I am working on a research project for an internship, and I an looking for information on wind turbine spacing. Are there any definite calculations which take several factors into consideration for the maximum efficiency? Any help would be greatly appreciated.

I cannot provide you with exact formulas for the calculations that might be used by a developer to do sighting, but I can provide you with some basic information that can help you understand the process. When siting more than one turbine in a given location it would be desirable to have the turbines as close as possible so as to save money on the installation costs such as buried cables and land leases. On the other hand, turbulence and the decreased velocity of the air after it has passed through one turbine can negatively impact the efficiency of a turbine downstream. If located to close the turbulence can also cause additional loads that cause the turbine to fatigue more rapidly. Therefore, it makes more sense to have the turbines further apart. In the end, a compromise is met between the financial costs of locating the turbines near each other and the benefits for the efficiency and equipment of spreading the project out. Check out the following links for more information.

The first resource is Windustry’s Community Wind Toolbox. Chapter 5, the Siting Guidelines, contains information about selecting wind turbines sites. The “Site Layout, Design and Planning” section will have a description of some of the methods used in siting turbines.

Another more technical resource is the Danish Wind Industry Association's website. The website contains a whole section on wind turbine siting that includes information for the mechanically and mathematically inclined. The link I am providing here goes straight to a page on siting more than one turbine in wind farms. If you sift through the rest of the available information you will find some helpful information.

I hope that this was useful.

Christopher Bassett
Windustry
christopher@windustry.org