Study suggests real-world generating capacity of wind farms at large scales has been overestimated

Feb 25, 2013
New research by David Keith suggests that we may not have access to as much wind power as scientists thought. Credit: Rose Lincoln, Harvard News Office

Research by Harvard professor David Keith suggests that the global capacity for energy generation from wind power has been overestimated, and that geophysical / climate effects of turbines will reduce the benefits of large-scale power installations.

"People have often thought there's no upper bound for —that it's one of the most scalable power sources," says Harvard applied physicist David Keith. After all, gusts and breezes don't seem likely to "run out" on a global scale in the way oil wells might run dry.

Yet the latest research in mesoscale atmospheric modeling, published today in the journal Environmental Research Letters, suggests that the generating capacity of large-scale wind farms has been overestimated.

Each wind turbine creates behind it a "wind shadow" in which the air has been slowed down by drag on the turbine's blades. The ideal wind farm strikes a balance, packing as many turbines onto the land as possible, while also spacing them enough to reduce the impact of these wind shadows. But as wind farms grow larger, they start to interact, and the regional-scale matter more.

Keith's research has shown that the generating capacity of very large wind power installations (larger than 100 square kilometers) may peak at between 0.5 and 1 watts per square meter. Previous estimates, which ignored the turbines' slowing effect on the wind, had put that figure at between 2 and 7 watts per square meter.

In short, we may not have access to as much wind power as scientists thought.

An internationally renowned expert on climate science and technology policy, Keith holds appointments as Gordon McKay Professor of Applied Physics at the Harvard School of Engineering and Applied Sciences (SEAS) and as Professor of Public Policy at Harvard Kennedy School. Coauthor Amanda S. Adams was formerly a postdoctoral fellow with Keith and is now assistant professor of geography and Earth sciences at the University of North Carolina at Charlotte.

"One of the inherent challenges of wind energy is that as soon as you start to develop wind farms and harvest the resource, you change the resource, making it difficult to assess what's really available," says Adams.

But having a truly accurate estimate matters, of course, in the pursuit of carbon-neutral energy sources. Solar, wind, and hydro power, for example, could all play roles in fulfilling energy needs that are currently met by coal or oil.

"If wind power's going to make a contribution to global energy requirements that's serious, 10 or 20 percent or more, then it really has to contribute on the scale of terawatts in the next half-century or less," says Keith.

If we were to cover the entire Earth with , he notes, "the system could potentially generate enormous amounts of power, well in excess of 100 terawatts, but at that point my guess, based on our climate modeling, is that the effect of that on global winds, and therefore on climate, would be severe—perhaps bigger than the impact of doubling CO2."

"Our findings don't mean that we shouldn't pursue wind power—wind is much better for the environment than conventional coal—but these geophysical limits may be meaningful if we really want to scale wind power up to supply a third, let's say, of our primary energy," Keith adds.

And the climatic effect of turbine drag is not the only constraint; geography and economics matter too.

"It's clear the theoretical upper limit to wind power is huge, if you don't care about the impacts of covering the whole world with wind turbines," says Keith. "What's not clear—and this is a topic for future research—is what the practical limit to wind power would be if you consider all of the real-world constraints. You'd have to assume that need to be located relatively close to where people actually live and where there's a fairly constant wind supply, and that they have to deal with environmental constraints. You can't just put them everywhere."

"The real punch line," he adds, "is that if you can't get much more than half a watt out, and you accept that you can't put them everywhere, then you may start to reach a limit that matters."

In order to stabilize the Earth's climate, Keith estimates, the world will need to identify sources for several tens of terawatts of carbon-free power within a human lifetime. In the meantime, policymakers must also decide how to allocate resources to develop new technologies to harness that energy.

In doing so, Keith says, "It's worth asking about the scalability of each potential energy source—whether it can supply, say, 3 terawatts, which would be 10 percent of our global energy need, or whether it's more like 0.3 terawatts and 1 percent."

"Wind power is in a middle ground," he says. "It is still one of the most scalable renewables, but our research suggests that we will need to pay attention to its limits and climatic impacts if we try to scale it beyond a few terawatts."

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More information: iopscience.iop.org/1748-9326/8/1/015021

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QuixoteJ
3.5 / 5 (13) Feb 25, 2013
"In order to stabilize the Earth's climate..."

Umm... what?
Shootist
3.2 / 5 (22) Feb 25, 2013
That green proponents lie is a given.
praos
3 / 5 (16) Feb 25, 2013
100 TW? The whole earth receives about 100 000 TW of solar energy, using about 0.25% or 250 TW of it to move the air about. Weather systems are extremely fragile. If 1% shift in global temperature (3K) courts dissaster, probably even less than 1% change in global wind energy, especially if not spred uniformly, could be fatal for environment. Wind energy is a joke, and a very dangerous one. Stop this scam and go nuclear, there is no other way.
antialias_physorg
3 / 5 (10) Feb 25, 2013
You'd have to assume that wind turbines need to be located relatively close to where people actually live

The man has heard of power lines and energy grids? Windfarms are already being built way off shore and large distance (meditarranean spanning) powerlines are already being planned for the DESERTEC initiative (which doesn't incorporate wind farms, but you can use similar supply lines for them).

as soon as you start to develop wind farms and harvest the resource, you change the resource, making it difficult to assess what's really available

Erm. How about: no? You change the resource downwind - but not the resource you planned your windpark for in the first place.

larger than 100 square kilometers...

I'm not aware of anyone planning such large wind parks. The larges wind farm in the world is barely a third that size
The Alchemist
2.8 / 5 (11) Feb 25, 2013
Goodness, just think about all the trees we cut down that used to do the same without generating power.
Still, we need to put small delocalized WGs on top our homes, etc.. The higher you get above 40 ft, the more constant the wind is.
kochevnik
3.1 / 5 (15) Feb 25, 2013
@praos 100 TW? The whole earth receives about 100 000 TW of solar energy...If 1% shift in global temperature (3K) courts dissaster, probably even less than 1% change in global wind energy, especially if not spred uniformly, could be fatal for environment.
A 1% change would be 1000Tw. World consumption from all sources is 15Tw. That's now 1%. It's 0.015%. You fail basic arithmetic yet you claim to be able to postulate scientific hypotheses? LOL!
That green proponents lie is a given.
They are often seen lying in the grass!
Goodness, just think about all the trees we cut down that used to do the same without generating power.
Trees and kittens are destroyers of worlds, at least according to our resident nuclear propeller heads
antialias_physorg
3.6 / 5 (9) Feb 25, 2013
That's now 1%. It's 0.015%.

And one might add that even the most fundamentalist green energy proponent wouldn't advocate wind-energy beyond 30% of the mix. So we're down to 0.005%. Max. I'd say the world could take that.

If 1% shift in global temperature (3K) courts dissaster, probably even less than 1% change in global wind energy, especially if not spred uniformly, could be fatal for environment.

I think you're missing a very basic concept here. It's not like the energy taken from wind gets 'lost to the environment' somehow. Like the wind it is taken from it eventually gets converted to heat - only via a different route.

Fossil fuels (and nuclear BTW) ADD energy to the environment that was otherwise sequstered.

Wind is a zero sum game when it comes to global energy shifts. Coal, gas, oil and nuclear aren't.
Modernmystic
1.8 / 5 (5) Feb 25, 2013
Wind is a zero sum game when it comes to global energy shifts. Caol, oil and nuclear aren't.


Neither is fusion :P
antialias_physorg
3.7 / 5 (7) Feb 25, 2013
Neither is fusion

Fusion is nuclear, isn't it?

Though there are degrees of effect and nuclear (any) is arguably more benign from a global warming perspective than fossil fuels.

I'm not sure I'd want fusion as the main source of energy, as it does create some radioactive waste.
But it would be one hell of a good backup source for those very occasional days when no other power sources are available - or for those particular endeavours where a lot of energy is needed and the grid wouldn't be able to supply it (several ways of lifting off into space come to mind)

And of course off world - especially if you're far away from the sun - having fusion energy is a must.
Modernmystic
2 / 5 (4) Feb 25, 2013
Fusion is nuclear, isn't it?


Come, come, now anti...I'm quite sure you and I know that isn't the nuclear you had in mind when you wrote that :) I could be wrong, and if so I apologize for the inference. I'm quite sure you were speaking of fission...I just wanted to point out zero sum sources of energy qua zero sum sources of energy should not be considered "good" on that basis alone.
Modernmystic
3 / 5 (8) Feb 25, 2013
@praos 100 TW? The whole earth receives about 100 000 TW of solar energy...If 1% shift in global temperature (3K) courts dissaster, probably even less than 1% change in global wind energy, especially if not spred uniformly, could be fatal for environment.
A 1% change would be 1000Tw. World consumption from all sources is 15Tw. That's now 1%. It's 0.015%. You fail basic arithmetic yet you claim to be able to postulate scientific hypotheses? LOL!
That green proponents lie is a given.
They are often seen lying in the grass!
Goodness, just think about all the trees we cut down that used to do the same without generating power.
Trees and kittens are destroyers of worlds, at least according to our resident nuclear propeller heads


I find it hysterical that most of the proponents of wind when pinned down are horrified that you're suggesting we run the world off wind power and then make estimates about how that might work...
blackwater
2.7 / 5 (7) Feb 25, 2013
Still no move on the Thorium reactors....17 years later. They could eliminate all the dangers of current reactors. I guess too much money has been invested in wind and solar energy projects and too many vested interests to diversify now....i say let them fall on their arses and get the thorium up and winning...does its name alone not give the game away????
antialias_physorg
2.6 / 5 (5) Feb 25, 2013
I'm quite sure you and I know that isn't the nuclear you had in mind when you wrote that

True. But as the global climate argument goes the point is still valid.
(The reason I threw nuclear in there was just because when running down the list of possible energy sources this is something I never actively realized before. The argument "adds to global warming" is certainly not in the top ten against fission, though)

I find it hysterical that most of the proponents of wind when pinned down are horrified that you're suggesting we run the world off wind power

Since no one ever suggested that we do - it's only hysterical that someone would even think that anyone ever proposed such a thing.
The only source that misconception can come from is from the hyperbole bandied about those that want to conserve the current mix of power production.
Modernmystic
3 / 5 (8) Feb 25, 2013
So what happens when the world consumption of energy is 150TW...1500TW?

What percentage of wind should cover those respectively?
antialias_physorg
2.6 / 5 (5) Feb 25, 2013
Why would the world consume that much power?
Power consumption per person is already dropping in top industrialized nations (and the population explosion isn't going to go on forever, either)

But even if we would take that ridiculous number of 1500TW: If we supply 30% of world power with wind we'd still only be at 0.5% of windopower extracted. And as noted: since wind energy extraction is a zero sum game it doesn't really matter how much you take.

Modernmystic
2.9 / 5 (7) Feb 25, 2013
And as noted: since wind energy extraction is a zero sum game it doesn't really matter how much you take.


And I don't accept that. You're transforming energy which DOES effect the system even if it doesn't add or subtract energy. It will effect heat distribution of the planet to one degree or another. This is a simple fact just as one more mole of CO2 in the air will have an effect...period.

World energy consumption as a trend is on the rise and has been since the human race existed. It's a fact, look it up.

Moreover you didn't answer my question directly, you deflected.
antialias_physorg
3.4 / 5 (5) Feb 25, 2013
It will effect heat distribution of the planet to one degree or another.

Yep. But it will not add to the GLOBAL energy content. It may affect local stuff very close to the wind farm (and that's pretty negligible the more you put these things off shore)

It will not add to the energy in the atmosphere so it will not make storms worse.
Actually it will make them less intense, as windfarms take energy from a concentrated source and distribute it to consumers over a much larger area to be turned into heat. So windfarms will, if anything, even out atmospheric energy distributions.

World energy consumption as a trend is on the rise and has been since the human race existed.

No trend lasts forever. Linear extrapolation is naive in any context.


you didn't answer my question

What question? What percentage should be covered by wind? I'm thinking 30% sounds about right (as noted in my post). But that depends on how easily other sources are deployed by comparison.
TheGhostofOtto1923
1.5 / 5 (15) Feb 25, 2013
Weather systems are extremely fragile
Who says?
If 1% shift in global temperature (3K) courts dissaster, probably even less than 1% change in global wind energy, especially if not spred uniformly, could be fatal for environment.
Who SAYS?
Wind energy is a joke, and a very dangerous one. Stop this scam and go nuclear, there is no other way
Well we'll have to do a study on the relative effects of cooling towers and the warming of rivers and the ocean from cooling water before we can begin to make a meaningful comparison.

Global warming is increasing winds and violent weather events is it not? Perhaps we NEED to slow winds down a bit.

Perhaps the strategic location of wind farms could help to mitigate increased wind and weather caused by the extra energy in the atmosphere.
TheGhostofOtto1923
1.6 / 5 (14) Feb 25, 2013
But I really dont see how wind towers which barely reach 5% into the troposphere can affect air circulation much, or even compare to the deforestation and urbanization which has taken place across the planet within the last 100 years.

If anything arent windfarms restoring this wind resistance in some small way?
TheGhostofOtto1923
1.6 / 5 (14) Feb 25, 2013
Still no move on the Thorium reactors....17 years later.
Wrong. Research.

""China is the country to watch," said Baroness Bryony Worthington, head of the All-Parliamentary Group on Thorium Energy, who visited the Shanghai operations recently with a team from Britain's National Nuclear Laboratory.

"They are really going for it, and have talented researchers. This could lead to a massive break-through."

"At the least, it could do for nuclear power what shale fracking has done for natural gas -- but on a bigger scale, for much longer, perhaps more cheaply, and with near zero CO2 emissions.

"The Chinese are leading the charge, but they are not alone. Norway's Thor Energy began a four-year test last month with Japan's Toshiba-Westinghouse to see whether they could use thorium at Norway's conventional Halden reactor in Oslo."
blackwater
5 / 5 (3) Feb 25, 2013
To TheGhostofOtto1923 ...thanks for the update, it has been a while since i read up on it so i wasn't aware it had taken off and was convinced it was still being ignored and underfunded. Will have to look into China and Norway now...
Caliban
2.4 / 5 (11) Feb 25, 2013
If I am not mistaken, our Pr Kieth of Harvard is the same one who had research published a few months back(and an article here on PHYSorg)saying that we were not, in fact, eperiencing longer, more severe (aka intensified, AGW-driven) drought in recent years, but rather, that these observations were merely an artifact of an incomplete set of metrics used to quantify them.

This research suggested that drought had more inputs than were commonly used to define what constituted drought and its relative intensity.

Long story short, he presented a fatuous, specious justification to attempt the invalidation of on-the-ground oservation of drought, in a backdoor effort to undermine the causality of intensified drought via AGW.

Even if it isn't the same researcher, the methodology remains the same, largely for the same purpose, probably funded by the same interests -which is to convince us that it is pointless to struggle to find any alternative to our inevitable fossil fuel energy future.
ODesign
3.7 / 5 (3) Feb 25, 2013
This only affects big dense wind farms with lots of windmills next to each other.

Seems like good science but we can easily just spread the windmills out more to avoid the problem. Zoning laws might need to be updated to allow this, but zoning seems like a small problem easily worked around now that we know about it. This research is what wind energy solution planning is about, and a good way to spend dollars for making a better next generation of wind power solutions.
mjlavall
3 / 5 (6) Feb 26, 2013
Even if it isn't the same researcher, the methodology remains the same, largely for the same purpose, probably funded by the same interests -which is to convince us that it is pointless to struggle to find any alternative to our inevitable fossil fuel energy future.


I think many of you have missed to boat on what this article is trying to express. Dr. Keith's research merely notes that the scalability of wind power is not as great as some have predicted. Due to the facts listed in the article, such as the wind shadows produced by wind farms and the effects that large numbers of wind farms would have on global wind patterns. Previous models ignored many of these side effects, leading to higher predictions of estimated wind power scaling. He is just pointing out that there are major differences between the theoretical and applied aspects of wind power. Wind power is fine and dandy, but not something that we will be basing our energy economy around.
The Alchemist
3 / 5 (6) Feb 26, 2013
Fossil fuels (and nuclear BTW) ADD energy to the environment that was otherwise sequstered.

SHAZAM! & well said!
kochevnik
2.7 / 5 (6) Feb 26, 2013
@MM
And as noted: since wind energy extraction is a zero sum game it doesn't really matter how much you take.
And I don't accept that. You're transforming energy which DOES effect the system even if it doesn't add or subtract energy.
It certainly doesn't effect it, and you failed to elaborate how energy conversion AFFECTS it either. Probably because you have no idea. Nobody noticed that even the wild numbers posted prior by a luddite amount to a 0.015% change. I challenge you to distinguish that from measurement noise
thingumbobesquire
2 / 5 (4) Feb 26, 2013
We require increasing density of energy throughput to accommodate humanity's need to industrialize and eventually colonize space. So called renewables are thereby ruled out. Nuclear fusion is the only source that fits this requirement. Beyond that matter anti-matter reactions will be the next plateau beyond fusion. These green energy "debates" are signs in fact of suicidal tendencies among "elites" governing our society.
baldur_norddahl
5 / 5 (2) Feb 26, 2013
The study claims 0.5 to 1 watt generating power per square metre for a 100 square kilometre farm. This equals 50 to 100 MW generating power for said wind farm.

However this is contradicted by existing large scale offshore wind farms. For example the Danish Anholt offshore wind farm has a generating power of 400 MW and is 88 square kilometres.
Steven_Anderson
3 / 5 (6) Feb 26, 2013
"Still no move on the Thorium reactors....17 years later. They could eliminate all the dangers of current reactors. "

I have attempted to get a petition signed by the public to study the efficacy of the thorium reactors. No luck. People are too lazy to sign up for a "We the People" account. I did however manage to get the White House to work on a future feature of the "We the People" site that will allow signing of petitions using Facebook, Google , Myspace identifications for quick signatures. I will try again in six months when that happens to push for work on the LFTR Reactors. http://rawcell.com
Modernmystic
2.3 / 5 (6) Feb 26, 2013
It certainly doesn't effect it,


It certainly does effect it. Lower wind speeds are going to effect how efficiently heat is circulated around the planet. It's not rocket science. If you take energy out of a system and move it to other work the work it otherwise would have done doesn't GET done. Do you need me to explain it as if you were three years old??
TheGhostofOtto1923
1.7 / 5 (11) Feb 26, 2013
It's not rocket science. If you take energy out of a system
-But it is atmospheric science which is a LOT more complicated yes? The fastest computers in the world are tasked with trying to model it. Lots of things affect circulation. For instance:

"the U.S. area devoted to roads and parking lots covers an estimated 16 million hectares (61,000 square miles), an expanse approaching the size of the 21 million hectares that U.S. farmers planted in wheat last year...

"At 61,000 square miles, that is bigger than the state of Georgia ...If you took all the paved area and made it into it's own state, it would rank 24th in area. Maine is ranked 39th at 35,385 square miles."

-All within the last century. Add to this deforestation for farms, homes, golf courses, fires, dams, reservoirs, mining, logging, etc.

How does all this work into your simple equation?
CapitalismPrevails
3.5 / 5 (11) Feb 26, 2013
I wonder if "climate change" has been overestimated?
Modernmystic
2.3 / 5 (6) Feb 26, 2013
How does all this work into your simple equation?


How does it escape your complex one?

If you slow down wind speeds how will it NOT effect the climate?

Will god make up the difference? The Easter Bunny?
LGeorge
3.7 / 5 (3) Feb 26, 2013
Each wind turbine creates behind it a "wind shadow" in which the air has been slowed down by drag on the turbine's blades.


I think this is less harmful then those big skyscrapers.
Modernmystic
2.7 / 5 (7) Feb 26, 2013
Each wind turbine creates behind it a "wind shadow" in which the air has been slowed down by drag on the turbine's blades.


I think this is less harmful then those big skyscrapers.


Harmful or not harmful doesn't even enter into the discussion. It's going to CHANGE things and no one knows how. That's what we're talking about with CO2...climate CHANGE.
Jadxia
not rated yet Feb 26, 2013
The game changes completely if they manage to develop atmospheric wind turbines as they've been trying to do. Of course, high-altitude wind farms will add a whole new set of problems, I'm sure.
antialias_physorg
3 / 5 (4) Feb 26, 2013
Harmful or not harmful doesn't even enter into the discussion. It's going to CHANGE things and no one knows how. That's what we're talking about with CO2...climate CHANGE.

If it's not harmful no one cares. Humans (and organisms in general) change stuff with every action. It's because CO2 creates PROBLEMS for us that we care (and try to do something about it).

Even if a windfarm would change the local airflow by a percent or two but it doesn't change anything for the worse - so what?

TheGhostofOtto1923
1.7 / 5 (12) Feb 26, 2013
How does all this work into your simple equation?


How does it escape your complex one?

If you slow down wind speeds how will it NOT effect the climate?

Will god make up the difference? The Easter Bunny?
How does it act in conjunction with all the much more significant ones, only some of which I mentioned? If there are 500 bunnies in a field that werent there yesterday, how will removing only one here and there affect the amount of grass you have left?

Your equation isnt nearly big enough. There are many cows in that field as well. Their manure affects your equation more than a few rabbits.

Say did you know that rabbits do not have cuds to chew? God screws up once again. His book of facts says they do.
rwinners
3.7 / 5 (3) Feb 26, 2013
I think we have some time before we have to worry about this problem... given current wind energy production.
http://en.wikiped...city.png
TheGhostofOtto1923
1.6 / 5 (13) Feb 26, 2013
I have attempted to get a petition signed by the public to study the efficacy of the thorium reactors. No luck.
How what way, this being time wasting when cold fusion is sitted upon by many big-deal scientists then? You are paid lobby person if?
blackwater
1.5 / 5 (2) Feb 26, 2013


I have attempted to get a petition signed by the public to study the efficacy of the thorium reactors.

Fair play to you i just read up on all the advances from China Norway and Japan and am delighted to see this finally moving...it has great potential as anyone who has heard of thorium knows.... We will still need solar and wind energy while its getting going but its potential to rule out any fukishma style melt downs is truely amazing...It can also burn up all plutonium waste as a fuel...mind blowing!
kochevnik
2 / 5 (8) Feb 26, 2013
@MM
It certainly doesn't effect it,
Do you need me to explain it as if you were three years old??
This from an American who doesn't know the difference between 'effect' and 'affect'? LOL
kochevnik
2.5 / 5 (8) Feb 26, 2013
To recap praos stated a 1% change would be 1000Tw. World consumption from all sources is 15Tw. That's not 1%. It's 0.015%. Will some Luddite please explain the significance of a 0.00015 factor? It's below measurement threshold yet the Luddites are hinting at the apocalypse
antialias_physorg
3.4 / 5 (5) Feb 26, 2013
Will some Luddite please explain the significance of a 0.00015 factor?

Especially since this isn't energy being lost or added - it's just energy ever so slightly being VERY locally redistributed.
Caliban
1.9 / 5 (9) Feb 26, 2013
It certainly doesn't effect it,


It certainly does effect it. Lower wind speeds are going to effect how efficiently heat is circulated around the planet. It's not rocket science. If you take energy out of a system and move it to other work the work it otherwise would have done doesn't GET done. Do you need me to explain it as if you were three years old??


But you ignore the obvious --the reduced CO2 emissions. I would expect that the reduction in heating represented by windpower generation would offset the VERY slight loss of energy in atmospheric circulation due to wind turbines. The very fact of AGW produces an increase in the overall energy of the system.

Modernmystic
2.3 / 5 (6) Feb 27, 2013
@MM
It certainly doesn't effect it,
Do you need me to explain it as if you were three years old??
This from an American who doesn't know the difference between 'effect' and 'affect'? LOL


Yes the difference is that the antecedent in this case would be putting up millions of wind turbines the EFFECT of that CAUSE would be a slowing of wind speed.
Modernmystic
2.3 / 5 (6) Feb 27, 2013
To recap praos stated a 1% change would be 1000Tw. World consumption from all sources is 15Tw. That's not 1%. It's 0.015%. Will some Luddite please explain the significance of a 0.00015 factor? It's below measurement threshold yet the Luddites are hinting at the apocalypse


The world will be at 1000TW at some point. At some point we'll be using 100,000TW. Where would you stop us from extracting energy from the wind? Which study have you seen that says we'll be taking too much energy out of the system which circulates heat around the planet and putting it to other uses?

This is the kind of blatant hubris that got us where we are with coal fired power plants.
Modernmystic
2.1 / 5 (7) Feb 27, 2013
But you ignore the obvious --the reduced CO2 emissions. I would expect that the reduction in heating represented by windpower generation would offset the VERY slight loss of energy in atmospheric circulation due to wind turbines.


YOU expect? Where's your evidence for this? Do you have any?

The very fact of AGW produces an increase in the overall energy of the system.


How do you not see that changing energy in a system that performs a specific function for the climate and diverting it could not be every BIT as bad as adding energy that was previously sequestered???


Uzza
5 / 5 (1) Feb 27, 2013
The study claims 0.5 to 1 watt generating power per square metre for a 100 square kilometre farm. This equals 50 to 100 MW generating power for said wind farm... For example the Danish Anholt offshore wind farm has a generating power of 400 MW and is 88 square kilometres.

From my understanding, their number is the average energy density of energy generated. The numbers for the Anholt wind farm is nameplate capacity, which is not the same.
From the official site, it says that the wind farm will amount to about 4% of danish electricity, which puts it at about 160 MW average generation, or a capacity factor of ~40%, giving an energy density of ~1.82 W/m2.

If the wind farm would have been onshore, where the average capacity factor usually lands at ~20-25%, energy density would have been 0.909-1.14 W/m2, which is at the higher end of the numbers given.
TheGhostofOtto1923
1.6 / 5 (13) Feb 27, 2013
The world will be at 1000TW at some point. At some point we'll be using 100,000TW. Where would you stop us from extracting energy from the wind?
I would stop it when it begins to approach all the elements we have changed in the last 100 years, only some of which I mentioned, which have accelerated winds around the world.

In other words never.

I wonder if wind farms placed strategically would help to mitigate events like sandy and Katrina?
Modernmystic
2.1 / 5 (7) Feb 27, 2013
The world will be at 1000TW at some point. At some point we'll be using 100,000TW. Where would you stop us from extracting energy from the wind?
I would stop it when it begins to approach all the elements we have changed in the last 100 years, only some of which I mentioned, which have accelerated winds around the world.

In other words never.

I wonder if wind farms placed strategically would help to mitigate events like sandy and Katrina?


This is like some people being for banning smoking entirely and legalizing SMOKING pot. It's hilarious. It's all OK if what we're talking about fits your personal biases....

It's OK to change the environment if its windmills, but not nuclear plants, or oil plants, or whatever bugbear you don't like. THEN pretending that your preference really doesn't change the environment, OR it changes it BENEFICIALLY while all the others are going to cause the sky to fall.
kochevnik
2 / 5 (8) Feb 27, 2013
To recap praos stated a 1% change would be 1000Tw. World consumption from all sources is 15Tw. That's not 1%. It's 0.015%. Will some Luddite please explain the significance of a 0.00015 factor? It's below measurement threshold yet the Luddites are hinting at the apocalypse


@MM The world will be at 1000TW at some point. At some point we'll be using 100,000TW. Where would you stop us from extracting energy from the wind? Which study have you seen that says we'll be taking too much energy out of the system which circulates heat around the planet and putting it to other uses?

This is the kind of blatant hubris that got us where we are with coal fired power plants.
Typical conservative: ignore the math and focus upon some imaginary society drawing 66 times more power than present total world consumption. Pure FUD
TheGhostofOtto1923
1.6 / 5 (13) Feb 27, 2013
This is like some people being for banning smoking entirely and legalizing SMOKING pot. It's hilarious. It's all OK if what we're talking about fits your personal biases....
I am saying that there may be some benefits to slowing down the atmosphere in some places. Whats wrong with that?
It's OK to change the environment if its windmills, but not nuclear plants, or oil plants, or whatever bugbear you don't like.
The environment is already changed. We have paved an area the size of Ohio in the last 100 years, and this has changed local air circulation patterns. Admit this.

How does the wind disruption caused by a shopping mall compare with the forest it replaced? Do you have any figures on this mm? Does anybody consider this when building shopping malls?

You read 'wind farm' and so start looking for wind-related problems, because there must be some right?
Modernmystic
2.3 / 5 (6) Feb 27, 2013
Typical conservative: ignore the math and focus upon some imaginary society drawing 66 times more power than present


Well since I'm not a conservative I guess I wouldn't be a typical one.

Moreover we're currently drawing ten times the power we were about a hundred years ago. If you keep adding energy to a quantity of total consumption do you end up with a larger or smaller amount? Are we currently adding to that pile or subtracting as a global civilization? Is civilization/technology on a linear or exponential curve? Can you extrapolate?

We've had an 18% increase since 1990 for crying out loud. We're not slowing down much less stopping....
Modernmystic
2.3 / 5 (6) Feb 27, 2013
The environment is already changed. We have paved an area the size of Ohio in the last 100 years, and this has changed local air circulation patterns. Admit this.


I've never disputed we're changing the environment...in fact it's unavoidable if we're going to live on the planet.

How does the wind disruption caused by a shopping mall compare with the forest it replaced? Do you have any figures on this mm?


I don't know, I do know it has an effect. Admit this. If anyone doesn't have any figures how can anyone say which way the effect is?

You read 'wind farm' and so start looking for wind-related problems, because there must be some right?


I read wind farm and look at how much energy we're going to need in twenty, fifty, a hundred, and two hundred years and then I SEE wind related problems...
Modernmystic
2.3 / 5 (6) Feb 27, 2013
I think the problem here is that some of you assume current trends are somehow going to magically reverse and save us from the "need" for more energy.

I'm assuming nothing of the kind, in fact I see an exponential explosion in energy needs with the industrialization of the rest of the world. I'm not assuming the rest of the world is going to see the light sing Kumbaya, dance around the daffodils holding hands and halt their economic, technological, or population growth...
Caliban
2.3 / 5 (9) Feb 27, 2013
I think the problem here is that some of you assume current trends are somehow going to magically reverse and save us from the "need" for more energy.

I'm assuming nothing of the kind, in fact I see an exponential explosion in energy needs with the industrialization of the rest of the world. I'm not assuming the rest of the world is going to see the light sing Kumbaya, dance around the daffodils holding hands and halt their economic, technological, or population growth...


That's the problem with your posts here, mm -you "SEE" all these trends- which makes them(in your mind) as good as done, while rejecting any other ideas as unrealistic or unsupported.

You are making projections regarding future energy needs which are based upon continued GROWTH, which is clearly insupportable
-we are already nearing collapse. The rest of us are arguing that windpower up to roughly 1/3 of current generating capacity is Pre-offset by deforestion and FFuel CO2 emissions.

Which is more likely?
Uzza
5 / 5 (2) Feb 27, 2013
I think the problem here is that some of you assume current trends are somehow going to magically reverse and save us from the "need" for more energy.

Energy usage will grow, but there are reasonable limits to how far it will go for a given population.

Americans use about ~10kW continuously throughout their life, the most of any country in the world.
Current population trends point towards a peak at 10 billion. If every person on earth then used as much energy as Americans now, we would use about 100 TW, compared to 17 TW in 2010.
But Americans waste a lot of energy. A European on average use only ~5.5kW. If the rest of the world followed Europe, we'd only consume ~55 TW, and efficiency could reduce that even further.

The only way the world would consume 1000 TW is if the population of the earth somehow reached 100-200 billion.
Modernmystic
2.7 / 5 (7) Feb 27, 2013
You are making projections regarding future energy needs which are based upon continued GROWTH, which is clearly insupportable


It's nothing of the kind, that's YOU projecting YOUR hoped for agenda on reality. It's insupportable with CURRENT technology, it has nothing at all to do with what the trends in technology and growth actually continue to be and are. What other bearing it has on the discussion or reality I don't know. Population is a direct function of technology there is nothing whatever to say the population of the Earth couldn't reach 15 trillion or 100...

The only way the world would consume 1000 TW is if the population of the earth somehow reached 100-200 billion.


OR if we simply continued to use more and more power in general with the same or less population since just as we have since the dawn of technical civilization.
Modernmystic
2.3 / 5 (6) Feb 27, 2013
FTR: I honestly hope I'm wrong. I hope we do pause and let our technology catch up with the burden the current levels of population are putting on the biosphere. It may be a moot point anyway because I'm quite confident the bulk (as in 99.999999999%)of human civilization will in "future history" be conducted, lived, and be off this planet.

I'm not sure what trends are going to cross what lines when though. No one can be. I just don't see us getting to that place with wind power as a significant percentage of our power production.

Fusion? Yes.
Fission? Yes.
Coal? No.
Oil? No.
Gas? No.
Solar? No. (qualified)
Wind? Hell no.
Hydro? No.

Most of the hydrocarbons because they're going to run out quickly, most of the renewables because they have what will become severe limits on capacity (with the possible exception of space based solar).

All the renewables are solar power anyway really, so are the hydrocarbons for that matter. It's all about capacity and quantity respectively.

chrisp
5 / 5 (1) Mar 02, 2013
I find it hysterical that most of the proponents of wind when pinned down are horrified that you're suggesting we run the world off wind power and then make estimates about how that might work...


Unfortunately we're playing the 'pin each other down game', make others wrong and us right is exactly why we haven't figured out how to take action to solve our energy/climate conundrum.
I feel the true proponents of wind, are going to understand that there are limits to its benefits. Nonetheless, wind must be added to the mix.
Lurker2358
2.3 / 5 (3) Mar 02, 2013
I wonder if wind farms placed strategically would help to mitigate events like sandy and Katrina?

lol. not even close.

The Integrated Kinetic Energy of Katrina and Sandy were exceptionally high, and a few dozen or hundreds of turbines would not make a significant difference, as entire forests don't even make a difference and they are much denser than a few wind turbines here and there.

Modern Mystic:

Humans (on Earth anyway) are unlikely to ever use anywhere near 100,000Tw because that would require an amount of energy above the carnot limit percentage of the solar constant(at the surface,) so unless you expect humans to quite literally be fusing the entire oceans to make energy, that sort of value is absurd, and seems inconceivable to achieve by any means other than the science fiction "Zero Point Modulus" being real...
Lurker2358
2 / 5 (4) Mar 02, 2013
OR if we simply continued to use more and more power in general with the same or less population since just as we have since the dawn of technical civilization.


For what conceivable purpose could humans average a megawatt or more each continuously every year?!

Even if there were ten labor robots for every human being you couldn't possibly use that much energy, besides by the time you're using that much energy (even conceivably) then you start to run out of space to put the machines which are allegedly using that much energy. Maybe if you covered the entire Earth in 100 story sky scrapers, and covered the oceans entirely in floating cities, floating farms, and floating solar collectors. Even then it is hard to imagine 1000TW, nevermind the 100,000TW you originally said....

100TW maybe, but 1000TW? What in the world could you possibly need that much energy for? If human population was that big, everyone would need to wade through feces just to check the mail....
kochevnik
3.7 / 5 (3) Mar 02, 2013
100TW maybe, but 1000TW? What in the world could you possibly need that much energy for? If human population was that big, everyone would need to wade through feces just to check the mail....
In London and San Francisco that's already the norm

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