<div><a href="http://www.earth-policy.org/Books/PB2/PB2ch10_ss3.htm">http://www.earth-policy.org/Books/PB2/PB2ch10_ss3.htm</a></div>
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<div>From source above:</div>
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<div>In retrospect, we now know that this was a gross underestimate of the wind potential because it was based on the technologies of 1991. Advances in wind turbine design since then enable turbines to operate at lower wind speeds, to convert wind into electricity more efficiently, and to harness a much larger wind regime. In 1991, wind turbines may have averaged scarcely 40 meters in height. Today, new turbines are 100 meters tall, perhaps tripling the harvestable wind. We now know that the United States has enough harnessable wind energy to meet not only national electricity needs, but national energy needs. 20 </div>
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<div>The "20" at the end of this paragraph refers to this article in the Journal of Geophysical Research:</div>
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<div><a href="http://www.agu.org/pubs/crossref/2003/2002JD002076.shtml">http://www.agu.org/pubs/crossref/2003/2002JD002076.shtml</a></div>
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<div>Abstract from URL above:</div>
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<div>This is a study to quantify U.S. wind power at 80 m (the hub height of large wind turbines) and to investigate whether winds from a network of farms can provide a steady and reliable source of electric power. Data from 1327 surface stations and 87 soundings in the United States for the year 2000 were used. Several methods were tested to extrapolate 10-m wind measurements to 80 m. The most accurate, a least squares fit based on twice-a-day wind profiles from the soundings, resulted in 80-m wind speeds that are, on average, 1.3¨C1.7 m/s faster than those obtained from the most common methods previously used to obtain elevated data for U.S. wind power maps, a logarithmic law and a power law, both with constant coefficients. The results suggest that U.S. wind power at 80 m may be substantially greater than previously estimated. It was found that 24% of all stations (and 37% of all coastal/offshore stations) are characterized by mean annual speeds ¡Ý6.9 m/s at 80 m, implying that the winds over possibly one quarter of the United States are strong enough to provide electric power at a direct cost equal to that of a new natural gas or coal power plant. The greatest previously uncharted reservoir of wind power in the continental United States is offshore and nearshore along the southeastern and southern coasts. When multiple wind sites are considered, the number of days with no wind power and the standard deviation of the wind speed, integrated across all sites, are substantially reduced in comparison with when one wind site is considered. Therefore a network of wind farms in locations with high annual mean wind speeds may provide a reliable and abundant source of electric power. </div>
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<p id="dates">Published <span id="published">13 May 2003</span>. </p>
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<p>Vision2020 Post: Ted Moffett</p></div>