It's no secret alternative energy and sustainability are hot topics. There are all kinds of ingenious ideas to harness "green energy" through wind, hydro, thermal and solar sources, but did you ever think about harnessing energy from the movements of crowds? Some guys at MIT seem to think people can move trains instead of trains moving us.

A "Crowd Farm," as envisioned by MIT architecture graduate students James Graham and Thaddeus Jusczyk isn't intended to promulgate crowds as the name implies but rather to harness energy from them as they move over small blocks imbedded in the pavement ( These blocks, or dynamos, slightly depress when stepped or sat upon and transfer the energy into electricity.

These students have run a couple models with the technology imbedded in train stations, and they have set up a chair that powers a tiny LED light. Still, the technology is expensive in its infantile stages.

Somehow, someone figured 28,527 steps on these dynamos is the magic number to run a train for a second. I put this in the context of Union Station in Los Angeles with about 1.4 million visitors last year. Assuming they walk a quarter mile on average when in or around the station, and their average step covers about a foot and a half, the 1.3 billion steps taken in Union Station last year is enough to power a train for 12.4 hours. LAX had 61 million visitors in 2004; imagine that all these footsteps in the quarter-mile walk through the security line would power a train for almost 22 days!

These gadgets would really be powering less exciting things than trains, but even feeding the power back onto the grid would help California reduce its greenhouse gas emissions. Mass produce them cheaply an install them at airports, train stations, concert halls even sports stadiums. "The wave" could be popular again at Dodger games if it helps global warming, and I could tolerate a couple standing ovations at the opera if they lit the exit signs.

It's just plain fun to consider, not to mention the fact that dynamos would add a new perspective to urban interfaces by encouraging movement and interaction. I imagine the blocks would give a little, like walking on gravel, and this would reduce stress on the joints and burn a couple extra calories on the way. I wonder if they feel like rubber sidewalks; I love the feel of walking on rubber sidewalks.

Another grad student at Princeton, not to be outdone by the likes of MIT, made a similar themed invention (converting kinetic energy into electricity) a couple years ago. Only this other project harnesses the tumultuous ocean surface on weekdays, and converts into a park for boats on weekends with the accumulated energy. Check out Yuske Obuchi's "Wave Garden" at or They're thinking this thing will succeed the Diablo Canyon nuclear power plant in 2026!

- Aaron Engstrom