Three Gourges Dam - Biggest in the World !!
Trip Start Jun 13, 2006
88Trip End Jun 12, 2007
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Everything about this project is staggering. Most of the figures are so big, they are incomprehensible but in 2009 when it is finished, it will produce 22,000 MW which is more than 4.5 times the entire Irish electricity requirement.
Plans for the dam go back a long time but in the late 30's an American team were invited by the Nationalists who controlled this area to came and have a look. The spot was chosen and described as the best location in the world for a huge dam, mainly due to the very good geological conditions
There were three main reasons for constructing the dam.
First it will produce loads of cheap, clean electricity. This will be done by the water spinning 32 turbines. 26 will be in the main dam wall but they then realsied there was enough water for more so they are putting in a bypass tunnel around the dam and will put another 6 turbines in there - just like that !!
Secondly it will improve the navigation on the river and now 10,000 ton or quite big ships will be able to sail to lots of cities 1,000 miles into China's interior year round and with a huge saving in fuel oil use. This will be possible with deeper and calm waters for 600 km's in the reservoir above the dam and by increasing the depth below the dam in the dry season with controlled water release.
Thirdly and probably most importantly, the dam will be able to control flooding which has claimed millions of lives in the past with a major floods every 6 years or so. The normal operating water height in the dam will be 175m above sea level. In the rainy season this will be dropped to 145m thus a huge amount of water can be stored and released gradually to prevent major flash floods down river.
There a two massive 5 stage ship locks that can lift a 10,000 ton ship up the 100m in about 4 hours. Only one is in operation right now but eventually, one will take traffic going up and the other will take traffic going down river.
There is also a ship elevator which will lift a 3,000 ton ship the 100m in about 30 minutes. The ship will sail into a massive tray of water and the elevator will lift the tray, the water and the ship totaling 19,000 tons the 100m. Pretty amazing stuff.
This is all positive but as I went through in the Chongqing update there are some major negatives.
To create the reservoir for 600 above the dam, the river level has risen 80 already and will go up another 20 meters in 2009
There will be considerable environmental issues as well. Several rare plants and animals will lose there natural habitat and there is sure to increased pollution form the increase shipping particularly the human waste from cruise ships if untreated. On the flip side, China is needs power and this a very clean way of producing it. Also moving goods by ship uses far less fuel than road or rail transport does.
The argument will probably go on forever but compared to the 10,000MW and 12,000MW Dam's at Guri and Itipu in Venezuela and Brazil respectively, the area flooded here is very small thus the evaporation losses are very small and the resultant change in the local climate will be very limited.
I guess if they find a cheap and very environmentally friendly way of producing power soon, history will call the dam a negative project but if they don't it will be considered positive. In Communist China though, its a mute point and there are already several more dams under contraction on the Yangtze which together will produce far more juice than this one. Either way, from a simple engineering point of view, it is truly amazing wonder of the industrial world !!