23 Feb 2009
The Dam Building Boom: Right Path to Clean Energy?
Led by China, the developing world is engaged in a flurry of dam construction, touting hydropower as renewable energy in an era of global warming. But critics point out that the human and environmental costs of dams remain high.
The Jinsha River tumbles down from the highlands of the Tibetan Plateau and courses through China for more than 1,300 miles before becoming the Yangtze. Until recently, it was a free-flowing waterway that ran through the picturesque landscape of Yunnan and Sichuan Provinces, but that is changing rapidly: Taking advantage of a drop of nearly 14 feet per mile, the Chinese government is building — or planning to build — as many as 12 large dams on the Jinsha. More than 300,000 people will be displaced, numerous cultural sites will be flooded, and river ecosystems irretrievably altered.
The Jinsha’s fate is typical of many of China’s rivers, as the country is engaged in a frenzy of dam building that has left it with more dams — 26,000 at last count —than any other nation in the world. In the past two decades, hundreds have been built for hydropower production, enabling towns like Shigu — famed in China as the site at which Mao and the Red Army crossed the Jinsha as part of the Long March — to leap forward from backwaters to regional centers.
“We wish to have a better life but still live in beautiful nature,” Cun Yanfang, who was born and raised in a village on the mountainous banks of the Jinsha, told me on a recent trip to China.
In China — and throughout the developing world — that is proving to be an increasingly difficult balance to strike. What is happening along the Jinsha, the Yangtze, and dozens of other Chinese rivers is emblematic of a major resurgence of dam building worldwide — a trend that is likely to intensify as growing concerns about global warming make hydropower look more appealing.
The rapid rate of dam construction today is akin to a form of environmental and social triage, with the need for a renewable, carbon-free source of electricity taking precedence over the rights of displaced local
The need for renewable energy is taking precedence over displaced populations and river preservation.
populations and the preservation of river ecosystems. As a result, governments, the World Bank, and even some environmental groups are embracing dam construction, some with an enthusiasm not seen since the heyday of industrial dam building last century when mammoth hydropower projects — from the Hoover Dam in the United States to the High Aswan Dam in Egypt — were built.
From Brazil — where large dams have been built or are planned along the Amazon River and its tributaries — to Mozambique, India, and Laos, hydroelectric power stations are being constructed at a furious pace. The World Commission on Dams reports that there are now 48,000 dams taller than 50 feet worldwide. Hydropower stations currently under construction around the globe will, when finished, produce 151 gigawatts of electricity — the equivalent of several thousand large, coal-fired power plants. That represents nearly 20 percent of the electricity being generated by all the hydropower projects ever constructed.
Given the threat of global warming and the essential nature of electricity to development, the arguments for erecting dams seem strong. China’s Three Gorges Dam — built from 1994 to 2008 — produces electricity equivalent to roughly 500 typical Chinese coal-fired power plants, which are far smaller than coal-fired power plants in the U.S. and Europe; Three Gorges is the largest hydropower station in the world. Its output avoids the production of at least 95 million metric tons of carbon dioxide, or roughly the emissions of Norway and Sweden combined. Even Greenpeace China has called for more hydropower development (with appropriate environmental safeguards) in its "Energy [R]Evolution" plan to produce half of China’s energy needs from renewables.
Yet this surge of dam building has come at enormous human, environmental, and cultural costs. Three Gorges Dam has displaced 1.2 million people. In recent decades, Brazil has built four large dams in its
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China’s Three Gorges Dam on the Yangtze River, completed last year, is now the largest hydroelectric power station in the world.
Amazon basin and is planning as many as 70 more, including two on the main tributary to the Amazon River, the Madeira. These two huge dams would displace thousands of indigenous families, flood large areas of rainforest, and alter the river so extensively that the migration of 750 species of fish would be affected, according to the dam watchdog group International Rivers.
Recent studies also have indicated that the 320 million tons of water in the reservoir behind the newly constructed Zipingpu Dam in China’s Sichuan Province might have triggered last May’s devastating earthquake by placing stress on a major fault line less than a mile away. More than 70,000 people died in that disaster.
China outpaces all other dam building nations; in the last decade, more than 60 percent of the hydropower projects completed worldwide have been in China.
“You can see and hear rational arguments from the Chinese: climate, air pollution, diversify [energy] supply,” says Patrick McCully, executive director of International Rivers, based in Berkeley, California. “On the ground, it’s basically unregulated with companies trying to build as much as possible as fast as possible… China’s just devastating its rivers and displacing millions of people. If they are going to build hydro, then they should do it in a rational, well-planned way so that it’s only the less destructive projects that get built and they get built with more safeguards for affected people.”
Dam building creates other significant impacts as well. Drowned trees and vegetation burp methane — which traps heat at 25-times the rate of CO2 — out of the reservoirs, particularly in tropical regions like Brazil. In fact, scientists at Brazil’s National Institute for Space Research calculate that the world’s large dams are responsible for producing 104 million metric tons of methane a year — making dams the single largest source of human-caused methane.
And, ultimately, human-caused climate change may send these modern monoliths into obsolescence faster than anticipated by changing river flows, most notably by speeding the melting of glaciers. Should the glaciers in the Himalayas and on the Tibetan plateau largely disappear in the coming century, for example, not only will the drinking water supplies of more than 1 billion people be affected, but flows vital to water storage and hydropower production on rivers such as the Yangtze would be significantly reduced. Chinese scientists have found that the more than 46,000 glaciers on the Qinghai-Tibet Plateau are shrinking by an average of 7 percent annually; the bulk of water in China’s two major rivers — the Yangtze and Yellow rivers — comes from glacial melt.
“Climate change is going to very adversely effect big dams,” says anthropologist Thayer Scudder of the California Institute of Technology, who has been a consultant on dam projects to the World Bank since the 1960s and is a member of the World Commission on Dams. “These dams are going to meet relatively short-term needs. What’s the situation going to be 30 to 50 years from now, which is when they think the glaciers may be gone?”
And, while the Chinese government continues to construct dams at a feverish pace inside China, it has also taken over a role once reserved for international development banks, such as the World Bank: funding
The dam boom could mean hydropower will one day supplant coal as China's chief energy source.
dam-building in developing countries from Asia to Africa. In fact, China is now involved in funding or building more than 200 dams around the world. According to Scudder and other analysts, the goal is not combating climate change or even fostering development. Instead, they say, China is building dams in exchange for access to natural resources, such as metals, fossil fuels, and even farmland—as well as lucrative construction contracts.
For example, the China Export-Import Bank has helped launch the funding for a new 1,500 megawatt dam on the Zambezi River in Mozambique, the Mphanda Nkuwa. Building the dam would eliminate any hopes of rectifying the impacts of a previously built dam on the Zambezi river delta, which has shrunk by half as sediment and water have been choked off, crippling local fisheries and reducing fertile farmland downstream. That dam, the Cahora Bassa — built in the 1970s — required the relocation of more than 10,000 people.
Richard Taylor, executive director of the International Hydropower Association, ascribes the worldwide flurry of dam building to the run-up in the price of fossil fuels, concerns over climate change, and the desire of nations to become less dependent on foreign sources of energy. Producing electricity has become the main reason for building new dams, supplanting issues of water storage, irrigation, or flood control.
“Where hydropower is feasible,” says Taylor, “it can be the most benign and long-term economic option to meet electricity supply needs.”
In China, some analysts say that the dam building boom could mean that hydropower will one day supplant coal as the country’s chief energy source.
“Within 30 to 50 years, hydro will be the main energy we [China] should rely on,” says Lai Hun Sen, a professor of sustainable development at Chongqing University and a municipal government official who has studied the Three Gorges Dam. “It is a choice we made when we had no other choice.”
But "there are many problems," Lai says, including massive relocations of people, natural disasters such as mudslides, and water quality issues. "When the water drops, areas are exposed in the reservoir in summer, as much as 400 square kilometers,” says Lai. “When [water pollution] deposition is exposed under the sun and temperatures, some disease will spread. This will happen every year."
What’s happening on the Jinsha is typical of the frenzy of dam building throughout China, where the southwestern corner of the nation may soon have as many as 114 dams on eight different rivers. The dam projects on the Jinsha may eventually generate some 33 gigawatts of potential hydropower, equivalent to roughly 730 of China's relatively small coal-fired power plants.
Many of these dams must be built for another reason besides electricity generation: to keep Three Gorges in business. The problem is silt, which will rapidly build up behind the megadam unless it is captured by other dams upstream. In other words, building one dam means building many more.
And, ironically, the conflicting goals of local, regional and national development means more dams are being built than may ultimately prove useful, with one dam effectively depriving another of water.
“Within the last four years, the water is less than we expect,” Chongqing’s Lai says. “This is really a big problem for us.”
The environmental effects are already being felt in China. Stretches of the
The World Bank has decided once again to get more deeply involved in funding dams.
Jinsha River — “Golden Sands” in English — run red as the iron-rich dirt removed to build these dams is dumped back into the river. Already, thanks to Three Gorges and other dams, the nutrient mix in the East China Sea, where the Yangtze empties, has changed dramatically as less water and silt reach the sea.
Another sign of hydropower’s resurgence is the World Bank’s decision to once again get more deeply involved in the business of funding dams. Once strongly criticized for backing massive dam projects that displaced millions and harmed the environment, the bank has announced plans to increase lending to hydropower as part of its commitment to fund renewable energy projects. The bank’s dam funding will rise to $1.3 billion in fiscal year 2011, up from $800 million in 2008.
The resurgence of dam building has slowed somewhat in recent months, due to the global economic crisis. But few think the slowdown will be anything but temporary, according to International Rivers' McCully.
For its part, China is relying on such massive infrastructure projects as part of its 4 trillion yuan ($585 billion) economic stimulus program. If such projects can gain additional credence by acquiring the patina of combating climate change, all the better. China has applied for at least 729 new dams to receive carbon credits under the terms of the Kyoto Protocol — more than half the global total of such hydroelectric project applications.
“This is a huge scam,” McCully argues. “Three-quarters of them are already built when they go for carbon credits. It’s hard to argue that they need the carbon credits to get built.”
The decision to construct dams has always presented governments with the dilemma of balancing economic development with the rights of local populations and environmental protection. For the most part, development has trumped other concerns.
Now, with dam proponents arguing that hydropower meets the most pressing environmental need of our time — reducing greenhouse gas emissions — opposing dam construction has become doubly difficult.
“Over the short and medium term, dams remain an important development option under certain conditions,” says Scudder. “Over the long run, large dams are unsustainable development.”
Correction, Feb. 25, 2009: An earlier version of this article misstated the amount of power being produced by China’s Three Gorges Dam and that will be produced by dams along the Jinsha River system. The Three Gorges Dam actually produces electricity equivalent to roughly 500 typical Chinese coal-fired power plants, which are far smaller than coal-fired power plants in the U.S. and Europe. Dams along the Jinsha River system will eventually generate power equivalent to roughly 730 of China’s relatively small coal-fired power plants.
ABOUT THE AUTHOR
has been covering energy and the environment for nearly a decade, the last three years as an associate editor at Scientific American
. He also hosts 60-Second Earth
, a Scientific American
podcast covering environmental news. In a recent article for Yale e360
, Biello wrote about how geothermal technology can contribute to the world's energy needs.