F’ing Windmills
It is good to see FRIAMers enthusiastically holding forth on another area of
their whimsy – the effectiveness of wind turbine arrays. Wind Energy can
provide a significant contribution to our energy supply. Understanding it
helps. Commenters might be interested in the first seminal paper, Energy
Effectiveness of Arrays of Wind Energy Collection Systems, (1976), by a clown
name of Lissaman. This paper has been referenced and improved upon many times
in the last 30 years. The most recent revision, by the same author, appears in
the book, Wind Turbine Technology, published by NASA, and reprinted by ASME in
2009. It’s ancient, but the principles, and our planetary boundary layer have
not changed.
The article in Science Magazine is an example of bad science reporting,
illustrating the red neck passion to simplify subtle issues into easily
understandable syllogisms (see contemporary Republican politics). The
reporter discusses “new” vertical axis machines! The Darrieus Vertical Axis
Wind Turbine was new in 1971, while the Savonius VAWT goes back to 1931. So
much for the writer’s research! That history is in most encyclopedias. In
1976, I gave a paper at the International Wind Energy Congress in Cambridge ,
England , funded by US DOE, noting that VAWT were not cost effective compared
with the propeller type. I think that’s still true. The FRIAM response seems
a little like superficial science; thinking things that “look like” or “sound
like” something are that thing. An intelligent, but untutored, opinion may be
interesting in philosophy, it usually isn’t in science.
FRIAM is supposed to be a place where knowledgeable folks can share it. For
those interested:
On complex terrain there are locations that have strong flows. This is a
function of topography and wind direction. One would like to install Wind
Energy Collection Systems at these locations. Usually space is limited, so
some WECS units will be in wind shadows, sometimes. The array can be designed
to maximize the annual energy capture. This requires annual detailed wind
records, a model to compute the flow over complex terrain and a turbine model
describing the turbulent wake and its dissipation -- indeed a complicated
process well suited to modern computers, and dependent still on poorly known
fluid physics, especially atmospheric turbulence.
The economic trade enters next, where costs are reconciled with the reduced
revenue of units in dense arrays. From hence cometh the most effective
array – not always the max. capture case. And, because costs are time variant,
different each year! The ideas are simple, the execution exceeding tiresome!
In the dark ages of wind energy, with funding from SBIR and DOE, Lissaman and
Quinlan developed, and AeroVironment marketed, a software model, AVENU, by
which one could take a contour map of a site, define a wind speed and
direction, place many turbines on it and compute the total energy capture
including interference. One could then drag the turbines to putatively better
locations, and observe the effect. Easy on a computer, not so in the cruel
world! I always thought that the verb “drag” was especially vivid here,
having actually, with a cursing crew, moved 30-ton turbines by dragging them
from one piece of CA desert to another.
We sold the software here and abroad for $25,000 a crack, including a free Mac
II, since our European customers were PC operators. It was not a successful
product financially, but has been used extensively in array design for the last
30 years.
I have not read my friend John Dabiri’s Caltech report, but have put in a call
to chat to him. I taught wind turbine stuff at Caltech to grad classes when
John was in grade school, and expect that his will be an excellent
contribution. I will report on same to FRIAM when I have studied the paper
itself.
My title, “f’ing”, referred to “flocking”, certainly very interesting
phenomenon, as is the other possible adjective. One can achieve favorable
array interference in water, air or on land. I have made technical
contributions to all: wet, dry and dirty flocking. The conclusions are
sometimes surprising. For example, in a Vee formation of migrating geese the
leader, at the tip of the Vee, experiences the most favorable interference.
It’s nothing like “breaking the trail”, the magical, anthropomorphical
explanation! Since I published this in 1970, folks have asked why the
strongest Alpha animal would take the easiest position.
My reply is, “They ain’t Boy Scouts! If you were the strongest member of
the team, wouldn’t you take the easiest job?”
I would, and do, as does every FRIAMer who employs a gardener!
Peter Lissaman, Da Vinci Ventures
Expertise is not knowing everything, but knowing what to look for.
1454 Miracerros Loop South, Santa Fe, New Mexico 87505,USA
tel:(505)983-7728
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On Nov 24, 2009, at 11:17 AM, Nicholas Thompson wrote:
The concept of celebrity is just this
confusion between village and mass culture.
Brilliant, Nick. Never thought of it that way, but it feels right.
"Whatever happens. Whatever what is, is what I want. Only that. But
that."
Galway Kinnell
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