Hoagy,
If you get 24.6 Watts/hour in yearly average, it is nearly 18 kWh per month per sqm or around 5% of average family use per month or my suggestion would only cover 2.5% of average family use. At the same time, it implies that we would need a wind turbine with 22 sqm swept area to cover 100% of one average family use and that does not sound right either and does not square with the numbers I have seen on how many families a large turbine cover or sizing recommendations on small turbines. If I then look at calculated power at 3.8 m/s and 4.3 m/s, it is 33 resp. 48 Watt and compare it with 87 resp. 101 Watt, I am even more confused. The power in the formula is related to the cubic of wind speed and I would expect a much larger difference between the power values. Not knowing the complete distribution of speed, make it very difficult to judge It is possible that you are right and I would need 4 times more swept area and rated power to cover 10%. I also think that it is equally possible that we have something wrong in our assumptions. If you are right, it mirrors back on almost all small wind turbines, since I took samples from manufacturers data to come to my conclusions. We have then to realize that it must be quite a crooked industry sector and that they are not truthfully, because it means that presented economy numbers do not square either. The fault that I might have done is systematic and based on industry information. It is not a technical calculation mistake, it has to do with statistical availability of energy in relation to sizing. Let us go further on this and do some more checking, we must be absolutely sure of what the Wind Power Density is. Let us first get a clear definition on it, so we know that we are not chasing ghosts here. Hakan At 18:48 11/01/2004, you wrote: >Thank you Hakan. > >Did some looking at the local wind data here, >Wind Energy Resource Atlas of the United States ><http://rredc.nrel.gov/wind/pubs/atlas/tables/C-1T.html>http://rredc.nrel.gov/wind/pubs/atlas/tables/C-1T.html > > >to get some idea whats possible annually. > >Anemometer Height in Meters and annual average Meters/Second >Anem Annual Wind Power > HT Speed Density >(M) M/S Years (Watt/m2) >7.9 3.8 1949-61 87 >8.5 4.3 1961-78 101 > >I don't understand the Wind Power Density above >but if I multiply by the efficiencies in >wind system design given your parameters, > >87Wh x 35%turbine x 85%generator x 95%mechanical >=87*0.35*0.85*0.95 = 24.6 Watts/hour per square meter. > >With a 0.3 m^2 swept area, 24.6 x 0.3 = 7.38 Wh >with a 0.5 m^2 swept area, 24.6 x 0.5 = 12.30 Wh > >Does that look right ? > > > > you wrote: > > Hoagy, > > > > With best efficiency numbers, > > at swept area 0.3 square meter > > Wind speed m/s Power Watt > > 5 6.5 > > 10 52 > > 15 175 > > 20 415 > > 25 811 > > 30 1402 > > > > at swept area 0.5 square meter > > Wind speed m/s Power Watt > > 5 11 > > 10 86 > > 15 292 > > 20 692 > > 25 1352 > > 30 2336 > > > > Darrieus best efficiency 0.35 > > Generator best efficiency 0.85 > > Mechanical best efficiency 0.95 > > > > This means that my suggestion is well within boundaries for a viable design > > and good margins for lower efficiencies based on the small size. With the > > correction of the Savonius efficiency, it will also fit in the design > concept. > > > > Hakan Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/index.php?list=biofuel Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/biofuel/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
