Introduction: Recycled Energy - $7.50 Generator! - ThermoElectric Generator

Picture of Recycled Energy - $7.50 Generator! - ThermoElectric Generator

We have been working on creating a stable way to charge our electronics while camping for a while. Solar panels work alright, but I find that when you really need your cell phone and GPS it is dark, sinister, and stormy out.

This Thermoelectric Generator can produce energy from common temperature differences such as snow, tail pipes, engines, candles, wood stoves, campfires, and anywhere else there is a temperature difference.

Check out this video of building and testing! :-)

https://www.youtube.com/watch?v=d-zvsVBT3yB-Q


What you will need for this instructable:

Materials:

- Peltier Plates (Seebeck Plates)

NOTE: Make sure the optimal and maximum operating temperatures suit your application.

- Copper pipe

- Copper heat sink

NOTE: Aluminum may be substituted for copper, but the generator will have reduced efficiency

- Thermal Paste

- Mechanics Wire

- Crimp Type Electrical Marrettes (crimp type wire connectors)

- Screw Type Electrical Marrettes (screw type wire connector)

- Small Computer Fan

- Voltage Regulator (with spare connection cable)

Tools:

- Pliers

- Hammer

- Punch

- Metal Working Bench Vice

- Drill Press

- Screwdriver

- Scraper

- Wire Brushes

- Sand Paper

- Side Cutters

- Wire Strippers

- Clopping or Hack Saw



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Step 1: How It Works (Scientific)

Picture of How It Works (Scientific)

Peltier plates "pump energy" because of thermal and electrical continuity differences in the materials they are produced from. At first glance, many people wonder if conductors may work better than the semiconductors, this is where the major predicament of the Seebeck effect falls. If a material has a low electrical resistance, it also usually has a low thermal resistance. If a material easily allows heat to pass directly through it, then it will disperse the temperature gradient the Peltier plates require to function.

Inside of the Peltier plates are many pairs semiconductors, the two semiconductors are placed thermally parallel (but electrically in series). The two semi-conductors (usually referred to as "P" and "N") have different electron densities (the measure of the probability of an electron being in a certain position, higher the density, the more electrons and the higher chance of hitting one), this difference causes electrons in the P semi-conductors to flow along with the heat, while allowing the electrons to flow against it in the N. This creates an electrical current as the heat flows through the Peltier.

Peltier plates are also able to force heat to move a certain direction, if an electrical current is applied in one direction it will flow through the semi-conductors pulling the heat in the direction of the current in the P semiconductor and against the flow of the heat in the N. If the current is reversed the heat pump will reverse as well, the heat will always flow in the direction of the current in the P semiconductor.

Because of the properties of Peltier plates they will hit a "wall." The plates can only disperse a certain volume of heat flux. To increase this volume there are multiple Peltiers in this generator are they are wired in series, this allows the plates to consume any excess energy passed on from the voltage regulator to pump heat. This increases the total heat flux volume of the generator.

We chose to use copper for our plate and heat sink because of its high electron density, meaning that it has an extremely high thermal transfer, allowing for energy production at very low thermal differences. This is why our generator can generate power from melting snow and solar rays, when ones with aluminum heat sinks are unable to. The animated heat sinks above show a simulated comparison of a copper and aluminum heat sink of the exact same dimensions, observe how the plate is cooler under the copper heat sink (on left) than the aluminum one (on right). Copper also has a higher melting temperature than aluminum, reducing the risk of accidentally melting our generator.

Step 2: Preparing Your Plate

Picture of Preparing Your Plate

Plate

Part 1 - Mark out the width and length of the heat sink onto the copper plate.

Part 2 – Cut the plate to height and width using a hacksaw.

Part 3 - Now use wire brushes and sandpaper to polish the copper, this will remove any corrosion, tarnishing, or debris. Polishing will improve the bond of the thermal paste and thermal transfer.


Pipe

Part 1 – Measure the circumference of the copper pipe, ensure that is wide enough to cover the Peltier Plates.

Part 2 – Mark out the length of the Peltier Plates onto the copper pipe, then cut the pipe using a clopping saw to approximately 1/6” longer than the Peltier Plates.

Part 3 – Place the copper pipe in a vice, and starting from one end, cut through one sidewall along the entire length of the pipe.

Part 4 – Now use pliers to open the pipe until it is bowed to an arc with a radius larger than 6”

Part 5 – Pound the copper pipe into a flat plate using a hammer on a rigid surface (such as an anvil or metalworking vice).

Part 6 - Now use wire brushes and sandpaper to polish the copper, this will remove any corrosion, tarnishing, or debris. Polishing will improve the bond of the thermal paste and thermal transfer.

Step 3: Prepping Your Heat Sink

Picture of Prepping Your Heat Sink

Part 1 - Scrape off old thermal paste if you have a used heat sink
Part 2 - Remove the screws and springs from the mounting bracket with a screwdriver
Part 3 - Drill out the mounts, make sure the drill bit is small enough to pass through the holes in the heat sink without damaging it, but will still make contact with the mounting bracket.
Part 4 - Some of the mounting brackets may fall off after being drilled out, but others may require a little encouragement with pliers.
Part 5 - Polish the contact surface of the heat sink using wire brushes and sandpaper to remove any debris, corrosion, or tarnishing. Polishing will improve the bond of the thermal paste and thermal transfer.

Step 4: Preparing Your Copper Plate for Mounting

Picture of Preparing Your Copper Plate for Mounting

Part 1 - Place the heat sink on top of the thermal plate and mark the holes onto the plate using a hammer and punch.

Part 2 - Using the same drill bit used to drill out the mounting brackets, drill holes into the plate using the punch marks as a guide.

Part 3 - Remove any debris and sharp surfaces created by drilling out the holes using wire brushes and sandpaper.

Step 5: Assembling the Generator

Picture of Assembling the Generator

Part 1 - Before you can mount your Peltier (Seebeck) plates you will need to wipe them off with a damp cloth to remove any dust or debris to ensure a good bond with the thermal paste.
Part 2 - Apply a thin layer of thermal paste to each plate and place them onto the heat sink using an angled motion (to prevent air bubbles). Ensure that the plates are evenly spaced and make good contact.

NOTE: Both too little and too much thermal paste will inhibit heat transfer, make sure your coating is thin and even.



Part 3 - Apply a thin layer of thermal paste to the copper plate and place it top of the Peltier (Seebeck) plates, making sure to line up the holes on the copper plate and heat sink.

Part 4 - Cut 4 pieces of mechanics wire at least 1.5" long
Part 5 - Poke the mechanics wire through the holes in the heat sink and copper plate. Then fold over the wires and twist the ends of each wire together using pliers. (If you use zip ties, be careful not to melt them off during use)

WARNING: Do not over tighten the mechanics wire, you can crack the Peltier plates

Step 6: Wiring

Picture of Wiring

The Peltier (Seebeck) plates must be wired in series, if they are wired in parallel and one Peltier plate begins to over heat and stops using up its fair share of the excess energy, the others will begin to transfer heat even faster, frying the Peltier that began to loose efficiency. Because they are wired in series, if one plate begins to over heat all of the plates will experience a voltage drop, causing less heat to be transmitted to the heat sink, allowing all of the plates to cool.

It is because of this unstable efficiency that a digital energy regulation device must be wired into the output. If you were to hard wire a transformer into the system you run the risk of either under powering or of frying your electronics.

NOTE: As pointed out by user UberGeeknz wiring the fan in parallel with the pelters wired in series will increase the efficiency of the generator.

Part 1 - Observe the above wiring diagram, trim and strip the wires between the Peltier Plates and between the Peltier Plates and the fan to be between 1” and 2” in length. Leave the leads to the voltage regulator at full length and only strip the ends of the wires.

Part 2 - Use crimp type marrettes on the orange connections (between the Peltier plates), and screw type marrettes on the blue connections (Peltier to fan and Peltier to voltage regulator). Since the polarity of the current will change depending on which side of the generator is hot, the polarities will need to be reversed.

Part 3 - Cut and strip the cable to your voltage regulator, remember that the center of the plug must always be the hot wire (positive). Make sure to mark it.

Step 7: Testing

Picture of Testing

Because Peltier (Seebeck) plates are capable of pumping heat in both directions, you must be careful not to back charge your voltage regulator. Once you know your generator you know it's polarity based on its heat direction.

For your first test I recommend a hot plate for a heat source and an incandescent lightbulb for a power test, as the bulb will light up with either direction of polarity. After the bulb lights up, change to your voltage tester and mark the hot wire, this wire will always be the positive when heating the copper plate, and negative when cooling the copper plate.

I have been able to Generate measurable levels off of electricity using snow in a warm room, a tea light candle, my truck's tailpipe, and a black metal plate in the sun.

When using a wood stove it is possible to stack two generators plate to plate, to produce more energy, and increase the efficiency of your generator, it also reduces the risk of melting the plates.

Step 8: Enjoy Your Reclaimed Power :-)

Picture of Enjoy Your Reclaimed Power :-)

Now you can charge your devices (Cellphones, GPS Units, Cameras, iPads) almost anywhere that you can find a temperature differential.

If you have any suggestions for improvement, or have any questions, we would love to hear from you and see what you have built. Feel free to comment below! :-)

Have a great day!

-Danno and

Comments

MayTheForth (author)2015-04-10

Just finished testing mine tonight. Lost track of time, it is three in the morning. The copper worked a lot better at all of the settings on my hot plate, creating power even when the aluminium would not. But the copper is heavy and soft when heated. I found the mixed metal models were a good compromise between weight and efficency and the aluminum on the outside helped to protect the copper.

Wired in series (shown in this instructable) I was able to produce about 1V and 0.5A at 5 degrees difference but I was able to create 0.694V and 0.395A at 3 degrees. So not much power but still generating. My voltage meter was unable to steady out on any current at temperatures less than 3 degrees difference.

When I heated it up to about a 100 degree difference from air temperature. I was able to generate about 10V and 5A with the use of a 6V computer fan to aid in cooling the heatsink. But I worry about melting off the wires in the peltiers. I might need to add some thermal silicone to go much hotter.

The electricity almost seemed to pulsate in a regular pattern, has anyone else noticed this?!

MayTheForth, are you sure about these numbers? They appear to be quite high in accordance with most of the TEG's i've been looking at. I'd expect at a deltaT of 3 you'd get closer to 0.2V and 0.009A! Did you have anything different in your setup? Was your plate actually 30" by 30" ;)

thanks

My voltage meter is reliable but my hot plate I am not so sure about. It says it is accurate to 0.5 of a degree Celsius. But I picked it up from a surplus sale from a local college a couple years back. What kind of results are you getting?

I also read that by wiring TEGs in series the flow of electricity through them helps to pump more heat somehow increasing it even more. I read it online so I do not know if it is true.

LOL! I wish! A 30" generator would be AWESOME! Someone should totally build that :)

MayTheForth (author)MayTheForth2015-04-24

Also those numbers are what my voltage meter seemed to dwell on, otherwise it seemed to jump around in a regular pattern, with voltage and ampage inversely related?

Has anyone else noticed this? Or do I need to check my equipment?

powerw6 (author)2017-06-05

Hi, I am unsure if you'll answer this as it is 2 years old, but I was wondering if it is possible to use this on a wood stove, as you've briefly mentioned, that goes up to 200-300C? The specs of all cheap TEC being sold on ebay says Tmax of 100C or so..

Just4Fun Media (author)2015-03-31

I am not sure, I have never done a full charge. I will test it out and post an update with some stats. Great idea! :-)

bedo1000 (author)Just4Fun Media2017-03-02

did you get the result

cheese123243567 (author)2017-01-31

does this draw cold enrgy two

opeyemi.seun2 (author)2017-01-17

please can you provide your readings? i mean the voltage and current output at some certain temperature differences.

quadsaphugus (author)2017-01-09

Dear Sir,

I am a senior at South High School, in Minneapolis. I am a part of a pre-engineering program called Project Lead the Way. As a final project in that program, I am required to conduct a novel research project. This project, when complete, will be presented to a review panel of faculty and professionals. Our project’s primary purpose is to generate electricity from human body heat for use in camping or hiking situations. We will achieve this with thermoelectric generators.

During the course of the class, we are required to find and contact an expert on some aspect of our project. This expert must be able to come into our classroom on two occasions, and agree to be on the panel who judge projects at the end of the class.

we believe that your expertise could be an asset to our project. If you are willing and able, please contact me at this email address, awinden1999@gmail.com. If you have any questions, please don’t hesitate to contact me, or my instructor Bill Ruff at billruff@comcast.net. If you are unable, can you recommend another expert who may be able to help us?

Any and all help would be greatly appreciated.

WestonG (author)2016-01-22

Where do I get these "Electrical Merits"? I looked around online, but all that came up were Boy Scout badges. Please help me.

Just4Fun Media (author)WestonG2016-12-09

Good morning,

They are also called "Electrical Nuts" or 'Twist Type" connectors.

All the best,

Danno

originalninja01 (author)2016-08-20

I am interested in running my a BBQ controller setup from some batteries that are charged by the heat of the fire in the pit, do you think a solar charge regulator would work?

A solar charge controller will definitely work. Just check the voltage and amperage ratings.

All the best,

Danno

CompostB (author)2016-10-16

I just wonder if i buld a house can i build the walls from tec modules.
I mean: when sun comes and too hot other sides cools / inside the house/ when winter hits outside cold so inside will heat up?

Is it it theory or fairy tale? Can i get byproduct electricity?

Awesome project u r doing thanks for freing human minds!

Just4Fun Media (author)CompostB2016-12-09

Thermoelectric solar is a very practical application of thermoelectric generators.

Most thermoelectric solar systems use black pipes filled with water and glycol to absorb the heat. This allows for a higher temperature difference on Peltier Plates and therefore more power.

All the best,

Danno

CompostB (author)2016-10-16

I m going to live in a tipi so i just wonder to replace the stone circle around the midle fire with tec circle so i ll have 'waste' electricity. ...Cheers greg

CompostB (author)2016-10-16

Can i download instruction pdf for free?

brantgoose (author)2016-06-23

Like this?

I apologize for the late response, I did not notice your comment.

This setup will work, but peltier A will reduce the generator's efficiency, because it will insulate the cold side of peltier B.

You could use a temperature switch which would power the generating peltier B to pump away excessive heat to avoid melting the peltier module.

The use of a switch would cause periods where the generator will cease to generate (and will consume power) but it will generate power and cool itself much more efficiently.

Have a great day!

ubergeeknz (author)2016-01-17

Great instructable, a couple of questions/observations if I may:

It looks as if you have the fan in series also, is that intended? Any reason you didn't put the fan in parallel with the load? Won't this severely limit the output?

IMO the wiring diagram would be clearer if you were to mark the red and black wires of the peltier plates, since they are all black it's not so obvious how to wire them.

Thanks!

Great point about the wiring diagram, I will replace it with a true diagram.

Wiring the fan in parallel with the peltiers would help to increase efficiency. I will add a note to the instructable.

Have a great day!

FabianR13 (author)2016-01-07

Can you just cover the cold side with water instead of using a heat sink ?? It won't go over 100 C, and the hot side could heat to what ? 300 C ??

Just4Fun Media (author)FabianR132016-06-25

Water cooling can most certainly be used (at the end of the above video I used snow as a coolant). Since water is not very thermally conductive the cold side of the peltier could be well over 100C, increasing the surface area of the metal touching the water can help if you run into thermal issues.

The best practice is to keep a careful watch with a thermometer until you know the cooling capacity of your system.

The maximum temperature of the generator is mostly limited by the fail temperature of the peltier plates you have purchased. The hottest I have heard of were around 800C hot side.

Have a great day!

brantgoose (author)2016-06-23

So if you wanted to use a peltier as a cooling device (plug it in)...could you stick another peltier on the hot side of it and place your cooling heatsink on the second peltier? Then you would be getting some of your power back?

This would restrict the efficiency of the primary peltier, resulting in less cooling. The secondary peltier would function as a generator.

Due to the laws of thermodynamics and thermal loss of the system would have a lot of "wasted" energy. It would be far more efficient to limit the power to the primary peltier to reduce the amount of cooling and not use a secondary.

It is common to stack different sized peltiers (small to large) to pump heat from a small source (ie CPU) to a large heat sink, but all of the pelters are powered.

Have a great day!

AlexanderH35 (author)2015-12-13

how is this $7.50 when the goal zero costs approx 40 dollars

The goal zero is not a required part of the generator, it is only for power storage and charging other devices. You could use any one of a million different charge/voltage regulators.

This instructable focuses on building the generator.

Have a great day! :-)

AlexanderH35 (author)2015-12-10

where can i buy a copper heat sink? not online though

I would recommend checking at computer component or recycling companies. The one I dealt with was quite happy to sell the copper for more than scrap value, without having to melt it down.

Have a great day! :-)

AlexanderH35 (author)2015-12-10

where can you buy a copper heat sink? and also can you use a computer heat sink?

The heat sinks that I used were purchased from a metal recycling company. I used heat sinks from an old server bank. If you look on eBay or Amazon there are a lot of large used heat sinks for sale.

Have a great day! :-)

RacquelleM1 (author)2015-11-14

My heat sink has a thing in the middle and I was wondering if I were to put my copper plate on top of it along with the Peltier plates will it still function properly even though it won't be flat. Also if it won't be able to work does anyone reccommend a way to remove it.

If Peltier plates are used as TEG's (Thermo Electric Generators) they will slightly slow the flow of heat, but if you supply power to the Peltier plates they will pump heat faster than any passive heat transfer material.

Just a word of warning, be careful as Peltier plates can easily cause sub zero temperatures and therefore condensation when used as heat pumps.

Have a great day! :-)

kkumar9 (author)2015-06-08

what happens if we connect peltier modules in parallel ?

Just4Fun Media (author)kkumar92015-12-10

If the Peltier plates are run in parallel, you will produce a high amperage low voltage current. This current will not be very effective at charging batteries.

According to research from the University of Toronto physics department "Thus the most common TE devices now in
use—connecting 254 alternating P and N-type pellets—can produce 12 to 16 VDC and only 4 to 5
amps in series (rather than 1000 amps at 60 mV when in parallel)"

You can wire an array of plates in either series or parallel although I have heard that series configurations are less prone to burning out at high temperatures.

Have a great day! :-)

MuhammadQ2 (author)2015-09-09

Hey.I really like your idea.I want to get suggestion from you which TEG module is suitable as I want to generate voltage that is able to charge my Laptop.I am little new to this, but I like this idea very much. So want to make a good portable laptop charger that I can use anywhere easily. But I don’t know which components I need that help in making that project.

It would totally depend on the charging voltage of your laptop. I would personally invest in a purpose built voltage regulator (you can readily find 12v to laptop chargers for vehicles) to avoid damaging your laptop battery.

TEG modules are generally classed by optimum (when they produce the most energy per degrees of gradient) and peak temperature (when they begin to melt :-/ ). What heat or cold source are you planning to generate energy from?

You want to choose a TEG module that has an optimum temperature as close as possible to your heat source.

Good luck! I wish you all the best in your tinkerings!

Have a great day! :-)

Techie5 (author)2015-05-29

This is bloody awesome... Why aren't these things sold in third world countries if they are so cheap to build?

warhead2354 (author)Techie52015-06-17

A better question is why do we not produce everything in cheap and efficient ways to benefit the world as a whole.

ssaxena7 (author)2015-05-14

How can I use this setup to charge a battery?

Just4Fun Media (author)ssaxena72015-05-18

As long as you are able to generate more voltage than your battery, you can charge it. If you supply too much voltage you will kill your battery and if it a liquid or solution battery it can "gas out".

The safest way to charge a battery would be to use a voltage regulator, as shown above.

Have a great day!

Jarhead Supreme (author)2015-04-27

Well teg plates got ordered. Will post if they work or not

Don't worry they will work

Jarhead Supreme (author)2015-04-26

Would these work? I found em on Alibaba...

Any TEG peltier plates. ya just need to make sure u don't overheat em. Then your generator is nothing but a metallic puddle. LOL :)

kanut.thummaruksa (author)2015-04-17

what number TEC do you use?

Sorry for the delay, I have been busy prepping for AP exams. I used 40mm*40mm TEC1-12724T325 Peltier plates. The deciding factor for me was the high heat rating. Almost any Peltier plates should work.

Have a great day!

Where did you get the TEC1-12724T325. Thanks!

I bought my peltier plates on sale from a China based company on Ebay.

Have a great day!

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