Washington, Nov.22 : Stanford University scientists have suggested that connecting wind farms can evolve a more reliable and cheaper power source.
According to Cristina Archer and Mark Jacobson, wind is the world's fastest growing electric energy source and can be groomed to become a steady and dependable generator of power.
Both say that the key lies in connecting wind farms throughout a given geographic area with transmission lines, thus combining the electric outputs of the farms into one powerful energy source.
"This study implies that, if interconnected wind is used on a large scale, a third or more of its energy can be used for reliable electric power, and the remaining intermittent portion can be used for transportation, allowing wind to solve energy, climate and air pollution problems simultaneously," said Archer, the study's lead author and a consulting assistant professor in Stanford's Department of Civil and Environmental Engineering and research associate in the Department of Global Ecology of the Carnegie Institution.
"The idea is that, while wind speed could be calm at a given location, it could be gusty at others. By linking these locations together we can smooth out the differences and substantially improve the overall performance," he adds.
In their study, which appears in the November issue of the American Meteorological Society's Journal of Applied Meteorology and Climatology, Archer and Jacobson, a professor of civil and environmental engineering at Stanford, evaluated 19 sites in the Midwestern United States, with annual average wind speeds greater than 6.9 meters per second at a height of 80 meters above ground, the hub height of modern wind turbines.
Modern turbines are 80-100 meters high, approximately the height of a 30-story building, and their blades are 70 meters long or more.
The researchers used hourly wind data, collected and quality-controlled by the National Weather Service, for the entire year of 2000 from the 19 sites. They found that an average of 33 percent and a maximum of 47 percent of yearly-averaged wind power from interconnected farms could be used as reliable, base-load electric power.
These percentages, they said, would hold true for any array of 10 or more wind farms, provided it met the minimum wind speed and turbine height criteria used in the study.
They said that another benefit of connecting multiple wind farms is reducing the total distance that all the power has to travel from the multiple points of origin to the destination point.
Interconnecting multiple wind farms to a common point and then connecting that point to a far-away city reduces the cost of transmission.
It's the same as having lots of streams and creeks join together to form a river that flows out to sea, rather than having each creek flow all the way to the coast by carving out its own little channel, claimed the authors.
The more wind farms connected to the common point in the Midwest, the greater the reduction in long-distance transmission capacity that is possible, Archer said.
"Due to the high cost of long-distance transmission, a 20 percent reduction in transmission capacity with little delivered power loss would notably reduce the cost of wind energy," added Archer, who calculated the decrease in delivered ower to be only about 1.6 percent.
Archer said that if the United States and other countries each started to organize the siting and interconnection of new wind farms based on a master plan, the power supply could be smoothed out and transmission requirements could be educed, decreasing the cost of wind energy.
This could result in the large-scale market penetration of wind energy-already the most inexpensive clean renewable electric power source-which could contribute significantly to an eventual solution to global warming, as well as reducing deaths from urban air pollution.
However, because wind is intermittent, it is not used to supply base-load electric power today.
Base-load power is the amount of steady and reliable electric power that is constantly being produced, typically by power plants, regardless of the electricity demand. But interconnecting wind farms with a transmission grid reduces the power swings caused by wind variability and makes a significant portion of it just as consistent a power source as a coal power plant. (ANI)
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