Comparisons

These two graphics were made using the geocoded addresses from Vermont’s E-911 data and the distances from wind turbines to the addresses was calculated using the Vincenty formula. I have checked enough of these calculations and be satisfied that they are correct.

These comparisons show that the turbine installation in Sheffield is a considerable distance away from most of the addresses there. A look at the area using Google Earth shows that many, possibly more than one-half, are separated from the wind turbines by Interstate 91

Sheffield, Vermont: Distance from address to a turbine

 

Windham, Vermont: Distance from address to probable turbine.

 

July 3, 2013. After originally posting charts comparing Windham and Sheffield I decided to make a comparison between Windham and Grafton.  I used the same data and methods and placed three turbine sites on the east side of the Stiles Brook tract. In other words, I placed the possible turbines as close as possible to Grafton and this is what it looks like:

 

Notice that no address in Grafton fall within .50 miles of a possible turbine site.

Otherwise it looks a lot like the Sheffield chart.

 

What follows is a description of the tools, data, and methods I used to make some comparisons of the Sheffield, VT wind site and the proposed site in Windham, VT.

The spreadsheets and overlays may be downloaded from the links at the end of this article.

First I used Google Earth to conduct a visual inspection to become familiar with the two sites. Many obvious differences can be seen and I wanted to quantify some.

I downloaded the Vermont E-911 data from the Vermont Center for Geographic Information( http://vcgi.vermont.gov/warehouse/search_tools ) I chose the Esites data because it has all Vermont buildings geocoded ( positioned by latitude and longitude)

Then geographic information system software ( http://www.qgis.org/ ) was used to extract addresses for Sheffield and for Windham. That data was then exported to a LibreOffice Spreadsheet. I created one file for each town.

I used the Vincenty formula ( explained here:http://www.movable-type.co.uk/scripts/latlong-vincenty.html ) to calculate distances between longitude/latitude pairs. I did this for each geocoded address for each town by copying the formula to a column in the spreadsheet.

A visual inspection using Google Earth shows that three turbines in the Sheffield site are nearest to residences and the coordinates of those three were used to calculate distances.  I calculated the distance from each address to these three sites and then used to shortest of the three to create the graph. I needed to create categories and place each distance in a category and how that was done is explained below.

The proposed site in Windham (called the Stiles Brook Site) is surrounded by most of the addresses and several sites would be needed to create a reasonable model. I downloaded 70 meter wind energy data from the Vermont Center for Geographic Information and used Qgis to extract data for Windham and create Google Earth overlays for the wind speed classes. These overlays shows what class of wind can be found throughout the Stiles Brook site and I used that information to select four very probable sites along Windham Hill Road and used the coordinates for those sites as a reference point.

Then I used the same formula as before to calculate the distance between each Windham address and those four sites.

Next I imported the spreadsheet data into LibreOffice Base ( a database manager and part of the LibreOffice suite) and created categories. Then I ran several SQL update commands to select the shortest distance of the four  ( three in the case of Sheffield) and to group the distances into categories. I returned the data to the spreadsheet where I used the categorized data to create the charts.

 

Here’s links to the Excel spreadsheets used to create the charts.

sheffield-addresses-and-distance-to-closest-turbine

windham-addresses-and-distance-to-closest-site

windham-and-sheffield-distances-categorized(two sheets)

Google Earth overlays.

To use these you’ll need to install google earth and then open the overlay.  The best way to used these files is to download the overlays and after Google Earth is started open the Windham parcels overlay which will outline the Stiles Brook track. Then, loading the wind speed overlays will assist you in visualizing the proposed site and wind speed on the site as created by the wind energy models.

After the overlays are loaded they may be clicked on or off using the left sidebar.

Windham parcels with the Stiles Brook tract outlined in purple

Class 4 = 14.6 to 15.7 MPH
Class 5 = 15.8 to 16.6 MPH
Class 6 = 16.7 to 18.3 MPH
Class 7 = 18.4 to 24.6 MPH   (no class 7 wind on the Stiles Brook site )

Google Earth overlay of Sheffield E-911 addresses

Google Earth overlay of Windham E-911 addresses

 

In case you do not wish to download and use Google Earth a screen shot of it with some overlays is shown below.

Open source software was used to complete all this work:

Operating system on my pc is Linux Mint

Spreadsheets and database manager are parts of the LibreOffice suite. LibreOffice reads and writes excel spreadsheets and the links are to spreadsheets created in LO and saved in .xls format.

The geographic information system is QGIS

All the software is free as is Google Earth.