Today’s Solutions: June 04, 2023

New technologies can help lessen the sonic impact of generating and consuming energy.

Marc van Dinther | July 2008 issue

Just name the noise, and chances are someone somewhere has launched a campaign to tone it down. Don’t like the sound of lawn mowers? Call in the California firm Goats R Us, which has been providing “environmentally friendly vegetation management” since 1995. Goats R Us will keep your grass neatly clipped, and the goats themselves are a lot quieter than the motorized competition—give or take a few bleats. Can’t stand car alarms, cellphones, MP3 players or loud neighbours? Check out the Noise Pollution Clearinghouse (; there may just be an activist group for you too.
When it comes to noise pollution, devices that make or use energy are some of the biggest offenders. The growl of a lawn mower early on a Sunday morning may be irritating, but living near a busy highway or airport can be positively hazardous to your health.
“Research shows that the lack of legislation coupled with bigger, noisier means of transportation is a deadly combination,” says Nina Renshaw, a policy officer at the European Federation for Transport and Environment in Brussels, Belgium.
In Europe, governments are starting to tackle the problem. Since last year, every European city with a population of more than 250,000 has been required to create a digital map indicating traffic noise hot spots, making authorities better equipped to divert traffic from hospitals and schools, for example, or erect sound barriers.
Diverted traffic and sound barriers may help. What would help more, however, is if transportation made less noise. To that end, researchers, entrepreneurs and businesspeople are devising quieter technologies to ease some of the pounding on our eardrums. Here’s a look at some of the most promising developments in planes, trains, automobiles—and windmills.
Inefficient communication among airports, air traffic controllers and pilots results in inefficient flight paths, excessive fuel consumption—and more noise. Dutch and Swedish air traffic controllers and the airlines KLM and SAS want to change that with BridgeT, a new kind of communication network. The innovative network is intended to streamline air traffic by making arrivals more predictable. If flights are properly timed, pilots can more often use a glide approach, which uses minimal engine power and reduces noise. And because manoeuvering is kept to a minimum, glide approaches reduce fuel consumption and emissions too.
Lennard Verhoeff, who manages the BridgeT project at the Dutch National Aerospace Laboratory, hopes to have a trial infrastructure in place during the second quarter of 2009. “This kind of technology is essential if major airports and airlines are to achieve growth targets for 2020,” he says. “That can only be done with acceptable noise and emissions levels.”
The airline industry is tackling flight noise at its source—the engine—through “active noise control.” The basic principle: Noise is detected in the engine and eliminated before it can escape. An electronic system on the plane emits sound waves with the same amplitude but the opposite polarity as the engine noise. When the two sound waves meet, they cancel each other out. Boeing is experimenting with “active noise control” in its new aircraft.
Similar technology will be tested in five households in the Dutch city of Hoofddorp, which is adjacent to Schiphol Airport. A noise cancellation box picks up the sound waves from approaching or departing planes and sends out opposing sound waves to drown them out. This technology can drastically reduce sound on the ground; the Hoofddorp trial will find out by how much.
The same technology is available for personal use. More and more plane and train travellers are resorting to noise-suppressing headphones, in which small microphones pick up noise and feed it to speakers that emit opposing sound waves to mask the noise. The devices can be pricey—Bose’s QuietComfort 2 costs $299, while Logitech’s Noise-Canceling Headphones will set you back $160—but they’re also available in less expensive versions, like Philips’ SHN2500 for $30.
If money is no object, an ultra-quiet electric sports car might be a good investment in silence. The Tesla Roadster ($98,000 for the basic model) is the flashiest: It drives 220 miles (350 kilometres) on a charge, and can go from zero to 60 mph (97 km/h) in less than four seconds. Less expensive alternatives include the Think car—currently available only in Norway, but slated to arrive in the U.S. soon—which can reach speeds of 65 mph (105 km/h) and go 110 miles (175 kilometres) on a charge ($25,000 estimated price); and Miles low-speed (up to only 25 mph or 40 km/h) cars and trucks ($18,400 online, plus a $795 delivery fee).
On the energy-generation front, researchers at Wageningen University in the Netherlands have come up with a way to use water to convert wind into electrical energy, without the need for noisy rotor blades. The invention, called an electrostatic wind energy converter (EWICON), looks like one of those wands children use to blow bubbles—except the EWICON is several stories high.
The installations could be situated at sea, along a coastline or in other windy locations. The wind blows electrically charged water particles into an electrical field, just as a child makes a bubble by blowing into the wand. This charged movement of water particles creates a current, which is harvested and sent to the power grid. The EWICON has no moving mechanical parts, so produces much less noise than a wind turbine.
So far, the EWICON can handle charges of 50 kilovolts, the output of 40,000 AA batteries. The device produces a sound akin to “drizzle,” says Jos Balendonck, an engineer at Wageningen University. That makes it an ideal candidate for placement on buildings. “Efficiency is still very low. You need a lot of water and wind just to power a bicycle light,” says Balendonck.
But EWICON’s capacity is set to improve soon. A one-watt prototype, equal to 800,000 AA batteries, is expected within two years, and an upgrade to one kilowatt will take five years. With electricity provided by the EWICON and vegetation management by Goats R Us, Sunday mornings need never be noisy again.
Marc van Dinther is a freelance journalist who lives in Sydney, Australia.

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