Wind turbine blades spin at a velocity of six to seven times wind speed and can reach 170 mph at blade tips causing significant radar clutter, that is electronic noise which needs to be filtered out.

This creates problems for long range radar for many government agencies. The Department of Homeland Security (DHS), Department of Defense (DOD), Federal Aviation Administration (FAA), and National Oceanic and Atmospheric Administration (NOAA) at various times have refused to allow many of the proposed wind turbines in the line-of-sight of their radar installations.

These refusals are stalling development of several thousands of megawatts of wind energy. Their large number of denials is a serious hindrance to US growth of sustainable energy.

A private research firm wrote a report for DHS reviewing current status of the conflict between the ever growing number of wind turbine farms and air security radars that are located less than thirty miles of a wind farm. The report says the nation’s aging long range radar infrastructure, 80% of which is 1950's designed and installed in the 1980s, significantly increases the challenge of distinguishing wind farm signatures from airplanes or weather.

Wind turbines with their large propellers are detected as moving targets by radar systems. Large wind farms with hundreds of wind turbine/electricity generators appear as huge moving targets, so large they can mask detection of actual nearby aircraft or tornadoes. This is a major concern for FAA, NOAA, DHS, and DOD.

The term RADAR was coined in 1941 as an acronym for Radio Detection and Ranging. RADAR is a system that emits electromagnetic waves (radio signals) and detects reflected signals to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain.
The time between sending the radio signal and receiving the echo indicates distance. Changes in the echo of the reflection indicates motion. To avoid confusion, radar systems have computing systems to remove the clutter of buildings and mountains from the operator's display.

To address the problem of wind turbine farms near long range radar sites, Department of Defense officials proposed a strategy of 'non-technical mitigation.' That means they simply eliminate wind farms that interfere with DOD assets. However, there is great potential for various other mitigation procedures, because there is currently no source of funding to test how any of the proposed mitigations would work in practice.

Wind turbines creating problems for RADAR are not new and have been studied since the 1990's by the United States Air Force, Research Laboratory, Surveillance Radar Technology Directorate. Now, the biggest stumbling block is that no single government agency has stepped up to the plate to take responsibility for compiling the test data and developing a flexible plan.

The plans could include ideas such as: modifying wind turbine blades with circuits and reflectors that would reduce the echo return to radar; changing aircraft flight plan regulations so the planes were at sufficient altitudes above wind farms to reduce radar signal confusion; sending data from wind farms to nearby radar installations; replacing the 80% of the 1950s designed radar systems that were installed in the 1980's; using additional smaller radar systems at wind farms to fill gaps in overall radar coverage. The lack of flexibility in long-range primary radar installations and their future planning is also a national security issue.

At a wind farm site, the simplest approach would be to install a small radar system on a high tower overlooking the facility (known as gap-fill radar). Then, there is the problem of integrating signals from the wind farm with the radar sites using digital signal processing hardware. That raises a big financial issue, because much of the US radar coverage comes from 1950's designed equipment which doesn't have as much computing power as new Internet-capable mobile phones. However, if the additional cost of gap-fill radar systems were added to the construction cost of wind farms, the increased cost will probably be less than 10% of the total wind farm installation.

Inventors Ben and Steve Parks received a patent for their wind farm telemetric data acquisition system. Their patent application (06/110,951) was based on 1970's pre-microprocessor, CMOS medium scale logic devices. They often used the then popular Radio Shack TRS-80, Model 100, with its built-in 300 baud modem for wireline transfer of data, as their display device. This data acquisition system used multiple circuits for checking wind turbine speed, wind direction, electric output, and for shutting down the wind turbine when there wasn't enough wind speed.

The Parks brothers' systems were also used for wind prospecting at remote sites where wind energy and optimum wind design speeds were being determined during development phase of a wind farm location. This type of device could easily send the necessary wind farm data over to a nearby radar installation, where up-to-date computers could integrate the radar's waveform and the wind farm's data.

There is obviously research and technology already developed to solve the wind farm turbine problems facing all these agencies' RADAR installations. After explaining to this writer how RADAR works, Jay Lemmons <www.technologyatwork.com> said, “The problems are really not very technical in nature. Instead, they are differing eco-political views which need to be integrated. Let the engineers and technicians solve them and somebody else can pay for the solutions.”

Will these US agencies continue to limit wind farm locations because they have old radar systems? Or, will someone take over the problem and show the way to improve radar information along with adding wind-powered, electrical-generating capacity to the US electrical grid? X