Offshore wind farms could tame hurricanes before they reach land
Computer simulations by
Professor Mark Z. Jacobson have shown that offshore wind farms with thousands
of wind turbines could have sapped the power of three real-life hurricanes,
significantly decreasing their winds and accompanying storm surge, and possibly
preventing billions of dollars in damages.
For the past 24 years, Mark Z. Jacobson, a professor of civil and environmental
engineering at Stanford, has been developing a complex computer model to study
air pollution, energy, weather and climate. A recent application of the model
has been to simulate the development of hurricanes.
Another has been to
determine how much energy wind turbines can extract from global wind currents.
So he went about
developing the model further and simulating what might happen if a hurricane
encountered an enormous wind farm stretching many miles offshore and along the
coast. Amazingly, he found that the wind turbines could disrupt a hurricane
enough to reduce peak wind speeds by up to 92 mph and decrease storm surge by
up to 79 percent.
The study, conducted by
Jacobson, and Cristina Archer and Willett Kempton of the University of
Delaware, was published online in Nature
Climate Change.
The researchers simulated
three hurricanes: Sandy and Isaac, which struck New York and New Orleans,
respectively, in 2012; and Katrina, which devastated New Orleans in 2005.
"We found that
when wind turbines are present, they slow down the outer rotation winds of a
hurricane," Jacobson said. "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."
In the case of Katrina,
Jacobson's model revealed that an array of 78,000 wind turbines off the coast
of New Orleans would have significantly weakened the hurricane well before it
made landfall.
In the computer model,
by the time Hurricane Katrina reached land, its simulated wind speeds had
decreased by 36-44 meters per second (between 80 and 98 mph) and the storm
surge had decreased by up to 79 percent.
For Hurricane Sandy,
the model projected a wind speed reduction by 35-39 meters per second (between
78 and 87 mph) and as much as 34 percent decrease in storm surge.
Jacobson acknowledges
that, in the United States, there has been political resistance to installing a
few hundred offshore wind turbines, let alone tens of thousands. But he thinks
there are two financial incentives that could motivate such a change.
One is the reduction of
hurricane damage cost. Damage from severe hurricanes, caused by high winds and
storm surge-related flooding, can run into the billions of dollars. Hurricane
Sandy, for instance, caused roughly $82 billion in damage across three states.
Second, Jacobson said,
the wind turbines would pay for themselves in the long term by generating
normal electricity while at the same time reducing air pollution and global
warming, and providing energy stability.
"The turbines will
also reduce damage if a hurricane comes through," Jacobson said.
"These factors, each on their own, reduce the cost to society of offshore
turbines and should be sufficient to motivate their development."
An alternative plan for
protecting coastal cities involves building massive seawalls. Jacobson said
that while these might stop a storm surge, they wouldn't impact wind speed
substantially. The cost for these, too, is significant, with estimates running
between $10 billion and $40 billion per installation.
Current turbines can
withstand wind speeds of up to 112 mph, which is in the range of a category 2
to 3 hurricane, Jacobson said. His study suggests that the presence of massive
turbine arrays will likely prevent hurricane winds from reaching those speeds.
Story Source:
The above story is
based on materials provided by Stanford University. The original
article was written by Bjorn Carey. Note:
Materials may be edited for content and length.
Journal
Reference:
1.
Mark Z. Jacobson, Cristina L. Archer, Willett Kempton. Taming hurricanes with arrays
of offshore wind turbines. Nature
Climate Change, 2014; 4 (3): 195 DOI:10.1038/nclimate2120
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"Offshore wind farms could tame hurricanes before they reach land." Science Daily, 26 February 2014.
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