National Security Imperiled By Wind Farms—Still

Somehow this story had completely escaped me, apparently for years, until now. Recent research from Britain’s Ministry of Defense has indicted wind turbines as interfering with military radar to the extent that they’re suspending projects until site-by-site reviews assess whether the proposed farms endanger air safety. According to the Times of London, the military is specifically objecting to four proposed wind projects in northeast Britain because they obstruct military radar’s ability to detect air traffic. The issue is troubling enough that NATO is now getting involved, with a dedicated committee and an agenda of action items ranging forward to 2010.

Apparently this was all a much bigger deal in 2006, when the U.S. Department of Defense began halting the installation of wind projects in Illinois, Wisconsin, North Dakota, and South Dakota, while the Pentagon investigated the threat. A DoD report, also from 2006, addressed several angles of the risk, including the impact of wind turbines on commercial air radar and ocean navigation systems. The report didn’t say much, other than that the issue was not very well understood.

The reason that a wind turbine is more problematic than other structures that might fall in a radar’s path is basically just its unusual size combined with the movement of the blades. A radar system consists of a transmitter that emits radio waves, an antenna, and a receiver. The system emits a beam, and anything that falls in its path will reflect some energy back to the receiver. The radar will receive reflections from buildings, as well as potentially from other sources of radiation nearby—say, the radio waves from cell phone towers. Even just visually speaking, there’s a parallel between a turbine blade and, say, an airplane’s wing—they’re both thin and aerodynamically designed, they move, and they’re off the ground. It’s not impossible to see why a radar’s microprocessor might have trouble distinguishing between the two. Not that that really clears things up, though, because numerous military bases have wind turbines installed—so obviously it’s not such a huge obstacle.

Now that I’ve done some poking around, I’m surprised that we’re still (and for some of us, only now) hearing about tension between defense departments and wind installations. The Federal Aviation Administration ended up approving those projects that were suspended in 2006 after it checked out the sites, but bureaucratic hurdles that delay the installation of renewable energy projects can cumulatively become a big deterrent to potential installers. In the solar industry, we’ve seen utilities go through several phases of reform before some—not all—began to embrace the distributed generation model of solar modules on rooftops. And I wonder, is this just another version of the whales and sonar dilemma?

For more background, check out the U.S. Department of Energy’s information center dedicated to wind and radar.