Here's a specific example of a wind farm to consider:

Shepards Flat is in Oregon along the Columbia River at a location that is particularly windy (which is why all the wind surfers make the pilgrimage to this area).

Here is the wiki page for Shepards Flat. This page does give us some data but it would be useful to understand the area that it occupies so we can check some of David's calculations. Several web sites list the area as 30 square miles or 80 square kilometers (can you check to see if these are the same?

Caithness Energy built the project and reports it's performance on this webpage. Can you see what is wrong with their statements on several levels?