The high winds of the upper atmosphere contain less renewable energy than previously assumed
Rotary wind turbines could hang like kites in the upper atmosphere where the jet streams blow. This photomontage shows what they might look like. Credit: Lee Miller
It seems that the energy mix of the future will have to differ from the current suggestions of some visionaries. This is because the jet streams that sweep the upper atmosphere with high winds would yield about 200 times less energy than previously estimated, according to calculations by researchers at the Max Planck Institute for Biogeochemistry in Jena, Germany. The high winds were thought to be a rich potential source of renewable energy. However, their speed is due to the near absence of friction and not to strong propulsion, which would be necessary for high-output wind turbines. Using climate simulations, the researchers also discovered that the climate system could be subjected to massive change if large amounts of energy were taken from the jet streams.
At heights of 7 to 16 kilometres, the air in jet streams moves at constant speeds of over 25 metres per second or 90 kilometres an hour. These high speeds suggest that the winds could be used as a practically inexhaustible source of renewable energy; and extensive investments are already being made in technologies that aim to tap into that source. However, the energy of the jet streams is limited. Like other wind and weather systems on Earth, the jet streams are generated because solar radiation heats the tropics more than the polar regions. The resulting temperature differential in the atmosphere leads to a drop in air pressure, and this pressure difference is the driving force behind the wind. Consequently, the disparate warming sets the upper limit on the strength of the wind. It also determines the maximum amount of renewable wind energy that is available for extraction.
The power and direction of the jet streams arise through the accelerating effect of pressure changes in the upper atmosphere and the Coriolis force generated by the Earth’s rotation. The Coriolis force deflects winds in the northern hemisphere to the right and winds in the southern hemisphere to the left. Meteorological science has shown that the jet streams are so fast because they arise in the upper atmosphere, far from the surface of the Earth. This means that they are subjected to almost no friction; experts speak of geostrophic winds. Consequently, very little energy is required to initiate and maintain these airflows.
A high level of kinetic energy does not necessarily mean that it can be used in wind power stations. Top: A model simulation of kinetic energy transport. Bottom: The maximum extraction rate. The transport of kinetic energy is often wrongly seen as a measure of wind output, whereas it merely reflects high transport in the near absence of friction. This is why the extraction rate (bottom) is several orders of magnitude lower. Credit: Lee Miller / MPI for Biogeochemistry
Jet stream energy extraction would cause massive climate change“It is precisely this low energy requirement that limits the potential for using the jet streams as a source of renewable energy”, explains Axel Kleidon, head of the Independent Max Planck Research Group on Biospheric Theory and Modelling. Based on atmospheric energetics and using climate simulation models, Kleidon’s group has calculated the maximum rate at which wind energy can be taken from the global atmosphere. According to their estimates, the jet streams have an output of just 7.5 terawatts (one terawatt equals a million megawatts). This means that they generate 200 times less usable wind energy than stated in previous studies, and only about half of humankind’s primary energy requirements, which totalled about 17 terawatts in the year 2010.
The Max Planck researchers also studied how climate would change if the jet streams were tapped into on a large scale as a source of renewable energy. Every wind turbine establishes a resistance in order to convert wind energy into power, and the balance of forces in the jet stream is altered as soon as that energy is removed from it. If turbines were to harvest the full 7.5 terawatts contained in the jet streams, this balance would be massively altered. The pressure difference between the equatorial region and the poles would disappear, and the whole climate system would slow down. “If we used wind turbines to take 7.5 terawatts out of the atmosphere at the level of the jet streams, about 300 terawatts less energy would be generated in the atmosphere as a whole”, explains Lee Miller, lead author of the study. “This would have a drastic impact on temperature and weather.”
Too little wind energy, too much risk – it seems like these high winds will contribute less to tomorrow’s energy mix than some had hoped. “Our investigations show that the potential of the jet streams as a source of renewable energy was overestimated”, says Axel Kleidon. “It is incumbent on us to carefully study the global impact of renewable energy technologies that seem environmentally sound.”
More information: Lee M. Miller, et al., Jet stream wind power as a renewable energy resource: little power, big impacts, Earth System Dynamics, 29 November 2011; doi: 10.5194/esd-2-201-2011
Provided by
Max-Planck-Gesellschaft
-
From lemons to lemonade: Reaction uses carbon dioxide to make carbon-based semiconductor,
32 comments
-
Thioridazine kills cancer stem cells in human while avoiding toxic side-effects of conventional cancer treatments,
3 comments
-
SpaceX private rocket blasts off for space station (Update),
42 comments
-
Climate scientists say they have solved riddle of rising sea,
31 comments
-
SpaceX capsule has 'new car' smell, astronauts say (Update),
4 comments
-
Need a rigid insulation material???
22 hours ago
-
magnets or EMF in car bumpers to protect from fender bender
May 26, 2012
-
length of wire in a coil of known dimensions?
May 25, 2012
-
India Engineering Powerhouse
May 25, 2012
-
electromagnet core dereference between hard and soft iron
May 25, 2012
-
Measuring water pressure in an open tank
May 24, 2012
- More from Physics Forums - General Engineering
More news stories
Browser wars flare in mobile space
The browser wars are heating up again, but this time the fight is for dominance of the mobile Internet.
15 hours ago |
5 / 5 (2) |
3
Probability of contamination from severe nuclear reactor accidents is higher than expected: study
Catastrophic nuclear accidents such as the core meltdowns in Chernobyl and Fukushima are more likely to happen than previously assumed. Based on the operating hours of all civil nuclear reactors and the number ...
Technology / Energy & Green Tech
May 22, 2012 |
3.6 / 5 (25) |
56
|
HyperSolar shows dirty water no barrier to power world
(Phys.org) -- The Santa Barbara, California, company, HyperSolar, is set to transparently share the ups and downs of its research experiences toward the company’s ultimate vision, successfully producing ...
Technology / Energy & Green Tech
May 24, 2012 |
4.8 / 5 (16) |
17
|
SpotterRF debuts Radar Backpack Kit (w/ Video)
(Phys.org) -- SpotterRF has announced a special radar backpack kit designed to enhance situational awareness for soldiers on the ground. The company says its special radar is designed for warfighters as part ...
Technology / Hi Tech & Innovation
May 26, 2012 |
5 / 5 (5) |
13
|
Tesla to launch electric sedan in US on June 22
Tesla Motors said Tuesday it would begin deliveries of "the world's first premium electric sedan" on June 22, slightly ahead of schedule.
Technology / Energy & Green Tech
May 22, 2012 |
4.5 / 5 (12) |
18
Stunning image of smallest possible five-ringed structure
Scientists have created and imaged the smallest possible five-ringed structure – about 100,000 times thinner than a human hair – and you'll probably recognise its shape.
'Unzipped' carbon nanotubes could help energize fuel cells, batteries
Multi-walled carbon nanotubes riddled with defects and impurities on the outside could replace some of the expensive platinum catalysts used in fuel cells and metal-air batteries, according to scientists at ...
Change in developmental timing was crucial in the evolutionary shift from dinosaurs to birds: study
At first glance, it's hard to see how a common house sparrow and a Tyrannosaurus Rex might have anything in common. After all, one is a bird that weighs less than an ounce, and the other is a dinosaur that ...
Computer model used to pinpoint prime materials for efficient carbon capture
When power plants begin capturing their carbon emissions to reduce greenhouse gases – and to most in the electric power industry, it's a question of when, not if – it will be an expensive undertaking.
T cells 'hunt' parasites like animal predators seek prey, study shows
By pairing an intimate knowledge of immune-system function with a deep understanding of statistical physics, a cross-disciplinary team at the University of Pennsylvania has arrived at a surprising finding: T cells use a movement ...
Land and sea species differ in climate change response: study
(Phys.org) -- Marine and terrestrial species will likely differ in their responses to climate warming, new research by Simon Fraser University and Australia’s University of Tasmania has found.
Dec 12, 2011
Rank: 1.6 / 5 (7)
You'd need high altitude balloons or gliders on tethers, and that's over complicated, and a hell of a lot more expensive than ordinary turbines. Not to mention, most of the energy is wasted just keeping the harvester flying...
The other thing is, their theoretical power calculations are incorrect anyway.
That would even be an over-estimate for 90km surface winds at 1 atmosphere pressure, because that would only be 9300 Watts/meter squared.
At altitude, the air is much less dense so there is much less MASS in the air, which means any given velocity wind has much less energy.
They didn't even adjust the power formula for the correct density of air at that altitude.
Complete incompetence.
Ghost Tard will attack me now, so I make a link for his slow mind.
reuk.co.uk/Calculation-of-Wind-Power.htm
Power = 0.5 x Swept Area x Air Density x Velocity^3
Dec 12, 2011
Rank: 1.6 / 5 (7)
Dec 12, 2011
Rank: 2.3 / 5 (3)
Dec 12, 2011
Rank: 1.6 / 5 (8)
Dec 12, 2011
Rank: 1.7 / 5 (6)
It would be devastating to economies world-wide. Just like legalizing drugs would bring many countries to their knees.
Dec 12, 2011
Rank: not rated yet
Just kickin' down the cobble-stones, lookin' for fun and feelin' groovy
Feeling groovy
Dec 12, 2011
Rank: 4.2 / 5 (5)
Also, you supporting claim of drug legalization crippling economies is also pure delusion. Canada has decriminalized marijuana, and their economy seems to be doing just fine. What country has legalized drugs only to be "brought to their knees"?
Drugs are illegal because we view their use as immoral not because legalizing them would devastate our economy.
That out of the way, I wish someone would study the effects of wind generation at a low level like this also. Obviously those winds are much more robust, but (IMHO) there must be a danger point somewhere that (at least locally) should not be crossed.
Dec 12, 2011
Rank: 1.4 / 5 (5)
Do you understand how much energy is available in wind?
Concerns over catastrophism from harvesting winds are ridiculous.
We already have mega-disasters caused by 100% natural wind events as it is, so it's not like removing energy from the atmosphere would hurt anything any worse.
Hurricanes Mitch and Katrina
Tropical Storm Jeanne
Cyclone Nargis and 30 other Bay of Bengal cyclones...
Humans use 17 Terawatts, which is 536 million TeraJoules.
Katrina's 10m elevation, 1 minute Sustained winds were 78m/s.
Using power formula, that gives 284,000 Watts/M^2 in the eye wall. Which is the equivalent of 323 Horse-Power per yard square.
Now figure that for area of the hurricane...yeah...
That makes the author's concern about some sort of climate disaster caused by harvesting winds look ignorant.
Dec 12, 2011
Rank: 3.4 / 5 (5)
Dec 12, 2011
Rank: 3.3 / 5 (3)
So, i'll comment on this article itself:
To quote: "The high winds were thought to be a rich potential source of renewable energy. However, their speed is due to the near absence of friction and not to strong propulsion, which would be necessary for high-output wind turbines. Using climate simulations, the researchers also discovered that the climate system could be subjected to massive change if large amounts of energy were taken from the jet streams."
The authors seem to want it both ways: saying harvesting a lot would be harmful, yet, in same breath, saying its impossible to harvest significant amounts.
Ya cant have it both ways gentlemen!
Dec 12, 2011
Rank: 2 / 5 (4)
That's just a 20km wide cross section. The whole storm had a 200 mile radius of TS winds I won't even begin to bother with.
Point is, this study misses the point.
It doesn't really get much worse than Katrina, short of Hypercanes, and of course, we've had Category 5 hurricanes naturally forever.
Taking some energy out of the amosphere with a bunch of turbines isn't going to make some "day after tomorrow" / 2012 movie BS happen...
More likely, pumping so much CO2 into the atmosphere probably will make much stronger hurricanes, but then again, CO2 heats the lower troposphere and oceans while cooling the stratosphere, so no brainer.
At the rate we're going, we'll make hurricanes much stronger by NOT using lots of wind power...
Dec 12, 2011
Rank: 1.8 / 5 (5)
The Japan Earthquake, which was not at all caused by man, was rated at 9800 gigatons of TNT equivalent (4.18 megajoules per KG).
that's 9.8 Quadrillion kilograms, and each kilogram is 4.18 megajoules.
That's 4.09E22 Joules.
That's 100 times more energy than humans used in a year in 2011, and at least 2 times more energy than humans have used in all of the history of the Earth.
What can these bozos possibly imagine a few wind turbines accidentally causing?
Ridiculous.
Dec 12, 2011
Rank: not rated yet
"At heights of 7 to 16 kilometres".
As to my comments, i'm just curious what the total number would be, because it has to have some finite limit somewhere. Not that we could ever come close to actually reaching it, but i'm just curious about it.
Dec 12, 2011
Rank: 5 / 5 (1)
Dec 12, 2011
Rank: 1 / 5 (3)
Just like popping a mountain range or a continent into the ocean would change climate around the globe so too all this harvesting of energy formally devoted to transporting weather around the planet.
In extreme case imagine extracting all natural energy from the environment. We would have net effect of no wind no waves and constant climate at all points.
Might be cause of massive world wide droughts.
Dec 12, 2011
Rank: 1 / 5 (2)
Right, understand the difference between legalizing drugs and decriminalizing. You obviously can't see that many people have jobs that are directly related and dependent on the fact drugs are illegal, from treatment to prison and much, much more, it doesn't just put money in dealers' pockets. And that money is a vital part of the economy, regardless of what side of the coin it comes from.
You think Cali or a few other western states would be doing so good right now if a pound of dope were worth $50 instead of $1500-2500 ?....noe
How about the 5-7k it brings on the East coast ? How about 100 pounds ? Or 500 ?
The problem here is people like you who have no experience in the trade are clueless about how much money it injects in economies, that's just due to your ignorance.
Dec 13, 2011
Rank: not rated yet
Dec 14, 2011
Rank: 2 / 5 (1)
Dec 14, 2011
Rank: 5 / 5 (1)
"Once consumed it is gone 'renewable energy' is as much a myth as 'anthropogenic globsl warming'."
Yeah...OK Brian. If you can site just one example of natural variability that could cause the current observed trend of warming, feel free.
Dec 14, 2011
Rank: not rated yet
yeah, because those stoners who are buying it would just burn their money instead of buying another xbox game? This isnt a zero sum game, sorry. Besides if it were legal the money wouldn't be flowing back into Mexico, it would be flowing into US farmers. Plus the money would flow more freely if you could use your visa debit to make the purchase, which would increase the velocity of that money, multiplying the effect.
Drugs being illegal has NOTHING to do with avoiding some economic melt down caused by making it cheaper. NOTHING.
Dec 14, 2011
Rank: not rated yet
Can some mod come by and just delete all these pointless off topic posts, this one included?
Oh wait, that would require physorg to hire some mods... damn it.
Dec 18, 2011
Rank: 1 / 5 (1)
----------------------------
As far as the premise of the article, sucking the energy out of the atmosphere and throwing weather patterns into chaos, I doubt we would be able to get to the point where we were harvesting that much from the upper atmosphere, it would require too much trial-and-error testing. By the time we could pull it off, we'll already have developed better sources of energy.
Besides, imagine what will happen the first time a flock of those things drops out of the sky on a residential area, or a downtown metropolitan area like NY city.
A bunch of them flying on tethers in the same space would be asking for a disaster.
Dec 18, 2011
Rank: not rated yet
Dec 18, 2011
Rank: not rated yet