February 24, 2013 – Vol.17 No. 50
NEXT UP: ROTOR-FREE WIND GENERATORS?
by Bruce Mulliken, Green Energy News
Wind turbines are like any other technology: They become obsolete. Old ones go out of date to be replaced with better machines.
The trend for years has been towards ever larger diameter, more powerful machines designed to directly reduce the cost of generated power. Other changes have been made, as well, to increase efficiency and reduce manufacturing and maintenance costs; also in the name of cutting the price per kilowatt hour of wind-generated electricity. One change, such as a switch to direct drive, no-gearbox turbines, simplifies generation equipment in the nacelle. Simple usually means easier and cheaper to build and maintain.
Aside from reducing costs to compete with conventional generation, cost reduction is also underway to be able to compete without subsidy. Though wind energy in the United States has been saved many times by 11th hour stays of execution with reinstatements of the production tax credit (PTC), eventually Congress will say no, no more Federal help. The wind industry and its technology better be prepared. Dramatic technological change might be needed.
One effort to dramatically reduce wind energy costs is now being researched. It's to replace the plastic composite rotor blades with fabric-on-frame ones. GE, which is spearheading the effort, thinks the blades will be much lighter (thus easier to be turned by the wind) and lots easier to transport to the wind site. Together, fabric-on-frame blades will make unsubsidized wind energy profitable, according to the company.
Fabric-on-frame blades are a return to wind energy's centuries old origins when turbine blades were "sails."
Another effort is underway to dramatically change wind turbines: Remove the blades and rotor altogether and leave the generation equipment on the ground where it belongs.
Though not the first to work on this technology, SheerWind is developing a wind generation device that captures breezes well above ground level in a horn-like scoop or portal. The force of the wind funnels down a pipe while compressing the air and accelerating the flow. At ground level the kinetic energy of high speed wind turns an electric turbine generator that feeds power to the grid or some point of consumption.
SheerWind, which calls the technology INVELOX, has verified generation costs to be as low as $10/MWH or a penny a kilowatt hour – well below the cost of current conventional wind energy and competitive with natural gas and hydroelectric power.
The company also says installation capital costs (manufacturing and installing the generator) are less than $750 per kilowatt. (A one megawatt machine might cost $750,000 or so.)
There are other advantages as well:
--- No worry about bird strikes. (Birds don't fly into solid objects.)
--- No low frequency turbine hum or groan. (There would likely be noise from the ground-mounted generation equipment. but it could be shielded.)
--- INVELOX towers would be less visually overpowering than utility grade turbines. (Though towers would have their own set of visual challenges.)
--- It would not need government subsidy to be profitable. (Yes!)
--- Existing wind turbine towers could be used as well as smokestacks retrofitted with INVELOX equipment.
--- Ground-mounted generation equipment would certainly be easier to maintain.
The company says its technology produces 600 percent more electrical energy than existing wind turbines and wind production capacity increases to a record high of 72 percent with operating wind speeds less than 2 miles per hour in low wind regimes (class 1 and 2).
Small, large and anything in between might be possible with SheerWind's INVELOX. One would think additional applications would be hybrid cell phone/INVELOX towers and the modification of high rise buildings to house internal INVELOX generators: A skyscraper with a scoop on top and a turbine generator in the basement.
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