Thermocouple Power 6/2/22

Science with Richard Bleil

Some time ago, I’ve written a post about how electricity is generated. The short answer is that most power sources are the turning of coiled wires in a magnetic field, so fossil fuel, nuclear, hydroelectric and other power plants simply turn turbines attached to generators that are nothing more than turning coils of wire in a magnetic field.

This is why the electricity entering your home is “alternating current”. If you draw an arrow on one of those wire coils, the arrow is constantly switching directions, from up, to down, to up again. This causes the electrons to “dance”, forward, then backwards, then forward again. Hence, alternating current, with a frequency equal to the rate of rotation of that coil (120 rotations per second, or 120 Hz). And yet, through all of this, I’ve wondered if there isn’t another way to generate electricity.

Yes, electricity (usually direct current, meaning the flow of electrons is always in the same direction) can be generated in other manners as well. Not wind power, because that’s just rotating smaller turbines, but solar power is an example. Sunlight hits the solar panels, “exciting electrons” from the ground state to an excited state, from which they flow out through a wire, around the circuit, and back into the ground state of the solar panel filling, once again, the hole that was left when the electron jumped to a higher energy state.

Beyond solar, we have chemical means of creating electricity. This is what batteries usually are, but some batteries are simply capacitors that store charge on one plate, separated by another by some form of insulator. Living organisms, such as electric eels, can also generate electricity, but this, too, is chemical. The problem with chemical batteries (aside from being notoriously inefficient) is that eventually the chemicals drain in the reaction that generates the electricity, and they must be replaced or recharged. Rechargeable batteries, like capacitors, can be forced to charge by supplying an external power source (like my car, currently plugged into my household current), but this just shifts the burden of creating the electricity to the central power grid and is really not power producing.

Today, I read that and article that engineers at MIT have created a heat engine, a kind of capacitor that generates electricity directly from heat. It’s not unlike solar panels in that it has a semi-conductor, but this time, instead of light, it’s heat that excites the electrons to a higher energy level, allowing it to flow around a circuit and back to ground state. I’m such an idiot; I should have realized that this is possible. When you heat a metal to the point of glowing, you’re exciting electrons from ground state to a higher state. The engineering comes in the form of holding those electrons in their excited state, and building a way for them to flow through a circuit.

This is exciting. Imagine a hot day simply generating new electricity which, in turn, would keep the house cool. This is simply thermodynamics. Heat would be converted into electricity, so that heat would not be available to be absorbed in the house. Or imagine a phone charger that works simply by holding it in your hand and allowing the heat to generate electricity. Or lining the walls around the motor of your electric vehicle so at least some of the heat loss is recaptured to keep the batteries charged.

We’re so keen on miniaturization that sometimes we forget about building large devices. I think about fossil fuels or nuclear power cores being used to convert water into steam, and the loss of energy in the process through dissipation in the pipes to the turbines, the heat lost in the recondensation into water, friction in the turbines and so on. Now imagine reconfiguring those same power plants with these heat converters, built to be so large that they can be used as the walls in the furnaces of these plants. Yes, there would still be loss (that’s just the second law of thermodynamics), but according to the article, these converters are more efficient than turbines. If that’s true, even non-green power plants would be more efficient as the very walls just absorb the heat and generate electricity, making it possible to burn less fuel, making these plants better for the ecology than they currently are, including fewer emissions as they could burn less fuel if, indeed, these panels are more efficient.

Is this real? Okay, let’s bring this down a bit. I’m very excited about the prospect this article is suggesting, but in reality, there are always barriers to be overcome. People were excited about cold fusion when it became news, but the technology was proven to be flawed and it never came to pass. So, we’ll have to wait and see, but I’m very hopeful that this will work.

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