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Stupid little electricity/math question....

Old 08-17-05, 10:23 AM
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Stupid little electricity/math question....

Hoover dam produces 2,080,000 killowatt hours of electricity. Random gas co-gen plant produces 250 megawatt hours of electricity. How much more electricity does Hoover dam produce?
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Old 08-17-05, 10:36 AM
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Originally Posted by kvrdave
Hoover dam produces 2,080,000 killowatt hours of electricity. Random gas co-gen plant produces 250 megawatt hours of electricity. How much more electricity does Hoover dam produce?
Just convert Hoover to MWh, Mega = 10^6, kilo = 10^3,
so Hoover is 2080 MWh vs gas plant 250 MWh.

Hoover could probably make more if it had more water. Most hydro plants are water supply limited. In general, and especially for any alternative energy like hydro, solar, wind, it is nice to know both the peak capacity in kilowatts or megawatts, and the total power generated annually in megawatthours, or whatever units. Most coal, nuke, and other base plants are up 24/7 except for a few days a year for maintenance, typically better than 8640 hours per year (of 8760). Most alternative energy are lucky to hit 1/3 that.
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Old 08-17-05, 10:36 AM
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1 megawatt = 1000 kilowatts

so randon gas co-gen plant produces 250,000 kilowatts

so Hover looks to generate about 8x as much
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Old 08-17-05, 10:43 AM
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Well, that's what I was coming up with, but it certainly seems like Hoover Dam ought to be able to produce far more than that. Probably due to the size of the thing.
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Old 08-17-05, 11:13 AM
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There's some confusion on watts and watt-hours here. (I don't know whether that applies to your gas plant too)

http://www.engineering.com/content/C...entId=41007006
Generation of low-cost hydroelectric power for use in Nevada, Arizona, and California. Hoover Dam alone generates more than 4 billion kilowatt-hours a year - enough to serve 1.3 million people. From 1939 to 1949, Hoover Powerplant was the world's largest hydroelectric installation; with an installed capacity of 2.08 million kilowatts, it is still one of the country's largest
More authoritative link but harder to c&p the facts I want:
http://www.usbr.gov/power/data/sites/hoover/hoover.html

The capacity is 2.08 million kW (or 2080 MW or 2.08 GW)
The total power per annum is 4 billion kWh (or 4 million MWh, 4000 GWh, or 4 TWh, depending on your unit preferences).

They only have enough water for about 2000 hours of full power per year. However, with 17 turbines, they could run a few turbines all the time instead. The government article admits generation is severely limited by water availability.

Last edited by OldDude; 08-17-05 at 11:16 AM.
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Old 08-17-05, 11:21 AM
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I have been comparing everything in watt hours. Looks like nukes currently running are anywhere between 500 megawatt hours and 1300 megawatt hours. We have a new 250 mega watt hour gas fired plant near us, and it is so small, comparatively, that I assumed other plants must really push out the power.

When you consider that the aluminum plants along the Columbia River can handle 500 megawatt hours of electricity at full capacity, it puts it in perspective.
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Old 08-17-05, 11:26 AM
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Think of it this way. Hoover dam can produce 2 GW of power. Since P=I^2R, you would get 1.4 amps across a billion ohm resistor. The Randon gas co-gen would only give you 0.35 amps across a billion ohm resistor.
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Old 08-17-05, 11:30 AM
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Originally Posted by kvrdave
I have been comparing everything in watt hours. Looks like nukes currently running are anywhere between 500 megawatt hours and 1300 megawatt hours. We have a new 250 mega watt hour gas fired plant near us, and it is so small, comparatively, that I assumed other plants must really push out the power.

When you consider that the aluminum plants along the Columbia River can handle 500 megawatt hours of electricity at full capacity, it puts it in perspective.
My dad used to tell freshman chemistry students that they used, per capita, x number of megawatt hours a year. He'd ask, "Have you used your share?" Then he'd explain that all that electricity went into aluminum plants, and start his lecture about metallic elements.
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Old 08-17-05, 11:33 AM
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Originally Posted by Nick Danger
Think of it this way. Hoover dam can produce 2 GW of power. Since P=I^2R, you would get 1.4 amps across a billion ohm resistor. The Randon gas co-gen would only give you 0.35 amps across a billion ohm resistor.
I would like to subscribe to your newsletter. Flesh that out for me if you would.
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Old 08-17-05, 11:51 AM
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Originally Posted by kvrdave
I have been comparing everything in watt hours. Looks like nukes currently running are anywhere between 500 megawatt hours and 1300 megawatt hours. We have a new 250 mega watt hour gas fired plant near us, and it is so small, comparatively, that I assumed other plants must really push out the power.

When you consider that the aluminum plants along the Columbia River can handle 500 megawatt hours of electricity at full capacity, it puts it in perspective.
You're not making a lot of sense, Dave. A kilowatt-hour is a unit that is much the same as a gallon of water. It's a fixed amount, not a rate of production. It's like saying that your kitchen faucet produces 300 gallons. 300 gallons total? 300 gallons per day? What?

Like OldDude posted above, Hoover produces 4 billion kWh's per year. Saying that a plant produces "250 mega watt hour" doesn't mean anything unless you say over what period of time it produces that.

The way you compare power plants is by capacity. Hoover has a capacity of 2.08 million kW, which is how much actual power it could pump out per hour, in theory. That's the max load, in other words.

Last edited by Otto; 08-17-05 at 11:56 AM.
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Old 08-17-05, 11:57 AM
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Originally Posted by kvrdave
I have been comparing everything in watt hours. Looks like nukes currently running are anywhere between 500 megawatt hours and 1300 megawatt hours. We have a new 250 mega watt hour gas fired plant near us, and it is so small, comparatively, that I assumed other plants must really push out the power.

When you consider that the aluminum plants along the Columbia River can handle 500 megawatt hours of electricity at full capacity, it puts it in perspective.
I think all those megawatt-hours are really just megawatts of capacity.

But you are right on size comparison. I recently toured a 1200 MW coal-fired power plant. It was really two 600 MW coal units in the same building; it was HUGE. They had a bunch of 100 MW gas-fired "peakers" (can be run up, shut off fast as load varies). Six of them would have been much smaller than the 600 MW units, but much more expensive to run.

Rember that Hoover is mostly dam, not mostly turbine. The turbine room is probab;y quite small. Even at the plant I toured, the turbine room was tiny compared to boiler, coal crusher, water conditioners.
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Old 08-17-05, 11:59 AM
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So, can I sell you a HUGE 3 MW wind turbine?
700 of them could roughly equal Hoover (if the wind blows 30 mph)
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Old 08-17-05, 12:03 PM
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Originally Posted by OldDude
Rember that Hoover is mostly dam, not mostly turbine. The turbine room is probab;y quite small. Even at the plant I toured, the turbine room was tiny compared to boiler, coal crusher, water conditioners.
Compared to the dam itself, yes, the turbines are a bit small. Compared to, say, an elephant, the turbines are a bit on the large side. There's also quite a lot of them. The turbine room itself is extremely large and somewhat vertigo-inducing when you're looking out from the upper viewing area.

It's worth taking the trip out there if you're ever in Vegas. The tour kinda blows now that you can't go down to the turbines anymore, but it's still a rather impressive feat of engineering.
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Old 08-17-05, 12:23 PM
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Originally Posted by Otto
You're not making a lot of sense, Dave. A kilowatt-hour is a unit that is much the same as a gallon of water. It's a fixed amount, not a rate of production. It's like saying that your kitchen faucet produces 300 gallons. 300 gallons total? 300 gallons per day? What?

Like OldDude posted above, Hoover produces 4 billion kWh's per year. Saying that a plant produces "250 mega watt hour" doesn't mean anything unless you say over what period of time it produces that.

The way you compare power plants is by capacity. Hoover has a capacity of 2.08 million kW, which is how much actual power it could pump out per hour, in theory. That's the max load, in other words.
Sorry. I was talking about what it produces in an hour. Not sure I have heard it compared or discussed differently around here ("here" being in dam country).
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