[ris]

"Don't both have their places?"

It's more that this "invention" has been bouncing around for a while and gets an unwarranted amount of attention for the amount of energy it can provide. Weird to think, but solar isn't "sexy" in the same way.

[scott_s]

"D'oh, we forgot to charge our solar light earlier today."

"No worries, we'll just use the gravity light for now."

That scenario seems reasonable to me. The point is not the amount of energy the technique provides. The point is the utility people get out of it. And I see a place for both; GravityLight and Solar Aid seem like great projects.

[aplummer]

I think they would be good in a mine safe room or something, no need to ever replace batteries right. There are a bunch of cases you might not have a charged light.

[kbenson]

Maybe that "unwarranted amount of attention" is because it has a different set of requirement for use than solar which makes it particularly attractive. Considering only the energy efficiency and not how it could or would actually be used by the target consumers seems shortsighted to me. It may yield a the most efficient product, but it may not yield the most effective product.

[ris]

Yeah, sure, but that set of requirements is, I'd argue anyway, probably more appropriately served by something clockwork or something crank-based that charges a battery.