HYDROPOWER CHALLENGE: The Three Gorges Dam holds back the broad Yangtze River near Yichang. Could building bigger dams help prevent the proliferation of even more environmentally-costly smaller ones?
Image: © David Biello
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The proposed Xiaonanhai Dam would stand athwart the mighty Yangtze River some 30 kilometers upstream of the industrial metropolis of Chongqing. The dam represents the single largest project in that municipality's 11th five-year plan, costing roughly $3.5 billion. The growing city hopes to harvest 1.7 gigawatts of electricity from the river current of the Chang Jiang, as the Chinese call the third longest river on Earth.
The dam is just one of 19 proposed dams on the upper reaches of the Yangtze, upstream from the massive Three Gorges project near Yichang—and one of nearly 200 proposed dams on the Yangtze and its tributaries. China is building hydropower at a record pace that has resulted in more dams—26,000—than in any other country. In the last decade more than 60 percent of all hydropower projects worldwide were in China and Three Gorges alone will avoid the emission of an estimated 95 million metric tons of carbon dioxide a year—more than the combined output of Norway and Sweden.
"Within 30 to 50 years, hydropower will be the main energy we should rely on," Lai Hun Suen, a professor of sustainable development at Chongqing University and municipal government official, explained to me during a visit to the city in 2008. "It is a choice we made when we had no other choice."
That choice has consequences: At least 1.2 million people moved to Chongqing, displaced by the rising waters behind Three Gorges. Decomposing submerged vegetation burps methane—a greenhouse gas which traps 25 times as much heat as CO2 over a century. And a planned dam, Xiaonanhai, that would be built in the middle of the last remaining untouched habitat of the Yangtze sturgeon, giant salamander and 66 other fish species of concern, says Yan Xie, China Program director for the Wildlife Conservation Society. In fact, the proposed dam borders the "core protected area" of the Upper Yangtze Native and Rare Fish Reserve—an area set aside to mitigate some of the impacts of the construction of Three Gorges Dam.
"There are 338 kinds of freshwater fish in the Yangtze River and 162 of them are endemic to the river—that is, found nowhere else," says ecologist David Dudgeon of the University of Hong Kong. "It seems obvious that many or all of them could be impacted by a dam in the middle of the reserve."
The question is: Can hydropower in China be done more sustainably?
A drop in the bucket
Xiaonanhai would generate 1,760 megawatts of electricity—three quarters the yield of the U.S.'s Hoover Dam, but just eight percent of Three Gorges potential 22 gigawatts, and three percent of the 60 gigawatts from the proposed dams planned along the upper Yangtze, also known as the Jinsha River.
That's why The Nature Conservancy is working on a plan that would invest Chongqing's dam-building money into making the other dams upstream slightly bigger. "They could own as much as three times the kilowatts as they could ever get out of the little dam and keep all the fish," says lawyer David Harrison, a senior advisor to the Conservancy's Global Freshwater Program. "Chongqing could get the economic development they want, and a fish reserve. They may not appreciate it now but they will, as will their children."
Already, the Chinese paddlefish, a six-meter-long endemic species, has not been spotted in more than three years in the region and may now be functionally extinct, much like the baiji—a freshwater dolphin—downriver. "Four famous domestic fishes"—the grass, silver, black and big carps—provide protein and a livelihood to more than 10 million Chinese, yet they are dwindling in the stretch of river beneath the Three Gorges Dam, victims of the dam's development and overfishing, says Daqing Chen of the Yangtze River Fisheries Research Institute.
The solution, according to the Conservancy, is to plan hydropower development on a watershed level rather than allowing the proliferation of projects from various levels of government: county, township, city, provincial and even national. "There's wildcat dam development going on. At some level, it's out of control," says Brian Richter, director of the environmental group's Global Freshwater Program, adding that the proliferation of dams of all sizes are "just getting built in an uncoordinated fashion."
As a result, a coalition of Chinese scientists and environmentalists signed a petition this May calling for a halt to "overdevelopment" of hydropower in the Yangtze River Basin. The central government's Ministry of Environmental Protection responded in June, suspending the Xiaonanhai project pending further review—along with two other nearby dams in the Jinsha River already under construction.
The problem is not dams per se. It is the lack of planning. After all, building hydropower will also enable the proliferation of intermittent renewable energy sources, such as wind and solar. "Xiluodu [Dam] could be used to stabilize against wind and solar to a very large degree because of its size and because it's got another reservoir downstream that can dampen out any fluctuations," Harrison notes. "How many kilowatts of other renewables can you enable if you develop smartly? Building small dams in small places doesn't help you with that."
Flood control
Of course, there is also the specter of floods. Inundations in 1931 and 1954 killed hundreds of thousands along the lower Yangtze and a similar flood in 1998 displaced at least 1.8 million people. Therefore, one of the primary reasons to build Three Gorges Dam, in addition to hydropower and improved shipping channels, was to restrain the periodic, devastating flooding of the Yangtze.
But a river basin regime that also restores some of the natural floodplains—without displacing the rich rice paddies and vegetable fields that provide 60 percent of the country's food supply—could also generate more power. After all, preparing for floods means lowering water levels in the reservoir to allow for extra water, resulting in reduced hydropower output. Allowing the Three Gorges reservoir to remain at a higher water level, for example, by opening some flood storage downstream could "generate $1 billion more in hydropower revenue," Richter argues.
The key would be to inundate several hundred thousand hectares of the agricultural lands periodically during times of flood to provide as much as 15 billion cubic meters of floodwater storage—three-quarters of the 20 billion cubic meters of flood control offered by the Three Gorges reservoir itself.
But it would also involve temporarily relocating the inhabitants of these lands through early warning and compensating them for lost harvest—something China already does, such as during the 1998 flood. And some of the $1 billion in extra hydropower revenues could go into a proposed compensation fund for such displacement and lost crops, Richter argues, a plan for which Goldman Sachs is preparing a feasibility study. "Using floodplains to store floods is more reliable, safer and more economical," Richter says.
Such a plan would also more closely mimic the natural flow of the river, which is naturally high during spring and summer and low in winter, the opposite of the flow pattern imposed by dams such as Three Gorges that attempt to reserve room for floodwaters. "Fish reproduction in the Yangtze and other rivers depends on the maintenance of natural flow patterns, because it is these that set the cues for breeding and stimulate breeding migrations," Hong Kong's Dudgeon notes.
Such river basin regimes could prove vital in other areas of the world undergoing a hydropower boom, as well, Richter says. In Central America there are more than 300 dams of varying sizes planned or under construction. "What we're seeing is a very rapid proliferation of hydropower development in these countries," he says. "It's a race to build dams and get them hooked up as quickly as possible, because the first in line are the first to be rewarded in terms of revenue."
And it might help ameliorate or avoid some of the other impacts from dam construction now coming to the surface. "More than 100 miles of [Three Gorges] reservoir banks are at risk of collapsing. More than 50 percent of the reservoir area is affected by erosion and an additional 500,000 people will need to be relocated," says Peter Bosshard, policy director at International Rivers, a dam watchdog group. Further downstream there is also erosion in the Yangtze's delta as well as seawater intrusion. "Shanghai is subsiding. All these factors need to be taken into account."
Despite these concerns, dam construction continues. Coffer dams—a temporary barrier that allows work on a permanent dam to proceed—are already in place for many projects, such as the Ahai Dam on the Jinsha River, closing off yet more sections of the waterway.
"It's not just dams versus no dams," Harrison adds. "It's about elegant dams—and if we can't do that, we shouldn't build them. The proliferation of small- and middle-size ones is chewing up the whole place."
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10 Comments
Add CommentOne big omission of this article is the flow-rates of these asian rivers, which are fed by glacial meltwaters high on the Tibetan plateaus. As these glaciers melt, flows will increase until all the ice is gone. Then china, which relies massively on irrigation, will be in dire straights.
Reply | Report Abuse | Link to thisThe answer of course is to take steps globally to reduce climate change.
The answer is many, cheap, small, non-obstructive in-river turbines. Not big, expensive, risky, tricky, environmentally damaging dams.
Reply | Report Abuse | Link to thisA proliferation of little affordable ones enabling anyone living on a river to generate some output, welcome private industry, competition, innovation, maintenance & servicing jobs, etc... Even purely from an economics standpoint, much more open and exciting.
Every big action has a counter big reaction. What will it be will depend whether it is progressive or retrogative. There are certain laws of nature that haven't been understood yet. Let's wait and see.
Reply | Report Abuse | Link to thisIn the event of a major cataclism, with a major source of energy out of order, it could paralyse a whole system for quite a long time and that could be disastrous for the economy.
Big, Small, what's the difference? Hydropower alone is not enough. Nuclear power can power our world for millions of years. It's time to get serious again about building stage IV nuclear power plants and everyone except the stupid environmentalists will be happy.
Reply | Report Abuse | Link to thisConcrete production is one of the most carbon producing of construction methods. So the 3 Gorges will reduce 'carbon' input to the atmosphere by replacing carbon based electricity production....well how much carbon was released to build the world's largest dam(s)? How big has the toll been on human capital with the relocation of more than a million people? Not to mention the loss of soil replenishment from annual flooding, the loss of salt removal from the same soils from annual flooding, the nutrient loading that supported massive downstream fisheries, the sediment transport that supported agriculture, sediment transport that sustained and created wetland/delta habitats that clean up the water quality and support massive fisheries (fish reproduce in these environs and we all know China's water quality is good).
Reply | Report Abuse | Link to thisOverall, this is/was a bad thing for China and the world.
How could this compare to the Tennessee Valley Authority dam system where water is also replaced during off-peak periods?
Reply | Report Abuse | Link to thisOur American history of environmental protection and power creation has been so exemplary that I think we need to lecture *no one* on how THEY exploit their resources.
Reply | Report Abuse | Link to thisWhether it be the Amazon Rain Forest or China's rivers--it's hubris to think *we* should be the lecturer.
Fortunately for China, environmental extremists are not tolerated, unlike the situation in the US. China is growing, while we head towards a 3rd world economy. This is the direct result of the massive amounts of money sent overseas to purchase energy ... and no, renewable energy by itself can not reverse that situation.
Reply | Report Abuse | Link to thisThe article you reference on methane emissions has a headline that states "Chinese Dam MAY Be A Methane Menace". The article does NOT state how it is able to measure this methane production from the surrounding marshes; and there is no accepted international standard for measuring methane from large reservoirs that presently exists.(Reference Hydro Review magazine, Dec 2008, "Greenhouse Gas Emissions From Reservoirs: Studying the Issue in Brazil"). Therefore, the authors that wrote this article (usually overeager environmentalists) cannot prove, to any acceptable standard that the Three Gorges dam has increased methane production in the area.
Reply | Report Abuse | Link to thisResearchers have ESTIMATED from Greenland and Antarctica ice cores (Reference Goddard Institute for Space Studies, "The Global Methane Cycle" http://icpgiss.nasa.gov/education/methane/intro/cycle.html) that worldwide wetlands produce 22% of the methane gas, and rice paddies 12%. However, these figures cannot be relegated to individual marshlands or rice paddies because the method of measurement for individual marshlands, rice paddies does not exist; and an acceptable international method of methane measurement for large reservoirs is presently in the process of being established.
Moreover, if and when methods of measurements are established for individual lakes, rivers, marshlands, etc.; the question should be: To what extent have the methane emissions been elevated or reduced by the creation and operation of the hydroelectric reservoir? All freshwater systems emit Greenhouse Gasses, including methane because of the natural marshes associated with the normal river flooding and receding. Therefore, there are already GHG emissions from the natural process.
I visited Chongqing last year and was struck by the fact that this city has the largest annual vertical variation of river level of any city in the world. As a practical matter, this means that if you are getting on a river cruise ship you have to descend hundreds of feet down broad concrete steps to get to the boat. Going from the boat back to the city is like climbing from field level of a huge sports stadium up to the nose bleed seats, about twice over.
Reply | Report Abuse | Link to thisWhen the up-river dam is complete, Chongqing for the first time in its history will have a sane, stable waterfront.
China is building dams. In the USA we are tearing them down on the bet that solar and wind energy will not only supply enough electricity to keep us warm in the winter and cool in the summer, but also to do other useful dam functions, like supply water for irrigated agriculture and also to control disastrous flooding.
Americans seem to be sold on the idea that we can create a fantasy green energy world and live in it without paying a ruinous price to get there.
I also must say that everything about the Three Gorges Project looked to me to be well in control. The Chinese have done an enormous amount of landscaping to make the whole project at least look like it is in harmony with nature and I did not see any obvious signs of landslides, although the Yangtze is so bounded by steep mountains all along its length that I suppose it must happen somewhere.