Or why isn't it ever on the lists of green power sources if it is green. I know it does have an environmental impact in that rivers are diverted, dammed, etc. Is that the reason it's never on the green lists? Do the benefits not outweigh the impact? I'm not being facetious - I really don't know the answer.

I'd think it would be at least preferable to, say, coal, which is terribly environmentally damaging in the mining process and in the burning process.

I ask all this because I'm on hydroelectric power, and I have the option of buying blocks of "green" electricity, presumably from solar or wind turbine projects.

subbing...i'm interested in the answer.

Yes, it is because of the diversion of rivers, etc. The d.amming (freakin' word filter wouldn't let me spell it out :rolleyes: ) of the rivers has enormous impact on the wildlife population both in and out of the water. Factor in the disturbance of then using the water (you can't send the fishies through the turbines) and what the entire process does in terms of changing the charge of the water and then the microbiology gets all messed with, which further effects things. Having lived in the PNW for most of my life the fate of the salmon and other fish in relation to the hydroelectric power was always a clear concern.

*Micro* hydro is green, though. You don't have to dam or divert to do it. You pull the power off a small brook or stream by using a small turbine-like device, I believe (I talked w/our local independent power guy and he explained it to me via phone...this is what I remember him saying).

So it's as I suspected, eh? I know that the hydro we use affects everyone South of us. And, just as an added bonus, our water comes from the same river/lake, and it's treated and returned. Imagine the biological upset of all that combined.

It's my understanding that it essentially splits one eco system into 2. Generally speaking the turbines prevent life from passing to the other side.

I believe there are friendly or at least forgiving systems that have breaks in the power to allow fish to move or migrate or whatever. But for the most part, they're not all that green.

There was some talk of a hydro system here in southern MN and the Dept of Natural Resources (fisheries) provided the argument against one and stopped it in the planning stage. But we still have dry cask nuclear waste storage sitting on the banks of the mississippi so.... :shake:

There is also a economic split between massive hydroelectric dams and smaller projects.

The justification for larger dams is not, usually, meeting demand. It's usual raison d'etre is to create electricity and presumably demand, and industry, employment, and prosperity will follow. Some of the outrage is from economists that these persistently backward regions persist in poverty despite the dam. To meet demands, usually, one chooses a least expensive option- usually coal. To create demand, one builds boondoggles. This includes the dam system running through central Texas, the Tennessee Valley Authority, and Aswan. There's a giant honking dam in China. I think it might actually be the only one built to meet current demand. Jane Jacobs writes about this in "Cities and the Wealth of Nations."

The "massive infrastructure debts" of the third world- many of these are for dams. Unfortunately, stripping the tax base, and the ground, is not a way to leave money for maintenance.

There's also, let's see, standing water- therefore there are mosquitoes, carrying heart-breaking diseases. Somehow, also, the ground gets salted up. I don't know how this works, or if this is a side effect of using da.mmed water for irrigation. Worms. schists, other parasites....

Also, construction projects= graft. Now, in a poorly run economy, anything=graft. But still, more money, more graft, more powerful kleptocrats. It's not a good feeling to be a sincere member of the world bank, supposedly well-travelled and worldly, getting taken by "third world businessmen." There is a strong element of racism, and colonialism mixed in with all this, although I don't know or understand how. I read about it vaguely and occasionally. I do know that big dams are things one "does unto" rather than being "done unto."

Smaller dams- micro generators- ones that are easier to maintain, and "fit" the energy needs profile of a region ( even the region of a single farm) are not as upsetting. In fact, if you google around, there's an article in this Sunday's NYTimes business section about the Aga Khan financing microdams in east africa. This is considered an extraordinarily good thing.

There's also the unease associated with dams. They always, always, always, upset the current balance of an economy. Monasteries figured them out in the middle ages, and became prosperous and serene. England figured them out, and became more stably wealthy than France. New England figured them out before the South. Lowell- Lowell, Cabot and Lodge (??) okay, lowell and his partners, opened the first integrated water mill powered mills for textiles.in AMerica Their descendants are still living on this patrimony ( Lowell the poet, sponsor of imagism) ( the death knell of popular poetry)

Mostly they employed young farm women who were out to earn dowries. They published a newspaper. They lived in dormitories. The paper's writing was uplifting and ambitious, but not radical. In a sense, they were the progenitors of "chick lit."\

must go.
ari

There is also a economic split between massive hydroelectric dams and smaller projects.

The justification for larger dams is not, usually, meeting demand. It's usual raison d'etre is to create electricity and presumably demand, and industry, employment, and prosperity will follow. Some of the outrage is from economists that these persistently backward regions persist in poverty despite the dam. To meet demands, usually, one chooses a least expensive option- usually coal. To create demand, one builds boondoggles. This includes the dam system running through central Texas, the Tennessee Valley Authority, and Aswan. There's a giant honking dam in China. I think it might actually be the only one built to meet current demand. Jane Jacobs writes about this in "Cities and the Wealth of Nations."

The "massive infrastructure debts" of the third world- many of these are for dams. Unfortunately, stripping the tax base, and the ground, is not a way to leave money for maintenance.

There's also, let's see, standing water- therefore there are mosquitoes, carrying heart-breaking diseases. Somehow, also, the ground gets salted up. I don't know how this works, or if this is a side effect of using da.mmed water for irrigation. Worms. schists, other parasites....

Also, construction projects= graft. Now, in a poorly run economy, anything=graft. But still, more money, more graft, more powerful kleptocrats. It's not a good feeling to be a sincere member of the world bank, supposedly well-travelled and worldly, getting taken by "third world businessmen." There is a strong element of racism, and colonialism mixed in with all this, although I don't know or understand how. I read about it vaguely and occasionally. I do know that big dams are things one "does unto" rather than being "done unto."

Smaller dams- micro generators- ones that are easier to maintain, and "fit" the energy needs profile of a region ( even the region of a single farm) are not as upsetting. In fact, if you google around, there's an article in this Sunday's NYTimes business section about the Aga Khan financing microdams in east africa. This is considered an extraordinarily good thing.

There's also the unease associated with dams. They always, always, always, upset the current balance of an economy. Monasteries figured them out in the middle ages, and became prosperous and serene. England figured them out, and became more stably wealthy than France. New England figured them out before the South. Lowell- Lowell, Cabot and Lodge (??) okay, lowell and his partners, opened the first integrated water mill powered mills for textiles.in AMerica Their descendants are still living on this patrimony ( Lowell the poet, sponsor of imagism) ( the death knell of popular poetry)

Mostly they employed young farm women who were out to earn dowries. They published a newspaper. They lived in dormitories. The paper's writing was uplifting and ambitious, but not radical. In a sense, they were the progenitors of "chick lit."\

must go.
ari



i want to be ari when i grow up

i want to be ari when i grow up

Me, too.

Tom the hydrologist says, "basically, because they dam rivers..before that it was considered green. In the right sort of place where damming is not done or minimized, it can be considered green"

Ok, so the power coming to my house isn't green (though it is less polluting, right? - the sewage treatment is a separate issue), but a better designed system without, say Buford Dam and the resultant Lake Lanier might be?

I was planning to buy some of the green power blocks, anyway (that was an entertaining argument with DH), but now I have more reasons. You know, in case he ever looked at the bill and asked. Which would never happen because that would require that he actually look at a bill. :rolleyes:

BLUSH!

ari

From a co2 perspective Hydro is very green, from a one time impact to the local wildlife hydro power is not so good. Of course the amount of flooding really varies on the local terrain.



Hydro Dams do not remove the electricity from the water, instead they use the water to turn the turbines and produce electricity. Here's a Wikipedia article. Fishes and other marine animals can go through hydro ****s safely. Since the water is pushing the turbine (as opposed to the turbine chopping up the water) small animals do not get chopped up, instead for the most part they just come out a little stunned and continue to swim on their way. BC Hydro has a great page that discusses the effects of Hydro Dams on local wildlife. BC Hydro - Environment - Water and Fish Habitat (http://www.bchydro.com/environment/waterlandair/waterlandair1773.html) The only kind of animals that have problems fitting through the turbine blades are already in trouble of they are in the water, think cows, sheep, goats etc.



The chief advantage of hydroelectric dams is their ability to handle seasonal (as well as daily) high peak loads. When the electricity demands drop, the dam simply stores more water (which provides more flow when it releases). Some electricity generators use water dams to store excess energy (often during the night), by using the electricity to pump water up into a basin. Electricity can be generated when demand increases. In practice the utilization of stored water in river dams is sometimes complicated by demands for irrigation which may occur out of phase with peak electrical demands.



Here in Manitoba, Manitoba Hydro actually controls the levels of the big lakes with their hydro dams which is really beneficial, in times of drought they slow the flow of water through those dams keeping the water level fairly constant, this helps the local wildlife and fish stocks.



Chances are Hydro isn't listed as a green power source because the poll creators didn't think of it.



Other people have thought of it and do consider it a green power source:

NYPIRG: Green Electricity (http://www.nypirg.org/energy/green_electricity/green.html#table1)

Green Power - Maine's Green Power Menu (http://www.mainegreenpower.org/menu/index.shtml)

Green Power - A Consumer Guide to Green Power in Canada (http://www.pollutionprobe.org/whatwedo/greenpower/consumerguide/c1_1.htm)

PM - Green power credits (http://www.abc.net.au/pm/stories/s615698.htm)

http://www.rmi.org/images/PDFs/Energy/E01-21_GreenPowerGospel.pdf

How does a dam change the dynamics of a river system?

http://img98.imageshack.us/img98/3893/dameffects63147aui4.jpg (http://imageshack.us)


Changes flow regime downstream (decreases variability):

prevents flooding.
active flood plain and or channel system can narrow (with associated loss of riverine habitat).
floods no longer act as recharge events for the shallow alluvial aquifer.
flood silts are no longer deposited on flood plain.
Changes water chemistry and temperature downstream:

exit water typically colder and lower or depleted in oxygen, with a higher organic content, and possibly hydrogen sulfide gas.
can cause change in biota.
can decrease the natural biodegradation capability of the river.
somewhat increased salinity of waters due to the evaporation.
Loss of water from reservoir basin due to ground seepage:

Loss of water due to evaporation:

Lake Powell is estimated to lose 10% of its capacity per year to evaporation.
function of local climate and surface area.
Changes sediment load downstream (decreases it), serving as a sediment trap.

can cause widening of river channel for several miles downstream.
can cause river downcutting.
may decrease shoreline sand budget.
eventual the dam can silt up. Typically a delta builds at the upper end of the reservoir.

Produces a shore line environment:

this can include increased marginal vegetation that can increase loss through evapotranspiration.