Regenerative braking for humans?

[amerikat]

This is just plain stupid. What are they smoking at MIT?

http://www.msnbc.msn.com/id/20201266/

An article about using the energy produced by the movement of large numbers of people.

Maybe this story is a hoax?

[Tunkamerica]

1. ?i don't get your confusion

It makes sense, the energy would otherwise be transferred as heat, sound, whatever. If you could capture a little bit, it might help. Nobody's saying this is imminent, just possible.

[amerikat]

2. The energy to build such an apparatus to capture the energy would

consume way more energy than could ever be extracted from it. I think we need simpler more practical ideas to deal with our energy dilemma.

[OKIsItJustMe]

3. No, I don't think it's a hoax

http://www.wired.com/wired/archive/9.02/baylis_pr.html

Issue 9.02 - Feb 2001

The Greatest Shoe on Earth

...

The heel insert, he shows me, is fashioned from piezoelectric crystal, a cheap, quartz-type compound polarized with zaps of electricity. When a piece of piezo is bent, squeezed, or struck, it produces a high voltage at very low current - rather like the static electricity created by rubbing fur on a balloon. "We then put that charge back through a little electronic circuit," says Baylis, "which sorts it out before squirting it into the battery of the mobile phone, held in a pouch sewn on the back of the boot."

Like most of his Alka-Seltzer moments ("when the idea hits my brain and starts to fizz"), this one came to Baylis in his sleep, more than 40 years ago. Drafted into the army, he served as a physical training instructor. "One of the things we used was a treadmill. We called it the runway and it was literally propelled by its user. I dreamed of putting a dynamo on it to create power. The electric-shoe concept has been in my mind all these years. As long as I have been getting my shoes resoled by the cobbler I have been aware that my feet are doing work."

He's not the only one. In 1998, the MIT Media Lab demonstrated some experimental shoes that generated just enough power to send out a radio identification code. But only with the advent of the wireless Web and low-power portable electronics did Baylis believe the concept's time had come. "All these WAPs and PalmPilots, they need fack-all power. And who are the biggest consumers of those gizmos? I'll tell ya: It's these techno kids with baggy trousers. They'll spend a fortune every few months just to keep up with the times, but even with the latest palmtop or whatever, they can't go very far away without recharging. They still can't take it to a weeklong rock festival in the desert or trekking through Nepal."

On January 10 of last year, Baylis and two longtime collaborators - John Monteith, a mechanical engineer, and Barry James, an electrical engineer - filed a patent for their electric-shoe idea. "It was 50 pages long and stuffed with as many schoolboy options as possible," Baylis recalls. "We threw it all in the pot, our attitude being quite frankly that if somebody had any claims upon any forms of technology that we embraced, then they would come at us, in which case we'd say, 'Fine, we'll either work with you or work around you.'"

...

[TreasonousBastard]

5. Feh! When I first heard about piezo...

I thought of tying a bunch of them to trees so they could generate when the wind blew, and hooking them up to floating piers for tide energy...

Never actually did any of this stuff, except for small experiments, but what the hell. If it's a good idea, someone will.

Next "discovery" will be Peltier devices.

[foo_bar]

4. it's a little out there, but the concept is valid

It seems like there'd be a better return placing such a system under roadways, since displacement of energy occurs on a greater scale and at greater expense, but maybe this could turn an energy profit in Hong Kong or New York before the maintenance costs kicked in (e.g., entropy in the form of potholes). If those other MIT guys figure out "WiTricity" we won't need this kind of infrastructure anyway, since our sneakers will Bluetooth the spare energy to the nearest Con Edison pylon.

[NoFederales]

6. Given MSNBC as the carrier of the story, it's pretty and sensational hoakem,

especially for believers in entertainment and fantastical thinking. My students have utilized regenerative braking in motors designed for solar bike and car races to help replensish limited energy allowed for battery packs--a specific system designed whereby an electric traction motor, during a braking phase, becomes a generator, thereby lending a small charge back to the energy storage system (the battery pack).

But isn't it the basic premise of that movie Monster's Inc whereby fear, and later, laughter is tapped for energy? Also reminiscent is the old Charles Schulz comic Peanuts where Lucy is concerned about the world population's ambulatory effect on the turning of the Globe. Conservation principles and thermodynamics notwithstanding, it is possible to recover some energy transformations to boost efficiency, but without better reporting about what is being claimed in the MSNBC article, I'll wait for a refereed technical report about MIT's efforts before I applaud or deride a conclusion: articles like this give science and technology a poor reputation.

NoFederales