Idea for rated windspeed
- View SourceWhen sitting through the Small wind committee meeting in Chicago, the
idea of the rating windspeed for small wind certification standard was
brought up. The idea that it is just a number was disturbing, Mike
Bergey told us that pioneer Marcellus Jacobs wanted it to be 25 mph, the
current si value is 11 m/s in the draft, but it is really not windspeed
that needs to be measured but the power in the wind, and since the solar
industry has settled on 1,000 watts/sq meter as a reference input , why
At standard temp and pressure, the 1,000 watt/sq meter is at a wind
speed of 26.3 mph or 11.8 m/s. Its not a nice round number but it does
give us a nice comparitive input, it matches standards in the industry
for other renewables and it just feels good.
In fact if taken to extremes we can use the input power/area as the
reference rather than windspeed and make the performance testing at
different sites even more comparable. If we declared input power/unit
area as the input and power out as the measured response it might be
imaterial about converting to standard conditions based on wind speed
alone. 600 watts/m^2 at 2,000 asl metere test site can then be compared
to 600 watts/m^2 at a 200 asl meter test site directly, no conversion.
The conditions are slightly different at the high altitude site the
density might be only 1.006 kg/m^3 and windspeeds of 10.6 m/s while at
200 m its 1.215 kg/m^3 and 9.9 m/s.
Referring everything to the input power instead of the more easily
measured windspeed might be more trouble, but makes lots of sense in
the way the other industry does their tests.
$0.02 worth of idea. Glad to see you all in Chicago and hope this effort
gets finished and used, no matter what form it winds up in.
Director, Alternative Energy Institute
West Texas A&M University, Canyon Texas
Phone 806 651-2295 Fax 806 651 2733
AEI web site: www.wtamu.edu/research/aei
"Watson," said he, "if it should ever strike you that I am getting a
little overconfident in my powers, or giving less pains to a case than
it deserves, kindly whisper 'Norbury' in my ear, and I shall be
infinitely obliged to you."