Posts Tagged ‘wind turbines’
Tremendous Wind Turbines Require Extreme Testing Facilities
A new rig for is set to open this summer in Germany, built to assess a new generation of mega turbines.
The biggest turbines in use today can generate about 2.5 megawatts with rotor blades that span about 200 feet. But new designs — including a 7-MW behemoth with a 260-foot rotor the turbine-maker Vestas unveiled last week — will need to be tested before they can be installed.
This entails mounting a rotor blade to a tiltable block and putting pressure on it, seeing how far it can bend. Along with validating a manufacturer’s design specs, the tests will simulate the forces acting on rotor blades as they spin in the wind.
The Fraunhofer Institute for Wind Energy and Energy System Technology in Bremerhaven is opening a new test facility with a tiltable steel and concrete mounting block that weighs 100 metric tons. A blade will be mounted in the block with its tip pointed at a slight angle. Weight-bearing cables are attached, and as the mounting block rotates the blade up, it starts to bend — the new machine can bend a rotor blade “as a finger to a blade of grass,” according to a .
The test bed will also simulate the cyclic forces acting on the blade as it turns, Fraunhofer says. A hydraulic cylinder will alternately push and pull on the blade, causing it to vibrate. Facilities like this will be crucial for testing new turbines like this monster below, designed to operate in the North Sea.
Vestas said the new design was the first ever built specifically for offshore wind farms, which are increasingly prevalent in Europe. The 443-foot-tall turbine’s rotor blades will trace a circle bigger than the gigantic London Eye ferris wheel, according to .
Other facilities have to test the turbine drive shafts, making sure they can generate electricity efficiently. In the U.S., the National Renewable Energy Laboratory has a that can test powerful turbine drive trains. These test facilities simulate years of wear and tear in a couple months. NREL is already building a 5-MW dynamometer to test the next generation of turbines.
Fraunhofer's new test rig opens on June 9, 2011, but is designers are giving a preview this week at the Hannover Messe technology fair.
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Attractive Italian Viaduct Has Wind Turbines Built In
The concept would use the space between an existing viaduct in southern Italy to install 26 wind turbines, which designers Francesco Colarossi, Giovanna Saracino and Luisa Saracino say could provide 36 million kilowatt hours of electricity every year.
The design team conceived the Solar Wind project for a contest that aims to repurpose some old, unused viaducts near Calabria, a region in the toe of Italy. It would cost about $55 million to demolish the viaducts, so town officials for proposals that would re-use them in an environmentally friendly way. The wind turbine bridge took second place.
The proposal also includes a solar-paneled roadway to provide another 11.2 million kilowatt hours, Colarossi and colleagues say. It turns the entire viaduct into a park, with spaces to pull over and take in the view off the Italian coast. Travelers could stop and buy fresh produce grown in solar-powered greenhouses located along the bridge. The whole roadway would be covered in a dense grid of solar cells coated in a thin, transparent plastic, the designers say.
All in all, the system would be capable of generating 40 million kWh each year, enough to power 15,000 homes.
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Nanotube-Tethered Flying Wind Turbines Could Harvest Energy At 30,000 Feet
Future could spin with greater gusto in the faster winds found at high altitudes, and send power back to Earth via nanotube tether cables. Swarms of energy-harvesting kites, or balloons could stay aloft for a year, and could be reeled in during storms or for maintenance.
This vision, outlined by a researcher at NASA, recently sparked the first federally funded research effort into airborne wind farms. In a bureaucratic infinite loop you just have to love, it’s a study of what it would take to actually study the value of these ideas.
NASA aerospace engineer Mark Moore says it’s worth examining how flying wind farms would work, and how tethered turbines would affect airspace, for instance. Each wind turbine could have a two-mile protected no-fly zone, causing headaches for airliners and of the future. But, while it could cause air traffic jams, an airborne farm would not take up any ground resources or cause any pollution, Moore points out.
Plus, wind is more consistent and its velocity is higher at higher altitudes, and the power goes up with the cube of that velocity. You can get between eight and 27 times the power production at 2,000 feet above ground, Moore says.
Offshore flying wind farms would present the fewest airspace problems, but then you would have to bring the energy from the ocean to power plants on land. In other words, it’s a big research problem. Several small companies are studying the concept, like the Italian startup , which proposes a pair of tethered balloons flying at 2,600 feet. Each balloon has a sail, creating an antagonistic relationship — the balloon with an open sail moves downwind and draws the other balloon upwind, and then the motion reverses. The sails’ movement is transmitted to the ground via the tether, and it can be used to spin a turbine to generate electricity.
But Moore says flying wind turbines involve so many factors — technology, geography, competition for airspace — that the federal government should assume a greater role.
“We’re trying to create a level playing field of understanding, where all of the concepts and approaches can be compared,” he said.
Moore will use $100,000 in federal funds to complete his pre-study study.
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Philadelphia Eagles to Be Powered by On-Site Renewable Energy in 10 Months
Those spiky things around the stadium's top? Those are 20-foot-tall wind turbines. 80 of them
Stadiums are quite conducive to this kind of renewable energy initiative: They're huge, with a ton of open air and roof space for devices like wind turbines and solar panels that need both room and sun. There have been efforts to capitalize on that before, as well as some other ambitious plans like Qatar's solar-powered stadium--but that's more than a decade off, at least. The Eagles have made some strides toward these kinds of projects before, switching to 100 percent recycled paper materials (napkins, plates, etc), composting many tons of organic waste, and converting used kitchen oil to biodiesel. But this project takes it to a totally new level.
The Eagles are partnering with Solar Blue, which will install the $30 million system consisting of 80 20-foot wind turbines (vertical, rather than bladed, to reduce noise and danger to nearby birds), 2,500 solar panels, and that 7.6-megawatt dual-fuel generation plant that'll be situated adjacent to the stadium. About 15 percent of the stadium's power will come from wind and solar, individually, with the remaining 70 percent coming from the plant. The plant is expected to create about 1.039 billion kilowatt-hours of electricity every year--enough to power 26,000 homes.
Solar Blue will be the exclusive energy supplier for the Eagles for the next 20 years, over which time the Eagles estimate the stadium will save about $60 million in energy costs. After those 20 years, the Eagles will be allowed to sell excess electricity back to the grid--in this case PECO, the local energy supplier.
[Philadelphia Eagles via CNET and New York Times]
Increasing Wind Turbine Turn-On Speeds Could Help Reduce Bat Deaths, New Study Says
At the North American bat convention, biologists seek ways to reduce bat deaths at wind farms
Warmer temperatures and drought brought on by climate change could disrupt migration and mating patterns, researchers said this week at the North American Society for Bat Research annual conference. Rick Adams, a biology professor from the University of Northern Colorado, published a paper in August that showed bat reproduction declines when conditions mimic climate change. Examining 15 years of data from bats along Colorado’s Front Range, he found as temperatures rise, the proportion of reproductive female bats goes down. A colleague at UNC, Mark Hayes, hypothesized that the same will hold for drier conditions.
A warmer climate could hold some unexpected benefits for — researchers think bats that are commonly found in the southeastern United States, like the tricolor bat, could move farther north and replace the little brown bat, which is being decimated by white-nose. What’s more, the fungus grows best in cold conditions, so if mid-Atlantic and northern caves get warmer because of climate change, it could spread more slowly or even die out. But Hayes’ study found warming climates will ultimately kill off bats, too.
Ironically, one method to ameliorate climate change could make matters even worse for bats. Wind turbines, favored for their carbon dioxide-free power generation, are deadly for bats, especially tree-roosting species that migrate over long distances. One study from the Blue Sky Green Field Energy Center in Wisconsin found for every megawatt of wind energy generated, 22 bats die every year.
Unlike birds, which often perish at wind farms when they collide with the turbines, bats die in blade vortices. Rotating turbine blades create negative pressure pockets, and when the bats fly through them, their lungs explode.
“Some wind sites are killing hundreds to thousands of bats in a single fall migration season,” said Paul Cryan, a research biologist with the US Geological Survey. One wind farm in New York is estimated to kill more hoary bats every year than have ever been collected for scientific studies, he said.
Some scientists have proposed turning off wind turbines during peak migration periods, and others have proposed unconventional solutions like to baffle the bats. But a new study to be published Monday in the journal Frontiers in Ecology and the Environment says there could be a simple fix: Reducing the cut-in speed, or the wind speed at which wind turbines switch on.
Most wind turbines in the US are programmed to begin rotating and producing power once wind speed has reached about 8 to 9 mph, according to the Ecological Society of America. Ed Arnett, a biologist with Bat Conservation International, says raising that speed to 11 mph can reduce bat fatalities from 43 to percent up to 93 percent. Even better, the annual energy loss was less than 1 percent.
Wind turbines will still kill bats — during two summers of study at a Pennsylvania wind farm, Arnett sometimes found fresh carcasses even when turbines turned on less frequently. But when they turn on at higher wind speeds, they will not kill as many. For the most part, bats don’t fly when it’s too windy.
“Rarely do you see such a win-win result in a study,” Arnett said. “There is a simple, relatively cost-effective solution here that could save thousands of bats. This is good news for conservation and for wind energy development.”
Researchers still don’t know why bats are attracted to wind turbines, however. Some hypothesize that they mistake them for trees, which explains why 75 percent of bat deaths are among tree-roosting species. Most bat deaths at wind turbines happen in early fall, which is mating season; the “tall tree hypothesis” suggests that bats think wind turbine towers are attractive mating sites. “Tall things are mistaken for singles bars,” said Craig Willis, a biologist at the University of Manitoba.
To study this, Willis and Cryan examined the mating readiness of bats killed by wind turbines in New York, Manitoba and Alberta, and found most male bats were ready to reproduce. The researchers couldn’t find evidence that the bats were copulating at the wind farm, but their genitalia indicated it was the right time of year, Cryan said.
“It’s easy to come up with these hypotheses, but this is one I hope we can disprove,” he said. “If you are selectively causing the death of the reproductive class, you are in trouble from a conservation standpoint.”
Bats are a keystone species — disruptions to their reproductive patterns and populations will have cascading effects throughout entire ecosystems. Protecting them from wind turbines is just one more thing for conservationists to worry about.
Chicago Garage Fires Up Helical Wind Turbines for Attractive, Earth-Friendly Parking
This summer, 12 turbines started spinning at Greenway Self-Park, which bills itself, somewhat oxymoronically, as Chicago's first Earth-friendly parking garage.
Open-screen walls on the 11-story garage provide ventilation and reveal the cars inside, but also let passersby marvel at the turbines. The garage also has a cistern rain-collection system, sustainable building materials, a recycling program and an electric car charging station.
Lobbies on each floor include information about how to live more sustainably, and the garage has energy-efficient lighting. The garage is pursuing pursuing LEED certification from the U.S. Green Building Council. It even has a reversible meter that can measure and return power to Chicago's grid throughout the year.
Architect Todd Halamka, director of design at the Chicago office of HOK, tells Fast Company he wanted to celebrate the building's function, not hide it.
One wonders how green a parking garage can really be, but it's not like cars are going away anytime soon, so garages might as well aim to ameliorate their impact.
And at the very least, it adds to the architecturally interesting experience of parking in downtown Chicago -- you can go underneath trains, curl up through , and now this.
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Massive Wind Turbine Survives Pummeling By Equally Massive Testing Machine
The 2.5-megawatt dynamometer at the National Renewable Energy Laboratory blasted the turbine’s drive train, built by Samsung, with 12.6 million inch-pounds of torque, the energy lab says.
In other words, the turbine drive train went through years of wear and tear in about two months. It was the largest full-scale dynamometer test of a wind turbine ever done in the United States, NREL says.
The dynamometer — a cool name for a machine that measures force and torque — has a 3,550-horsepower electric motor coupled to a three-stage epicyclic gearbox, according to NREL. It can produce speeds up to 30 revolutions per minute, meaning it can simulate anything from a slight breeze to a full-force gale.
Computer models simulate the tower, rotor and turbine blades, and other models calculate what the main shaft torque should be, depending on weather conditions. The shaft therefore responds to various wind conditions just like it would in the field, NREL says.
Samsung has a 2.5-MW turbine in operation in Texas, but it’s never been tested above 600 kilowatts. Samsung wanted to take its drive shaft out for a spin, so the company shipped the 185,000-pound device from Houston to Golden, Colo., using a gigantic 185-foot-long, 19-axle rig.
All this bigness is peanuts compared to future wind turbines, however — NREL is already building a 5-MW dynamometer, which would be capable of testing the next generation of huge wind turbines.