CHICAGO: Chicago has long been known as the Windy City. Now it’s trying to determine whether it can save kilowatts by living up to the nickname.
Chicago plans to bolt four “aeroturbines’’ to the roof of the Richard J Daley Center courthouse to measure, harness and convert into electricity the air currents barreling off Lake Michigan. At 684ft (208m), the building is the city’s tallest public structure.
The result may lead to turbines on a skyline now known for North America’s tallest building, the Sears Tower, as crude oil prices hover near record highs.
The new design of the machines – double-helix rotors caged in cylinders instead of exposed blades – is intended to limit bird kills, ice buildup, roof-rattling vibrations and howling noise. The turbines, which their designer says will be the world’s highest rooftop wind-power generators, are untested on high rises.
Engineers are making custom brackets to prevent the 500-pound (227kg) machines from coming loose over the financial district of the third most-populous US city.
“Our machine is built to like turbulence,’’ says Bil Becker, who designed the turbines and founded Chicago-based Aerotecture International Inc. “Turbulence looks like little tornadoes, and our machine looks like that.’’
The turbines use galvanised steel tubes 5m in diameter and 10ft long to house a rotating plastic helix. They will contribute less than 2% of the Daley Center’s power needs when installed in July, says Becker, 64, who teaches industrial design at the University of Illinois in Chicago.
The turbines avoid the three-pronged propeller design that power companies use atop poles to generate electricity in rural areas where the wind is steady and blows from one direction.
Each rooftop turbine generates 1,000w in a 40mph (64kmh) wind, reducing use of power from Exelon Corp’s Commonwealth Edison. Four of the machines arranged on a rooftop 40ft above the ground would generate 8,000kw hours a year, the amount needed to light a house, Becker says.
Doubling the height from ground level increases the generating capacity 15% because of added wind strength, Becker says. At 684ft, the four turbines are capable of generating 24,000kw hours.
Becker says the city will pay about $100,000 for the purchase and installation of the turbines, including a one-year service contract. The turbines are just a trial and won’t pay for themselves over the undetermined length of the experiment.
If city officials find the turbines to be useful, they will add more to other public buildings as part of Mayor Richard M Daley’s plan to generate 20% of the electricity for city property from renewable sources by 2010, says Larry Merritt, spokesman for Chicago’s environmental department.
The turbines will be attached vertically with a metal bracket system designed by Chicago-based K2. Architects to the four corners of the courthouse’s elevator penthouse above the parapet to determine the direction of the strongest wind. They won’t be visible from the street.
“Safety – that’s the one big issue,’’ says Lesleigh Lippitt, Aerotecture’s customer relations director. – Bloomberg
|
