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Renewable Energy: Hydroelectric power

© Savithri Shimada

Hydroelectric power plants use the movement of water to turn turbines which generate electricity. The hundreds of years, people have used the motion of water to help irrigate fields and pump pistons. The Chinese used waterwheels to begin a chain of cogs turning, which eventually moved a huge block of wood up and down to pulverise grain. Simpler water wheels placed in flowing rivers and streams were used to move water through pipes into fields.

Hydroelectricity has been used since the late 1800s, and its technology was implemented on a grand scale during the Great Depression, when Franklin D. Roosevelt commissioned the Grand Coulee Dam on the Columbia River. This was hailed as one of the greatest achievements of the time, and the plant generated more than enough electricity to power its surrounding population and send more to power-hungry California far to the south.

Hydroelectric power plants require the creation of huge dams along waterways. Water flows into the dams and is only released over ledges or spillways. The concentrated flow of rushing waters travels through turbines, usually more than once, and electricity is thus generated. Many conservationists warn that this apparently clean power source is in fact not at all environmentally sound. Damming rivers can cause a lot of harm to river ecosystems, not to mention the displacement of people living near the river. The negative impact of the co-called clean and renewable energy sources will be discussed in later articles.

Despite increasingly negative attitudes, in 1991 the Chinese National People's Congress approved a plan to begin construction on a $10 billion dam at the spectacular Three Gorges on the Yangtze River. The purpose of the dam was both to control flooding, which had already killed over 300,000 people since 1900, and to help meet the country's huge demand for electricity. Operating costs of hydroelectric dams are relatively low, and this dam is being designed to deliver 18 thousand megawatts of power, over 18% of the nation's generating capacity at the time of the proposal.

It is difficult from our standpoint to judge the merits of this decision. It has been seen throughout the world that damming great rivers have reduced their flow and scenic value considerably. The Snowy River Scheme in New South Wales, Australia, was supposed to have been a great social achievement as well as an engineering marvel, bringing together labourers and professionals from all over the world to construct a hugely successful hydroelectric dam on the Snowy River. The Snowy River, once a roaring waterway that inspired Banjo Patterson's great ballad, "The Man from Snowy River," is now reduced to a mere trickle at times, because of the huge amounts of water diverted to the dams. We know from this example and many others that the environmental costs of damming rivers can be significant, but when facing a nation where millions of people have less electricity than is needed to light their small homes, it is hard to know whose needs should come first. If there is an alternative, environmentally sound alternative to creating sufficient electricity, then it should be taken. But if not, what is the right decision?