Saturday, February 09, 2008 12:36:34 PM
Charging batteries could soon be a walk in the park
SFU researchers' Biomechanical Energy Harvester fits around each knee and generates electricity as you walk
Chad Skelton, Vancouver Sun
Published: Thursday, February 07, 2008
A team of researchers at Simon Fraser University has invented a device that could tap into one of the most reliable sources of clean, cheap energy: you.
Called the Biomechanical Energy Harvester, it fits around each knee and, using the force naturally created at the end of each step, generates electricity as you walk.
Max Donelan, one of the device's inventors, said at normal walking speed, and with little extra physical effort, the device can generate about five watts of constant electricity - meaning a single minute of walking could power a cellphone for 10 minutes or an MP3 player for 40.
"All of our portable devices could start running on people power," said Donelan. "You're the juice, essentially."
An article detailing how the device functions will be published in Friday's edition of the prominent journal Science.
Donelan's device is not the first to try to capture electricity from normal human movement.
What sets it apart is that it does so without requiring the person using it to exert much extra effort.
This is accomplished through what's known as regenerative braking, the same mechanism, interestingly enough, that allows a hybrid car to create electricity every time you tap on the brakes.
"You can think of walking a lot like stop-and-go driving," said Donelan.
Every time you take a stride, your leg muscles at first propel your leg forward and then, as your foot nears the ground, your hamstrings pull back to slow your foot down.
It's that last moment - when your leg muscles, essentially, tap on the brakes - that Donelan's device does its work.
"It engages the power generation [and] the generator helps slow down the leg," he said. "And as it's slowing it down, it's also producing electricity, because the leg is moving the generator."
The device can also operate in "continuous generation" mode, which creates more power, but also puts extra resistance on the joint and requires more effort on the part of the wearer.
Donelan has formed a spin-off company, Bionic Power Inc., which he hopes will have a working prototype of the device ready within 18 months.
At the moment, the Harvester is 15 centimetres long and five centimetres wide and, with the leg brace used to attach it, weighs a total of 1.5 kilograms per leg.
Donelan said he's hopeful future versions of the device will be lighter and less bulky, making it easier to use.
He refused to predict how much the device might cost, but said the first versions will likely run "a few thousand dollars".
For that reason, he said, the device will likely be most attractive at first as a way of powering expensive prosthetic limbs or for use by the military.
"It's not unusual for a soldier going out for 24 hours to carry 13 kilograms of batteries. They need them for night-vision and communications and GPS," he said. "If they could charge a smaller central battery with their own motion, then you save them from carrying that weight."
As the cost comes down, however, Donelan hopes it could catch on with the general public, who could use it to power their everyday portable devices.
And someday, he said, it could even serve as a power source in poor parts of the world without reliable electricity.
"It's an intriguing idea: Children having to take a break from their homework to go outside and play to generate the power to charge their computers," he said. "Even better if they're playing video games."
(To learn more about scientific discoveries in B.C., check out The Vancouver Sun's Science in B.C. blog at www.vancouversun.com/news/blogs)
http://www.canada.com/vancouversun/news/story.html?id=b2dbc7cb-f89e-4be1-8e30-1c67b6e1ad94&k=6617
SFU researchers' Biomechanical Energy Harvester fits around each knee and generates electricity as you walk
Chad Skelton, Vancouver Sun
Published: Thursday, February 07, 2008
A team of researchers at Simon Fraser University has invented a device that could tap into one of the most reliable sources of clean, cheap energy: you.
Called the Biomechanical Energy Harvester, it fits around each knee and, using the force naturally created at the end of each step, generates electricity as you walk.
Max Donelan, one of the device's inventors, said at normal walking speed, and with little extra physical effort, the device can generate about five watts of constant electricity - meaning a single minute of walking could power a cellphone for 10 minutes or an MP3 player for 40.
"All of our portable devices could start running on people power," said Donelan. "You're the juice, essentially."
An article detailing how the device functions will be published in Friday's edition of the prominent journal Science.
Donelan's device is not the first to try to capture electricity from normal human movement.
What sets it apart is that it does so without requiring the person using it to exert much extra effort.
This is accomplished through what's known as regenerative braking, the same mechanism, interestingly enough, that allows a hybrid car to create electricity every time you tap on the brakes.
"You can think of walking a lot like stop-and-go driving," said Donelan.
Every time you take a stride, your leg muscles at first propel your leg forward and then, as your foot nears the ground, your hamstrings pull back to slow your foot down.
It's that last moment - when your leg muscles, essentially, tap on the brakes - that Donelan's device does its work.
"It engages the power generation [and] the generator helps slow down the leg," he said. "And as it's slowing it down, it's also producing electricity, because the leg is moving the generator."
The device can also operate in "continuous generation" mode, which creates more power, but also puts extra resistance on the joint and requires more effort on the part of the wearer.
Donelan has formed a spin-off company, Bionic Power Inc., which he hopes will have a working prototype of the device ready within 18 months.
At the moment, the Harvester is 15 centimetres long and five centimetres wide and, with the leg brace used to attach it, weighs a total of 1.5 kilograms per leg.
Donelan said he's hopeful future versions of the device will be lighter and less bulky, making it easier to use.
He refused to predict how much the device might cost, but said the first versions will likely run "a few thousand dollars".
For that reason, he said, the device will likely be most attractive at first as a way of powering expensive prosthetic limbs or for use by the military.
"It's not unusual for a soldier going out for 24 hours to carry 13 kilograms of batteries. They need them for night-vision and communications and GPS," he said. "If they could charge a smaller central battery with their own motion, then you save them from carrying that weight."
As the cost comes down, however, Donelan hopes it could catch on with the general public, who could use it to power their everyday portable devices.
And someday, he said, it could even serve as a power source in poor parts of the world without reliable electricity.
"It's an intriguing idea: Children having to take a break from their homework to go outside and play to generate the power to charge their computers," he said. "Even better if they're playing video games."
(To learn more about scientific discoveries in B.C., check out The Vancouver Sun's Science in B.C. blog at www.vancouversun.com/news/blogs)
http://www.canada.com/vancouversun/news/story.html?id=b2dbc7cb-f89e-4be1-8e30-1c67b6e1ad94&k=6617
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