Shawn Frayne won a 2007 Breakthrough Award for his wind power from membrane vibration prototype: aero-elastic flutter drives a simple button-magnet air coil. I love innovation: even if Shawn’s idea doesn’t prove to do what he hopes, it is at least fun, and may generate other innovations that do work. Check out the Windbelt website for info.
Shawn says that third-world lighting is the target market for the Windbelt. According to the PM article, the prototype has generated 40mW in 10 mph of wind. Since solar power, and typically wind power, is unavailable when people are looking for reading light, practical application is going to require storage. It isn’t clear why any Niger villagers are going to buy a stand-alone micro-power source — which demands that they acquire and configure suitable charging/storage to make light on demand. My speculation is that sale of Windbelt to the 3rd world lighting market to replace kerosene is going to require delivering a complete generation/charging/storage/lighting solution.
On the charging & battery subsystems, consider just one example of the product of the focus of some bright minds — take a look at the novel lithium ferro-phosphate battery solution adopted by the One Laptop per Child project for the XO Laptop. This battery pack is claimed to be replaceable for $10.
Wondering how Shawn’s concept might scale I did a bit of googling around. One interesting analysis I’ve found is Peter Glaskowsky’s “More alternative-energy innumeracy” — which raises a number of critical questions — best to read his post in full.
Peter offered up a Home Depot “complete system” for $27 that includes solar panel, batteries/charger, and 3 LED lamp. Home Depot doesn’t quote wattage in their spec, but this is clearly much less than the 5 watts Glaskowsky posits is required to replace a hurricane lamp. Geoduck offers a “seven LED Solar rechargeable LED Lantern” for $10. For both these complete lighting solutions, I wonder how useful for reading for how long? What does the owner do when the rechargeable battery only holds 50% charge? Etc….
Back to the Glaskowsky critique:
…In a 40-mph wind, the Windbelt could potentially extract more than 2.5 watts…but in practice, the membrane would simply tear.
could be correct, or not. The interface of fluid dynamics and materials is a serious challenge, and not yet reducible to closed-form equations of motion and stress. But scaling up to 40-mph is not the right focus in the first place — the few places on the planet with meaningful 40-mph winds are not markets for micro-power.