Wind energy vs. wind energy - Solar, Wind and Land: Conflicts in Renewable Energy Development - page 49

Parcel D

Parcel U

Property
line

Predominant
wind direction

Site D

Site U

Wake
impact area

Safety
setbacks

Figure 3.1 Turbine wake interference

Suppose that the proposed turbines at Sites U and D are both eligible for
permitting approval because each lies outside a 500-foot “safety” setback
applicable in the controlling jurisdiction. These setbacks, which are fairly
common minimum setbacks for commercial wind farms, are sufficiently
wide to prevent turbine towers from ever falling across property lines. 2
Unfortunately, if the developers each proceeded to install turbines at Sites
U and D, the Site U turbine would create a “wake” behind it when rotating
that would materially diminish the energy productivity of the turbine on
Site D. The two developers involved in this example are thus locked into a
simple bilateral conflict over competing rights to capture the energy in the
wind currents above their respective parcels.
Wakes like the one at issue in the preceding example can extend for a
distance of eight to ten rotor diameters behind a commercial wind turbine—
an entire kilometer or more than half a mile. 3 These wakes reduce average
wind speeds, which can decrease the energy production of turbines situated
downwind . 4 In addition to reducing turbine productivity, such wakes can
accelerate turbine “fatigue,” causing the gears and machinery in downwind
turbines to wear out more quickly than normal. 5
In western nations, parties in the position of Upwind Developer in the
fact pattern above may try to assert that they have superior rights in the
wind blowing across their leased property based on the ad coelum rule. As
described in Chapter 1 , the ad coelum rule provides that “[to] whomsoever
the soil belongs, he owns also to the sky and to the depths.” 6 In the wind
energy context, one could argue that, based on this rule, ownership of a