There's a lot of reasons why this is cool, but I'm skeptical about it's aims to get rid of kerosene lamps.<p>Kerosene lamps are made with garbage. They can be replaced in minutes if there's a problem. Fuel costs are high, yes, but capital costs and maintenance are low. Those matter.<p>To really make this a long term win, you need to make it indestructible and easy to repair with on-hand parts. I hope they can do that.
I implore people to support something far more practical like <a href="http://www.solar-aid.org/" rel="nofollow">http://www.solar-aid.org/</a> than this.<p>Solar lights are many times more thermodynamically efficient, cheaper to make, smaller and much more robust (no moving parts!).<p>This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
Years ago there was a similar 'potential energy to electricity' buzz and I was initially quite excited. Then I did the math on how much energy is actually available (even at 100% efficiency) from such a scheme. Spoiler - it's minuscule.<p>E = mass x 9.81 x height<p>So a 10kg mass at 2 meters can (@ 100% efficiency) provide 196 joules of energy. A modern cell phone battery has about 25000 joules. To charge said phone would require raising that weight well over 127 times.
Here's what people said about it 3 years ago: <a href="https://news.ycombinator.com/item?id=4889266" rel="nofollow">https://news.ycombinator.com/item?id=4889266</a>
Its cool our energy problems are being solved in two directions at once. We are (slowly) making better energy storage and generation devices. At the same time many of our energy needs go down by the rapid decrease in energy needed to power the electronics. It would be cool to see a graph of the watts/lumen efficiency of light bulbs over the last 50 years and of the joules/operation of CPUs.
The basic idea here is actually a very old approach -- clocks have been powered this way for centuries. But it's very cool and refreshing to see a modern electrical spin on it.
Perhaps a bit of a novelty given the rechargeable battery argument others have mentioned. I imagine distributing a bunch of these with batteries and having a central dynamo-powered recharging station that gets shared throughout a community would be even more practical.<p>The first thing that came to mind when I saw that it lasts 20 minutes would be to use it as a pomodoro timer. Code for 20 minutes, then be forced to take a break, stand up, lift the weight, etc. You get a micro-workout as a small bonus. Again, it's a novelty but sort of a cool one at that.
Loads of great social tech ideas including this one on Social Tech Guide (<a href="http://socialtech.org.uk/" rel="nofollow">http://socialtech.org.uk/</a>), nominations are open for new ones at the moment if you come across any more..
A 12kg weight hanging 6 feet in the air seems a little dangerous to me. Definitely less dangerous than a kerosene lamp, but I'd be worried about poorly attached weights falling if someone bumps their head on it.
12kg * 10 m/s^2 * 1 m = 120j. Best 100 w equivalent led is 18 watts, 120j/18w < 10s. Let's say optimistically a next gen led gets 10x efficiency (this might violate laws of physics), you're buying one minute of good light per 1 m lift.
For those interested on exactly how to set one up and how it works, there is a great Vimeo video outlining installation and operation:<p><a href="https://vimeo.com/128802766" rel="nofollow">https://vimeo.com/128802766</a>
You need to lift a 10KG weight about 2 kilometres to get a teaspoon of kerosene's energy, so it's not a great replacement on that front, and having 10KG weights dangling around at variable points between ceiling and floor sounds if anything even more of a liability than a lamp with a naked flame, which does at least stay where its put. Sorry to be negative but it's difficult to conceive of a realistic scenario where decent battery plus solar doesn't knock this into a cocked hat.
It looks quite a bit more plausible than the specs in <a href="http://www.howtospotapsychopath.com/2008/03/03/stop-press-pixie-dust-unsuitable-for-household-lighting/" rel="nofollow">http://www.howtospotapsychopath.com/2008/03/03/stop-press-pi...</a> , but based on my experience with things like shake/crank torches, the light output would have to be really low to last as long as they claim it does.