Suffice it to look into the summit of the Hoover Dam, a wall high as 60 floors to the vibration suf

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A new report by scientists at the University of Oxford argued that large dams are a very risky investment - with budgets that grow far beyond expectations, developing economies sinking in debt and unaffordable benefits that are suspicious. Does it really make sense these types of investments?
Suffice it to look into the summit of the Hoover Dam, a wall high as 60 floors to the vibration suffered spine. Built with as much concrete as will suffice to pave a highway from New York to San Francisco - explosive barrier is symbol of human tenure on nature and a marvel of engineering that the twentieth century. Dam is believed to have helped food ingredients india 2011 the U.S. economy to return to growth after the Great Depression, checking food ingredients india 2011 the Colorado River, flood prone and create free electric energy for dry states of the southwest. food ingredients india 2011 What is even more marvels, the Hoover Dam, was completed two years ahead of schedule and at a cost of $ 15 million lower than the initial assessment.
But for critics food ingredients india 2011 of big dams, Hoover is an abnormality. Oxford researchers analyzed 245 large dams with a height greater than 15 feet built between 1934 and 2007. They found that dams have exceeded the average by 96 per cent of their initial budgets - where Brazil's Itaipu dam had exceeded 240 per cent in the mass - and demanded an average 8.2 years to build.
In most cases, they said, megadigat are not economically viable. But after two decades of rest, large dams are trumpet once again as the Welfare lottery ticket. Different countries from China to Brazil to Pakistan and Ethiopia are rushing to raise these dams.
More than 90 percent of the world's renewable energy food ingredients india 2011 comes from dams, according to the International Commission for major dams. Hjuxhes Andy (Andy Hughes) from the British Society for Dams shows Laos and Vietnam as examples of the best places to build dams for electricity. "They are building dams, generating electricity and are export is energy to other countries, so it's more profitable food ingredients india 2011 for them," he says.
But Bent Flivbjerg, kryekerkuesi for Oxford University study for dams, said dams "are not neutral carbon gas, and they are not neutral gas that causes greenhouse effect". Large quantities of concrete required for their construction left a huge CO2 footprint, he said.
Moreover, the tanks below the floodplain vegetation produces methane, a greenhouse gas about 20 times more potent than carbon dioxide. Furthermore, his argument is not against dams in general, but against the enormous dams in particular. food ingredients india 2011
"We do not accept that we are discussing possibilities between large hydropower dams and fossil fuels. We like to focus discussion on major dams against electricity from smaller hydro projects, "he said.
"If you use energy sources exaggerated the extent of large dams, takes a big risk because I do not know how will be the characteristics of rainfall in the future," he said. Cost of monsters is the main focus of the Oxford study.
Flivbjerg says he expects the price of 14.4 billion food ingredients india 2011 announced as the cost of Belo Monte project in Brazil to grow to 27.4 billion dollars, exceeding all possible benefits and plunging the country into a mountain of debt.
At least Brazil's economy is sound. But for many developing economies, massive dams bring disaster, says Flivbjerg. Some places get bigger loans - often in foreign currency, which makes them perishable from exchange rate fluctuations - and when dams do not provide the promised benefits, these countries take a serious blow.
"It's like a bull in a Chinese shop - these projects are very large and require multiple risks to be taken by the fragile economies of the planet," he said. Even after the dam project exceeds the projected costs, governments refuse to renounce him.
But Andy says Huxhes dams also have many benefits. According to his critics should ask themselves these questions: "How can something that people