Could Too Many Wind Turbines Offer Diminishing Returns?
A new study conducted by an international research group has raised the question of what happens when too many wind turbines begin affecting the low atmosphere.
Over the last decade there have been several attempts to determine the impact of wind farms on the atmosphere and regional and global climate. The concern rests primarily with the way wind turbines affect the wind that powers them. As a wind current hits a wind turbine to move the blades the strength of that current is lessened — so scientists have long since determined that turbines should not be placed directly one behind the other in line with prevailing wind currents if the wind farm is to be as efficient as possible. Therefore, concerns have been raised over what impact this will have on regional, and even global climates — whether or not daytime or night time is adversely affected by too many wind turbines, etc.
New research that was recently published in the Proceedings of the National Academy of Sciences (PNAS) has similarly attempted to answer the question, “What happens to the wind when a larger number of wind turbines removes more and more of the energy of atmospheric motion?” Two atmospheric science professors from the University of Kansas were part of the international research group which co-authored the paper, which “evaluated the effects of large wind farms on atmospheric flow and its implications for how much renewable energy the turbines can generate.”
“Wind turbines generate electricity by removing energy from the wind, so a larger number of wind turbines should result in a slowdown of the winds in the lower atmosphere,” explained David Mechem, who along with Nate Brunsell, represented the University of Kansas on the team. In the abstract for the report, the authors explain further, saying that “wind turbines remove kinetic energy from the atmospheric flow, which reduces wind speeds and limits generation rates of large wind farms” — which appears to be the focus of the report, rather than any attempt to dismiss wind energy as a valuable renewable form of energy. Furthermore, the authors of the report note that “the limited replenishment of kinetic energy from aloft limits wind power generation rates at scales sufficiently large that horizontal fluxes of kinetic energy can be ignored.”
The report evaluates these factors and demonstrates by use of a regional atmospheric model based on the central United States the scale that is required for such a drop off to occur. The researchers noted that there is currently no current or planned wind farm that even comes close to the size or concentration necessary to begin pushing towards diminishing returns, they are nevertheless cautious to advise developers of the possibility, and the need for this new research to be incorporated into further planning.
Have a tip for CleanTechnica? Want to advertise? Want to suggest a guest for our CleanTech Talk podcast? Contact us here.
CleanTechnica Holiday Wish Book
Our Latest EVObsession Video
CleanTechnica uses affiliate links. See our policy here.
cool.
FREELANCE AT HOME SPECIAL REPORT………After earning an average of 19952 Dollars monthly,I’m finally getting 98 Dollars an hour,just working 4-5 hours daily online….It’s time to take some action and you can join it too.It is simple,dedicated and easy way to get rich.Three weeks from now you will wishyou have started today – I promise!….HERE I STARTED-TAKE A LOOK AT…..pwv….
================= Jobs367.com ☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣☣
This came up two years ago in an article titled “Look out! PEAK WIND is COMING, warns top Harvard physicist” which made this scary statement:
‘The realistic limits on wind power are probably much lower than scientists have suggested, according to new research, so much so that the ability of wind turbines to have any serious impact on energy policy may well be in doubt. Even if money were no object, the human race would hit Peak Wind output at a much lower level than has previously been thought.”
Has all the logging throughout the world increased the kinetic energy of the winds at all? If not trying to replace the trees that used to fill our world with a few turbines won’t be noticeable either.
Removing trees for farms surely must have increased wind velocity. Trees are a major effect reducing wind speeds. The effect can be seen in wind vs height estimates which change when land features are rougher.
Mining on line tabloids? The Register? Without showing the URL? Tsk tsk.
http://www.theregister.co.uk/2013/02/26/oh_no_its_peak_wind/
“Tabloid newspapers traditionally aim for sensationalist stories, celebrity news and aim for a down-market reader. By the very nature of concentrating on technology, tech tabloids tend to have a much more educated and literate readership. The tabloid tag does not apply to the paper format, as many of these publications are web-based only, such as The Inquirer and The Register.”
“The Inquirer even, in its 20000th article, refers to itself as “redtop tabloid rags like the INQUIRER”,[1] later in the same article calling itself “cheesy”: determining the irony of this is left as an exercise to the reader. Both the Register and the Inquirer do generally have red banners at the top of their home pages.”
https://en.wikipedia.org/wiki/Tech_tabloid
The authors, Keith, et al, don’t make quite the fuss the rag online journal does.
“what negative impacts emerged from wind turbine use could be eased, fairly economically, by better turbine design and placement.”
http://www.politifact.com/truth-o-meter/statements/2015/jan/15/facebook-posts/widely-shared-meme-oversimplifies-joe-bartons-2009/
This sensational tabloid journalism is moot for several reasons outlined in Archer and Jacobsons paper.
Global total wind power predictions have always been subject to uncertainty for many reasons. This in no way limits wind powers growth, not the least reason being that we are nowhere near that potential and the total potential is never used, to wit:
1. Definitions and assumptions in assessing are inconsistent.
2. Wind speed measurements at height are few and sparse.
3. Global model maps vs data are not available at high resolution.
4. Feedbacks between large scale circulations and wind are just starting to be understood and cause large reductions in expected power.
page 1.
http://web.stanford.edu/group/efmh/winds/Applied_Geography_practical_wind_2013.pdf
There are several factors that mitigate this.
1. Climate is increasing wind according to this paper. Wind goes up as precipitation increases from data, mostly in the tropics, but averages higher over the globe.
“Kinetic energy is proportional to the global is proportional to the earths condensation rate.”
page 7.
http://www.researchgate.net/publication/276882099_Reassessing_thermodynamic_and_dynamic_constraints_on_global_wind_power
2. Taller towers and new technologies change the estimate, by both increasing the amount and increasing the areas of practical wind generation.
Its far too early to be discussing absolute limits to wind generation. Even under the most pessimistic assumptions the scale of wind potential is vast. Solar even more so.
On another site using Disqus if I post a link it immediately turns the post into “awaiting moderation”. Is that not the case here?
Whether or not The Register is a “tabloid” is irrelevant. They aren’t quoting Kim Kardashian on wind potential in this article, they are quoting a couple of professors.
You can buy a professor’s opinion very easily. It’s like buying an attorney.
Could be bought, could be wrong, or could be right. After the 2008 Financial meltdown and the oil problems of the last decade, I think minority voices should be heard and their comments analyzed, since we have seen the majority opinion be wrong.
Can’t bother to track down all the comments. Pretty soon you’ll be giving equal time to every UFO and religious person. Scientists who study if it is possible to have too many wind turbines on the planet leave me shaking my head wondering why they are doing so.
Can’t both to track down all what comments?
You denigrate religion and yet you take a religious view towards renewable energy.
Can’t be bothered to track down all the idiotic comments and reply to them.
Denigrating religion is like denigrating gambling. Sure it makes a lot of people happy however I’d rather have a useful hobby. Renewable energy is a useful hobby.
Very true Ivor. The classic example for this is the tobacco industry and the number of “scientists” they bought to pontificate on how smoking tobacco has no or minor adverse health effects. We ALL know how much bullshit that was
One of those scientists had been a prof of mine. After about 20 years in his position it was discovered that he had never completed his dissertation. Obviously he lost his position and went to work for a tobacco company.
BTW, I find the ” can buy a professor’s opinion very easily” offensive and incorrect. Most of the faculty members I’ve known have been very ethical individuals. Like any other group there will be the bad apple from time to time.
I don’t know those “scientists” or “professors”. However I do know people. Labeling somebody an expert and then deferring blindly to them is something that always ends badly. They are people and have all the problems people have. So what I do is run things through a common sense filter.
I’m not sure why you would find it offensive and incorrect. Maybe you should watch “Fox News” to get some examples. History is full of experts with titles being bought.
You mean like Tom Harris.
“Fake Heartland “Scientist” Infiltrates Canadian University”
http://www.desmogblog.com/fake-heartland-scientist-infiltrates-canadian-university
Very sad.
“I’m not sure why you would find it offensive and incorrect. ”
Because you lump all “professors” into the dishonest, unethical bucket. That includes a lot of extremely ethical people whom I know.
Had you said “a few” I would have agreed.
It’s like the people lump all elected officials or government workers into the same camp.
Nuance: buying a professor to say what you want in the popular press is easy. Having a professor come up with the research results that you want is harder due to the peer review process.
That’s why most scientists publicly arguing that climate change is irrelevant or non-existant have never written a publication saying that.
You may believe that. However influential Republican politicians are saying the opposite. That scientists say AGW is faked. Last week you could hear it on Real Time With Bill Maher. So who are the experts behind these politicians? And you don’t have to look for scientists swearing nuclear power is the solution to all our future energy needs. It’s a big world full of different viewpoints. Usually controlled by the who has the most money.
And a professor can also make a good faith attempt to analyze a situation. So you can’t make a blanket denial against anyone who says something negative or positive about something.
I don’t make blanket denials. However I’ll say what’s on my mind. So if the emperor is not wearing any clothe I’ll say he’s not wearing clothe regardless of what the experts say. Unless my personal safety is involved…
If I was a coal or natural gas company executive and I wanted to buy a professor’s testimony to fight wind turbine development, I would have them say that wind turbines didn’t return as much as they cost to build and maintain, or their return on investment was very low or they had limited lives and high maintenance and replacement costs. Or I would have them attack their intermittency and problems with grid integration and the need for fossil fuel plants to be online as backup. Or talk about bird and bat killings. Saying that we won’t be able to build as many as we think seems pretty weak for stopping them from being built. In fact, it would seem to have no effectiveness initially.
They just keep throwing things up against the wall in the hopes something will stick. So it may seem totally stupid to you and me but it did get enough traction to be studied by groups of professors. Some of the crap they throw at the wall, despite being mind numbingly stupid, does stick. Sometimes because the sound bites merely sound good when said and become a popular jingle. People get paid lots of money to throw things against the wall in the hopes of something sticking.
Depends on whether one is on the “whitelist” or not. If you’re not on the whitelist and append a link then your comment goes into moderation. We had to do that due to the high number of spam comments we get per day.
After I’ve seen someone comment a few times and color within the lines I whitelist them.
But what about skyscrapers?
I am not a scientist, but Isn’t there an energy conversion when wind turbines turn? Energy in the moving air is converted to windmill motion and then to electricity. I don’t see skyscrapers converting energy. If they formed a solid wall, then they could be seen to hold the energy in the wind back I guess, but we haven’t yet figured out how to make solid skyscraper walls, They still have gaps between them in which the wind speeds up to get around them.
Wait we need to take down every building over one story tall.
“kinetic energy from the atmospheric flow”
So two numbers are important:
1) How much kinetic energy is in the atmosphere? Over a whole year.
2) How much kinetic energy do 10,000 5MW turbines remove in a year.
We can only hope we get to such large numbers of turbines that it becomes of interest.
Yes. “The researchers noted that there is currently no current or planned wind farm that even comes close to the size or concentration necessary to begin pushing towards diminishing returns”.
Yes, The headline fizzles a bit when you read further. Sort of like soda pop left open a day later. OK, I was using poetic license. But who can resist?
Hey. It’s an excellent and interesting modelling excercise with a few practical implications for wind farm design (bigger is not always better).
If that’s not delivering on its promises, I wonder which studies you find worthwhile :p
I was referring a bit more to the Register headline that says
“Look out! PEAK WIND is COMING’ than to this one which is a bit milder.
The studies on the other hand hardly raise anyones pulse, but are valid and useful. Hope I didn’t offend.
Its not the studies I have a problem with. Its headlines that distort them.
It’s the fact that the headline will be frequently used as an anti-renewable talking point that bothers me.
The wind bagger deniosphere echo machine.
Oops. My bad, sorry.
If it’s any comfort, they’re not particularly anti-wind. Just anti-science.
LOL. Anti rational, too. Heavy on the sarcasm and exaggeration.
Given the fact that mountain ranges provoke far more aerodynamic resistance than the number of wind farms needed to produce 100% of the entire energy demand would, isn’t it then a miracle that wind even exists in the first place? Or is there simply a calculation error in this study?
Well here is another thought, Winnipeg, Manitoba, Canada (also known as Winterpeg to some) has the highest recorded winds (in the inner city) of any large city’s in Canada, because of their tall buildings.
Now a second thought, due to climate change and more kinetic energy in our world, wind farms, on a number of places around the world, have been getting record outputs. (see cleantechnica articles)
There are variables in all RE systems, some small, some larger, some vary by season, some by location.
Even the sun’s output of solar energy has some variables. ( not that we have to worry to much about that, except for the odd solar flare.)
Well, it isn’t the same. Something that block the air generate a pressure and wind surround the obstacle. Something is dissipated by this deformations (turbulence dissipate some energy as heat), but not so much.
A Wind turbine is designed to absorb the energy of the wind. The wind don’t surround the object. It is (partially) absorbed and turned into electricity slowing the wind.
I readed other articles about the same matter. Previous studies was based on that wind travel as “layers” so the energy of the layers is lower than expected.
But I’m not too much conviced of the data, because the values was so low that they was inconsistent with real turbines. I think that there is not real data about the interaction of the layers. I think that if a layer is altered, has been slowed down, the friction of the layers rise and more energy is exchanged between layers. The obstacles like the mountains should add more exchange by turbulences.
It is possible that this effects has importance between near parks or very flat zones (not the best for wind), but I doubt that has too much importance between far ones.
A wind-turbine cannot extract more energy than what the Betz-limit allows. Since the number of blades isn’t infinite and the maximum tip-speed ratio is limited by drag, it’s less than 50%.
A mountain on the other hand doesn’t have to worry about any Betz-limits and could essentially even bring the wind to a halt (which is why mountainous regions often don’t have very good wind resources).
While mountains can impede the wind, Mountain passes can be good because they channel wind. Some areas are affected by the wind shadow of mountains downwind. They can also create turbulence which is not ideal.
Mountain peaks are good because the wind is swept up and concentrated. Also, height is generally good for increased velocity.
Green Mountain Power in Vermont has a wind farm on ridges.
http://www.greenmountainpower.com/upload/photos/236KCW_Turbine_19_pad_looking_north_-_10-13-2012.JPG
http://www.greenmountainpower.com/innovative/wind/
Come to think of it , there is some of the best wind in the continental US in Wyoming at high elevation. But that is sort of a high plateau.
http://www.laramieboomerang.com/news/local_news/article_605166bc-4950-11e5-9ac4-3fbd19422dfc.html
Flat treeless areas like the Midwest. or offshore like the ocean can also be good. Nothing to impede the wind.
That’s true one can get good wind resources at certain locations in mountainous, but in general the best wind resources are closer to the coasts.
http://kartoinfo9.hostzi.com/Karten/W_Leistung.jpg
True, but this map has a rather crude resolution. It is quite possible to have small zones of excellent wind potential in the yellow-ish bits and dead zones in the green area.
Mountain passes are too small and too few in number to seriously affect a map at this resolution, but that doesn’t make them less attractive to wind developers.
True. Wind power varies as velocity cubed, so it can get concentrated in areas like that. Just look at Tehachapi, the San Gorgonio Pass Wind Farm, and the famous Altamont Pass wind farm.
https://en.wikipedia.org/wiki/San_Gorgonio_Pass_Wind_Farm
Great map. Most coastal areas and offshore are higher wind speeds here. Swiss Alps have lower wind speeds. Appenines and Scottish Highlands are the exceptions. North Sea and Atlantic are exceptional wind power houses. Looks lie Norway has as much potential or more than Denmark on land.
With Germany having the most wind capacity, we can see clearly that the amount of wind power in these locations has more to do with policy than economic feasibility.
I wish they broke out wind for Scotland. It might be higher than that UK estimate by now. And break out offshore vs onshore. Nice to see the offshore wind potential.
Here’s a wind map of Switzerland and in this case one can see that the mountains have some locations which are excellent, but this is because they are either channeling or are simply getting to much higher wind layers (which were less affected by the rest of the European landscape – sort of like a very tall tower).
http://wind-data.ch/_downloads/maps/wind_2011_50m_d.png
Ausgezeichnet. Just as expected.
While storing away the onshore wind map you posted I noticed I have an offshore wind map for Europe.
Thanks, ‘my map’ was just a random google images map.
Very nice. Now we can see that the Northern Part of England and Ireland has really high offshore potential. Since the North Sea side is shallower, we can expect offshore development there first. Now we can also see why Denmarks offshore potential is so great on its Western side. So too, the Southern coast of Mediterranean France.
Why on mention of Scotland?
Good question. Most of UKs wind comes from there. And its potential is quite large. Its doing a large part of the heavy lifting. And thanks for asking.
By the way, Scotland has some of the worlds highest capacity factor wind farms. There is some serious wind there.
Scotland is a windswept hellhole.
Aw, it makes nice whiskey and the lasses are beautiful.
Lower air density at higher elevation. Though that can be offset by higher averave windspeed.
Yes. All that is taken into account, to be sure. The higher density combined with high average velocities helps offshore wind.
Here is the wind equation. Velocity dominates because its cubed.
http://mcensustainableenergy.pbworks.com/f/1286919393/power%20equation.jpg
Here is the Betz limit.
http://patentimages.storage.googleapis.com/WO2010036678A1/imgf000010_0001.png
The part about no wind at all, not so much, but mountain building, or orogeny has its effects. Scientists think that recent ice ages were affected at least in part by the emergence of the Himalayas, whose peaks absorbed carbon dioxide from the air by weathering.
Its not hard to imagine them having major effects on global atmospheric circulation, but atmospheric circulation is driven by the suns energy and temperature differences. I don’t think that would ever stop completely.
http://www.global-climate-change.org.uk/2-6-1.php
Neither would I, especially given the fact that most of the earths surface area is water.
(My point was: If one looks at the size of all the mountain ranges and what aerodynamic resistance they inherently must have, it’s very hard to believe that anybody could ever build the number of wind-farms to even get close to this.)
I see your point and its a good one. Yes, its hard to see a meaningful effect happening due to this.
In any case, any older energy estimate would be swamped by new improvements like taller towers and other advancements. Taller towers alone increase the amount of practical wind energy many fold by increasing both the productive area of wind and the output.
Other advancements like floating offshore, and the improvement in conventional offshore would also increase estimates.
Shall I mention someones favorite? Kite Sails.
We could use some numbers here. How many terawatts of turbines do you need before dropoff becomes a factor? I suspect that this is an exercise of purely armchair relevance.
Perhaps it would be helpful as well to have some numbers for energy removal by multi-story buildings. Or even single story residences.
Does a 3 MW wind turbine block the wind more than a Walmart?
What’s the surface area of a wind turbine, blades and tower? How to the rounded shapes compare to the flat surface of a 3 bdrm, 2 ba house?
How many millions of buildings have we stuck up into the wind?
A few numbers taken from the study:
– An area of 213 000 km2 (Kansas) was considered, in which 2,7GW of wind turbines were installed. This represents 0.013W/m2.
– The upper limit for efficient deployment is 1W/m2
From those two, Kansas alone could host 210GW of wind turbines. Or in other words, Kansas alone has the potential to produce slightly more wind power than the entire US does today.
Feel free to repeat the same calculation for your jurisdiction of choice, keeping in mind that usable land area is lower in most nations than it is in Kansas. Use an appropriate CF estimate for your region to convert to net generation (for Kansas, a value of up to 47% suggested).
Perhaps the most interesting conclusion of this study is not the upper limit of deployment, however. It is the comparison that it makes between US and UK wind farms. It finds that UK wind farms are more efficient than US ones after correcting for confounding variables like wind speeds.
The reason? They are much smaller, and thus a greater percentage of turbines is on the edge of the wind farm. There might be an important lesson here: if big wind farms are less efficient, the current trend towards ever larger projects might have to be reviewed.
The study is open acces btw (as it should be!): http://www.pnas.org/content/early/2015/08/18/1408251112.full.pdf
Nice calculation. Illustrates that worrying about winds global maximum potential is a bit misguided and a bit premature.
Even in Archer and Jacobsons paper, its estimated including climate effects that wind power potential greatly exceeds electrical demand.
see page 2. Practical Potential
Researchers are still studying the effects of climate and wind turbines. Its hardly a well established area and still under study.
http://web.stanford.edu/group/efmh/winds/Applied_Geography_practical_wind_2013.pdf
40TW according to Archer and Jacobson. Probably conservative as it does not include far offshore wind.
http://web.stanford.edu/group/efmh/winds/Applied_Geography_practical_wind_2013.pdf
Your armchair is safe.
“I suspect that this is an exercise of purely armchair relevance.”
Correct. For Germany the reported “saturation” value is much much higher than the demand.
Archer and Jacobson hardly sat still since the paper that framed this idea came out from Keith. They are all researchers in the area of renewables.
Since then, Archer and Jacobson did an estimate including climate feedback effects in 2012, but only for near shore and land at 100m hub height.
Their estimate shows 40TW including climate feedback , while global electrical demand was 2.44TW in 2012 (IEA)
This does not include farther offshore wind and increases in hub height, both of which greatly expand potential.
i think its important to interject here, that researchers rightly concluded that the amount of wind energy practically extractable was vast and so much more than current electrical demand, that the numbers were somewhat academic.
Estimates of total global generation have always been approximate for many reasons.
1. Definitions and assumptions in assessing are inconsistent.
2. Wind speed measurements at height are few and sparse.
3. Global model maps vs data are not available at high resolution.
4. Feedbacks between large scale circulations and wind are just starting to be understood and cause large reductions in expected power.
http://web.stanford.edu/group/efmh/winds/Applied_Geography_practical_wind_2013.pdf
With that much uncertainly, and still having estimates exceeding global electrical demand, there has not been much fuss about estimates.
Until a few tabloid headlines later. 🙂
But I guess we have them to thank for the exposure showing how vast wind energy is.
40 TW seems too much but we are comparing it to electricity. In a postcarbon world we need to transform all energy uses into renewable energy through different uses modes and conversion. And we hope to develop third world too, so it isn’t wild to point a global renewable energy power of 100-400 TW in a future of ten billion people living in northamerican-european life style (with minor changes to allow sustainability).
With the limit of 40TW then most of the 100-400 TW should be solar.
Err…400TW! i.e. a 10fold increase?
Even given increased electrical use (i.e. to offset FF for heating and so forth), and increased demand from Asia and Africa, I think even expecting demand to double is stretching credibility.
60% of the energy we use now is wasted. Largely through burning FF in power plants to generate electricity. See this diagram for a US example: https://flowcharts.llnl.gov/content/energy/energy_archive/energy_flow_2013/2013USEnergy.png
When we generate direct electrical energy through wind or solar, then we don’t waste any (except through transmission losses) – the only “loss” is how much wind or how much sunlight we convert – i.e. the capacity factor.
Most estimates I’ve seen for the US, EU etc have said that even with 100% electrification of everything, then demand would not be more than 125% of current demand. And I think they are underestimating how much can be saved through efficiency. A back of the envelope calculation suggests that if every *house* (not business, streetlights and so forth) moved from CFL lighting to LED lighting, the saving would be almost 10% of demand (about 4GW).
I think that ensure the efficiency on all areas is a bit too optimistic. To reach 100% renewables a significant fraction will need a energy to fuel convertion, like capture Co2 and reduce it to create carbon for industry, plastics and things like this with great innefficiency, so I assume that consumption from fossil to renewable will be similar. Better in some areas, worse in others.
Add later a lot of people that needs to increase the consumption to reach a high level of life quality.
Add more people because population growth until reach end of growth around the end of the century.
And add more power because the low capacity factor of renewable.
Well… add efficiency (this time is “substract”)
I think that 400-100 TW of renewable power although a consumption of 100-25 TW of power equivalency (100% capacity factor).
It seems reasonable for me.
There are some questions and misunderstandings here I think:
“a significant fraction will need a energy to fuel convertion”
For example? We will need some solid/liquid fuels, although I expect most of this to be biofuels/biomass.
“create carbon for industry, plastics and things”
We can already do this – it takes no CO2 from RE – nor is it particularly energy intensive (and even if it is – remember that we expend at awful lot of energy exploring, drilling, transporting etc etc etc – all of that can go…) – there are various routes for making the ethenes and esters required for plastic manufacture – from sustainable and renewable sources. The issue is doing it cost-effectively at the moment, although I’ve read some interesting work going on with nanotube catalysts. Once you’ve got the basic building blocks, it plugs straight into our existing methods of plastic production.
“Add later a lot of people that needs to increase the consumption to reach a high level of life quality.”
True – this will happen anyway and has been taken into account in the calculations – if the “developing” world plugs straight into RE, rather than coal, then it doesn’t matter – the issue is getting rid of CO2 producing sources that exist.
“Add more people because population growth until reach end of growth around the end of the century.”
Again true, but this can be built out slowly as countries need it (see above), so it’s not strictly relevant at the moment.
“And add more power because the low capacity factor of renewable.”
This is a misunderstanding surely? Electricity generated by RE is electricity generated. Yes, the CF effects the nameplate capacity (i.e. if you install a 1GW nameplate wind farm and the CF is 30%, then the average power is 300MW), but what we’re interested here is replacing 100% of CO2 producing energy with 100% RE (or carbon-neutral).
You underestimate efficiency as well – a car running on petrol has an efficiency of about 20%. An electric car has an efficiency of about 80% (which will improve). We throw away so much energy.
Global electricity demand at the moment is about 16TW (not 40TW) – since most estimates from RE experts say 125% or lower, even when fully electrified, that would “only” be 20TW demand.
Thus this theoretical 40TW max for wind is still more than double our total energy needs!
Actually 400TW is a bit wild. That estimate is in line with estimates of unabated growth and little gains in efficiency while simultaneously ignoring the effects of resource depletion and pollution among others, on population and consumption.
Really, we are already seeing how it would become impossible to continue with the large negatives mounting.
The wind estimates compare well with total global energy consumption, a task they will not need to do with a mix of renewables helping out.
There are quite a few estimates that only assume a modest multiple of 2009 energy use. For example the one in the graphic of the earlier comment, which shows global energy use expanding from 16 TWh to 28 TWh by 2050.
Energy future estimates are what is technically possible, not a prediction of human behavior which can be wildly impractical.
The total global energy estimates by Archer and Jacobson are at the other end of the spectrum, but they are referenced here to put perspective on a renewables future.
A switch to more energy efficiency reduces estimates. A switch to EVs reduces energy use because of its greater efficiency over ICE.
We are currently undergoing a major energy transformation, not least in part because excessive FF consumption has lead to depletion and the scarcer resources are becoming more difficult to supply at the massive rates of consumption.
So what? Has a wind turbine a much different impact as a large tree or small group of trees? What with large building blocks?
You spotted that. Nice. 🙂 Down at the end of the discussion, ivor did, too.
The effect is much the same, that is to say irrelevant on a global scale. This study worries about a much more local effect though: the tendency of a wind turbine to reduce the wind available to the next turbine in the farm.
A tree in your garden does not meaningfully affect global winds, but it can noticeably reduce the amount of wind you feel when you sit in your yard. It’s the same with turbines: their local impact can be huge even if they don’t affect winds on a larger scale.
The take home message from the study is that huge wind farms (many times larger than the ones we build today) are impractical and that the theoretical limit of global wind production is smaller than initially thought (though still larger than our entire energy demand).
Note that this is not a new observation. It’s just a more accurate model of a known phenomenon.
As that tree moves around energy is being transferred from wind to tree motion. We probably can’t measure the impact of one tree but there are lots of trees in the world.
Now, as far as the study, people have been building wind farms for three decades or so. I’ll bet that engineers have figured out how far apart to space towers so that upwind turbines don’t block significant wind for downwind turbines.
Yes. The wind turbine spacing and array methods are pretty well understood by now as far as limiting output is concerned.
The concern here is that there may be large atmospheric effects at massive scales of 40TW. The thought is that it will actually slow winds on a global average.
It really is academic at this point. Estimates of total global wind potential are not exact.
That might be a good thing. The main way heat gets transferred from the tropics to the poles is by (warm) wind. If the wind is slowed, poles won’t warm up so fast.
If future technology allows it, what about turbines of varying heights? I wonder what the ‘3d’ effect of wind flow would be per turbine?
Or use kites that can exploit a much bigger area and not shade another at all. That’s why KiteGen generators are supposed to reduce spacing between units compared to hawts.
Kites would make that sort of calculations much harder.
Yup, we can do that . . .
http://scitechdaily.com/high-altitude-blimp-wind-turbine-will-harness-stronger-winds/
I’m not sure how well this iteration works (and how you would factor the energy required to make the helium,) but getting the turbines way up in the atmosphere to where the wind currents are strongest makes sense.
From what I understand, the strongest wind currents in the world are along the perimeter of Antarctica. Suspend thousands of these along there and you could get unlimited amounts of wind energy. The problem (well, one of them)
would be the long range transmission of the electricity generated. But southern Australia/New Zealand and the southernmost portions of South America might be able to benefit.
The Japanese project to position solar panels in space and beam the power back down –
I’ll add my probably off the wall. Wind farms on Antarctica, beam the power up to transfer station satellites and back down to where it’s needed.
Now back to reality. If folks are familiar with it here’s a site where one can see what is happening with the wind anywhere on the planet at the moment. Drag the globe to see different views, zoom in, click on a spot to see the current wind speed. The waters around Antarctica are almost always very windy.
http://earth.nullschool.net/#current/wind/surface/level/orthographic=-95.46,29.45,289
Very cool interactive globe map, Bob!
Yes, string of these around the Antarctic perimeter would be
a bit far fetched, the floating wind turbine itself might not be too far fetched of an idea (although, I’m sure, with a rather long ROI.)
The effect of wind farm turbine arrangements is better known on a turbine to turbine effect. This effect has more to do with large scale atmospheric effects. They are actually saying if there are enough wind farms, the global, not just local wind speeds are reduced.
i’m hoping on a large effect. i’m a cyclist so i hope holland will add so many wind turbines into the north see that i will never have to cycle against the wind any more!
🙂
Lets put things in perspective.
http://c1cleantechnicacom.wpengine.netdna-cdn.com/files/2011/08/energy-resources-renewables-fossil-fuel-uranium.png
“No other energy source compares to the energy potential of sunshine. Looking at the image above, make sure to note that circles for Coal, Uranium, Petroleum, and Natural Gas are TOTAL recoverable reserves, whereas the renewable energy circles (including the giant yellow solar energy one) are for energy potential per year.”
Even considering limiting estimates, total wind generation is greater than total global energy consumption. Not just electricity. (Archer and Jacobson estimate wind 40TW)
But we needn’t power the world on wind alone. Look at that massive solar potential.
We will use both and geothermal, hydro, etc.
Are they circles (data proportional to area) or spheres (data proportional to volume)? Tufte fail. Charts should not mislead or confuse in the interests of grabbing attention.
I’d guess circles that someone “artistically” shaded which makes them look more like spheres.
Were I redoing the graphic I’d put all the ‘yearly’ stuff inside the solar circle. Leave the finite energy sources stacked up outside.
It would be harder to read, but more dramatic if it was done as areas or even a linear scale graph. The kind the show the other sources as tiny invisible dots in a sea of yellow solar.
Not saying thats the best approach though, because I can see why its hard to represent such orders of magnitude on a linear scale.
Judging from the diameters it has to be volume. Thats the only way the yellow sphere could be 23,000 and the grey one 900. The diameters certainly are not a factor of 23,000. I guess this gives it a logarithmic quality. One has to do that to represent vastly different sizes.
In that sense, it reduces the graphical sense of proportion. Its harder to grasp the difference in volumes.
Could these windmills slow earth rotation down, making the days longer?
I bet the makers of Sharknado could have some fun with this.
“Turbinado Apocalypse” . . . here’s what I’ve got so far:
The only thing between us and disaster, a series of carefully coordinated demolitions of all the world’s offshore wind turbines whose whirling blades, as they enter the water, eviscerate giant schools of a vicious new species of jellyfish/human eating shark seeking massive aerial uptake from an epidemic of tornadoes caused by the planet-slowing rotation of those very turbines.
For a more CleanTechnica friendly ending: a maverick scientist/industrialist proves the turbine/tornado math wrong and saves the day by selflessly deflating his own secret fleet of tethered balloon wind turbines.
Sort of like this:
https://www.youtube.com/watch?v=fL2FbGH2DDs
Douglas Adams, how we could use you these days.
Not losing any sleep over it. Unless I stay up late to watch Sharknado. 🙂
Sharknado – funny movie.
**Could these windmills slow earth rotation down, making the days longer?**
Bwa ha ha. Actually, the rotation of the Earth is slowing. Over the course of billions of years tidal effects are causing the Earth’s rotation to slow. Tidal energy is not a free lunch. But this is nothing to worry about on our puny time scale. We probably won’t last another 1000 years due to nuclear war or machines taking over. We will probably be able to divert asteroids but super volcanos will kill off the majority of humans sometime in the next 100,000 years if we haven’t already killed ourselves off.
> Could these windmills slow earth rotation down
http://www.theonion.com/video/in-the-know-coal-lobby-warns-wind-farms-may-blow-e-20876
classic! LOL.
BS. According to that picture nuclear will only last 5 to 15 years. The picture is cute but it does not pass basic commonsense tests.
Nuclear is like coal, worse actually, but there is no way there are only 5 to 15 years of it left.
The graphic shows that if the world got 100% of its electricity from uranium we’d run out in a few years.
Do you have data to the contrary?
Oh. Nope. Misunderstood. Thanks for pointing that out.
There is also this business that the wind and solar are shown as yearly values, but the coal, nuclear, etc. are shown as the total of reserves. Its kind of slanted in the direction of being conservative about the renewables that way.
In small white letters it says annual in the wind circle and total reserves in the coal circle. Not that noticeable.
The total annual world energy consumption in 2000 and 2050 are those two orange circles on the lower left corner, 16TW/year and 28TW/year.
Since we will never get all the FF reserves for many reasons and the rate we can extract them is limited, we have several reasons to get off FF before they become harder to get and more expensive.
It’s interesting how nuclear advocates always talk as if nuclear is unlimited and we should switch all our energy needs to it. I didn’t realize it would only last 10 years that way. Yet people want to still jump on to that sinking ship!
Our current authoritarian politicians like *control* (both in the US and UK) – to them “variable” generation through wind and solar feels like surrendering control.
Nuclear advocates talk in glowing terms about waste reprocessing and so forth. Yet there isn’t a single fast breeder reactor in the world. They also talk about Thorium etc etc.
All of it is rubbish.
The only nuclear option worth considering is Fusion. Clean, safe. But perhaps very expensive and perhaps unviable for power generation. Only time will tell on that one.
Theres the whole nuclear classified as a renewable silliness.
http://cleantechnica.com/2015/02/06/nuclear-power-counts-renewable-arizona-senate-committee-says/
This going to depend on the technology used to extract energy from Uranium. Once through (no reprocessing) LEU in light water reactors gives you a very different number compared to fast breeder reactors. Fast breeders give me nightmares as they breed Pu from U-238. Many nations breeding lots of Pu means a low cost of entry to the nuclear weapons club. Nuclear war is the biggest threat we face as a species, at least until the machines get the better of us.
They never worked, either, being uneconomic and thoroughly messy, costing more to clean up after than they were ever worth.
Only if an open cycle is used rather than reprocessing and reuse. And unlike many other more pie-in-the-sky ideas of nuclear advocates, reprocessing is actually done on an industrial scale already.
Not that it matters one bit just how long uranium supplies last, since nuclear power is just too expensive.
I’m very close to saying this is a dumb article. The thought that we could build enough wind turbines to affect our wind is silly. Most of these things are only 100 meters of the ground, and most of your wind is in higher altitudes. And of course the fact we have cut the number of trees, (3 trillion just in today LOL), by half, means we can use all the wind turbines we can build to make up for the loss of resistance by all those trees cut down.
A study is needed to determine if wind turbines can offset the world’s climate changes that have resulted from deforesting and logging. Can a sufficient number of wind turbines be deployed or must we worry about the impending global dust storm that will undoubtedly leave our planet inhabitable?
😉
“Could Too Many Wind Turbines Offer Diminishing Returns?”
Yes. Duh.
I hope you realize that it works exactly the same for “too many coal plants”, “too many nuclear reactors”, “too many hydro plants”, “too many gas plants”, etc.
Build enough of anything and you hit a point at which you’ve got to curtail some of the capacity.
Exactly. If there were not a problem, there would not be too much.
I’m having trouble deciphering your second sentence.
Let me just point out, in case you weren’t aware, we overbuild capacity now. The capacity factor for US gas plants is under 30%. Most of our gas plants sit idle most of the time.
It will probably make financial sense, in some circumstances, to build wind and solar farms that will be curtailed some of the time because that will cost less than building storage or dispatchable generation.
You jogged my mind in a good way. Why the heck are we nitpicking over solar CF when its doing a good job as a peaker and displacing gas peakers with CFs of 30%?
They are the same because of peak load, not generation characteristics.
Solar is an ideal peaker substitute. It dramatically reduces the use of peakers, relegating them to the early evening hours.
In that sense, all peakers are overbuilt. But thats silly, because CF plays the game as if 24/7 operation matters. Thats not what matters in load matching. Operating when the load is not there is a negative economic factor, not a positive one. So also is inflexibility causing the need for other generators.
If we were honest about base load, we would add the cost of gas peakers to it as a negative economic factor instead of dividing out each generation source and using the CF factor.
CF is so abused, its frustrating. It is not a figure of merit.
A single source that follows the load would be ideal and would not have a 100% CF.
So CF by definition is not ideal or a figure of merit. Its just a mathematical number used to calculate output.
….how about “too many solar PV farms” and the heat island effect ? Mr. Wallace you are totally correct that there could be too many or too concentrated
You’re kidding. Aren’t you? Please tell us you trying to kid….
…so there is no heat island effect ? Solar PV is about 20% efficient, what is the other 80% of the sunlight doing ? We need to be careful that we don’t exchange an industrial scale fossil fuel system for an industrial scale renewable energy system. Obscuring our ridgelines and coastal areas with wind generators and paving our planet with solar PV farms seems to be the new “green”. These lifeless, obtrusive structures are not green and they have an ecological effect, at least hydro offers a created, living environment with their impoundments. More needs to be done with curbing consumption instead of keeping pace with the ever increasing demand
With all the roads and parking lots we build do you think solar farms will contribute meaningful heat island problems?
Solar farms probably do lower albedo over the area they cover. At the same time they replace a lot of fossil fuel use and lower the GHG problem, so the tradeoff is very much in our favor.
Probably not significantly. Although I’d need to do the maths to be certain.
As you say radiative forcing from GHG in the atmosphere likely to be a much greater effect.
No. PV solar does not contribute to the heat island effect. It lowers it. This ought to end that pesky meme. It should be stamped out once and for all. Asphalt creates much more heat that PV.
http://www.treehugger.com/renewable-energy/ask-pablo-do-solar-panels-contribute-to-the-heat-island-effect.html
From what I see in western New England, parking lots are not being covered….the largest community solar in the Northeast will be on 12 acres in western Massachusetts and 19,000 panels are to be installed on 50 acres of open land in Southeastern Vermont and there are others. Sure roads and parking lots are bad for heat islands but lets not make it worse with solar PV. Maybe you can tell me Mr. Wallace, which is better: green grass or solar PV panels ?
And talking about tradeoffs, consider hydro that extracts energy from flowing water without any albedo effect, at efficiencies far greater than solar PV or wind. I don’t see any regulations about the placement of solar farms but hydro is sure regulated to death
You are digging a deeper hole for yourself. What is the albedo of roads, open land, and parking lots compared to solar cells?
Solar cells will reduce the heat island effect, the very thing you are concerned with.
http://www.treehugger.com/renewable-energy/ask-pablo-do-solar-panels-contribute-to-the-heat-island-effect.html
But that is only a fraction of PV effect on heat. Solar cells will reduce GHG, which reduces temperature much more.
You have it all backward. If we want to reduce heat island effects, cover parking lots and roofs with PV.
There are pluses and minuses to hydro. Some don’t like it. On balance its pretty good, but it can’t do it all alone.
And your distaste for wind and solar is not in balance with comparative perspective. You need to ask in each case, what is the effect compared to other methods.
although this is not scientific….when I touch a solar PV panel at mid day it is hot, the green grass next to it is not hot….what can I deduce from this ?
I have no distaste for wind and solar PV. I am presently putting a new roof on so solar can be installed. I have visited with Pika Energy about installing a residential wind generator. I also have been waiting for over 5 months now for a FERC jurisdiction determination for my Pico hydro. I walk the talk.
I can install the wind and solar PV “tomorrow”. But the real dependable energy producer, hydro, gets strangled by government regulation.
Not much. Green grass transpires water from the soil, and so cools itself in other ways.
Its good to ask these questions though. While you have touched on the issue of heat is landing, there are many other areas of concern.
We don’t want to be displacing valuable farm land for solar. Thats why the land used is brown fields, rooftops, parking lots, deserts, etc.
Little solar is being built over grass areas, instead mostly brownfield and rooftop, areas already affecting heat is landing by human habitation.
Even taking those limits into consideration, the amount of area necessary to supply energy from solar is small.
For example, it is estimated that California could supply all its electricity from brownfield solar.
http://www.ecobuddhism.org/solutions/game_changers_/sbspc
If fully agree with you that we want to live “gently on the land”, if I may describe so.
Eveee, you may not believe this but I just got a call from a solar business, NRG Home Solar telling me that I qualify for solar without having solar on my roof. He said that they acquired “unused farmland” and are placing “industrial size solar panels” on it.
large rooftop and parking lot installations cost more than using farmland, likely a new roof would be needed to last the life of the panels for roofs and additional structures are needed for parking lots. From what I can see, this solar revolution is being hijacked by the money men and the only green they are interested in has pictures of dead presidents on it.
Here is their number if you want to hear it for yourself: 732 825 8251
Are you equating the sea of human foibles with technology? I mean car salesmen have cheated people. Is that supposed to make cars bad?
Can we avoid logical fallacy here, please? Read Larmions comment. I just proved that there is no heat island effect for PV over grass. Then Larmion says a lot of grass is fine with lower sunlight and can grow under the PV.
Now you are back to an example of PV over grass.
But you switched horses to these guys are swindlers.
Not quite a broken record, but your pattern is getting familiar. Cheese with that?
Starting to detect a whiff of eau du concern troll in the air?
Trying to apply some air freshener. 🙂 I will try to be nice. Nice is good.
Nobody’s being cheated, nobody’s being swindled. Everything these guys are doing is legitimate. Our government is providing incentives for these guys to build these solar farms anywhere they want. They should only provide incentives when it is done in the least disruptive way and taking farmland is not the right way…it happens to be the cheapest way and that’s why they do it. ( I believe Japan had to pass laws to stop the taking of farmland for solar)
This is not whining, this is pointing out, I hope, the unintended consequences of the solar revolution left in the hands of profit driven installers. This is not green, it is government approved greed.
There’s farmland and there’s farmland.
Some farmland is so degraded that it’s worth little in terms of producing food or textile crops. It’s hard to believe that critically needed farmland is used for solar farms.
Japan is building solar farms on abandoned golf courses. If they needed farmland they could plow up those areas and plant them.
Abandoned golf courses are a good choice for solar given the non-native plants growing there and the level of fertilizer and pesticide residue…..this IS disturbed land……and I suspect you may be right about farmland being similarly degraded also by fertilizer and pesticides
I don’t think farmland should be used for corn to make ethanol, either, but that is being done anyway. I agree we don’t want to turn valuable farmland into solar instead. Don’t know where you see that happening, but in California where there is over 10GW utility solar, none of it is over productive farmland. And an estimated 50% more is over roofs.
The locations of land based solar should be selected properly. Perhaps some legislative nudge in the right direction is required.
Thing is, utility solar should be under the guidance of the PUC. That should be possible to sway.
Can you give specifics about the areas developed over grasslands and what type of parties are involved?
Solar deployment on pastures is common, at least in Europe.
For land used for extensive (low density) grazing of smaller ruminants like goats or sheep, solar farms can coexist with pasture with only a limited decrease in productivity.
Many fodder grasses aren’t that bothered by partial shading and neither are common meadow flowers. That’s the underlying idea behind agroforestry, and it holds just as well for solar farms.
yes I have seen these high mounted solar installations allowing grazing underneath…..they are an excellent idea.They should be required for all grassland installations. But what I am seeing being built are the lower mounted version that require periodic weed trimming to prevent panel shading. The local solar installer tells me that the high mount solar costs 150% of the same capacity roof mount
I sure wish your message was heard better in England. They are on a NIMBY kick in rural areas. At least the politicians are.
What is the other 80% doing? You seem to have your mind made up that solar and wind are bad, but hydro is good. I don’t know where you get this from.
Solar panels create less heat than an asphalt roof.
Here is an article that could clear that up a bit.
“Photovoltaic panels range from blue to black but they are smooth and have an albedo around 0.3. But it is not the albedo itself that matters, it is the relative change in albedo from the status quo. Since most solar panels are roof-mounted, and most roofs are covered in dark tar-paper shingles, covering the roof with solar panels may actually represent a positive change in reflectivity. The solar panels would absorb 1.8 kWh per square meter per day, far less than the 5.4 kWh absorbed by asphalt.”
http://www.treehugger.com/renewable-energy/ask-pablo-do-solar-panels-contribute-to-the-heat-island-effect.html
as I have said many times, we must promote ALL of our renewables ….with the understanding that ALL have environmental effects. As I answered Mr. Wallace, I am not seeing much solar PV rooftop mounting, the big installations that I see are on open land or farm land. Wind generators still keep appearing on the ridgelines.
I am not against solar PV or wind, I just think that a 24/7 energy source that doesn’t have solar’s toxic footprint or wind’s siting and recycling issues is better and needs to be promoted. Unfortunately many “environmental” groups and government regulations don’t see it that way as the discrimination against hydro , even Small and Micro hydro persists.
And once again, adding solar reduces heat. Solar does not have a toxic footprint compared to other sources. You switched to a different meme. Apparently we are going to have to knock these down one by one.
Discussing toxicity is complex. One has to look at manufacturing, lifetime, and disposal. Then there is the full range of effects.
There might not even be a single meaningful metric.
However, compared to coal and oil, which both have carcinogenic properties and are used in massive quantities with exposures to large populations, there is simply no contest.
Renewables as a class are much better than fossil fuels, and the differences between renewables pale in comparison.
I was comparing the toxic footprint of solar compared to hydro……care to comment ?
Sure. Hard to make comparisons here, because they are dramatically different sources. Wind compares favorably to dams in LCA on energy balance, because its the least energy intensive construction. Its also easier to compare, because both are mainly civil construction projects involving things like concrete and steel, earthmoving, etc. and involve transportation in the construction phase. Because both involve construction, but wind is less energy intense, there is less emissions due to transport of materials. Hydro requires large quantities of energy in construction, thus has higher initial emissions. Wind has some factory construction and that part is different from hydro. Further down the line is the impacts of copper, steel, and other materials used in manufacturing.
Solar is quite different, with most of its impact being in manufacturing. Its mostly glass and aluminum. Much has been made of its content of things like Cadmium (thin film cells) and things like Arsenic for Silicon Cells. But it has been exaggerated. Cadmium is in the form of Cadmium Telluride which does not have Cadmium metals toxicity. Its also locked in the glass and cannot leach out easily.
Arsenic is not used for the most common Silicon solar cells.
Other materials are used during processing, which is where they can have the most negative effects, but this depends on manufacturing methods and practices. Silicon PV is like integrated circuits. With proper methods, the emissions are minimal.
Downstream effects are also minimal. The substances are locked into the Silicon and are in extremely low quantities.
In use, scale of danger of toxic substances from PV is on the scale of ordinary house glass and integrated circuits.
Their composition is similar.
There are many metrics in this graph. Notice that CdTe solar and CIGS solar are similar to hydro on the ecotoxicity scale.
http://breakingenergy.com/wp-content/uploads/sites/2/2014/10/roman-low-carbon1.jpg
http://gadgillab.berkeley.edu/wp-content/uploads/2013/02/Muller-M.2010.pdf
A given amount of sunlight strikes a square meter of land and heats said land. 100% of heat is stored on said land and gradually released as infrared radiation.
A given amount of land is covered by solar panels. 80% of heat is absorbed by the panels and given of as infrared radiation, just under 20% is converted into electricity and later turned into heat again when it is consumed by an electrical device.
The amount of heating, either local or global, is thus not meaningfully altered.
It would be different if we were going to replace high albedo land or dense forests with solar PV. So far, however, we are not building huge solar farms on top of glaciers. Maybe the penguins will start doing so once they reverse engineered our PV technology.
….so we need not be concerned with any source of heat islands….it will all average out, right ?
The last thing he said was it would be different if we changed albedo.
PV changes asphalt roof albedo to lower heat.
It reduces the heat island effect.
agreed that solar PV over asphalt is much better…..my question: is solar PV over grass better ?? Remember that sunlight on grass does not all get reflected, plants use solar energy to make plant tissue thereby sequestering this energy……..its nature’s “battery”
Yes. The albedo of solar PV is 0.30. The albedo of grasslands is 0.18 to 0.25. So PV would lower heating there. Not that we would want to or need to use PV over grasslands.
http://www.sonoma.edu/users/f/freidel/global/table%2002-01.jpg
http://www.treehugger.com/clean-technology/ask-pablo-do-solar-panels-actually-contribute-to-climate-change.html
All of California electricity could be generated from rooftop and parking lot.
http://cleantechnica.com/2015/05/23/nothing-rooftop-parking-lot-solar-installations-needed-power-california/
Desert is 0.3 to 0.5. So, in extremes, PV could raise the heat in the desert, which is otherwise a more reflective surface. That says we should balance desert PV with urban PV if that effect matters to us. But the amount of heating due to that is tiny compared to GHG.
“Although white asphalt shingles are an improvement over dark asphalt shingles, they do not have a high albedo. In preliminary tests, we found the albedo of a white asphalt shingle to be 0.22, compared to 0.05 for a black asphalt shingle.”
https://heatisland.lbl.gov/sites/all/files/lbl-32467.pdf
Can’t say that I’ve ever seen a roof covered with white shingles. Light beige is about as close to white as I’ve seen.
I’d guess the albedo of solar panels would not be very different than beige shingles. Along with the higher albedo compared to dark shingles rooftop solar is likely bouncing a lot more energy back into space than shingles would do.
Solar panels could create urban cool oases….
Heat islands arise when an area is covered in low-albedo surfaces, supplemented by heat emissions from buildings and vehicles. Add in highrise buildings that create a thermal canyon and the picture is complete.
PV does not have a meaningfully higher or lower albedo than the surfaces it is most commonly attached to (tile roofs, desert land, pasture and so on), does not emit any heat of its own and does not meaningfully alter airflow even at a local level.
In short, it does not create a heat island by itself and does not even contribute to an existing heat island in most cases.
I wouldn’t put it past these guys…
“the limited replenishment of kinetic energy from aloft limits wind power generation rates at scales sufficiently large that horizontal fluxes of kinetic energy can be ignored.”
Can anyone explain this sentence?
No. I gave up on that one.
I’ll give it a try.
I think it’s saying that vertical mixing is low, so the level of the wind turbines can be treated as being isolated, and that the size and scale of the turbine level is large enough that it can be treated as isotropic too.
The whole line seems to be superfluous to this article, frankly. It likely makes more sense in the context of the original report.
I am sure that wind turbines impact on weather and climate is only fraction of impact made by coal industry… even if we cover whole Earth with wind turbines. Largest wind turbine height is about 120m, Earth atmosphere is 100km thick so it’s only 0,12%
Yes, it does pale in contrast to the effects of carbon dioxide and global warming, doesn’t it?
This article is a total waste of time because it does not give numbers. It does not give numbers for a good reason: it would prove that this is total nonsense.
The first of such studies estimating Wind Power’s generation impact on the environment came out of Princeton. It gave numbers: it presumed 10,000 wind turbines at 1 mile grid at 100 meters height would cause enough friction to have measurable impact raising the ambient temperature of the surrounding area by a couple of degrees due to the friction.
However since they gave numbers one can compare this impact with the impact of the same amount of electricity generated by nuclear or fossil fuels. 10,000 wind turbines spaced on a grid a mile apart at 100 meter would generate more electricity a year than the needs of all of New England!!! The thermal impact of either nuclear or fossil fuels for this much electricity would be at least two orders of magnitude bigger than the thermal impact from wind. Of course fossil fuels’ dirty air from that much electricity also causes an epidemic or asthma and bronchitis and would contribute to the climate change holocaust. Nuclear while safer than fossil fuels also has externalities, as into what to do with the radioactive wastes, if one does not have former colonies to ship it (if you know what I mean).
Removing kinetic energy from global wind to make it a problem would require generating millions of times more electricity that is needed for all human needs even if we were to power our rockets with electricity for planetary travel. Do the math before spouting theoretical nonsense that confuse the amathematicals.