The Straight Dope

Go Back   Straight Dope Message Board > Main > General Questions

Reply
 
Thread Tools Display Modes
  #1  
Old 09-17-2012, 08:14 PM
Notassmartasithought Notassmartasithought is offline
Guest
 
Join Date: Apr 2009
Wind mill spacing

A couple of days ago my brother and I drove through the Fowler Ridge Wind Farm ( http://en.wikipedia.org/wiki/Fowler_Ridge_Wind_Farm ) in Indiana. We'd never seen one so large, and we'd never seen one at night. So we wonder about two things.

First, the spacing of the windmills. It seemed the rows were about a quarter mile apart, and I suppose the towers were 300 hundred yards apart, or so. Things were somewhat irregular, which we attributed to land ownership, or other issues. Our question is whether there are aerodynamic factors that might specify an ideal spacing of the windmills.

Second, at night, all the red lights on the windmills blink simultaneously. That must be intentional. What's the thinking there? Why not have them all blink independently?
Reply With Quote
Advertisements  
  #2  
Old 09-17-2012, 08:42 PM
johnpost johnpost is offline
Guest
 
Join Date: Jul 2009
you need no causes of wind turbulence for quite a few distances (based on height) for good functioning.

if the flashing was all independent it would be very disorientating to aircraft and not give a accurate representation of the obstructions. by all flashes synchronized it outlines the whole obstructed area.
Reply With Quote
  #3  
Old 09-17-2012, 08:59 PM
Notassmartasithought Notassmartasithought is offline
Guest
 
Join Date: Apr 2009
Well, we got that far speculating on both issues. Perhaps I misstated our questions.

What is the optimum spacing, and why? Blade length? Height? RPM (including gearing)? Average wind speed? Blade pitch? Anything else? Any aerodynamicists out there?

As for the simultaneous blinking, iIs there an FAA ruling on this? Was it a long regulatory fight, or relatively quick? Other red lights around airports don't blink simultaneously. Are there other things going on?
Reply With Quote
  #4  
Old 09-17-2012, 09:10 PM
DSeid DSeid is offline
Guest
 
Join Date: Sep 2001
Some work on optimizing spacing inspired by biological systems.
Quote:
Dabiri realized that one major problem on wind farms is interference between neighboring turbines. When placed close together, they funnel wind into each other, reducing energy output and increasing wear and tear. To avoid this, wind farms space turbines hundreds or even thousands of feet apart.

Dabiri found an analogous problem in the ocean. When fish move as a school, they push water against each other, potentially slowing the whole group. But they’ve found ways of moving together more efficiently and with less energy. Dabiri modeled their motion mathematically and used the results to develop software to define the optimal placement of wind turbines. He says his math makes it possible to squeeze more turbines onto a given plot of land and yield 10 times more energy. He started the company Scalable Wind Solutions to commercialize the software and plans to start selling it in the next two years. “He was the first person to think of” modeling wind farms on fish schools, says Alexander Smits, one of Dabiri’s engineering professors at Princeton. “It’s a game-changer.”
Reply With Quote
  #5  
Old 09-18-2012, 07:36 AM
MikeS MikeS is offline
Charter Member
 
Join Date: Oct 2001
Location: New London, CT
Posts: 3,295
Quote:
Originally Posted by Notassmartasithought View Post
As for the simultaneous blinking, iIs there an FAA ruling on this? Was it a long regulatory fight, or relatively quick? Other red lights around airports don't blink simultaneously. Are there other things going on?
I can answer the first question at least: FAA Standards for Obstruction Lighting and Marking (PDF), which includes the standards on marking wind turbines (p. 33 & 34). Basically, the lights do have to be synchronized, and if the turbines are in a line, there has to be at least one light every half-mile along the line.
Reply With Quote
  #6  
Old 09-18-2012, 07:44 AM
MikeS MikeS is offline
Charter Member
 
Join Date: Oct 2001
Location: New London, CT
Posts: 3,295
Oh hey, here's a technical report from 2005 on the development of lighting standards for wind farms. Concerning the synchronization:
Quote:
Operating in the non-synchronous mode, the obstruction lighting array presented a most confusing and unsatisfactory appearance and, in the opinion of all present, did not accomplish the objective of outlining or warning of the presence of dangerous projections (i.e. 345 foot high wind turbines) above the surface of the ridgeline. This result was expected, and was the reason why synchronization of the light flashes was added to the proposed obstruction lighting system design. Photographs and video tapes of the system were taken at that time.

...

[In synchronous mode,] the limits of the turbine farm was immediately evident, since all 14 lighted wind turbines were defined by high intensity red strobes that were flashing simultaneously. The effect was in strong contrast to the previous night’s presentation, in that the simultaneously flashing lights very clearly defined the extent of the entire wind farm, from one end to the other, and also provided a most dramatic warning of the potential hazard.
It's also noted in the executive summary that bridges and arrays of radio towers also use synchronized lights, and that the wind farm standards were based off of these previous practices.

Last edited by MikeS; 09-18-2012 at 07:45 AM..
Reply With Quote
  #7  
Old 09-19-2012, 07:59 AM
hibernicus hibernicus is offline
Charter Member
 
Join Date: Oct 2000
Location: Dublin, Ireland
Posts: 1,966
Quote:
Originally Posted by Notassmartasithought View Post
Things were somewhat irregular, which we attributed to land ownership, or other issues.
I just want to comment on the irregularity. In areas I am familiar with, there are a large number of constraints on the positioning of wind turbines. One such constraint is distance from the site boundary. Others are steepness, distance from dwellings, lines of sight and forested areas. By the time you have overlaid 5 or 6 maps showing areas that are "out of bounds" for various reasons, the number of available locations can be very limited.
Reply With Quote
  #8  
Old 09-26-2012, 09:19 PM
core_dump core_dump is offline
Guest
 
Join Date: Jul 2012
How exactly are the blinking lights syncronized? I live in the middle of a wind farm and noticed that a few of the lights have lost sync and don't blink with the rest. I'm assuming this is done via communication over the powerline, but if something broke with that one and the light can't even be controlled, does that also mean the utility has lost control of the turbine?
Reply With Quote
Reply



Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:28 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@chicagoreader.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Publishers - interested in subscribing to the Straight Dope?
Write to: sdsubscriptions@chicagoreader.com.

Copyright © 2013 Sun-Times Media, LLC.