Cities Extract Energy from Everyday Activities

Roanoke, Va., and other cities are experimenting with new technologies that capture energy from footsteps, cars and more.
by | January 2012

Could one answer to energy independence lie in our own movements or in the momentum of the vehicles we drive? Maybe someday. That’s the premise behind an emerging category of energy-harvesting technologies.

These devices collect energy from ambient sources -- wind and solar power are two common examples. But researchers and innovative companies are scaling down the approach to extract power from a growing number of everyday activities. Many of these technologies are just reaching the prototype stage, but ultimately they may help cities and counties cut their energy bills.

That’s the idea in Roanoke, Va., where the city recently tested a roadway “rumble strip” that generates electricity when vehicles drive over it. The device -- a portable speed bump that’s laid on the roadway surface -- was placed at the Roanoke Civic Center on a busy Saturday in October. About 600 vehicles traveled over the strip, actuating a series of small hinged plates that produce power through a technique similar to regenerative braking used by electric and hybrid vehicles. Over the six-hour test, the strip produced enough electricity to power an average home for a day, according to its manufacturer, Maryland-based New Energy Technologies.

Roanoke Transportation Manager Mark Jamison says the technology tested by the city needs to be proven and refined before it can be considered for actual use. But it has a lot of promise, he says. “All local governments are feeling the pinch, and based on what is going on at the federal and state level, we are going to continue to feel that pinch. So anything that we can do to minimize the expense on our citizens and our city is a good thing.”

Eventually, energy-harvesting technology could be sunk into pavement at high-traffic intersections throughout the city to power traffic signals, street lamps and other infrastructure. “If we’re able to take our equipment off the electric grid and power ourselves, obviously, that saves us some money,” Jamison says.

Roanoke already embraces cleaner and more efficient technologies -- its sustainability efforts include LED traffic signals and running much of its heavy equipment on biodiesel. But as these technologies get better, more cities are experimenting with them. For instance, energy-generating pavement slabs are being installed at the 2012 London Olympic site. The slabs, made of recycled rubber, will capture kinetic energy from footsteps to help power an urban mall adjacent to the Olympic stadium.

It’s too early to tell how well these experiments will translate into practical application -- and how long these devices can withstand the daily pounding of traffic and pedestrians. But the prospect of generating “free” electricity from the everyday actions of residents and visitors might be too good to pass up.

For Roanoke’s Jamison, it’s a possibility the city can’t afford to ignore. “I think that we certainly owe it to ourselves and our citizens to at least think about using these types of things,” he says. “Obviously there is a lot more work that needs to be done to prove that it is going to work, but it makes perfect sense to me.”

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