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Windletter
Volume 27, Issue 3
March 2008

Mission Accomplished: Getting Wind Turbines and Radar to Work Together

A civilian Air Force official gives his first-person perspective on successfully working with wind power developer RES to create a win-win outcome.
 
By Dwight Williams

Both wind power and radar are here to stay.  All stakeholders, therefore, understand that members of the wind energy industry and federal government need to work together to find solutions when challenges arise. Fortunately, that’s very achievable, as has been exemplified already.

Approximately three years ago, Dyess Air Force Base (AFB) in Texas received proposed construction notices from the Federal Aviation Administration (FAA), for the in stallation by developer Renewable Energy Systems (RES) of wind turbines.  The RES projects were proposed for Shackelford and Callahan counties in West Central Texas, approximately 30 miles northeast of Abilene and 100 miles west of Ft. Worth. The experience of how Dyess AFB officials and RES worked together to overcome challenges and find solutions that everyone ultimately found acceptable may be helpful to those working through similar situations in the future.

Unexpected interference
As the "airspace manager" at Dyess AFB, I head up a team of experts that we refer to as our Encroachment Team. We are the clearing house for all construction notices affecting Dyess AFB, including low-level routes and other training airspaces. We manage over 100,000 square miles of airspace, from Las Vegas, Nev., to eastern Colorado, to West Central Texas. Our Encroachment Team consists of a GeoBase specialist, community planners, weather support staff, and airspace and range management personnel.

When I received the construction notices on this particular wind project from the FAA, I basically blew it off. To me, these were ground-based structures in areas that were not near any of our “low-level” flying routes, so in my mind the turbines would not be a threat to our aerial activities, or to Dyess AFB as a whole.

Big mistake.

This is still a learning process for a lot of us on the military installation; in fact, it may be helpful for members of the wind industry to remember that this is probably true across the entire Department of Defense (DOD). Without knowing the impact to our Next Generation Weather Radar System (NEXRAD) (as opposed to military training routes and C-130 Drop Zones with which I am normally concerned), I was sure that we were in the clear.

One challenge confronted by our team is that the FAA’s Obstacle Evaluation/Airport, Airspace Analysis (OE/AAA) does not always catch the problems that military installations might have. The instance of the RES project is a perfect case in point; moreover, to complicate matters more, three separate government agencies were to be affected by the wind facility: DOD; the National Weather Service (NWS), which is part of the Department of Commerce; and the Federal Aviation Administration, which falls under the Department of Transportation.

It wasn’t until some 18 months later, in the spring of 2007—when construction was already underway—that I realized the potential impact of the project. Quite telling is the fact that, looking back, I’m not even sure how we initially “re-learned” of the project (even though the notice of construction had come across my desk and I had quickly dismissed it as innocuous). We may have taken note of the project by driving by it, or perhaps someone asked us about it. At any rate, eventually the weather people at NWS in Oklahoma City started asking a lot of questions about the project.

That is when I understood I needed to find out exactly what kind of impact the turbines would have on our weather radar, and what we could do to minimize that impact. The whole project had caught me by surprise because the issue was not with our training routes or drop zones—which naturally is our No. 1 concern—but with the weather radar, which also plays a very important role at Dyess AFB. NEXRAD is owned and maintained by Dyess AFB but is primarily operated by NWS out of San Angelo, Texas. NEXRAD is part of the Nationwide Weather Coverage System and is heavily used by the FAA as a means of routing air traffic around severe weather in and out of the Dallas/Ft.Worth metro area.

So, instead of being ahead of the game, we instantly found ourselves behind the proverbial 8 ball.

I responded to the situation by immediately contacting RES’s Andrew Oliver, whose name was listed as the proponent in the FAA Obstacle Evaluation/Airport, Airspace Analysis. Needless to say, he was surprised to hear from me, especially when I told him that we might have a problem with some of the turbines from the 800 MW in projects that RES was either building or developing in the area. Specifically, we had concerns regarding the turbines that would be located in northern Callahan County and southern Shackelford County.
That really got his attention. I explained that these turbines would affect weather radar returns that could impact nearly 200,000 people in West Texas, an area that includes Dyess AFB.

Wind power and the principles of radar
In order to understand our concern over the placement of wind turbines, it’s helpful to understand how radar works. The principle of radar is “reflective energy,” which travels from the radar antenna to an object and back to the antenna. The speed at which that reflective energy is received back to the antenna is plotted on a monitor (RADAR is an acronym for Radio Detection and Ranging).  If something were to block that energy from either being transmitted or being returned, the result could be false echoes or a masking of the object all together.

The NEXRAD radar system takes incremental snapshots beginning at 0.9 degrees above the horizon and moving upward. This 0.9-degree area was our biggest concern. The particular NEXRAD antenna located in the area that would be affected by the turbines is not on the highest terrain; since it’s a little lower than the surrounding land mass, any vertical construction could be a problem.

An additional feature of the radar system that concerns us is “velocity” reporting. Velocity refers to the wind speed and rotation of a severe thunderstorm at the lower levels (that is, the 0.9-degree area), where cyclonic activity capable of producing a tornado could form. A spinning wind turbine could send velocity information to the NEXRAD, causing it to produce inaccurate readings.

Problem solving by working together
Once we explained our concerns and potential impact to RES, I received an email from Scott Caldwell, RES’s director of development, requesting a face-to-face meeting to discuss the issues and what could be done to mitigate the problem. Understandably, RES already had a lot invested in the wind energy project and did not want to see that investment jeopardized.

We were very excited to meet with RES and agreed to host the meeting at Dyess AFB on July 11, 2007. As it turned out, we had a great meeting, which I believe was the first-ever such gathering involving an Air Force bomber unit and wind energy developer on a military installation. To its credit, RES suggested the in-person meeting: I find it is always more beneficial to speak to someone face-to-face rather than through email or phone calls. Face-to-face meetings are where the “rubber meets the road.”

In an open and frank discussion, RES was very amiable, listening to our concerns as well as our suggestions to mitigate and minimize potential radar problems. Those suggestions included:
altering the location of 14 turbines that were in direct line-of-site to Abilene and Dyess AFB, and
realigning several other turbines perpendicular to the radar beam, lessening the overall impact by lining them up in rows.

Three months after the initial meeting, we had a second meeting, again at Dyess AFB.  RES Project Developer Philip Moore and Technical Engineer Erin Shea confirmed the company would be able to make the changes to the project that we had requested.

Good neighbors
In the instance of Dyess AFB and RES, creating a good working relationship between the developer and federal agencies turned out to be beneficial to all stakeholders. From our perspective, we were delighted to find that RES bent over backwards to listen to our concerns (traveling from Austin twice to visit with us) and made every effort to minimize the impact of wind turbine development in the area. Technically, RES had no obligation to make these changes since the turbines were already deemed as “No Hazard” by the FAA, but they wanted to be good neighbors and were willing to work with us.

Over the past four years I have become very familiar with wind energy development, but this didn’t happen over night. It took time, lots of phone calls to county officials, and personal meetings with many stakeholders. Without some sort of road map to go by, the Encroachment Team at Dyess AFB struggled early on trying to find out what—if anything—we should be doing. We learned on the fly, you could say, and mainly out of necessity. But as with many things, you can either stand in front of the bus and get run over, or you can get on board and influence the bus’s direction. The Encroachment Team decided to do the latter by learning about wind energy, how it affects us, and what we can do to minimize its impact. Perhaps most of all, we appreciate the hard work and cooperation from everyone at RES. Together we proved that when it comes to wind and radar, you can create win-win solutions.

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