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A $5 Lamp Powered Solely by Gravity

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Re: A $5 Lamp Powered Solely by Gravity

#61

Post by FrojoS »

marquis wrote: post #45
NathanKP wrote: post #23

Maybe I'm stupid for asking but what is the advantage of this over a spring powered wound clock? My wristwatch can tick for two days on a wind, and while it isn't as cheap as this gravity powered wound clock I'm sure it could be made cheaper. There is nothing special about this invention; purely mechanical "gravity powered" clocks have existed for centuries in the form of old grandfather clocks etc.

Yes, I was thinking the same thing. You can buy now on Amazon a hand-crank LED light for $12, so surely these can be made far more efficient and cheaper with $200,000.

But those require a battery, which will only survive so many (hundred?) recharges, no?

Re: A $5 Lamp Powered Solely by Gravity

#62

Post by tonyarkles »

ars wrote: post #26
tonyarkles wrote: post #5

Earlier quoted context omitted.

If you read some of the followups and tweak the math a little bit, it works out reasonably well. Instead of 20kg and 1m, 20lb and 2m, which comes out about the same (49.42mWh). If you have to lift it every half hour, that's 100mW for a half hour. That's more than enough power to get a useful amount of light out of an LED. For example, this LED uses 68mW https://www.sparkfun.com/products/531 and is marketed as "so bri…

It's hurts to look at it because it's focused into a very narrow beam. Very bright sure - in one tiny spot, and totally useless to illuminate a room. They even include a photo of the beam pattern - it's almost as focused as a laser. (You can tell on an LED by looking a the top - round tops are focused, flat ones spread out.)

That's fine! It's enough to read a book or do homework after the sun sets. We're not talking first-world style lighting; we're talking about a $5 light that is better than sitting in the dark because you have no electricity and ran out of kerosene to burn.

Re: A $5 Lamp Powered Solely by Gravity

#63

Post by SoftwareMaven »

dsl wrote: post #4

Not to nitpick, bit it's not powered by gravity, it is powered by people going over every 30 minutes and lifting a weight back up to its top position. EDIT: Apparently people don't understand that using gravity to generate energy is a thing, and the title "Powered Solely" suggested someone found a way to do that.

I'm pretty confident that most comments that start with "not to nitpick" would be better sent to /dev/null. Nitpicking is usually a sign that deeper, more interesting arguments aren't available, but negativity must reign supreme!

Shouldn't it be said that it is powered by vacuum energy, since that is what kicked of the Big Bang? (And, before anybody tells me I'm wrong, let me say, "I'm wrong!" Instead of telling me I'm wrong, educate me. I love learning about this stuff, and I know my knowledge is weak.)

Re: A $5 Lamp Powered Solely by Gravity

#65

Post by morsch »

NathanKP wrote: post #23

Maybe I'm stupid for asking but what is the advantage of this over a spring powered wound clock? My wristwatch can tick for two days on a wind, and while it isn't as cheap as this gravity powered wound clock I'm sure it could be made cheaper. There is nothing special about this invention; purely mechanical "gravity powered" clocks have existed for centuries in the form of old grandfather clocks etc.

The advantage of this lamp over a spring powered wound clock would be that it emits light. The disadvantage is that it's comparatively poor at keeping the time.

Re: A $5 Lamp Powered Solely by Gravity

#66

Post by mynameishere »

FrojoS wrote: post #61
marquis wrote: post #45

Earlier quoted context omitted.

Yes, I was thinking the same thing. You can buy now on Amazon a hand-crank LED light for $12, so surely these can be made far more efficient and cheaper with $200,000.

But those require a battery, which will only survive so many (hundred?) recharges, no?

I think they use capacitors. At any rate, almost anything would be better than "gravity power". Even a flywheel.

Re: A $5 Lamp Powered Solely by Gravity

#67

Post by NathanKP »

morsch wrote: post #65
NathanKP wrote: post #23

Maybe I'm stupid for asking but what is the advantage of this over a spring powered wound clock? My wristwatch can tick for two days on a wind, and while it isn't as cheap as this gravity powered wound clock I'm sure it could be made cheaper. There is nothing special about this invention; purely mechanical "gravity powered" clocks have existed for centuries in the form of old grandfather clocks etc.

The advantage of this lamp over a spring powered wound clock would be that it emits light. The disadvantage is that it's comparatively poor at keeping the time.

True, but my question is if a clock winding mechanism can keep going for days without need of winding could a clock winding style mechanism be more efficient than a gravity weight powered one.

Re: A $5 Lamp Powered Solely by Gravity

#68

Post by nwh »

biot wrote: post #46
dsl wrote: post #4

Not to nitpick, bit it's not powered by gravity, it is powered by people going over every 30 minutes and lifting a weight back up to its top position. EDIT: Apparently people don't understand that using gravity to generate energy is a thing, and the title "Powered Solely" suggested someone found a way to do that.

I was a bit disappointed by the title. I was hoping for something akin to a sterling engine, which is powered solely by a heat differential. As long as the heat differential is present and barring any mechanical issues, the sterling engine will operate continuously without intervention.

They're incredibly efficient. There's one on my wireless router that happily spins away all day.

Re: A $5 Lamp Powered Solely by Gravity

#69

Post by ceol »

fhars wrote: post #38
lusr wrote: post #35

Earlier quoted context omitted.

Why are you limiting your scenario to only one of these lights?

Because if you used a sufficient number to light a room you would have to hire people to lift the weights continuously, and if you have to to that, it would be far more efficient if you hired them to generate electricity using a pedal powered generator, because that is still the most efficient way to transform human labor into electricity. Come to think of it, pedalling for the time it takes to lift the weight and ch…

Like others have said, this is in no way a replacement for a pedal-powered generator, nor is it a replacement for a standing lamp. It's for folks in developing countries who would gladly trade lifting a pound or two of weight for 30 minutes of dim light.

Be cynical about the math, sure, but if the math works, don't assume technology is useless because it doesn't have a place in a 25 year old's San Francisco apartment.

Re: A $5 Lamp Powered Solely by Gravity

#70

Post by morsch »

NathanKP wrote: post #67
morsch wrote: post #65

Earlier quoted context omitted.

The advantage of this lamp over a spring powered wound clock would be that it emits light. The disadvantage is that it's comparatively poor at keeping the time.

True, but my question is if a clock winding mechanism can keep going for days without need of winding could a clock winding style mechanism be more efficient than a gravity weight powered one.

SCNR. I suppose the advantage of clock winding mechanisms is that they can deliver (mechanically) a constant, relatively low level of power. Compared to an LED, a wristwatch uses very little power (about 1µW according to Wikipedia). Of course this lamp may be more comparable to a grandfather clock than a wristwatch; I don't know how much power a grandfather watch requires, but the energy you store winding it up can't be that high since it's not that much work, and the strength of the mechanism is that the stored energy is then delivered over a long time, ie. days.

Also, with clocks, you get to skip the conversion of the energy completely. That immediately gets you a much higher efficiency than this lamp, which is potential energy converted to electricity (losing heat), converted to light (losing heat). Of course energy transmission losses still apply, ie. it's not free to get the mechanical energy from the spring to the hands of the watch.

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