Interconnecting wind farms
Wind power is one the world's fastest growing electric energy source, but as wind is intermittent, a single wind farm cannot deliver a steady amount of energy. This is why scientists at Stanford University want to connect wind farms to develop a cheaper and reliable power source. Interconnecting wind farms with a transmission grid should reduce the power swings caused by wind variability and provide a somewhat constant and reliable electric power (or 'baseload' power) provided by other power plants. The idea is attractive, but will the various companies involved with wind farms adopt it? Time will tell.
As you can see on the map above, there are plenty of windy places in North America. This map shows estimates of wind speeds at 80 meters in the year 2000. (Credit: Stanford University). You'll find maps of other parts of the world by reading "Global wind power at 80 m."
This research about connecting wind farms has been led by Mark Jacobson, a professor of civil and environmental engineering, and Cristina Archer, a consulting assistant professor at Stanford. Here is an additional link to Wind power at Stanford University.
Now let's look at some facts behind the study. "As one might expect, not all locations make sense for wind farms. Only locations with strong winds are economically competitive. In their study, 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 in the Midwestern United States. They found that an average of 33 percent and a maximum of 47 percent of yearly-averaged wind power from interconnected farms can be used as reliable, baseload electric power. These percentages 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."
Besides providing a steady production of electricity, connecting wind farms would present other cost benefits by "reducing the total distance that all the power has to travel from the multiple points of origin to the destination point" and by combining all the power on a single transmission line.
Here is Archer's somewhat optimistic conclusion. "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 reduced, 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."
This research work will soon be published by American Meteorological Society's Journal of Applied Meteorology and Climatology. The latest issues are available online on this page, but the November 2007 issue is not yet available. The article should be named "Supplying baseload power and and reducing transmission requirements by interconnecting wind farms" (Volume 46, Pages 1701-1717, November 2007). For your convenience, a preview of the paper is available from Stanford University (PDF format, 65 pages, 1.00 MB).
A question remains. As there are many utility companies operating in the U.S., even in the wind energy sector, will these companies find their interest by consolidating their various wind farms? I'm somewhat skeptical.
Sources: American Meteorological Society news release, November 21, 2007; and various websites
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