Fellow Science Lovers,
Game update: Nothing to report this month. I’m still revising Scribes Emerge. If you’d like to be a beta reader, please let me know, but it would be a massive help if you read Scribes’ Descent and Scribes Aflame first.
I hope you had a merry Christmas and have something fun planned for New Year’s Eve. I will probably be working on Scribes Emerge. 
This newsletter doesn’t relate to the holidays, except that it talks about heat and electricity–two things well all need this time of year.
Follow the Bouncing Electron
In Scribes’ Descent, Mallory and Leah make a device that takes the heat from a worm, called a fire eem, and converts it into electricity for a tiny drone. While fire eems exist only in their universe, we use that same energy conversion in ours. Let’s look at the physics to see how.
Most power plants heat water to make steam, which turns the turbines of generators to produce electricity. This involves at least two energy conversions:
heat -> kinetic
kinetic -> electrical
But what if we could turn heat directly into electricity? Turns out, we already do this with thermoelectric generators. Space probes venturing far from the sun get their power from RTGs (radioisotope thermoelectric generators). RTGs use a radioactive element like Plutonium-238 as a heat source.
A more common example is a thermocouple thermometer, which works in reverse, measuring the voltage drop between two points to calculate temperature. The thermostat in your home probably uses a thermocouple. (I’m trying to pack as many therm words as possible into one paragraph 
)
So how does this direct transform energy transformation happen? Let’s define some terms:
Electricity is the flow of charged particles (usually electrons–more on that later).
Temperature is the average vibration of atoms in a material. The faster they vibrate, the hotter they are.
Heat is the transfer of kinetic energy from a hot area to a cold area until both end up with the same temperature.
When you heat an object, its atoms move faster and collide with each other more often, making them spread out and expand to a colder part of the object where they get bunched up:
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The image says “free charged particles” to indicate two important points:
1. The particles are free to move around within the material. In the case of electrons, we’re talking about the ones that gained enough energy to escape their orbit around the nucleus.
2. This works not only for electrons, but also for their absence, called “holes”. These are empty slots in the outer electron shell of an atom where an electron should go. If free electrons get close enough, they slip into those holes to complete the outer shell. Atoms are more stable and happy when all those spots are filled.
When the charged particles in question are electrons, they get more densely packed on the cold side (making it more negative) and more thinned out on the hot side (making it more positive). This charge difference creates voltage. And when you induce voltage in a closed loop, electrical current will flow.
This converting of heat into current is called the Seebeck Effect, and how much voltage it produces depends on a few factors:
-The material used (some have a higher “Seebeck Coefficient” than others)
-The temperature difference (the bigger it is, the bigger the voltage)
Other factors exist, but I omit them here for simplicity. Let’s say we connect two wires end-to-end to form a loop. One wire has a higher Seebeck Coefficient than the other:
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In the image above, the black wire has a higher coefficient than the yellow one, producing a higher voltage on top, even when both wires are subjected to the same temperatures. Both sides want to send current from left to right, but because the charges are higher on the top half, it will overpower the bottom half to make a net clockwise current. And because the bottom half tries to flow counterclockwise, its flow will be subtracted out of the net current flow. (An unfortunate inefficiency of the design.)
This setup is called a thermocouple. In Scribes’ Descent, this is what Mallory and Leah referred to as a “thermoelectric module.” Here’s an example of one in our universe:
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-By Gerardtv https://commons.wikimedia.org/w/index.php?curid=23208759
The device in the photo above somehow reminds me of a Claymore mine.
It’s Reversible
By applying a voltage across a thermocouple, one side heats up and the side cools down. This is called the Peltier Effect. Such devices are generally used for cooling because heating is done more efficiently via other methods, such as Joule heating.
Both the Seebeck Effect and Peltier Effect are examples of the Thermoelectric Effect. (There are so many terms named after scientists, and I can’t mention any of them in the Scribes Series because those people don’t exist in the Scribeverse.)
Why Not Use This More?
Despite skipping the extra conversion involving kinetic energy, the thermoelectric effect isn’t that efficient. Materials used for this must be good at conducting electrical current but poor at conducting heat. If the material conducts heat easily, the temperatures across the hot and cold ends would quickly equalize, removing the needed temperature difference. Problem is, most materials good at conducting one are usually good at conducting the other.
How efficiently a material converts heat into electricity is called its Seebeck coefficient, measured in units of volts per kelvin. Researchers are trying to develop new materials with higher Seebeck coefficients to produce more power, hoping to use this for power production on an industrial scale someday.
In Scribes’ Descent, I don’t name the material Mallory and Leah used for their thermocouple. But I imagine their high-tech civilization had developed more suitable materials than we have today, making this a more viable power supply in their world than it currently is in ours.
References
-Super clear explanation: https://www.youtube.com/watch?v=O6waiEeXDGo
-Seebeck Coefficient Calculator: https://calculator.academy/seebeck-coefficient-calculator/
Writing update: I’m redesigning events in the final few chapters of Scribes Emerge, which is adding to my revision time. However, I’m moving some chapters from the end of Scribes Emerge into Scribes Beyond (book 4), which will help speed things up a bit and keep things more focused.
See you next month (and next year),
Dylan West
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