"Power Walking" as a Power Source?

I'm a big fan of power walking - and although I don't do it nearly as regularly as I should, I'll be one of the first to support the benefits of said activity. Especially after I heard about the kinetic watch -- a device that converts the momentum of a swinging arm into milliwatts. That's what I'm talking about - make some energy while expending some energy! According to a recent article on ScienceNow (www.sciencenow.sciencemag.org) -- researchers have done the kinetic watch one better: unveiling a new accessory for your knees that puts the hi-tech wristwatch to shame. Get ready for the "Biomechanical Energy Harvester" -- a knee brace that generates more than 1000 times more energy than the kinetic watch - while at the same time paving the way for powering the portable devices of the future.

The Biomechanical Energy Harvester is amazingly simple. According to project leader Max Donelan -- director of the Simon Fraser University Locomotion Laboratory in Burnaby, Canada - "...Every time you take a step - whether it's walking or running -- you use two different groups of powerful muscles connected to the knee..." The first group of muscles pushes to extend the lower leg out and just before full extension, the second group of muscles pulls to put the brakes on. Donelan feels that this "braking process" is just useful energy going to waste.

To this end, Donelan and his team created a modified knee brace with a drive train that converts the mechanical energy of walking into electricity. In fact a similar principle - referred to as generative braking is used in hybrid cars to make electricity when you press the brakes.

According to a follow up article in Technovelgy.com (www.technovelgy.com), six volunteers wore the Biomechanical Energy Harvester brace while they walked on treadmills. Embedded sensors detected the angle and velocity of a subject's legs, switching the device on only during the braking phase of each swing. As pointed out in the article in ScienceNow, the braces produced 5 watts of power -- enough to run 10 cell phones. And although it took a bit more effort to swing the added weight of the brace - the prototype weighs 1.6 kg - -the volunteers on the treadmill didn't have to work harder when the power-harvesting mechanism was turned on. The amount of oxygen they consumed - a typical measure of metabolism and effort pointed out Donelan -- didn't increase. So in effect, the harvester actually helps the muscles by decelerating one's limbs.

This is not the first time someone has tried to tap into the human body's ability to produce real energy. According to an article in Onemobile.it (www.onemobile.it) in 2005, Lawrence Rome -- a biologist at the University of Pennsylvania designed a biomechanical backpack. But even he admits that this latest device "...is the most sophisticated attempt to harness biomechanical energy to date..."

According to Planetnews.it (www.planetnews.it), if the researchers can lighten the load of the device, the first users will likely be people whose lives depend on reliable, portable power: for example patients with insulin pumps or pace makers. Other researchers have a more all-encompassing vision. Douglas Weber -- a team member and mechanical engineer at the University of Pittsburgh School of Medicine in Pennsylvania -- believes that the device may also be incorporated into the design of cutting-edge neuroprostheses -that is, artificial limbs directly controlled by brainwaves and deep-brain stimulators like those developed for Parkinson's disease patients. Others still see the energy device as something that might prove useful for anyone out in the field - be they soldiers, relief workers or someone out on a hike.