Nice little idea for lighting without power , lift up a weight ( earth filled bag/ plant pot) and the light runs for 30 minutes (not sure what lumen output is ?)
Possible benefit for those in developing world

http://www.indiegogo.com/projects/282006
"Following the initial inspiration of using gravity, and years of perspiration, we have refined the design and it is now ready for production. We need your help to fund the tooling, manufacture and distribution of at least 1000 gravity powered lights. We will gift them to villagers in both Africa and India to use regularly. The follow-up research will tell us how well the lights met their needs, and enable us to refine the design for a more efficient MK2 version. Once we have proved the design, we will be looking to link with NGOs and partners to distribute it as widely as possible. When mass produced the target cost for this light is less than $5."

20 pound weight, they say. Let's say 10 kg mass so 100 newton weight. Lift in 3 seconds, say 2 metres height. Total energy stored 200 joules. 30 minutes they say. That's 1800 seconds. 200 J/1800 s = 0.11 W. There's a reason the company's web site is http://deciwatt.org/ Dunno how many lumens that'll give but not a lot, I feel.

Thanks james for the heads up. Just contributed

Or tonnes even, and a lot of breakfast.

Now all though people that go a gym first thing could help out here.

In the video they do say "Up to 30 minutes" rather than always 30 minutes. It also has a dial to adjust the output (i assume speed at which the weight is dropped). So perhaps it is more a questions of selective information about performance.

Anyway, I like it. If you were to use wind up technology, you would also need batteries, which have a limited life expectancy, so it is the sort of thing that will just work and work and work. Subject to mechanical things breaking in some way.

i guess the simple question , does it produce more energy in it's life time than it consumes, EROEI
cradle to grave ( I would like to say cradle to cradle if constructed of the correct materials )
If so it's a good product.

Posted By: jamesingrami guess the simple question , does it produce more energy in it's life time than it consumes

It can't as you have to take food energy into account, and we are not that good at converting fat to kWh.

Now I have a craving for a bacon sandwich.

\i'm not sure what the advantage vs a wind up radio/light is? I'm talking about the ones that use a constant force clock spring to store the energy and deliver via a small generator.

As far as I can see the gravity storage version just adds more bulk and more restrictions on where and how it can be used (needs headroom must be vertical, can't be used when mobile etc).

Plus that strap looks very vulnerable to damage/tangling and doesn't look amenable to local repair/manufacture.

Still, the basic idea of replacing kerosene lamps is a good one.

Posted By: jamesingrami guess the simple question , does it produce more energy in it's life time than it consumes, EROEI
cradle to grave ( I would like to say cradle to cradle if constructed of the correct materials )
If so it's a good product.

It's not really intended to save energy, just to remove the need to burn a particular fuel.

"Maybe it should be: does it produce the needed amount of light using less energy/causing less environmental harm than other means?"
Yes that's a better way to put it.

Posted By: Ed Daviesdoes it produce the needed amount of light using less energy/causing less environmental harm than other means?

That's still not quite it. How much less is less enough?

does it produce the needed amount of light using no more energy/causing no more environmental harm than than the planet's repair systems can simultaneously cope with?

It's not necessary, and completely impossible, to aim for zero damage. Every form of life, indeed of being (e.g. if you're just a dumb rock lost in space) 'causes damage' - it's called entropy.

Local systems e.g. Earth, or the phenomenon of life itself, may or may not have ability to 'steal' negative entropy from elsewhere in the cosmos (increasing entropy elsewhere), and that can translate into resources to repair the existing local ecoststem.

Such auto-stable repair systems (e.g. animal immune systems) do depend upon external energy input, or more precisely, external supplies of negative entropy robbed from elsewhere. Earth has such an auto-stable repair system, but of defined capacity. Until the 1980s, human damage to the planet was still broadly within the planet's repair capacity, but since then we're increasingly outpacing that capacity - currently, Earth's annual capicity is 'used up' by October each year, heading for September. Unrepaired damage is therefore accumulating, and already there wd have to be several years with absolutely nothing happening on Earth, for the planet's repair systems to catch up.

It is conceivable that humans could devise ways of increasing Earth's rate of capture of external (solar) energy, and its rate of stealing negative entropy from elsewhere, and humans could design everything the build, make or do to consciously aid and accelerate Earth's natural capacity to repair the accumulated damage overload that we've created.

That's how to assess any new gadget!