Horace Heffner wrote:
It probably isn't necessary to locate in North Dakota.
Maybe not. North Dakota has the most wind at ground level, but I do
not know if there is as much variation at high altitude.
Based on the map of high altitude wind linked to the SkyWindPower
site, I would say they should go to Canada. Today, anyway. Maybe it
varies from day to day. See:
http://weather.unisys.com/upper_air/ua_vect_300.html
Also the article implies an altitude of 15,000 ft is necessary: "But
how do we
get a working turbine up to the necessary height -- at least 15,000
ft (4600 meters) above the earth's surface? That's where helicopter
technology comes in." It doesn't seem likely that altitude
is necessary either. There is a diminishing return for higher altitudes.
See their explanation:
http://www.skywindpower.com/ww/page012.htm
They quote a prof: "The strongest, steadiest and most persistent
winds occur in bands at the jetstream level some 10km above the
earth's surface. . . . The planetary boundary layer [where there are
problems] grows throughout the day as the thermal heating increases.
It varies in size from a few hundred metres at night to as high as 2
km on the most convective days."
The power from wind is proportional to the cube of the velocity, so
the power increases with the 3/7 power of altitude. At 15,000 ft
the power is only 60 percent more than at 5000 ft.
2 km = 6,600 feet. They want to go well above the planetary boundary
layer, up to at least say 3 km (10,000 feet). I suppose they have a
reason for aiming for 15,000 feet (4.6 km).
It isn't just high wind power they want. It is consistent wind, with
few changes in direction, to avoid . . . luffing, I guess you would
call it, if this were a sailboat.
Say, wouldn't it be a hoot if the biggest industry of the late 21th
century used a bunch of words from the age of sailing ships?!? "Come
about, into the wind. Bear away from those storm clouds!"
- Jed
