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Can Wind Power Be Wildlife Friendly
As birds and bats migrate along windymountain ridges—the same ridges that are optimum sites for wind turbines--new researchaims to stop turbines from killing animal
By Joseph Caputo Smithsonian.com,February 27, 2009, Subscribe
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The wind turbines had just been put up on BackboneMountain when Keith Lott arrived in the summer of 2003. The field technicianhad been hired by a wind energy consulting company to survey bird fatalities atthe new Mountaineer Wind Energy Center in West Virginia. Every other week, Lottwalked concentric circles around some of the facility's 44 turbines, sweeping a200-foot radius in search of victims that had collided with the swooping bladesabove.
Bird surveys became standard procedure after thousandsof raptors, including federally protected golden eagles, were found to becrashing into the nearly 5,000 turbines on the Altamont Pass Wind Farm, builtin California during the 1970s. Lott was hired in response to concerns thatwind farms on Appalachian ridges, which act as corridors for migratingsongbirds and hawks, might invite similar misfortune.
To Lott’s surprise, the dead bodies surrounding theturbines weren’t birds, but bats. Lott and other surveyors found 475 bats, manybroken-winged and bloodied, at the West Virginia facility that year. He and histeam estimate that 2,092 bats were killed. Scientists knew that turbines poseda threat to birds, but nobody had predicted they’d be such a problem for bats.
Research at the Mountaineer Wind Energy Centerhelped raise awareness about bat fatalities at turbines. Five years later, ithas been recognized as an international problem, with bat deaths documented inAustralia, Britain and Canada. Along with deaths of endangered birds, thecarnage has added another speed bump to wind power’s ability to win overenvironmentalists. But there is good news. Research spurred by the batfatalities has conservationists and wind industry representatives hopeful thatan effective solution will be in place within the next five to ten years.
Whether or not this time frame is good enough isstill unknown. The most common species found dead around North American windfarms—the hoary bat, eastern red bat and silver-haired bat—are killed byturbines as the bats migrate between Canada and Central America. None of thesespecies are listed as endangered, but no one knows the potential impact fromthousands of deaths each year. According to Robert Barclay, a University ofCalgary biologist who studies bat fatalities, the impact could be serious:females from these species give birth to only one set of twins a year, a muchslower reproductive rate than birds, which may have half a dozen young a year.
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Though bird deaths prompted wind energy companies tostart monitoring turbines' impact on wildlife, it turns out that Altamont Passwas an exception. Bird fatalities are approximately 2 per turbine per year,according to the National Wind Coordinating Committee, compared to the 21 to 70bats killed per turbine per year along their Eastern migration routes.
Why do so many bats fall victim to wind turbines?With good eyesight and the ability to echolocate, or detect their surroundingsthrough sound, it seems that they ought notice the potential danger. Someinsight came last year from Erin Baerwald, a graduate student working withBarclay in Canada. She noticed that half of the bats scattered around turbinesdo not have any visible injuries. After conducting autopsies, she found thatthey all showed evidence of "barotrauma." That is, their lungs hadburst due to a sudden drop in air pressure.
Baerwald suggests that bats are attracted to theturbines. “In order to be killed [by barotrauma], the bats have to be prettyclose to the blades,” she says. “The zone is a meter or two around.” Why themigrating bats would be drawn towards the turbines is still a mystery.Scientists hypothesize that bats may see turbines as tall trees or roostingsites.
According to Edward Arnett, a scientist with BatConservation International, wind turbines are going to be built no matter howlittle we understand about bat biology. “We have an industry moving forwardwith or without the science,” he says. This puts researchers like Arnett undera tight deadline to work with the wind industry for a solution. Approximately55 new wind turbine facilities were built in 2008, reports the American WindEnergy Association, 40 more than in 2007. “It’s not necessarily how scienceshould be conducted but it’s how we have to approach what we are faced with,”Arnett says. And he is making progress.
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Arnett, a program coordinator for the Bats and WindEnergy Cooperative (BWEC), a partnership between conservationists, governmentagencies and the wind industry, is experimenting with a bat deterring device.The latest model in development contains 16 speakers that emit ultrasound,which should jam bat echolocation and coerce a bat to change its flight course.They are now working to test the device and evaluate reduction in bat kills.
Arnett’s second solution is to increase the minimumwind speed necessary for wind turbine blades to start turning. Research showsthat bats are more likely to be hit on calm nights in late summer and fall.Because this could cause a drop in a wind facility’s energy production, Arnetthad trouble getting a company to sign on to study this solution. It was theworld’s leading provider of wind power, Iberdrola Renewables, that finallyagreed to collaborate, giving Arnett access to all 23 turbines on its CasselmanWind Power Project in Pennsylvania. According to Andy Linehan, the company’swind permitting director, the benefits of finding a solution to the batfatality problem outweighed the costs of producing slightly less energy. “Wemarket ourselves as a green industry,” he says. “If we’re going to continue totake that seriously, we’ve got to continue to show it.“
The experiment was a success. By curtailingproduction during low wind conditions, and increasing the wind speed thresholdrequired to jump-start the turbines, bat fatalities dropped between 56 and 92percent. The costs to the company were small: a less than one percent overallpower loss for the year. Arnett now wants to test this strategy at several moresites.
“This is a worldwide issue,” says Barclay, who isalso a science advisor for BWEC. “Most of the research is being done in NorthAmerica, but wind turbines are going up at an incredible rate in other parts ofthe world, and so the research we do here can have a potentially biggerimpact.”
Read more: http://www.smithsonianmag.com/specialsections/ecocenter/energy/Can-Wind-Power-Be-Wildlife-Friendly.html#ixzz1XrLto0ek
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September 6, 2011
TheFirst Supernova
Astronomers are getting a bit of a treat this week—they’re watchinga supernova exploding 21 million years ago (that is, 21 million light yearsaway) in the Pinwheel Galaxy. That’s pretty close for a supernova (they’re usually arounda billion light years away), and you might even beable to see itwith a simple pair of binoculars.But what was the first supernova?
OK, that was a trick question. We can’t know what was thefirst star to explode. But we can look at the first recorded supernova, SN 185.
In 185 A.D., someone in China looked up in the night sky andsaw a new star. It sparkled and did not move, so it couldn’t be a comet. This“guest star” stayed in the sky for eight months and then disappeared forever;it was recorded in the Bookof the Later Han, which told the history of Chinafrom 25 to 220 A.D.
The guest star was a supernova, astar that had run out of fuel and then collapsed in on itself in a thousandthof a second. The core of the star heated to a billion degrees and destructivegamma rays were produced. Neutrinos were generated in huge quantities. Only atiny fraction were absorbed by the stellar gas, and they had so much energythey ripped apart the outer layers of the star. This violent explosion, whichcould have been brighter than an entire galaxy, also produced X-rays, gammarays and ultraviolet light. The resulting shock wave produced radioactiveelements such as cobalt and titanium. Any planet too close to such adestructive event would have been torched.
In2006, scientists using the Chandra X-rayObservatory and the XMM-Newton Observatory determined that the supernova remnantRCW 86 was the leftover bits of SN 185. They calculated how fast the energizedshell of the remnant was moving to estimate the original date of the supernovaand determined that the star had gone supernova about 2,000 years ago.Scientists had thought RCW 86 might be SN 185 because the remnant’s locationmatched historical records of the supernova, but previous calculations gave theremnant an age of 10,000 years. It appears those calculations were based onmeasurements of a part of the shock wave that had encountered a region of densematter and slowed down.
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August 26, 2011
TheSatellite Eyes On Irene (And Other Great Resources)
Notthat long ago, people got little to no warningabout hurricanes. They couldn’t know when the winds would kick up, when thesurge of water would arrive, what kind of destruction a storm might bring. Butnow we have satellites orbiting overhead, powerful computers that can forecasta trackdays in advance and plenty of scientists tomake sense of a wealth of data. We may not be invulnerable, but we can, atleast, limit the amount of destruction and loss of life. (If anyone asks, “whatgood is science?” here’s a great example.)
And because this is mostlygovernment-funded science, the public gets plenty of access to information andtools to help us better understand hurricanes and prepare for them.
“Understanding the history of hurricane landfalls in yourcommunity is an important step toward assessing your vulnerability to thesepotentially devastating storms,” says Ethan Gibney, a senior geospatial analyst for NOAA. He’s oneof the developers of NOAA’s Historical Hurricane Tracksonline mapping application. Users can map the tracks ofstorms around the world and get detailed information about tropical cyclonesgoing back to 1842.
Information about Irene (as well as Tropical Depression 10,brewing in the Atlantic) is available from the National Hurricane Center. Most of us will be satisfied with the array of maps,advisories, podcasts and videos produced by the center, but even more detailedanalysis tools are also available to those who areinterested and understand it.
NASA monitors storms from above the Earth and publishesthe best of its imagery online. Instruments on the GOES and Terrasatellites provide great visible images along with temperature (of both air andsea surface), pressure, wind and cloud data. The TRMM satellite, meanwhile,measures the hurricane’s rainfall and gives insight into the storm’s structure.
And anyone who lives near Irene’s projected path shouldconsult FEMA’shurricane site and learn what they should do toprepare.
越障 (803 words)
Asia’s economiesClaws or jaws
Asia’seconomies can weather a Western slowdown—but not prevent it
Aug 27th 2011 | HONGKONG | from the print edition
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IN THE English-speaking world,people escape from frying pans into fires. In Thailand, the proverb is coucheddifferently: people are said to escape from tigers only to be eaten bycrocodiles. The Thai economy, like many in Asia, sprang free from the greatrecession surprisingly quickly. This year the bigger threat has been thewidening jaws of inflation. With that in mind, the Bank of Thailand raisedinterest rates on August 24th for the ninth time since mid-2010. But it was asplit decision. The economic woes of America and Europe have darkened Asia’smood. Some can again hear the tiger’s growl.
After last year’s swift recoveryfrom recession, policymakers in developing Asian countries congratulatedthemselves on the resilience of their economies. Their docile banking systems,high saving rates and hoards of foreign exchange shielded them from the worstof the financial chaos. Their efforts to tighten fiscal and monetary policybefore the crisis struck gave them room to loosen up in response, as exportscollapsed and confidence evaporated. In April 2009 the Thai central bank cutrates to 1.25%—lower than in most Asian economies—alongside a fiscal push worth3% of GDP. Emerging economies were hit harder than optimists expected, butresponded better than pessimists feared.
That resilience may be tested againsooner than anyone would have liked. In announcing its latest rate decision,the Bank of Thailand noted the dangers posed to the economy by a slowdown inAmerica and Europe. Thailand remains highly exposed to global trade: exports,including air conditioners, video cameras and fridges, as well as tourism,accounted for over 70% of its GDP in 2010. But the bank found consolation inThailand’s growing sales to its neighbours and to “new” markets farther afield.Last year China overtook America to become the country’s leading customer.
That trend is not unique toThailand. Most of its neighbours now sell a smaller share of their exports toAmerica and Europe than they did before the crisis (see chart). The precisepercentages may be misleading. These exports include parts and components thatmay end up in the West, after first being assembled into final products inanother country. But there is no denying the trend.
The region’s economies are not,then, as vulnerable to the tiger’s claws as they were in 2008. The crocodile,on the other hand, is uncomfortably close. Thailand’s headline consumer-priceinflation (4.1% in the year to July) was too high for the central bank’s comfort,but lower than in many of its neighbours, such as China (6.5%), India, wherewholesale prices rose by 9.2%, or Vietnam, where consumer prices rose by analarming 23% in the year to August.
Asia’s campaign against inflationhas dragged on longer than its central bankers hoped. Higher food and commodityprices were expected to drop out of the inflation figures eventually, butinstead seem to have leached into other consumer prices. One consequence ofthis prolonged fight is that nominal interest rates have been raised off thefloor. Indonesia’s policy rate is now 6.75%; India’s is 8%. That gives centralbankers some room to cut if the world economy sags. The big exceptions areTaiwan, where the discount rate is less than 1.9%, and Singapore, which carriesout monetary policy by setting a path for the exchange rate, not the interestrate. With rates in America at rock bottom, and the Singapore dollar set tostrengthen against its American counterpart, interest rates in Singapore areextraordinarily low.
Reducing rates would help Asia’seconomies withstand a modest slowdown in the West. Goldman Sachs, for example,has cut its 2011 rate forecast for Indonesia, Malaysia, Philippines and Taiwan,but has barely trimmed its growth forecasts for these countries. But rate cutswould also weaken the region’s exchange rates, sharpening their competitivenessand doing little to help economies outside Asia.
A fiscal response would do more tobuoy demand in the rest of the world, as it did from 2007 to 2009, when budgetbalances deteriorated markedly throughout the region. Thailand’s new primeminister, Yingluck Shinawatra, is contemplating another budgetary splurge. Butpolicymakers elsewhere will be reluctant to spill the red ink again. It tookChina’s central government until June just to count the cost of its massivestimulus, which added greatly to the huge debts now burdening its localgovernments.
With luck, another stimulus packagewill not be necessary. America will overcome its current economic woes andEurope will muddle through. A modest slowdown in the West might even take thepressure off prices in Asia, without doing undue harm to the region’s growth—acase perhaps of the tiger eating the crocodile. But it would be too much tohope that Asia’s resilience might be sufficient to carry the rest of the worldalong, preventing a downturn in the first place.
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发表于 2011-9-14 23:08:54
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