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 have here... Is "The Enema Within!"
You have no right to exist!
Oh ho ho ho... That's good!!! They, like Hunter, have no redeeming social value!!!
Ahhhhhh Yes... Of cours... NOT!!!
Chornobil? It was a kind of combination of meltdown and burnup. The initial power transient caused significant comminution of the fuel and some melting, with decay heat causing the additional melting. The dispersion was driven primarily by the subsequent graphite fire. Fission products were being released from the fuel as the burning proceeded and likely wouldn't have gone far unless borne aloft by the heated air from the fire.
There were some destructive tests done in the 1950s as part of the SPERT and BORAX tests, but those were test reactors.
So your point is valid. Certainly LWR technology as used in the West is a very forgiving design. For a zero-emissions source of reliable, affordable baseload electricity, it is hard to beat.
BTTT!!!!!
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PERSPECTIVES: RISING CO2 LEVELS - THE REASON WHY ~~The earth has a cycle
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DO ADJUST YOUR SCREENS>>>>
The left wants us to be naked cave families.
Peta wouldn't be happy about the fur coats
we would wear. No power or fuel no more
synthetic fabrics.
They aren't called the Loony Left for nothing.
I forgot to mention that the left will never
live the lifestyle they preach about.
First a correction to my previous post... "over 24 times the current level" was intended to read "almost 24 times the current level".
Second: What about the world wide mass of vegetation that decays along every water way and coastline, every creek, stream, river, lake and sea? Vegetation decay due to dams is miniscule in comparison.
Yet methane levels have not increased. Go figure.
Where are the real scientists today?
Life in general is a bad thing for the environment.
Especially Human life.
What a crock!
I hope that idiot don't get his water from one of them bad boy reseviors or I would call him a hypocrite!
Burn off the vegetation before it rots! Get fast results over the time released version of emissions.
A log on the fire releases no more CO than decaying matter, but it releases stored energy faster. But the wackos don't like anything that benefits mankind or gasp......makes a profit!
Its called "I've got mine."
So, global warming or global cooling? From what I've seen of either model, the measured data points seem "noisy". That is, they have large error bars. Attempting to benchmark various models with such data comes close to GIGO, and basing public policy on GIGO is probably a bad idea.
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