Questions tagged [hydroelectric-dams]
21 questions
25
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5 answers
Why don't hydroelectric plants use cascades of turbines instead of single turbines?
In a gas turbine engine there're multiple sets of blades - one set after another and combustion products pass all the sets and each set of blades gets some of the power. This increases utilization of power from burning gas.
Meanwhile hydroelectric…
sharptooth
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Why do hydroelectric plants use turbines instead of an efficient 'water wheel' configuration?
I have been thinking about hydroelectric plants and I have been wondering why they are built the way they are. As in understand it, a stream of water is sprayed at a turbine, located at the bottom of a dam (Pelton Turbine.) This does not seem to…
Hoytman
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Does a spillway failure have different consequences versus dam failure?
I noticed this Tweet about the Oroville Dam concerns this week:
Seems most media is not emphasizing/noting the distinction. Is there a difference in the consequences of a spillway failure? Seems intuitively that the release of water might be…
JeopardyTempest
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How and WHY does the tension in an arch dam or bridge change as the degree of curvature and radius of curvature change?
Arch bridges operate according to the following (I am assuming arch dams are the same):
Tensional force in arch bridges are virtually negligible. The natural curve of the arch and its ability to dissipate the force outward greatly reduces the…
K-Feldspar
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Different equations for Hydropower
I was doing some reading in hydropower and I came across these two power equations:
$$P = ρghQ $$
and
$$ P = QHg $$
Q is flow rate, ρ is water density, g is gravity, h is height, and H is head.
I do not understand why the second equation has no…
STOI
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Why do dams deplete rivers?
I have often heard of cases where dams reduce the flow rate of rivers downstream. This makes sense in cases where some of the water that is captured by the dam is used for irrigation and such, but in some cases, dams are built solely for hydro…
kloddant
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Pumped storage hydropower, how to power the pumps?
Regarding pumped storage hydropower,
In the case of some high altitude upper reservoir that feeds several turbines located at the bottom of a valley, where there's a lower reservoir too.
Assuming in this case turbines are not reversible by design,…
user12750
1
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0 answers
What's the smallest hydropower plant that can blackstart a grid?
One of the most underrated capabilites of classical, large-scale hydropower plants is their ability to "black start" a dead electric grid. I'm not going to go into details on the blackstart process here, or why hydroelectric plants are better at it…
ThreePhaseEel
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How can a masonry dam not require mortar?
A Masonry Dam is build out of individual stones or bricks. The Wikipedia link says that it is "sometimes" joined with mortar, and has a cite for it but the link is 404 dead.
Is that really true? How could a masonry dam not require mortar? The dam…
DrZ214
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Where are the energy losses here?
This hydroelectric system, described in The Study of Syphon and Applied in Hydroelectricity Power Production, is said to be continuous once it has been set up. Once set up it is claimed that it will continue to generate electricity without any…
n7unity
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Does the volume of water going through a hydroelectric dam matter?
How does the volume of water going through a hydroelectric dam affect electricity production? Could the flux of the generators not be modulated to different amounts of electricity with the same flow of water? If so, what would the minimum flow be?
Derek Seabrooke
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Instead of dams to tap hydroelectric power, why not just pipe the river from further upstream, and then let the water fall down a great height?
Using a canal/aqueduct system for hydroelectric power rather than a dam
The hydroelectric power extracted by a river dam is related to the height of the water at the dam (with greater heights translating to higher water pressure at the bottom of the…
Ash90
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Can the kinetic energy formula (1/2 m v²) be used in finding amount of energy a hydro electric station can produce?
Say you have 20 kg of water moving at a speed of 10m/s, if the KE formula is used, it would have 1000 joules of energy per second. Is this accurate or is there another way of calculating it?
user29722
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How to move water to a new dam?
There are many videos on Youtube about opening of new dams, where the water is already ready to go though the dam.
What I wonder is how engineers moves water to a new dam.
To me it seams as a chicken and egg problem.
Are explosives involved?
And…
0
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calculation for hydropower project
I'm studying a hydro-power project in high rise building.
given a 100 story building(3 meter per floor) with 2.5 cubic meter of water per floor DAILY with 1 or more tanks within the floors and turbine at the ground. goal is to have the highest…
yon1000
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