brazil.

Background

A dam is defined as a barrier placed across a river to stop the flow of water. It can be a small earth or rock structure or a huge concrete dam. Controlling or stopping the flow of water, a dam creates a reservoir behind it. The stored water can be made available for irrigation, flood control, municipal or city water supplies, recreational activities, and hydroelectric development. Hydropower can be created by releasing the higher water in the reservoir through penstocks in the dam that can be delivered to turbines, which use the gravitational force of the falling water to power generators, which create electricity. Transmission lines carry the electricity to different locations for a variety of uses.

People have always opted to settle near water sources and have felt the need to control and manipulate water for their own use. The first recorded dam was made by Egyptians about 2800 b.c. and was located on the Nile River. Ancient Romans built dams out of stone and connected water wheels to grinding stones to mill grain in the fourth century b.c. Early in North American history, dams provided power for gristmills with water wheels that operated by water falling onto the wheels much like those used by the Romans. They created small mills and water wheels to grind flour and to operate forges in the 1700s. These mills were essential in rural areas and were later used to make paper, powder, textiles, and lumber. However, early settlers found themselves at the mercy of the hydrocycle. They could not operate their mills during times of flooding or drought and soon found it necessary to further control their water supply. Rudimentary dams were constructed to store water for use during times of drought and for flood protection. These dams were made of locally available materials, such as trees, rocks, and soil.

As rural areas began to enter the market place, larger mills were being used on a larger scale, particularly for lumber and textile factories, and towns began to form around these operations. America began to shift from a rural lifestyle to the industrialized town, but the increasing use of the steam engine caused a decline in the use of waterpower, and some of the villages around the mills began to die. Water-power was to have its rebirth through the growth of the electric lighting industry. In 1842, the Fourneyron turbine had been introduced to the United States, a highly upgraded version of the water wheel. Later the development of electric generators in the 1870s made it possible to produce a constant and reliable electrical current in commercial quantities. Parallel wiring allowed people to use the lights they wanted, when they wanted, unlike lights that had previously been wired in a series. Incandescent lamps along with an alternate current system began to be used instead of a direct current system. These advancements laid the basis for the giant regional station.

The use of electricity increased in the late 1800s, and the first dam built specifically to create hydroelectric power was built in Appleton, Wisconsin, in 1882. It powered two paper mills and one home. The larger Niagara Falls project in New York was a culmination of European and American technology and went into operation in 1895. The 5000 hp station supplied power to both Ontario and New York, and spurred many ambitious projects after it.

Impact

The beginning of the twentieth century led to bigger stations servicing larger areas. The Reclamation Act of 1902 authorized a series of federal irrigation projects. The focus was on irrigation but some produced small amounts of hydro for use around the dams. Excess amounts were sold, and the revenue was applied to the projects. The first of many hydro projects in the U.S. in the early 1900s was the Keokuk Canal and Hydro Plant on the Mississippi River at Keokuk, Iowa. The canal was constructed in 1877, but the hydro plant was not built until 1913. At the time it was the largest hydro plant in the world. It was 4,649 feet (1,418 m) long, and had a head of 34.5 feet (10.5 m).

During the same period, the American Southwest was being hit with floods and drought, and the Bureau of Reclamation began to work on ways to solve these problems. In 1928, President Herbert Hoover (1874-1964) signed into law the Boulder Canyon Project. Dam construction began on the Colorado River on the Arizona-Nevada border in 1931, and was completed in 1935. The dam's purpose was to improve navigation, regulate the flow of the Colorado River, and to store and deliver water to cities and towns. Hydroelectricity was a secondary function. The dam was a huge engineering marvel. The Boulder Dam, later to be named the Hoover Dam after President Hoover, was 727 feet (222 m) high, and 1,244 feet (379 m) long. The hydro plant capacity was 1.5 million kilowatts. The reservoir created behind the dam, called Lake Mead, after the Reclamation Commissioner Dr. Elwood Mead, remains one of the world's largest artificial lakes at 110 miles (177 km) long and 500 feet (152 m) deep. The Hoover Dam is a National Historic Landmark and a National Historic Civil Engineering Landmark.

In 1933, the national Industrial Recovery Act authorized the construction of dams and other public works as an antidote to the dour economic effects of the Depression. The development of the Colombia River was a part of this plan. Some of the dams constructed include the Grand Coulee, Bonneville, and Foster Creek. In 1933, construction began on the first of these, the Bonneville Dam. That same year construction was authorized on the Grand Coulee Dam, the third largest hydro plant in the world and the largest in the United States.

The "big dam era" of the early 1900s had a profound impact on the twentieth century. The shift to large central electric stations and large hydro projects encouraged urbanization and economic growth in many areas. Populations congregated around the large plants and encouraged industrialization. Initial construction and operation of the plants created jobs, and later businesses and industries were attracted to areas like Tennessee and New York by the lure of excess economical hydroelectricity. These large projects provided much-needed jobs during the Depression of the 1930s and helped revive local economies.

Towns and cities benefited directly from the cheap hydro, as in the case of the TVA (Tennessee Valley Authority) customers who pay approximately half of the average cost of electricity. Farms and ranches in many areas depend on hydropower to run their farms and also use the water stored by the reservoirs for irrigation and flood control, like areas along the Colorado River. Large plants like these also encourage tourism by providing reservoirs for recreation. Lake Mead is a popular vacation and recreation spot, and the Hoover Dam itself is a tourist attraction because of its size and grandeur. Government revenues from hydro plants are applied to other projects, and decrease the amount that has to be taxed.

Hydropower is a flexible, cheap, reliable, and renewable source of energy and could be of great benefit to areas like South America that have low coal resources but an abundance of water resources. The largest hydro plant in the world is located in Brazil on the Parana River. The plant began operation in 1983 and has an installed capacity of 12,600 megawatts. Hydropower does not produce pollution in its creation the way coal does, and in a time when nonrenewables like coal and oil are a concern, a renewable and clean source of energy could become even more important.

Hydropower can still have a huge impact on the environment. Areas behind the dam are flooded and habitat and land are destroyed. Substances, such as mercury, trapped in the soils, accumulate in the reservoir and poison fish stocks. Dams interrupt fish spawning by blocking their movement, and the increased siltation destroys spawning beds. People living in areas behind the dams are displaced by flooding, sometimes losing their homes and whole way of life. Some aboriginal communities in the Canadian north have lost their land and traditional way of life because of flooding caused by hydro projects. Negative impacts like these have made large hydro projects the subject of hot debate.

An effort has been made to lessen the impacts of dams and hydro projects. Some dams have fish ladders, stepped pools that allow fish movement through the dam areas, so they can continue to move up the river. However, these are not always successful. In 1968, the Wild and Scenic Rivers Act was passed to protect rivers in a natural state from hydroelectric projects. Other efforts include the push for smaller developments that serve smaller areas. These projects will not have the same profound impacts on the environment that large projects do, and could make use of many smaller dams in the country that currently do not have hydroelectric operations.

KYLA MASLANIEC