Half a croissant, on a plate, with a sign in front of it saying '50c'
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candle powered light

Power a light with a peltier element and candle
  [vote for,

How is this, increase the thermal energy to light conversion efficiency of a candle by placing a Peltier element over it. The heat causes the peltier element to generate electricity, which powers ultra bright LEDs.
brewer, Nov 16 2003

Candle Power (energy / time) http://jchemed.chem.../Dec/abs1596_3.html
More energy in a candle than TNT [csea, Oct 04 2004]

Explanation of candle power http://www.caves.org.uk/led/foot1.pdf
LED & halogen lamps compared [Ling, Oct 04 2004]

LED Caving Lamp http://www.stenlight.com/
The light that I wished I could afford [dlapham, Feb 02 2006]

heat powered led http://www.cbc.ca/n...ence-fair-1.1317745
Body heat runs LED flash light. [travbm, Nov 01 2015]

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       A Seebeck element rather than a Peltier device, surely?
DrCurry, Nov 16 2003

       Actually peltier elements can heat, cool, or generate electricity when heated and cooled on opposite sides. It's the same effect, just the other way around.
brewer, Nov 17 2003

       Whoa. A couple of AA's can run a maglite. That's a LOT more powerful than a candle. Something's screwy here. (Are candles THAT inefficient?)
Madcat, Feb 19 2004

       Candles generate a lot more heat than light, so it's not at all unreasonable to harvest some heat and turn it into light. see [link].   

       A 1 kilogram candle contains 40 MJ of combustion energy, and might burn for 100 hours or about 4x10^5 seconds with a power of about 100 W. Thermo-electric conversion is pretty inefficient, but you should still be able to get a good part of a Watt to light the LEDs.   

       One could also store the electricity generated in a battery or ultra-capacitor, and have a night-light after you blew out the candle...
csea, Feb 19 2004

       How about using the burning wax to heat a thorium mantle? I've seen kerosene lamps that operate on that principle (and of course, Coleman lamps even moreso). I would think efficiency could be improved greatly with such a change.
supercat, Feb 20 2004

       This would take a lot of trouble just to get a little bit of extra light out of a candle, but if you made a candle powered battery charger, then I'd buy it in 0 seconds.
elvatoedwardo, May 12 2004

Ultrabright LEDs are brighter than a candle over a small angle. But a candle will light the whole room.
But using the candle for main lighting, and the waste heat for spotlighting via Stirling engine/ generator may work.
The link mentions that LEDs not as efficient as we expect.
Ling, May 16 2004

       Niether are candles, I expect most of their energy goes into heat, not light.   

       LEDs on the other hand turn most of the energy into light, not heat.   

       LEDs are getting brighter and brighter...it won't be many years until they replace flourescents in some cases.
Melchior, Feb 01 2006

       I think this is a fascinating idea and a good discussion. +
bristolz, Feb 01 2006

       As a caver maybe I can shed some light (pun intended) on the issue. While I only cary a candle for emergencies and then more for heat than light. I do however use carbide lamps from time to time which produce much more heat and light that a candle. This idea would work great with a cap lamp. By the way another name for a peltier used to generate electricity is a thermo-couple. They are used as safety devices on gas appliences as well as to generate electricity on nuclear space exploration vehicles like voyager.   

       The info on LEDs is out of date. I use a 1 watt headlamp as my main caving lamp and while I do not have the stats it outperforms halogen lamps of the same wattage. A three watt led lamp produces about the same amount of useable light as a 6 watt halogen taglight. See link..
dlapham, Feb 02 2006

       <boring anecdote> Carbide reminds me of a tale my father told me when I was a child.   

       He attended, as a boy, a camp on a lake where the lighting was all calcium carbide. The carbide gas (acetylene?) was conducted through a manifold system of piping that ran all through the camp providing carbide lamps in each of the various buildings.   

       The carbide was supplied in drums and mixed with water in a small dedicated building that was, in effect the "head end" of the carbide system. There were 3 or 4 drums full of carbide kept in the building and comprised a year's worth of lighting fuel.   

       Midway through his stay at camp one year, on a night before the parent visit day, he and a couple of other boys sneaked into the carbide shed and rolled a drum of carbide out and down to the lakeshore where one of the boys punched two holes in the drum head. They then loaded the drum into a row boat and rowed to the middle of the lake and pushed the drum overboard. They waited for the gas bubbles to come to the surface and then threw a match.   

       There was a flame two stories tall in the middle of the lake that burned for over a week.   

       (Now, it could be that my father was passing on a story that was told to him but I remember the story as having been him. It sounds like something my father would have done.)
bristolz, Feb 02 2006

       Yes carbide is good stuff. Cavers use it because it cost less than batteries and has a good full light (like a candle only whiter and brighter). The gas released when mixed with water is indead acetylene. The story told you could be true. It does still come in large drums. The only way that it could have lasted a week would be if they had punched a very small hole into it that only allowed a small trickle of water at a time. This is how a carbide cap lamp works.. Off topic -- a baloon mixed about 50/50 with pure oxygen and acetylene either from carbide or a oxy/acetylene cutting torch makes a nice bang when lit (from a large distance unless you want to blow your eardrums and get burnes or worse)
dlapham, Feb 03 2006

       when camping as a child my father would take a small coffee type tin add carbide, put a can of water with a small hole in the bottom inside the larger tin, put on the lid with a hole in that. The acetylene gas would escape through that hole.   

       He would light the gas and we would have a simple camp light/stove. If things went wrong it was possible for the flame to burn into the can and blow the lid off - more fun than dangerous.
radical 1, Mar 02 2007

       CaC2 is FUN Okay, if one is going to be upstanding, pack out the waste and/or neutralize with huge amounts of vineager the resulting byproducts (beat up a high schooler chem student to tell you the stoichiometric necessities, if you like your freedom.)   

       the drum/lake plan is accurate- I've made the Macguyver fireball/mushroom cloud with a pound and the local lake. But such is highly illegal in every state and so the getaway car was hummin.   

       I can't wait to finish my math to review my chemistry again! as it is all illegal and fun to risk death, severe burns, ecological wastelands and all manner of tickets/jail if one could care less about healthy freedom, but I'm not that person anymore.   

       on a m ore practical side, truly a few ouces are plenty for a week of true camping. water wet trees and some carbide make a faster --smokey!--fire in a pseudo--emergency. and a carbide generator and lamp do truly weigh less and provide better lighting for a good week of camping than some other methods. I'm curious as to why I can't find a burner / stove "proper" for a carbide generator though. *it isn't a bad idea to ziplock or vacuum seal the fuel though as it does heavily degrade in damp weather. being older may be less dangerous and thus less fun, but practical uses of fun things aren't out of order.
smallrougeone, May 16 2007

       Well the thing about that is you need a big heat sink for cooling. And a similar thing has been done in Siberia to run radios using kerosene lamps. But I read where one girl made a thermoelectric flashlight using your own body heat.
travbm, Nov 01 2015

       // But I read where one girl made a thermoelectric flashlight using your own body heat. //   

       You can read ? Sheesh, who knew, eh ?   

       Do you actually know what a "girl" is ? Admittedly, we are a trifle vague on the subject, but we may still be better informed than you are.
8th of 7, Nov 01 2015

       I did take that biology class but I decided to skip human anatomy in favor of chemistry.
travbm, Nov 01 2015


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