Posted on 02/24/2005 7:47:51 AM PST by samtheman
Contrary to popular belief, hydroelectric power can seriously damage the climate. Proposed changes to the way countries' climate budgets are calculated aim to take greenhouse gas emissions from hydropower reservoirs into account, but some experts worry that they will not go far enough.
The green image of hydro power as a benign alternative to fossil fuels is false, says Éric Duchemin, a consultant for the Intergovernmental Panel on Climate Change (IPCC). "Everyone thinks hydro is very clean, but this is not the case," he says.
Hydroelectric dams produce significant amounts of carbon dioxide and methane, and in some cases produce more of these greenhouse gases than power plants running on fossil fuels. Carbon emissions vary from dam to dam, says Philip Fearnside from Brazil's National Institute for Research in the Amazon in Manaus. "But we do know that there are enough emissions to worry about."
In a study to be published in Mitigation and Adaptation Strategies for Global Change, Fearnside estimates that in 1990 the greenhouse effect of emissions from the Curuá-Una dam in Pará, Brazil, was more than three-and-a-half times what would have been produced by generating the same amount of electricity from oil.
This is because large amounts of carbon tied up in trees and other plants are released when the reservoir is initially flooded and the plants rot. Then after this first pulse of decay, plant matter settling on the reservoir's bottom decomposes without oxygen, resulting in a build-up of dissolved methane. This is released into the atmosphere when water passes through the dam's turbines.
"Drawdown" regions
Seasonal changes in water depth mean there is a continuous supply of decaying material. In the dry season plants colonise the banks of the reservoir only to be engulfed when the water level rises. For shallow-shelving reservoirs these "drawdown" regions can account for several thousand square kilometres.
In effect man-made reservoirs convert carbon dioxide in the atmosphere into methane. This is significant because methane's effect on global warming is 21 times stronger than carbon dioxide's.
Claiming that hydro projects are net producers of greenhouse gases is not new (New Scientist print edition, 3 June 2000) but the issue now appears to be climbing up the political agenda. In the next round of IPCC discussions in 2006, the proposed National Greenhouse Gas Inventory Programme, which calculates each country's carbon budget, will include emissions from artificially flooded regions.
But these guidelines will only take account of the first 10 years of a dam's operation and only include surface emissions. Methane production will go unchecked because climate scientists cannot agree on how significant this is; it will also vary between dams. But if Fearnside gets his way these full emissions would be included.
With the proposed IPCC guidelines, tropical countries that rely heavily on hydroelectricity, such as Brazil, could see their national greenhouse emissions inventories increased by as much as 7% (see map). Colder countries are less affected, he says, because cold conditions will be less favourable for producing greenhouse gases.
Despite a decade of research documenting the carbon emissions from man-made reservoirs, hydroelectric power still has an undeserved reputation for mitigating global warming. "I think it is important these emissions are counted," says Fearnside.
What we need is more windmills. Thousands of windmills.
When it comes to powering the globe and all it's inhabitants, I doubt there really is any clean way....just some that are less dirty than others.
There are hidden contradictions in the minds of people who "love Nature" while deploring the "artificialities" with which "Man has spoiled 'Nature.'" The obvious contradiction lies in their choice of words, which imply that Man and his artifacts are not part of "Nature" -- but beavers and their dams are. But the contradictions go deeper than this prima-facie absurdity. In declaring his love for a beaver dam (erected by beavers for beavers' purposes) and his hatred for dams erected by men (for the purposes of men) the "naturist" reveals his hatred for his own race -- i.e., his own self hatred.
In the case of "Naturists" such self-hatred is understandable; they are such a sorry lot. But hatred is too strong an emotion to feel toward them; pity and contempt are the most they rate.
As for me, willy-nilly I am a man, not a beaver, and H. sapiens is the only race I have or can have. Fortunately for me, I like being part of a race made up of men and women -- it strikes me as a fine arrangement and perfectly "natural."
Robert Heinlein
He is full of crap just how would this tripe compare to say Lake Powell's sand and rock??
Once you buy into the global warming and its Mankind's fault scam, you have to conclude that the world would be better off with out mankind. (Even camping and living in tents we burn fuel for cooking.)
I agree, dams and resevoirs contribute CO2 to the atmosphere. Not only filling the lake, but constructing the dam in the first place. There is no free lunch, but dams also contribute to water shortages and flood control, So on the whole maybe they are still valuable in the right circumstances. So are nuclear power plants.
And don't forget that old growth forests are net polluters anyway. They produce more CO, CO2 and CH4 (via decay and respiration) than they consume. So if you just LEAVE the forest alone, it "pollutes". These rocket scientists also forget that CO2 and methane are REQUIRED for other parts of the bio-cycles on earth and in the oceans.
Ignorance is boundless.
Already claimed in a law suit filed in California against the Altamont Pass wind turbines -- too many birdies getting whacked by the turbine blades.
Completely oil independent with about 2000 nuclear reactors in the country. Electricity would be extremely cheap, maybe enough to power cars properly.
That's mainly due to the number of people who mistake the DAM for the DISNEY WATER SLIDE.
And I will bet these nutball scientists are evolutionists to boot. 8^>
The Earth is a giant feedback control system - it has to be to counter emissions from volcanic eruptions, solar insolation variations, etc. Mankind is a very minor factor and the main debate is really over the size of that factor.
It is true, though, that nutcase left opposition to nuke power and fossil fuel power has made building dams more attractive than it might otherwise have been.
There is quite a bit of opposition to hydropower among so-called environmental activists (really Luddites). There was a hydropower dam in Maine that lost it's operating license a few years back because of opposition from some local groups, who claimed the presence of the low-head dam (which had been there for something like 40-50 years) was "disrupting the natural flow of the stream". Well, duh, that's what dams do. So they got the thing shut down and eventually blew it up.
That case is ironic because other "environmental" groups who agitate against nuclear and fossil-fueled baseload plants always tout low-head hydropower as the Golden Child of distributed power generation. To hear them tell it, there are thousands and thousands and millions and billions of suitable sites for development of low-head hydropower. Well, make up your minds, you idiots. Are you for it or against it?
There was a group out West that was demanding the "removal" (i.e., blowing up) of the Glen Canyon dam, because it had irretrievably altered the natural environment. These people are truly certifiable.
Do any of you remember the hew and cry from San Francisco when Donald Hodel suggested removing Hetch Hetchy reservoir (SF's main water supply) and restoring the Hetch Hetchy vally (touted by Muir as more beautiful than Yosemite)?
The schizophrenia is boundless.
>>>Hetch Hetchy reservoir (SF's main water supply)
Is it really? Next time I'm up there I'll have to take a ceremonial whiz...
Some of these nuts would only be happy if there were just 10 humans left on the planet.
They just dislike the human race.
"The Earth is a giant feedback control system"
I know ... I was joking about the dinosaur farts.
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