Electric Power From Heat
Once you peek into the world of thermoelectric generators, you’ll wonder, “Why is this not a thing everywhere?”
TECs are devices that create electricity from temperature differences. They have no moving parts and they rely on thermocouples and thermoelectric effect to create voltage.
That particular effect is called the Seebeck effect, named after the German physicist Thomas Johann Seebeck, known for observing the relationship between heat and magnetism. Primarily, he observed that the flow between hot and cold regions in a Thermo conductive material also carries a certain voltage.
Some years later, a watch dealer turned physicist, Jean Charles Athanase Peltier, discovered that reversing the effect (running a charge through the conductor) can lead to a heating or cooling effect. This discovery eventually resulted in numerous appliances you probably already have in your possession.
Currently, the most prominent applications in the form of electricity generators can be described as situations where there are excess heat and easy temperature contrasts. Like in space stuff. The Mars Curiosity rover generates electricity using a radioisotope thermoelectric generator with a radioactive element as a heating element. A little closer to everyone’s home, you’ll find these guys on gas pipelines generating power for radio communication and other “smaller” jobs.
There are also quite a few patents floating around that aim to introduce this tech to other fields – the automobile industry, solar energy, and even personal use or a new energy source for regular households.
Though this technology still has some major limitations, the global market for it measures in hundreds of millions of dollars. With the growth of the green sector, it is expected that this little corner of the market will grow as well.
How Do Thermoelectric Generators Work?
Outside of, you know, physics, the magic happens because of this little bit called a Peltier module. It’s a thin, square-shaped disc with two wires that come out of it (most of the time, red and black). They are widely used in heating and cooling gadgets and appliances. You can get your hands on some very easily since they are stocked by a lot of hardware and DIY store. Of course, there are the interwebz as well.
When they make an appearance as a part of a thermoelectric generator, they are usually sandwiched between two pieces of metal or radiators. One side responds to heat, while the other reacts to cold. The interior of the module holds multiple transformers (not that kind; I know, I was disappointed as well) that turn the potential into electricity. The wires are, I guess, there for a bit more than decoration.
The potential we’re talking about here is the movement of electrons in metals. Quick recap, all atoms are made out of 3 particles – protons and neutrons in the nucleus, and electrons in the outer layer. Most of the activity we can get from an atom without going super kaboom is due to electrons being up to all kinds of shenanigans.
Electrons can move freely in metals and this is why they are very good conductors of electricity. Now, just like any sane person, electrons are not too fond of heat. Yep, they are smart enough to pack up and move somewhere cold (like Greenland). This movement generates “potential”, and this is where our Peltier modules make another appearance. They translate this traffic into electricity that you can use for important things like cooling your drink or charging your phone.
Quite simple, right? Wrong. There is a bit of a problem that prevents this technology to fully bloom – as one side of the setup heats up, inevitably, the cold side will heat up as well. Automated maintenance of the temperature on the cold side requires extra energy, effort, or ingenuity. Though there are a few solutions that are designed to dissipate the heat, none of them is 100% perfect. Yet.
Are Thermoelectric Generators Affordable?
Kind of, but it still depends on what number you consider to be affordable. As of now, you can spend triple digits on a standard setup. In essence, the main components are affordable, but the finished product can get pricey.
However, if you’re suffering from a bad case of ticket shock, do not despair. This is a rapidly developing field and in recent years, there were quite a few steps made forward to make these guys more affordable and accessible.
Can I Make My Own Thermoelectric Generator?
Yes. And you don’t need an extensive list of tools and supplies to do so. The only thing that you can’t do without is a healthy understanding that you’re working with electricity.
Most of the tutorials that you will find online (and that can be replicated in a more casual setting) are for setups that are good enough for charging phones. Like this video that literally features a loaf cake pan and some tea lights. But, instead of a slice of a sticky lemon poppy seed cake after a romantic candle-lit dinner, you’ll end up with a 10V generator that can breathe some life into your dying phone battery.
What are the Best 3 Thermoelectric Generators?
I think that the one in the Mars Rover is not too shabby, don’t you agree? But if you don’t suffer from a mild case of the NASA budget, maybe these guys can do the trick.
A complete DIY solution for someone who likes to play with their tech or who wants to learn more about it through practice. The kit contains the TE module, bipolar boost circuit, strobe circuit, heat sinks, clip leads, fan, thermal grease, resistive loads, and instruction manual with experiments – in short, everything you may need to build a basic fully operating thermoelectric generator.
The manual doesn’t only describe how to set everything up, but it also covers descriptions of Thermoelectric theory and experiments that will be very much of interest to the prospective developer. Quite a few tips as well, to make the learning experience that much smoother.
However, the manufacturer expects that you are already someone who likes to play with electricity (at least from time to time) because you should have on hand soldering iron, a multimeter, and a digital thermometer.
This could be the best “casual” model on the market right now. It has the output power of 10V, making it suitable for general use and emergencies. The tower can at the same time power up several lights or charge a couple of smartphones.
There’s no battery that has to be pre-charged – just turn on the heat and let it do its thing. The preferred heat source is a regular gas stove. The setup sits perfectly over camping size bottles, and you really don’t have to keep a very high flame running.
The temperature difference comes from water that is poured into the opening at the top of the tower. When it heats up and it’s time to change it, you can get rid of it through a built-in tap before you refill the top with a fresh, cold batch. The water doesn’t get hotter than 160 degrees Fahrenheit, which is kinda useful since it’s a perfect temperature if you want to brew some green tea or make another instant hot drink. Recycle, reuse, and all that jazz.
The unit takes about 15 minutes to “warm-up”, but after that, it provides consistent power output.
And if this is something you really care about, it comes in 4 very pretty colors – black, grey, blue and green.
There is another similar device to this one, but it didn’t make this list for a couple of reasons. Even though it has a higher output, it’s 50% more expensive and quite a bit more difficult to install.
And yes, you will have to install this one somewhere. Ideally, you should choose a place where you have a lot of heat loss, so you can get at least something out of it. For the best performance, attach it to a vent that leads outside.
It can handle up to 750 degrees Fahrenheit and it has an output of 30V max. The device comes pre-set at about 14V, but you can adjust the voltage as needed via a screw that is located on the side. The top features a 5-inch fan that consumes 3 watts at ideal speed.
This guy also has to be hooked up to a battery. This means that once you crank up the heat in winter, you can also turn it into a juice stash in case of a snowstorm and a complete blackout.