Scientists have known since 2004 that wind farms kill bats, just as they kill birds, even though the flying mammals should be able to avoid them. Many biologists thought that the bats, like their avian counterparts, might be falling victim to the fast-spinning turbine blades. But an examination of 188 hoary and silver-haired bats killed at a wind farm in south-western Alberta in Canada between July and September in 2007 showed that nearly half showed no external injuries—as would be expected if the giant blades had smashed the flying mammals to the ground. Instead, 90 percent of the 75 bats the researchers ultimately dissected had been killed by burst blood vessels in their lungs, according to results presented in Current Biology—suggesting that the

Air pressure difference created by the spinning windmills had terminated them, not contact with the blades.” As turbine height increases, bat deaths increase exponentially,” says ecologist Erin Baerwald of the University of Calgary in Alberta, who led research into the deaths as part of her master’s project. “What we found is a lot of internal hemorrhaging.”

As the wind moves through a wind turbine’s blades, pressure drops behind them by five to 10 kilopascals (a pascal is a unit of pressure), and any bat unlucky enough to blunder into such an undetectable low pressure zone would find its lungs and blood vessels rapidly expanding and, quickly, bursting under the new conditions. The Summerview wind farm, which Baerwald studied, kills hundreds of bats every year, particularly during the fall migration period that has just begun. But bats that find their way via sonar should have no trouble detecting fast-moving objects like the 200-foot- (60-meter-) long blades on the 300-foot- (90-meter-) tall turbines that spin as quickly as 160 miles (255 kilometres) per hour. And before the installation of these new, taller turbines bat kills had been practically nonexistent. Pressure drops of as low as 4.4 kilopascals kill common lab rats and all the bats autopsied showed internal damage and bleeding consistent with this type of death, known as barotrauma. “If bats have a lungful of air as they fly through the air-pressure change, there’s nowhere for the air to go,” Baerwald explains. “The small blood vessels around the lungs burst and fill the lungs with fluid and blood.”

This may also explain why, although some birds are killed by wind farms, the majority of casualties are bats.

Birds‘ lungs are much more rigid and their capillaries are stronger, making them capable of withstanding extreme pressure changes, according to Baerwald. Those birds that are killed typically show damage from being struck by the actual turbine blade. “This offers an explanation of why bats, once they come across these turbines, are so likely to end up dead,” says research biologist Paul Cryan of the U.S. Geological Survey, who has studied the issue but was not involved in this study. But “we don’t have a satisfying explanation for why we’re seeing such large numbers of bats. It seems they’re being attracted to turbines.”

Wind farm owners are well aware of the problem—and the potential hit to their environmental credibility. The corporation that owns Summerview, TransAlta Wind, along with ENMAX, Suncor Energy, Alberta Wind Energy and even Shell Canada teamed with Austin, Tex.–based Bat Conservation International to fund this study led by Baerwald. (TransAlta did not return calls for comment.)It is unclear what measures, if any, can be taken to eliminate this pressure problem other than stopping turbines from spinning during times of lighter winds at night when bats tend to be most active. Of course, that would also curtail their electricity production: An experiment in August 2007 that stopped 19 of Summerview’s turbines when winds fell below 18 feet (5.5 meters) per second cost TransAlta at least $50,000 in lost electricity production.

In the future, bat conservationists suggest, wind farms should be built away from known bat migration flight paths. The problem is: bat migrations are poorly understood at best. “We don’t even know if they use migratory routes,” Baerwald says, though she plans to begin looking for them in September.” We don’t have a clear idea of what a bad site for wind turbines is in terms of bat fatalities,” Cryan adds. “We’re not to the point yet where we can suggest solutions.”

The full impact of these bat-killing pressure zones extends far beyond the wind farm, however. Such migrating bats travel from Canada as far as Mexico, eating thousands of insects en route, including crop pests such as moths and beetles. “They are one of the only things that fly around at night and eat bugs,” Baerwald notes. “Bats killed in Canada could have a detrimental impact in America or Mexico. It’s not local. It’s an ecosystem-wide issue.”

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“Centrica, the owner of British Gas, is in talks to bring in outside investors to take up to half of its planned £3.5bn wind farm programme.

Credit Suisse was hired earlier in the year to advise on the process and Centrica is now in exploratory talks with a number of potential investors.

Centrica is looking for financial investors to take a significant minority stake in its wind farms, up to just under 50 per cent. This could raise more than £1.5bn to fund the construction programme.

There has been a high level of investor interest in renewable energy this year in spite of the turmoil in financial markets. However, doubts have been raised about the financial viability of offshore wind power, which will comprise the majority of Centrica’s portfolio.

Centrica today has less than 200 megawatts of wind power, roughly half onshore and half offshore.

It is also building another 180MW project in the Wash, East Anglia, which will be the world’s largest offshore wind farm when it comes on stream, scheduled for the end of the year.

Three more projects have been proposed, to take the total to 1,600MW: roughly the output of a typical nuclear power station.

Shortages of equipment, including turbines and the vessels to install them, and skilled staff have sent costs in offshore wind soaring. On some calculations, wind is the most expensive form of electricity generation capacity. Centrica’s programme is likely to cost up to £3.5bn at today’s prices: a heavy commitment for a company with a market capitalisation of £10.6bn.

Centrica is unlikely to follow the route taken by European companies such as Iberdrola of Spain and Energias de Portugal, which have floated off minority stakes in their renewable energy businesses, although that option has not been ruled out.

Instead, its wind power programme is expected to interest private equity investors, who could take a stake either in the wind portfolio as a whole, or in individual projects.

Earlier this week Blackstone, the private equity group, announced plans to invest €1bn (£799m) in offshore wind farms off the coast of Germany.

Mark Muldowney of Fortis Bank said he expected to see more offshore wind deals as the market was maturing fast

“The offshore wind market has huge potential in Europe. It’s a very interesting market and we expect to see much more activity in this space,” he said.

However, confidence in the industry suffered a blow in May, when Royal Dutch Shell pulled out of the London Array, a planned 1,000MW offshore wind farm, which would be the world’s biggest on completion. Shell is in talks to sell its one-third stake to its partners in the London Array, Dong Energy of Denmark and Eon, the German energy group.

Shares in Centrica fell 4.5 per cent to 285.50p.”

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If New York City’s environmentally-daring Mayor Michael Bloomberg gets his way, Manhattan’s illustrious skyscrapers could soon be topped with wind turbines. Generating energy renewably is part of the mayor’s ambitious plan to harness the power of wind via skyscraper-mounted propellers and offshore wind farms.

New York’s climate and topography are quite different from those of Texas and California, both highly conducive to wind-generated power. Still, dynamic winds blowing at skyscraper altitudes might just be powerful enough to propel the rooftop turbines. In the current absence of tangible plans Bloomberg has asked renewable tech innovators to garner “their best ideas for creating both small- and large-scale projects serving New Yorkers.” “When it comes to producing clean power, we’re determined to make New York the number one city in the nation,” he said.

According to CNN, for offshore sites “the city is looking at the windy coast off Queens, Brooklyn and Long Island for turbines that could generate 10 percent of the city’s electricity needs within 10 years.”

I know a few ‘wind cities’ in our country that could be used for power generation. Think of turning Coega into a Green Industrial park, where all manufactured goods were made from energy harness from renewable generation.

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