The Three Gorges Dam

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The Three Gorges Dam in China is officially the largest hydroelectric power station in the world and while its benefit to the region with regards to power supply is not in doubt there have been major environmental repercussions, controversy and furious debate. The power supplied by this power station has been vital to the growth of the Chinese economy which along with India has become one of the economic powerhouses of the world.

The initial idea of a hydroelectric power station

Situated in Sandouping, Yichang, Hubei, China the Three Gorges Dam spans the Yangtze River and is one of the largest power generation related projects in living history. However, the idea for the Dam was originally floated back in 1919 and in 1932 the nationalist government initially began work on the plans for the Three Gorges Dam. However, in 1939, during the conflict with Japan, a number of Japanese military forces occupied the area and initially began to create their own plans for a hydroelectric power plant although this was later dropped as the Japanese invasion failed and China took back control of the region.

Delays with the project

In 1944 we saw the US take a serious role in the creation of the Three Gorges Dam when a US engineering firm visited the region and assisted the Chinese authorities in putting together a more detailed plan. Such was the US involvement in the project that 54 Chinese engineers were actually sent to the States to train for the building phase only to return in the midst of a Chinese Civil War and further delays to the project in 1947.

Even after the Communist victory in 1949 the push towards the creation of the Three Gorges Dam appeared to be at full speed only for an about turn and the creation of the alternative Gezhouba Dam, then came the economic problems and cultural revolutions which dominated China for many years. In 1958 a large number of the engineers earmarked to work on the project were jailed after speaking out against Chinese rule in the infamous “Hundred Flowers campaign”.

Finally the Dam is built

The 1980s saw a strong revival in plans for the Three Gorges Dam and it was finally pushed through the National People’s Congress in 1992 although even this was not without controversy. Construction began on 14 December 1994 and finished in October 2008 (although there is still one lift to be installed) although the full power of the project will not be felt until 2011 when it will be running at full speed.

The size of the project

The Dam Wall itself is constructed of concrete and around 2300 m long, over 100 m high with walls which are 115 m thick at the bottom and 40 m thick at the top. In total the project has used over 27,000,000 m³ of concrete, nearly 500,000 tonnes of steel and around 102,000,000 m³ of earth have been moved for the project.

At full capacity the water level of the Dam will be 175 m above sea level (91 m above the level of the river) and the reservoir itself will be around 410 miles in length and nearly 1 mile wide. In total the reservoir will hold 39.3 km³of water, have a surface area of 1045 km² and flood over 600 km² of land.

The project itself has come in at around 10% under budget and is said to have cost in the region of US$30 billion although there is some confusion as to the exact cost. The Dam is expected to produce enough power to pay for itself within 10 years when it is expected to have created 1000 TWh of electricity. This is a very impressive payback period and while economically it may well justify the creation of the Three Gorges Dam there are concerns about the environment.

Generating capacity

As we mentioned above the Three Gorges Dam is the largest hydraulic power station by capacity in the world and will have 34 generators installed upon completion. Each generator has a capacity of 50 MW and upon completion of the project are expected to generate over 100 TWh per annum between them, which is some 18% more than predicted when the project was started.

To give you an idea of the size of each generator they weigh 6000 tonnes each and can accommodate a flow rate of between 600 m³to 950 m³ per second with each generator rotating at a speed of 75 rpm. On average each generator is over 94% efficient with the highest reading so far to date around the 96.5% level meaning there is very little leakage and the Dam must be one of the most cost-effective power generators in the world.

Facts about the Three Gorges Dam

The Chinese authorities estimate it takes 366 g of coal to create 1 kWh of electricity which means that the Dam itself is saving more than 31,000,000 tonnes of coal being used per year and the emission of over 100,000,000 tonnes of greenhouse gas, millions of tons of dust, 1,000,000 tonnes of sulphur dioxide, 370,000 tonnes of nitric oxide, 10,000 tonnes of carbon monoxide and a marked reduction in the amount of mercury released into the atmosphere.

The creation of the reservoir was also added a new route for the delivery of goods to China and exporting of goods around the world. It has also reduced the amount of greenhouse gases released into the atmosphere and increased efficiency of the river prior to the building of the Dam.

While the Chinese authorities were heavily criticised for the large area of land which was flooded to create the massive reservoir, they have undergone a major reforestation of the country and a net area of forestry land has been introduced since the Dam was built, even taking into account the forestry which was taken away when the reservoir was created.

Conclusion

While there is no doubt that the creation of the Three Gorges Dam now provides the Chinese authorities with the most efficient power generation system in the world it must also be remembered that a large area of China paid the price for the creation of the massive reservoir which feeds the generation system. Homes were lost, forestry was lost, animal habitats were lost which is why the project has and continues to attract so much controversy and argument amongst governments and environmentalists around the world.

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