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Climate ChangeDisasters & Extreme WeatherRenewable EnergyScience

Off-Shore Wind Farms Can 'Tame' Hurricane Winds, Surges, Stanford Study Finds [VIDEO]

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Climate scientists have been predicting more intense seasonal temperature variations and storms for several years now and recent winter ice storms in the deep south of the US, as well as ‘super storm’ Sandy, seem to lend much credence to this forecasting.

And although this past hurricane season was less than spectacular — discounting Sandy, of course — intensified hurricanes are expected to become the norm over the next few decades and continuing through the rest of the century.

But what if there was a way to de-intensify the damaging winds and storm surges that come with hurricanes and generate cost-saving electricty in the process?

Well, now it seems, there is…just five words sum it up: large off-shore wind farms.

According to a new computer simulation study by Mark Z. Jacobson of Standford  University, strategically placed, off-shore wind farms have the potential to reduce peak hurricane wind speeds by as much as 92 mph and decrease storm surges by as much as 79 percent.

Jacobson has been computer modeling the interactions of air pollution, energy, weather and climate for the past 24 years. More recently, he has helped design a computer model that simulates hurricane development along with a second model to determine how much energy wind turbines can extract from the world’s wind currents. Given these efforts, it was only natural to start wondering: what would happen to a hurricane if it encountered a large scale wind farm prior to hitting land? Also: would the turbines slow the hurricane winds, or, would the winds destroy the turbines? 

To answer these questions, Jacobson, along with colleagues Cristina Archer and Willett Kempton of the University of Delaware, decided to conduct a new study with a more developed version of his computer model. The study sought to determine what would happen if a hurricane encountered an extensive wind farm (i.e., an “array”) — one composed of thousands of turbines and stretching for many miles along the targeted coastline.

The study simulated three past hurricanes: Sandy, Isaac (which struck New York and New Orleans, respectively, in 2012), and Katrina (which devastated New Orleans in 2005).

In summing up the results, Professor Jacobson, observed:

“We found that when wind turbines are present, they slow down the outer rotation winds of a hurricane. This feeds back to decrease wave height, which reduces movement of air toward the center of the hurricane, increasing the central pressure, which in turn slows the winds of the entire hurricane and dissipates it faster.”  [source: see link, below]

The new simulations revealed that a wind farm (array) of 78,000 turbines situated off the coast of New Orleans would have “significantly weakened” Katrina well before making landfall. Specifically, Katrina’s wind speeds would have been reduced by as much as 80 – 98 mph and diminished its storm surge (what eventually caused most of the damage to that city) by as much as 79%.

In the case of the more recent hurricane Sandy, the new simulation projected a reduction in wind speed of 78-87 mph and a 34% diminishment in its surge (recall that Sandy was a ‘super storm’, far more massive than Katrina, so this lower percentage reduction is still quite sizable).

Simulation of Hurricane Katrina wind speeds in the absence (left) and presence (right) of offshore wind turbines, showing significant reduction (blue-purple) of wind speeds (in meters/sec) (credit: Mark Z. Jacobson et al./Nature Climate Change)

Admittedly, there is much political (and even aesthetic) resistance to wind farms; some groups find the large arrays of hundreds of turbines to be a blot on the landscape (and there are still issues with bird and bat deaths); one can imagine even greater resistance to the idea of tens of thousands of such turbines lining the coast lines of our major cities.

But when one considers the tremendous reconstruction costs following such natural disasters due to wind damage and storm surge-induced flooding — commonly several billions of dollars, with Sandy costing in excess of 80 billion (over three US States) — it may be time to take a more reasoned look at the technology.

One additonal postive factor in favor of such extensive arrays is the cost savings to the cities that deploy them; wind turbines, according to Jacobson and colleagues, would pay for themselves over the medium to long term by generating electricity (providing energy stability) and reducing carbon pollution to boot.

Wind turbine can withstand wind speeds of up to 112 mph (encompassing category 2 – 3 hurricane winds) and the arrays would likely prevent winds of that intensity from ever happening, according to the new model.

As coastal cities currently contemplate building massive sea walls to prevent (or reduce the impact of) storm surge flooding which will cost tens of billions of dollars (and do nothing for energy generation or stability), it should be noted that such walls will not stop or diminish hurricane winds which add significantly to the cost of repairing hurricane-related damage.

And lastly, compared to tinkering with the atmosphere and global ecosystems via geoengineering strategies — and there are no such strategies for mitigating super storms — wind farm arrays may ultimately prove themselves to be the best and smartest alternative.

Notes Jacobson:

“The turbines will also reduce damage if a hurricane comes through. These factors, each on their own, reduce the cost to society of offshore turbines and should be sufficient to motivate their development.”

Watch this video showing the new Stanford computer simulations of wind farms ‘taming’ hurricanes

 The hurricane study was published online in Nature Climate Change under this citation:

Mark Z Jacobson, Cristina L Archer, Willett Kempton, Taming hurricanes with arrays of offshore wind turbines, Nature Climate Change, 2014, DOI: 10.1038/NCLIMATE2120

Some source material for this post came for the Kurzweil Accelerating Intelligence news article: Offshore wind farms could tame hurricanes before they reach land, Stanford-led study says

Abstract of Nature Climate Change paper (Jacobson et al)

Hurricanes are causing increasing damage to many coastal regions worldwide. Offshore wind turbines can provide substantial clean electricity year-round, but can they also mitigate hurricane damage while avoiding damage to themselves? This study uses an advanced climate–weather computer model that correctly treats the energy extraction of wind turbines to examine this question. It finds that large turbine arrays (300+ GW installed capacity) may diminish peak near-surface hurricane wind speeds by 25–41 m s1 (56–92 mph) and storm surge by 6–79%. Benefits occur whether turbine arrays are placed immediately upstream of a city or along an expanse of coastline. The reduction in wind speed due to large arrays increases the probability of survival of even present turbine designs. The net cost of turbine arrays (capital plus operation cost less cost reduction from electricity generation and from health, climate, and hurricane damage avoidance) is estimated to be less than today’s fossil fuel electricity generation net cost in these regions and less than the net cost of sea walls used solely to avoid storm surge damage. {reference: Mark Z Jacobson, Cristina L Archer, Willett Kempton, Taming hurricanes with arrays of offshore wind turbines, Nature Climate Change, 2014, DOI: 10.1038/NCLIMATE2120}

 Top photo: Offshore wind turbines near Copenhagen, Denmark [source: wikipedia.org]

Video: Jacobson et al/Standford University via the Kurzweil Accelerating Intelligence blog




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