INTERESTING INFORMATION

Wind farms can tame hurricanes: scientists

Huge offshore wind farms can protect vulnerable coastal cities against devastating cyclones like Katrina and Sandy by tempering winds and ocean surges before they reach land. researchers said.

Had such installations existed at the time, Hurricane Katrina which ravaged New Orleans in 2005, and Sandy, which smashed the coastlines of New York and New Jersey in 2012, would have been reduced to strong but not devastating winds.

The study, published in the journal Nature Climate Change, is the first to demonstrate that wind farms, deployed on a grand scale, can buffer violent hurricanes, the researchers said.

The team simulated the impact from farms of tens of thousands of turbines, placed miles offshore and along the coast of cyclone-vulnerable cities.

They found that turbine blades extracting energy from the wind on a very large scale can have a marked effect on the internal dynamics of a cyclone.  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 centre 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 Hurricane Katrina, sustained peak wind speed would have been reduced by as much as 98 miles per hour. Katrina's storm surge -- waves whipped up by the exceptional winds -- would have abated by up to 79 percent, said the study.

In the case of Tropical Storm Sandy, the model projected a drop of up to 87 mph in sustained peak wind speed and a 34-percent decrease in storm surge. When Sandy, at an earlier stage, was rated as a powerful Category 3 hurricane, it packed gusts of up to 115 mph.

According to the study, the turbines should not be damaged and would continue to produce power during these events. By taming the leading edge of the storm, they would also dissipate the buildup of the winds that followed.

As a result, the wind speed would not exceed the turbines' designed cutout speed -- a threshold that prompts the device to go into lockdown and feather its blades to prevent damage.

But, according to the study, these mega-farms would pay for themselves by generating electricity in addition to providing storm protection.

A 20-mile installation off the New York coast would cost about $210 billion  to build.

By way of comparison, Tropical Storm Sandy inflicted about $80 billion  in damage when it hit three states in 2012. The disaster spawned plans to build higher sea walls to shield New York from rising storm surges expected from climate change -- a project that carries estimated costs of between $10-29 billion but produces no revenue.