GravityLight: Generate light with gravity • Hacker News Board

Re: GravityLight: Generate light with gravity

#71

Post by scott_s » Fri, Jul 31, 2015, 9:42 PM UTC

ris wrote: post #64

kbenson wrote: post #62

Earlier quoted context omitted.

Don't both have their places? There are benefits to having a power source that is a) not dependent on a resource that is not available at all times and b) does not require a charging period. It's sort of like people in the late 19th century saying you shouldn't support the development of automobiles, because boats are much more efficient way to move cargo. While true, it does nothing to address the fact that in some…

"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.

"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.

Re: GravityLight: Generate light with gravity

#72

Post by fla » Fri, Jul 31, 2015, 9:42 PM UTC

mattgrice wrote: post #68

fla wrote: post #38

Earlier quoted context omitted.

Rotor systems like in some automatic watches produce very little energy. Even at 100% efficiency it wouldn't be able to sustain an electronic circuit. Edit: I was wrong. See below.

Seiko Kinetic watches are quartz watches that are powered by movement. That's 30 year old technology.

I stand corrected

Re: GravityLight: Generate light with gravity

#73

Post by Vexs » Fri, Jul 31, 2015, 9:44 PM UTC

fla wrote: post #38

Vexs wrote: post #18

Earlier quoted context omitted.

Might be fun to make an electric clock that uses gravity, go full circle.

Rotor systems like in some automatic watches produce very little energy. Even at 100% efficiency it wouldn't be able to sustain an electronic circuit. Edit: I was wrong. See below.

Not only is that not what I was thinking of, which was more akin to a grandfather clock, but I don't believe that at all. Just using piezoelectric vibration sensors I was able to charge a cap to light up an LED- a rotor mechanism would generate much, much more power, and consider today's energy efficient ICs I see know reason why it wouldn't work.

Re: GravityLight: Generate light with gravity

#74

Post by jackdawjack » Fri, Jul 31, 2015, 9:45 PM UTC

I was rather hoping this would be a hawking radiation method, i.e. actually generating light using gravity

Re: GravityLight: Generate light with gravity

#75

Post by jackdawjack » Fri, Jul 31, 2015, 9:45 PM UTC

I was rather hoping this would be a hawking radiation method, i.e. actually generating light using gravity

Re: GravityLight: Generate light with gravity

#76

Post by dchest » Fri, Jul 31, 2015, 9:46 PM UTC

dang wrote: post #26

scribscrob wrote: post #5

Earlier quoted context omitted.

It's amazing the amount of people who immediately cry hoax. Someone raised a good point about taking money from locals and bringing it to Europe/America/China, but clearly this isn't breaking the law of physics.

It's gratifying to see how much more substantive and less dismissive this thread is than that one from 2012. Partly it may be that the project itself has developed, but I'd like to think that HN threads have improved too.

The previous thread was linked to a crowdfunding campaign, which this may have influenced the conversation substantially.

Re: GravityLight: Generate light with gravity

#77

Post by [deleted] » Fri, Jul 31, 2015, 10:08 PM UTC

achr2 wrote: post #31

pavel_lishin wrote: post #28

Earlier quoted context omitted.

But this isn't for charging a phone; it's for having light, right now.

I get it, I am just saying that there are a lot of ways to make a single LED light shine, potential energy from a weight is likely the least sensical.

[deleted]

Re: GravityLight: Generate light with gravity

#78

Post by hanoz » Fri, Jul 31, 2015, 10:26 PM UTC

beardicus wrote: post #16

hanoz wrote: post #9

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…

> 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 This says nothing of light output. If you want light, and most of kerosene's output is heat, your energy calculation is not helpful. > 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…

Okay, okay, you are right of course, the light efficiency is very different, although the heat may not be an altogether unwanted by-product in many cases. There are also more efficient ways of getting light from petroleum than sticking a wick in it. But if you do want the benefits of LEDs, there are better ways of getting the energy than lifting sacks to the ceiling. It's still 180 meters for a pair of AA rechargeables.

I genuinely don't think the hazards are at all contrived, and range from the grave if unlikely to the mild but virtually certain. You are surely going to knock your head on this massive hovering, albeit reasonably well lit, object on a regular basis, and it might not be as soft and rounded as the illustration. On the floor, in dark mode, you'll be tripping over it, which doesn't always end comically. Reasonable precautions not withstanding it's not impossible that it could crush or smother something beneath it even at its snail's pace, but more likely it could come down hard through overloading, wear or misuse. It's really not something I'd want in a family home.

It is a nice idea and obviously of the very best intentions but I'm afraid it's simply misguided and efforts would be far better directed towards battery plus solar. Sorry.

Re: GravityLight: Generate light with gravity

#79

Post by effie » Fri, Jul 31, 2015, 10:29 PM UTC

leanthonyrn wrote: post #34

hanoz wrote: post #9

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…

Can't you suspend a bed wired to one of these to the ceiling? At night before you go to sleep climb the stairs and get into the potential energy elevated bed. Then in the morning, after the bed descends, you have enough reading light energy stored for the next night.

How do you lift the suspended bed back up again?

Re: GravityLight: Generate light with gravity

#80

Post by CyberDildonics » Fri, Jul 31, 2015, 10:38 PM UTC

Gravityloss wrote: post #61

pavel_lishin wrote: post #28

Earlier quoted context omitted.

But this isn't for charging a phone; it's for having light, right now.

1 watt of led light would require 1 Newton at 1 meters per second. Assuming 100 kg is the highest practicable mass, so that's 1000 Newtons -> 1/1000 m/s for each watt. Assuming a height of 2 meters, you could operate a very dim 2 watt led light for 17 minutes. I think that's not practical.

You can use it to read and it is free.