Thermoelectric Emergency Low Voltage Lighting

About: I am just a nature loving, fantasy cherishing, vegan & raw food eating, stuff inventing, junk hoarding, recycling, steampunking, staff spinning ..ordinary guy.

The idea is that oil you used for cooking and now you don't need anymore, can be used for lighting.
Not super bright but it's a very prototype and for emergencies it's enough.


Heat from a candle goes through the Peltier module into the pot. That produces electricity. And because we have just one flame and the voltage is about 0,6 ... we need something called "Joule Thief" to light up an LED with a proper voltage.

You can connect even ten diodes at the same, place them here and there and they will all work (but,best to use switches), wardrobe, pool, bathroom...whatever you want.
No batteries, just one little flame.

....and that's it.

The whole generator is portable and it's not that hard to make. Internet is full of instructions and tutorials for thermoelectric stuff,you should see that before you start doing it. Mine isn't so stable.
So ..what i've used:

Peltier module (they are used in computers and ect.)

solar garden light (in..a gaden shop propably)
aluminium heat sinks
used cooking oil
LEDs (must be white for best results)
aluminium "cup" from a candle
any short cup
toothpaste (or thermal paste)
steel building blocks
hard paper

*These pictures are much darker, like in the first one you can see just
the sink, but really you can see the whole room and orientate in it with no problem. And that's just one diode.

YouTube channel:

Step 1: The Base

Let's start with a base. You should have one for many reasons...heat, handling, rotating...just many reasons.

I've made it from hard paper. (just for test)

BUT best is to use steel, you know, something that's not flamable.

Step 2: Stand

Next thing you'll need is something that will hold the Peltier and heat sinks, it needs to be strong and not flamable. Be more crative then me. I'm still working on it, upgrading and ect.

Step 3: Fuel

As fuel you can use used wood, used cooking oil, paper, anything that burns. Even an ordinary candle.
I'm using oil, because it burns with still flame and you can control it much better and of course - it's a waste that almost everybody throws out.

Step 4: Fuel Cannister/holder

Take an aluminium cup from burned out candle and pour used cooking oil into it. This cup place into an another cup filled with water.
I recommend this because it will cool down the oil, preventing it to boil and eventually catch fire!

Step 5: Hot Block

You don't actually need this aluminium block,but it's better - it spreads the heat, so the surface of Peltier will be hot equally and if wind blows into flame, it still will work thanks to stored heat in it.

Step 6: Placing Peltier

I'm sure that most of you guys already know how Peltier module works. But anyway...
When one side has different temperature then the other, it generates electricity. If it is all hot no matter how much, it will not do anything. The heat has to go through the module. That's why you need heat sinks. Heat one side, cool the other side - then it works. the module onto the heat sink (hot side) but before that use thermal paste and put it between them (usually can be bought in PC or electronics store). You definitely should to this,because every millimeter counts when the heat goes through. If you place peltier right on it, you will never get so good results and you can also damage the module itself. (i've used a toothpaste, i saw it somewhere on the internet, but toothpaste dries out,so thermal paste is worth buying. It works much better.)

Place it there and apply pressure a bit so the layer is not too thick .

Step 7: Cold Side

Now,as i said, the heat has to go somewhere. If not, both sides will have the same temperature soon and it will stop working.
You can use an another aluminium heat sink, but much better option i think is this what i've made. A little pot filled with water with alum heat sink in it. It removes the heat really quickly.

Only  thing is that the pot needs to have really flat surface.

And as we did before, apply the paste between.

Step 8: Wick

Well everybody knows how to make a wick, i've used just a piece of toilet paper.

Place it into the oil and when it soaks, light it up and place your new candle under the aluminium block.

Step 9: Test

Take your volt meter and test it. It will take a while to heat up. You will need about 0,6 to 1,5 volts. Testing is important, because now you know what is the maximum voltage it can reach. It all depends on many things; the module, heat sink, environment temperature....

If you don't get enought voltage, simply place the wick higher like i did OR use more wicks OR use a smaller "hot block"
If it produces to hight voltage, place the wick lower. Just play with it and test it good ;)

Step 10: Joule Thief

You will need a thing called "Joule thief" (oh my,i just love the name:D) Because Peltiers has one issue and that is voltage. It is quite low unlike the current which is very good. You would need a really good setup and good module to produce enough volts so you can light up an LEDs. It's not a problem to get like 5 or even 12 volts, but in that case, you will also need more heat and bigger setup.
....or do it like me.

Propably the only "Joule thief" that you can buy almost everywhere today is the one that's inside a "Solar garden light". This one i have needs about 0,6 volts to start working.

Just take everything off until you have only that circuitboard. I removed solar panel and that LED from it also. It might looks bad and complicated, but there are just two wires we need - power inputs. Before you rip everything off, find out which one is plus and which one is minus and then connect it right to the peltier. If it doesn't work,you might made a mistake - check if the voltage is good and try an another combinations. You will get it after some time. It's not that hard just a bit irritating:D

Step 11: LIGHTS ON!

Last step

After you figure everything out, it's time to make this "toy" actually usefull.

Take some long wires,some white LEDs and switches and place LEDs where you need a light. Connect them in parallel because connecting them in series propably will not work. I have like ten white LEDs connected to it all over the house at the same time and it works great.

Just one LED is more than enough to read a book. Having three or more next to each other is like a regular flashlight.

* Burning used oil inside your house can be dangerous for your health! Best thing you can do is to place the "generator" outside OR behind a window and secure it, so kids or pets can't reach it and cause fire!

If you have any questions, ideas, photos, anything to you like to share or there is something unclear in this instructable...pls,post it into comments. Thanks & Enjoy!!!



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    2 Discussions

    Eva Reigns

    4 years ago

    This is just an idea, so do with it what you will.

    Use 2 liquid containers, one for your hot side, the other for cold. Sandwich your Peltier module between them. Fill the cold side container with water. Fill the hot side container with hot oil.
    Use a thermometer to monitor the oil temperature as it is heated over a fire (rocket stove) and remove the oil when it reaches the maximum working temperature of your Peltier module, so as to not damage your module by over heating it.

    At this point, any heat source capable of heating a cup of oil to 300 F or so----rocket stove, parabolic concentrator, Fresnel lense, gas burner---becomes a source of electric power.

    Just a thought.

    1 reply

    Reply 4 years ago on Introduction

    i made it mostly from junk, but the peltier is quite cheap. sorry i don't remember the exact price, but in your country it would be different anyway (my wild guess - 10 to 20 US dollars)... All things i've used for this project are very common now, so buying online or go to some computer shop (components) is easy. That solar garden light costs here about 50 Czech crowns, that's 2 Us dollars. Kinda small investment when you think of it.