The Three Gorges Dam

IB SL

Hydroelectric Power

• A dam is built to trap water, usually in a valley where there is an existing lake.

• Water is allowed to flow through tunnels in the dam, to turn turbines and thus drive generators.

• Notice that the dam is much thicker at the bottom than at the top, because the pressure of the water increases with depth.

• Hydro-electric power stations can produce a great deal of power very cheaply.

Hydroelectric Power: Pros Vs ConsPros Cons

Once the dam is built, the energy is virtually free.

The dams are very expensive to build.However, many dams are also used for flood control or irrigation, so building costs can be shared.

No waste or pollution produced. Building a large dam will flood a very large area upstream, causing problems for animals that used to live there.

Much more reliable than wind, solar or wave power.

Finding a suitable site can be difficult - the impact on residents and the environment may be unacceptable.

Water can be stored above the dam ready to cope with peaks in demand.

Water quality and quantity downstream can be affected, which can have an impact on plant life.

Hydro-electric power stations can increase to full power very quickly, unlike other power stations.

Electricity can be generated constantly.

What Is It?

• The Three Gorges Dam is a hydroelectric dam that spans the Yangtze River by the town of Sandouping, located in the Yiling District of Yichang, in Hubei province, China.

• It is the world's largest electricity-generating plant of any kind, and second in production.

• The dam body was completed in 2006 and the originally planned components of the project were completed on October 30, 2008, when the 26th generator in the shore plant began commercial operation. Each generator has a capacity of 700 MW.

• Six additional generators in the underground power plant are not expected to become fully operational until 2011.

What Is It?

• Coupling the dam's 32 main generators with 2 smaller generators (50 MW each) to power the plant itself, the total electric generating capacity of the dam will eventually reach 22.5 GW.

• The project produces electricity, increases the river's shipping capacity, and reduces the potential for floods downstream by providing flood storage space.

• From completion through September 2009 the dam has generated 348.4 TWh of electricity, covering more than one third of its cost.

Controversy

• The Chinese state regards the project as a historic engineering, social and economic success, with the design of state-of-the-art large turbines, and a move toward limiting greenhouse gas emissions.

• However, the dam flooded archaeological and cultural sites and displaced some 1.3 million people, and is causing significant ecological changes, including an increased risk of landslides.

• The dam has been a controversial topic both in China and abroad.

Facts

• 2 km long and 100m high.• The lake is over 600 km long.• Over 1m people have been moved (resettled)

to make way for the dam and lake.• The Yangtze river provides 66% of China’s rice

and contains 4m people.• The Yangtze drains 1.8m km2 and discharges

700 km3 of water annually.

Advantages

• Flood Control. • Chinese officials note that the dam will relieve the danger of

flooding.• Emissions reduction. • Another advantage of the dam is to reduce emissions of

sulphur dioxide and carbon dioxide.• China is enforcing tight rules aimed at preventing

construction work from causing environmental pollution, while advanced facilities are being installed to treat construction waste.

• By the year 2000, over 90 percent of waste water from construction is expected to be treated.

Disadvantages• Relocation. • Chinese officials estimate that the reservoir will partially or completely

inundate 2 cities, 11 counties, 140 towns, 326 townships, and 1351 villages. • About 23800 hectares, more than 1.1 million people will have to be resettled.• It will threaten the river's wildlife. • The dam will alter the natural environment, and therefore, an almost infinite

number of species will be affected by the project.• The Three Gorges project will submerge some of China's most famous

historical scenery and tourist sites.• The weight of millions of tons of water behind a dam can increase the chances

of an earthquake.• The dam will disrupt heavy silt flows in the river. • It could cause rapid silt build-up in the reservoir, creating an imbalance

upstream, and depriving agricultural land and fish downstream of essential nutrients.

Pros Vs Cons

• Supporters say the benefits of the project far outweigh thecosts.

• The principal advantage of the project is to generate power to keep pace with China's economic growth.

• It is estimated that China's power output must rise by 8 percent annually to keep pace with 6 percent annual increase in gross national product.

• In practical term, that means the nation's total 1990 power capacity of 130 million kilowatts must grow to 580 million by the year 2015.

Activity

• Using Geography An Integrated Approach P540 answer the following questions...

1.Discuss the benefits and problems of hydroelectricity for both people and the environment.

2.Explain the importance of the 3 Gorges Dam specifically on China’s development.

3.What economic costs and benefits will the 3 Gorges Dam bring to China?