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pleco
SFN Addict
USA
2998 Posts |
 Posted - 08/16/2005 : 18:35:36 [Permalink]
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quote:
Originally posted by Dr. Mabuse
quote:
Originally posted by pleco
I had heard that wind farms change the airflow to the point of having an affect on the weather...anyone know about this?
Hardly much more than say... A Redwood forest.
Yeah, but the forest has been there a while and occurred over a long time...here we are talking about a sudden change...
but, you may be right. It might not amount to anything. I wasn't suggesting it would, just if anyone had heard that. |
by Filthy
The neo-con methane machine will soon be running at full fart. |
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 08/16/2005 : 19:36:42 [Permalink]
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quote:
Originally posted by R.Wreck
Wind takes a lot of room for the amount of energy produced. US electricity consumption was 3.66 trillion kwh in 2002. Assuming a 1.5 MW wind turbine with a (very optimistic) 50% capacity factor, you would need more that 557,000 wind turbines to supply the US needs. If Dave's figure of 17 acres/MW installed generation is correct, then you need over 14,000,000 acres for those wind turbines.
Now wait a second, there.
Your assumptions take a single 1.5 Mw turbine, and plops it down on 25.5 acres (17 acres/Mw). But the page I linked to said that at that time, turbines of less than 500 Kw made up the bulk of then-installed systems, and doesn't seem to mention anything larger than a 600 Kw turbine by specific number. 17 acres/Mw seems clearly the wrong number to use with individual 1.5 Mw turbines.
But, it's the only number we've got. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dr. Mabuse
Septic Fiend
Sweden
9687 Posts |
Posted - 08/16/2005 : 20:06:35 [Permalink]
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quote:
Originally posted by pleco
quote:
Originally posted by Dr. Mabuse
quote:
Originally posted by pleco
I had heard that wind farms change the airflow to the point of having an affect on the weather...anyone know about this?
Hardly much more than say... A Redwood forest.
Yeah, but the forest has been there a while and occurred over a long time...here we are talking about a sudden change...
but, you may be right. It might not amount to anything. I wasn't suggesting it would, just if anyone had heard that.
The height of the structures, and given that they aren't tightly packed, most of the wind goes between them and above them. Definitly above them. What's the average height of clouds? Rain clouds or cumulus?
Back in the school days I think I read the efficiency of a windmill was below 30% for the area it covered, so the influence should be minor. |
Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3
"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse
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NubiWan
Skeptic Friend
USA
424 Posts |
Posted - 08/16/2005 : 20:38:45 [Permalink]
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I think one real unspoken issue here, is the possible outcome of people in large numbers, unplugging from the grid all together. Think I saw a blurb about some engineers had come up with a (?) gearbox thingy that could make this more likely, just a few days ago. I think it would be a 'good thing,' but then there are those who don't.  |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 08/16/2005 : 22:13:48 [Permalink]
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That number of 17 acres/Megawatt doesn't seem right...
If there are single wind turbines that can produce up to 4.5Mw...
http://www.vestas.com/uk/Products/products2004/prodOverview_UK.htm
Even GE (evil corporation that they are) makes a 3.6MW wind turbine....
http://www.gepower.com/businesses/ge_wind_energy/en/index.htm
The thing is big, but it doesn't sit on 17 acres.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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H. Humbert
SFN Die Hard
USA
4574 Posts |
Posted - 08/16/2005 : 23:03:17 [Permalink]
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quote:
Originally posted by NubiWan
I think one real unspoken issue here, is the possible outcome of people in large numbers, unplugging from the grid all together. Think I saw a blurb about some engineers had come up with a (?) gearbox thingy that could make this more likely, just a few days ago. I think it would be a 'good thing,' but then there are those who don't.
I read an article about this idea not too long ago, but I've forgotten almost all of it.  Essentially the idea is everyone gets a little windmill (or whatever) in their backyard and supplies only the electricity they need for their house. Sounds like a good idea to me. Besides technological limitations, what are the cons? I mean, why doesn't eveyone think this would be a good thing?
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"A man is his own easiest dupe, for what he wishes to be true he generally believes to be true." --Demosthenes
"The first principle is that you must not fool yourself - and you are the easiest person to fool." --Richard P. Feynman
"Face facts with dignity." --found inside a fortune cookie |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 08/16/2005 : 23:34:19 [Permalink]
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Or, you make a small investment in your house, get a couple turbines, and sell your surplus back to the local power company...
You buy power from the grid only when there is no wind. Put some solar panels on your roof to supplement...
I pay, averaged out, $160/month in electricity for a 900sq/ft dwelling. Friend of mine I just asked has a 1800sq/ft house, his power bill averages out to $280/month for electricity.
I have no idea what an initial investment would be like to convert a house to a wind/solar combo set up to sell any surplus back to the grid, and draw from the grid only when needed....
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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Tim
SFN Regular
USA
775 Posts |
Posted - 08/17/2005 : 00:59:08 [Permalink]
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Believe it or not, there really is some real efforts to harness wind power. Down here on the US Gulf Coast we have some things starting up. This involves using the old offshore oil rigs for wind farms. There's a few pluses to this idea. The rigs act as natural reefs and cost extra dollars to remove. The only people that will see them are fisherman, offshore workers and pilots.
The drawbacks include the cost of laying the electrical cable and other financial considerations that I'm not really convinced of, yet. And, of course, the danger to birds in one of the world's most imprtant migratory routes is often cited. The bird problem is a very serious consideration here. Most of the migratory birds fly pretty much non-stop across the Gulf. When they reach the coast line between New Orleans and Galveston they really can't fly anymore. They're so tired that we've been able to get within just a few feet of normally skittish wading and perching birds.
I hope they can they could find a way to prevent these birds from attempting to perch around the wind turbines.
Relying on only one source of energy is never too bright. Look at the problems we'd face if OPEC cut us off here in the US, and we also use coal, natural gas, waste oil, hydroelectric and nuclear power for alternative energy sources.
The chemical plant I now work for, (for one more week!), has their own power plant. They use oil to heat boilers. Then, they use the steam to drive turbines. The company routinely produces much more steam than they use, and can produce much more power than they consume with limited increased environmental impact. They only run two or three of six turbines at one time. They used to sell this extra potential back to the power company, but no longer do. I've heard that new laws make this deal unprofitable for one or both of the companies involved. I wonder if anyone else here would know anything about this. Does state or federal governments no longer provide tax incentives for these types of deals?
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"We got an issue in America. Too many good docs are gettin' out of business. Too many OB/GYNs aren't able to practice their -- their love with women all across this country." Dubya in Poplar Bluff, Missouri, 9/6/2004
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Dr. Mabuse
Septic Fiend
Sweden
9687 Posts |
Posted - 08/17/2005 : 05:37:11 [Permalink]
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quote:
Originally posted by Dude
That number of 17 acres/Megawatt doesn't seem right...
<snip>
The thing is big, but it doesn't sit on 17 acres.
17 acres gives a ~260x260 meters area. The last link pointed to a rotor with a diameter of ~110m that leaves a little more than 50% to spare to the "boundary" of that acre, perpendicular to the wind. As long as all the windmills are located that way, then yes 17 acres is much. And the power rating, is that an year-average, or calculated on a minimum wind force?
But the rotor is creating turbulence, which means that any power-station downwind will experience a drop in efficiency when the wind turns from the optimal angle from the line of mills set up.
To me, the 17 acres/MW seems reasonable. |
Dr. Mabuse - "When the going gets tough, the tough get Duct-tape..."
Dr. Mabuse whisper.mp3
"Equivocation is not just a job, for a creationist it's a way of life..." Dr. Mabuse
Support American Troops in Iraq:
Send them unarmed civilians for target practice..
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 08/17/2005 : 06:58:45 [Permalink]
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With a 3.6 Mw turbine, you'd have to "reserve" 61.2 acres of land to drag the average power generation down to 1 Mw per 17 acres. 61.2 acres is a plot of land 250m by 990m.
But, technically-speaking, if you make a line of these things perpendicular to the wind, you should be able to only use about 150mx150m for each one (allowing 46m between turbine blade sweeps), or 5.6 acres each. That gives an average of 1.56 acres per megawatt, or almost 11 times the power density of the 17-acre figure.
But, land "use" is a bit of a misnomer, since apparently there are people grazing cattle around wind turbines, and I imagine that there could be lots of different recreational uses of such land.
In none of the technical specs for the 3.6 Mw turbine do I see land-area requirments. I'm guessing they depend more on the geography and prevailing winds than the design of the turbine itself. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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R.Wreck
SFN Regular
USA
1191 Posts |
Posted - 08/17/2005 : 15:18:54 [Permalink]
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quote:
Originally posted by Dave W:
quote:
--------------------------------------------------------------------------------
Originally posted by R.Wreck
Wind takes a lot of room for the amount of energy produced. US electricity consumption was 3.66 trillion kwh in 2002. Assuming a 1.5 MW wind turbine with a (very optimistic) 50% capacity factor, you would need more that 557,000 wind turbines to supply the US needs. If Dave's figure of 17 acres/MW installed generation is correct, then you need over 14,000,000 acres for those wind turbines.
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Now wait a second, there.
Your assumptions take a single 1.5 Mw turbine, and plops it down on 25.5 acres (17 acres/Mw). But the page I linked to said that at that time, turbines of less than 500 Kw made up the bulk of then-installed systems, and doesn't seem to mention anything larger than a 600 Kw turbine by specific number. 17 acres/Mw seems clearly the wrong number to use with individual 1.5 Mw turbines.
But, it's the only number we've got.
Yes, these were some "back of the envelope" calculations using some numbers that were thrown out here. What the calculations assume, though, is that all that energy use is spread out evenly over the year across the country, which is not how actual consumption works out. You have to have installed capacity to cover your peak load, and you can't average over the whole country because of transmission restraints. So to actually supply all US electricity consumption with wind (as I read Dude's OP as suggesting) would take even more MW of installed capacity than my calculations assumed. Even adjusting the MW per turbine and the acreage per MW, it still works out to a hell of a lot of windmills taking up a lot of ground.
Again, this is not to say we shouldn't harvest wind energy. Just realize that practically speaking, it is only part of the answer. |
The foundation of morality is to . . . give up pretending to believe that for which there is no evidence, and repeating unintelligible propositions about things beyond the possibliities of knowledge.
T. H. Huxley
The Cattle Prod of Enlightened Compassion
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 08/17/2005 : 16:03:11 [Permalink]
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quote:
So to actually supply all US electricity consumption with wind (as I read Dude's OP as suggesting) would take even more MW of installed capacity than my calculations assumed.
I wasn't suggesting that we only use wind, but rather an astonishment that wind could provide more power than the planet uses.
Obviously, with a power source dependent on something like wind, you'd have to have other sources to supplement. Not to mention the need, as you pointed out, for peak demand in population dense areas.
I was thinking that something more like a combination of solar, wind, hydro, and nuclear would be more than capable of eliminating the use of fossil fuels, with no sacrifice in convenience or reliability. The technology is readily available, it works, and it would only increase in efficiency as it was used more.
The barrier, as I see it, is political, rather than any technological or practical barriers to implementing a comprehensive plan. Which was what my initial point was meant to be.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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R.Wreck
SFN Regular
USA
1191 Posts |
Posted - 08/17/2005 : 17:40:57 [Permalink]
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quote:
Originally posted by Dude:
I wasn't suggesting that we only use wind, but rather an astonishment that wind could provide more power than the planet uses.
Obviously, with a power source dependent on something like wind, you'd have to have other sources to supplement. Not to mention the need, as you pointed out, for peak demand in population dense areas.
I was thinking that something more like a combination of solar, wind, hydro, and nuclear would be more than capable of eliminating the use of fossil fuels, with no sacrifice in convenience or reliability. The technology is readily available, it works, and it would only increase in efficiency as it was used more.
The barrier, as I see it, is political, rather than any technological or practical barriers to implementing a comprehensive plan. Which was what my initial point was meant to be.
Sorry if I misunderstood your OP.
The chart on this page shows that fossil fuels account for about 70% of our electricity production (coal ~50%, natural gas ~16%, and oil 2%). That's a lot of megawatts to replace. There's not really any hydro left to develop (in fact, in the northwest, they are removing some dams to restore the rivers close to their original state). And I don't think the country is ready to quadruple the number of nuclear plants. Too much social and political opposition currently, although you would think the lack of emissions would please environmentalists.
That leaves wind, solar, geothermal, and tidal/wave power, none of which is currently ready for such large scale deployment. There are some technical / economic limitations to wind and solar. You need to find sites with enough wind or sunshine to generate economically, and then build transmission to those sites, because many of them are, if not exactly in the middle of nowhere, pretty close to it. Although there are megawatts to be had with wind and solar farms, I think there is at least as much promise for wind and solar in small scale distributed applications. Windmills and solar panels on buildings, solar water heating, etc. Building designs which minimize power use can also save power. Can solar, wind, and conservation replace coal? I don't know. The big advantage of coal is that it works whether or not the sun shines or the wind blows.
I'm all for saving gas and oil for their best uses. I think it is criminal to burn natural gas for baseload electric generation, when it is so much more useful (and there are less alternatives) for home heating and some industrial processes. Same for oil. You can't put coal or wind power in your gas tank, so why burn oil to make electricity? |
The foundation of morality is to . . . give up pretending to believe that for which there is no evidence, and repeating unintelligible propositions about things beyond the possibliities of knowledge.
T. H. Huxley
The Cattle Prod of Enlightened Compassion
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Dave W.
Info Junkie
USA
26020 Posts |
Posted - 08/17/2005 : 19:04:16 [Permalink]
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R.Wreck, how does one properly convert between kWh and required generation wattage? Assuming a steady flow and no peaks, is it as simple as multiplying, say, 3.6 Mw by 24 for kwh in a day's use, or by 24*365.24 for kwh for a year's use? I mean, is it the case that if that 3.66 trillion kwh were evenly spread over a year and over geography, we'd need 418 Gw of generating capacity going 24/7?
If so (going back to dreaming, here), with your generous 50% capacity factor, and a 30% availability factor for wind, then we'd really need 2790 Gw of generation, or about 620,000 of those 4.5 Mw monsters. Guessing at 4 per square km, we can install all of them on 155,000 km2 of land (or sea), or about the size of Georgia. Yeah, 2% of the US - including Hawaii and Alaska. |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
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Dude
SFN Die Hard
USA
6891 Posts |
Posted - 08/18/2005 : 00:17:48 [Permalink]
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quote:
That leaves wind, solar, geothermal, and tidal/wave power, none of which is currently ready for such large scale deployment.
I'd say that if the incentive, political and financial, were there the technology we currently have would easily be ready to use. GE sells the things commercially.... how much more "ready" would it have to be, for wind anyway? Tidal also is just a different application of hydro power. Solar could stand to be a little more efficient, yes, but the current state of the technology is certainly viable for some use. Geothermal... still just a concept.
I'm not suggesting a sudden total conversion.
The demand for power is always increasing. More and more is demanded of the grid everyday. New generation capabilities are brought up, old stuff gets worn out and has to be replaced.
Why use fossil fuels to expand and replace, when you could just as easily use wind, solar, nuclear, or (in the right places) hydro?
If the political incentives were in place (like the subsidies and tax breaks for current fossil fuel sources) to encourage new power rescources to be exploited (wind, solar, etc) and the incentives for expanding the fossil fuel burning removed, we could phase out the large majority of fossil fuel burning power plants.
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Ignorance is preferable to error; and he is less remote from the truth who believes nothing, than he who believes what is wrong.
-- Thomas Jefferson
"god :: the last refuge of a man with no answers and no argument." - G. Carlin
Hope, n.
The handmaiden of desperation; the opiate of despair; the illegible signpost on the road to perdition. ~~ da filth |
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