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Offshore Wind Farms Could Protect Cities from Hurricanes

SAN FRANCISCO — Giant offshore wind farms could do more than provide electricity for major cities. They could suck the life and the power out of hurricanes barreling toward those cities, too, according to Stanford University research presented Monday at the American Geophysical Union fall meeting.

Stanford civil and environmental engineering professor Mark Z. Jacobson and his research team found that if it was feasible to build tens of thousands of wind power turbines off the shores of some of America’s cities most vulnerable to extreme weather, those cities would see lower wind speeds and less severe storm surges from approaching hurricanes.

Offshore wind farm at Redcar Beach, England.
Click image to enlarge. Credit: Stevie Gill/flickr

The researchers imagined what would have happened if a massive wall of tens of thousands of wind turbines had been built before hurricanes Katrina and Sandy and ran computer simulations of both storms with and without offshore turbines constructed in their paths.

They concluced that the wind turbines could have sapped Katrina of so much energy that wind speeds would have been reduced by up to 50 percent at landfall and the hurricane's storm surge could have been reduced by about 72 percent, Jacobson said. It also would have generated 0.45 terawatts of wind power.

Hurricane Katrina, which devastated New Orleans and the Louisiana Gulf Coast in 2005, was the costliest and and one of the deadliest hurricanes to ever hit the U.S. 

Jacobson's Katrina simulations assumed arrays of 70,000 turbines  — 300 gigawatts of installed power  — had been built 100 kilometers offshore southeast of New Orleans and were designed to withstand winds of up to 50 meters per second, just above the strength of a Category 3 hurricane, or roughly 111 mph.

The simulations showed that the turbines would create a net energy reduction in the atmosphere, slashing wind speeds as energy was sapped from the storm and dramatically reducing storm surge, which is caused by high winds pushing water inland as a hurricane barrels toward the coast.

Wind speeds would have been reduced enough to allow the wind turbines to survive the storm themselves, with winds never reaching 50 meters per second, above which the turbines could topple. 

A similar array of wind turbines just offshore of New York and New Jersey could have reduced wind speeds of Hurricane Sandy by up to 29 meters per second, or 65 mph, with a storm surge reduction of about 21 percent, he said. 

“If we have large arrays of offshore wind turbines — large walls of turbines — we could dissipate winds and storm surge quite a bit,” particularly in the vicinity of the turbines themselves, Jacobson said.

Jacobson did not address the feasibility or the political and environmental challenges of building such massive offshore wind farms along hurricane-prone coastlines. Proposals for smaller offshore wind farms have generated significant opposition and controversy, especially along Cape Cod in Massachusetts.

A study Jacobson co-authored in 2012 showed that offshore wind power can generate enough power to meet a third of U.S. energy needs. 

“You’re generating electricity year-round, so (an array) would pay for itself,” he said Monday. 

Jacobson said he has also envisioned constructing turbines worldwide to produce green energy that would meet half the world's energy needs. He said it would require 4 million wind turbines globally to do so. 

"1.5 billion turbines would reduce wind speeds worldwide by 50 percent," Jacobson said. 

Asked by an audience member how wind-farm construction on a such a large scale would affect local wind speeds and global weather patterns during normal conditions in the absence of hurricanes and other extreme weather, Jacobson said the large turbine arrays would likely reduce local shoreline wind speeds at most times, but would not likely affect global weather patterns overall, even if offshore wind farms were constructed on a global scale.

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Studies: Offshore Wind Potential Is Huge

Comments

By dan_in_illinois
on December 10th, 2013

It is my understanding that wind turbines cannot operate in extremely high winds and generally have to be completely shut down and braked in winds exceeding about 25 miles per hour.

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By Georgine Thorup (94301)
on December 12th, 2013

You are right.  I don’t what kind of turbines he was thinking of.

Reply to this comment

By Steven Blaisdell
on December 15th, 2013

A key phrase in the report is “if feasible.” As Bruce points out below, this is future oriented thinking, probably not much different than certain men, say about a hundred years ago, in liquid hydrocarbon extraction envisioning a world powered by “Texas Tea.” And look where we are now….

Reply to this comment

By Bruce
on December 13th, 2013

The “cut-out speed” is significantly higher than that for large offshore turbines, but even when shut down,  the blades and towers break up the wind and create turbulence, reducing speed.  The latest offshore turbines have blade tip heights around 200m, and the wake effect can extend up to double that height..

Much of Dr. Jacobson’s work looks far into the future and thinks about what the buildout/end game would look like for maturity of renewable energy technologies.  I recommend reading his papers if you like that stuff, no heavy math required (usually).  A serious scholar with a futurist angle.

Reply to this comment

By David Manwell
on December 28th, 2013

According to a website for GE, their 1.5, MW wind turbine, as available in 2007, would automatically shut down at around 62 MPH wind speed, not 25 MPH.  They shut down by making their blades spill the wind; in that state, they don’t offer any more resistance to the wind than any other structure of their height.  Presumably that would somewhat reduce the wind’s force downwind of them.

Reply to this comment

By Judy Sanborn (Windsor, Wyoming)
on December 10th, 2013

Katrina is not the deadliest storm to hit the United States.  The Galveston storm of 1900 killed an estimated 6000+.

Reply to this comment

By FJD
on December 12th, 2013

Yes, the Galveston hurricane was the deadliest, but the author stated Katrina was “one of the deadliest hurricanes to ever hit the U.S.” Look forward to reading a journal article detailing the methods and results.

Reply to this comment

By EC
on December 10th, 2013

What is the maximum velocity of a wind turbine?

Reply to this comment

By RWC
on December 10th, 2013

Instead of turbines where the wind still gets through why can’t we build a wall to keep the wind out altogether?

Reply to this comment

By nickshaw (Escazu, Costa Rica, 33102)
on December 10th, 2013

First of all windmills are designed to shut down at winds above 70mph.
Should they continue to spin during a hurricane, you’d have to go looking for 21,000 blades somewhere in the Gulf.
Then, there’s the bird problem. Of course, if you don’t care that just about every migratory bird is shredded versus the chance of a hurricane, well….

Reply to this comment

By Steven Blaisdell
on December 15th, 2013

Wind-related bird fatalities are .003% (3 thousandths of a percent) of bird fatalities across the US. Where are all the posts and studies criticizing and improving monitoring of bird deaths because of chemical-industrial agriculture, cars, air travel, golf courses, over-development, and meat production (due to habitat destruction, especially for migratory species in the Amazon)? All of which seem ok with the folks so fond of complaining about the ‘threat’ to birds from wind turbines. Any one of those projects alone kills thousands or millions of times more birds than wind generation. Where are the complaints about coal-fired electricity, which kills 17 times more birds per unit of energy? 

The solar and wind economy is better for all animals and plantlife, while the continued use of fossil fuels WILL destroy a habitable Earth. Wind and solar energy are by far the best thing humans have done for wildlife – and – humanity in modern history.

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By Dave (Basking Ridge, NJ 07920)
on December 10th, 2013

I am all for well sited and designed offshore wind farms as a means for generating climate friendly, renewable energy. Offshore wind energy – in the US at least – is a vastly unexploited resource along with wave and tidal power. But this study goes well beyond the normal renewable energy application and ventures into the mystery zone of grand hypotheticals where massive overcapacity would be designed so as to mechanically help protect a local city and coast from storms. Practical offshore wind farms built solely for renewable energy have very much fewer turbines than the numbers given here and yet still tend to face very difficult political, environmental and economic obstacles to implementation. Grand hypotheticals can sometimes spur the imagination and eventually lead to practical ideas and be of great value. But if Jacobson is serious about the net benefits of this specific aspect of large offshore wind farms then I think he really needs to refine his ideas into something a lot more practical sounding than that described here.

Reply to this comment

By Steven Blaisdell
on December 15th, 2013

“he really needs to refine his ideas into something a lot more practical sounding than that described here.”
Agreed, but that’s not really the intent of this paper. As stated by “Bruce” above:
“Dr. Jacobson’s work looks far into the future and thinks about what the buildout/end game would look like for maturity of renewable energy technologies…... A serious scholar with a futurist angle.”
The next steps are for mechanical engineers to find and develop stronger materials and structures capable of handling the loads. This hardly seems impossible, especially given that work in these areas is an exploding field. (Almost every issue of Science has a report of some advance in this area.) At the same time, we need to get used to failures; they’re bound to happen (Deepwater Horizon, anyone?). Wind ‘spills,’ however, would tend to be rather….tame compared to those pesky ecology destroying oil spills, don’t you think?

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By ertdfg
on December 10th, 2013

So in yo0ur view all the wind forming a hurricane was within building range of the ground?
The clouds aren’t really that high up and we can manage them with ground based fans?

How high did these “scientists” think the troposphere runs?  50 feet or 100 feet?

Reply to this comment

By Brent Newman (Hughesville, PA 17737)
on December 11th, 2013

Whether or not turbines could significantly reduce coastal wind speeds during a cyclone or reduce global wind at the surface is probably anyone’s guess, but the Planetary Boundary Layer can be as low as 100m especially over open water. There are existing 100m tall offshore turbines, so I have to believe that a buffer of large turbines offshore would create enough turbulence would propagate into the lower levels of the cyclone.

Reply to this comment

By Darren (75605)
on December 10th, 2013

@EC:

African or European?

Reply to this comment

By GMay
on December 10th, 2013

Windmills built to withstand winds at hurricane force level while still operating would not be able to generate power in normal wind conditions.

Hurricane Katrina devastated the MS and AL coasts much more extensively than LA’s coast. [It’s spelled ‘coast’, not “coat” by the way.] Also, Katrina was a Cat 3 storm when it made landfall and most of the human toll could have been avoided with a stable levee system which failed due to engineering error and not from the mediocre power of Katrina.

So world wind speeds would supposedly be reduced by 50%, but that’s not going to effect global climate patterns?

It’s good to know that Stanford is no longer as reputable as it once was and that this site won’t be worth revisiting.

Reply to this comment

By Brent Newman (hughesville)
on December 11th, 2013

This is novel. Do you know whether the simulations included a traditional linear arrangement of turbines or staggered? I read that a staggered pattern could yield something like a third more power/unit area.

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By dan_in_illinois
on December 11th, 2013

Nick,

Excellent points.  I do not understand the fascination of “environmentalists” with these ridiculous wind turbines.

Reply to this comment

By Eric Peterson (Front Royal, VA 22630)
on December 11th, 2013

70,000 turbines at 2 million a piece is 140 billion.  It would be cheaper to relocate everyone in the surge zone.  That cost also doesn’t include ongoing maintenance.

Reply to this comment

By MorinMoss (New York)
on December 11th, 2013

Not opposed to wind power but this sounds very farfetched and would be hundreds of billions just for New Orleans.

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By Haiku Guy (Cranford NJ 07016)
on December 11th, 2013

Hurricane Sandy?
No longer a Hurricane
When it struck Jersey

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By High Treason (Bondi)
on December 13th, 2013

The turbines would not work in such high winds, so the power claim is bogus. The blades would probably be blown off and tower damaged. The repair bill would be as much or more as the repair bills for the city the hurricane was headed to. If landfall was in a sparsely inhabited area, the turbine repair bill would still occur. This is yet another apologist argument to try to justify the insanity of wind farms. Needless to say, the “environmentalists” who make these ridiculous suggestions never take in to account the effects on birds. Do they REALLY care about birds?

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By Steven Blaisdell
on December 15th, 2013

Coal fired electricity generation kills 17 times more birds per unit of energy than wind, and far, far more wildlife of all kinds, as well as people. Every kilowatt hour of coal we replace with wind power saves lives of all kinds, never mind the 50 tons of elemental mercury emitted each year from U.S. coal-burning powerplants. You remember what mercury does to wildlife and human development, right? 

Want to save 70 million birds a year? Do everything you can to help wind energy replace coal. Want to save humans, trees, crops, our food supply? Redouble the efforts to switch to wind, solar and efficiency. Want to have a planet on which our civilization, or something like it, can exist? Wind power, in massive amounts, is going to be part of a sustainable future. Without it…..hope you like living Neanderthal style, ‘cause if we don’t reverse carbon emissions - fast - that’s where we’re going to end up.

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By Cassie Curnutt (Dallas, TX 75234)
on December 19th, 2013

This is a logical theory. Anyone who has lived in “tornado alleys” knows tall obsticals, to block and slow down winds (trees, hills, buildings), will make storms less severe.

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By Jerry Scherer (Tulsa, OK )
on April 29th, 2014

How it that “They could suck the life and the power out of hurricanes ...” yet not impact the weather? It sounds of if we really don’t know what impact wind farms will have on the weather.

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