The inspiration for the project came from a talk she hear where someone calculated that meeting the power needs for North America would require solar panels covering half of the state of South Dakota. This seemed wrong to Kennedy, and she started thinking about the smallest units of light that could be created, considering the fireflies that she watched as a child in Woods Hole, MA. “What’s the smallest increment of useful light.”
To build useful light solutions for the global south, products should be simple, reliable, durable, lightweight and adaptable. “You can’t just stick these things on buildings. People move.”
Rather than wait for technology to improve, Kennedy chose a very architect-like solution to the problem – she looked at what she was able to buy today and see whether they could be adapted into a new structure. The system she’s created uses white LEDs, like those found in traffic signs; sealed plastic switches from dishwashers; Lithium ion batteries from mobile phones. The power source for the lights is a flexible solar cell, more similar to a non-woven fabric than a traditional solar panel. To demonstrate, she hits this panel with a hammer (it deforms, but doesn’t break), and then shatters a traditional glass solar panel. (Joel Johnson, sitting next to me, points out that glass solar cells are hardly state of the art anymore, and this isn’t exactly a fair comparison.)
Wrapped around the light is a soft fabric shell that difuses and reflects the light. The “soft optics” fabric is quite inexpensive, letting Kennedy offer a large shell around the light source. The device, currently in prototype, produces 100 lumens, using a 3.7 volt battery at 1.8 amps. It takes about three hours to charge in full sunlight, and provides 10 hours of light, or 5-6 hours with two lights. (40 lumens, she tells us, is usually enough light to read by.)
There’s a fairly clever system used to charge a set of lights, giving power first to the least charged lights – Kennedy refers to this as “digital intelligence”, which seems a bit much, but the idea of group charging is quite smart. She demonstrates the shippability of the solution by tossing a few across the stage – this is a good thing, given how much breakage occurs with traditional glass cells in harsh environments.
She shows prototypes of the lighting device in southern Mexico, where it’s being adopted by women who use it to let their children read and to cook meals well into the night. Some women are building their own devices by combining Mesoamerican weaving techniques with the tech from the lights to build very cool-looking local solutions.
The devices currently cost about $40-50 to build in batches of 500. Kennedy wonders what these devices could revolutionize education and the mobile phone industry in the developing world. I wonder whether a team of hackers and makers could make a slightly less visually impressive version of this for about a quarter of the price…
Update: Joel at BoingBoing has an, ahem, less sypathetic review of Kennedy’s talk.
The session ends with Andrew Zolli’s favorite blog, Jessica Hagy’s Indexed. It’s an often funny set of cartoons that combine “set theory, Venn diagrams and 8th grade math to tell jokes.” She offers a set of jokes based on connecting the ten most popular undergraduate majors in America – tying two together creates a career path – nursing plus business = HMOs; political science plus engineering = building bridges for your constituents.
Technorati tag: poptech2007