I would swear I saw Tom Scott interview one lab that was planning on building a fusion generator that worked like a diesel engine. Like, the fusion reaction drives a piston.

Yeah; somehow converting the plasma directly into electricity at a 1:1 ratio using... Uh... Dilithium or something.

Not a better plan but just a curiosity as a physicist enthusiast.

Regarding nuclear fission and nuclear waste (and ignoring the big elephant in the room that are nuclear weapons)....

What are the technical difficulties to turn the radiation emitted by nuclear waste into electricity?

I mean, if the nuclear waste is still radiating, it has stored energy that is radiated as photons, right?

Then, we have the photo-electric effect which turns photons into moving electrons as long as the frequency surpasses a minimum threshold.

Given that the radiation of nuclear waste has frequency way higher than UV, why can't it be used to feed a photoelectric generator?

Also, we have tons of nuclear waste, so the argument that a single rod doesn't generate enough radiation seems kinda bogus since we could just store the nuclear waste into a safer recipient that turns the harmful rays directly into electricity and we have a shit-ton of them stored in thick lead or concrete barrels just so this radiation don't harm the surroundings.

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It is a genuine question that I had, but never had enough physics class to understand where this logic falls apart.

Because, if it were feasible and "cheap", I bet that the US would already be doing it and having access to "free energy" (not really, but a long-standing generator that doubles as removing nuclear waste from the ambient).

Just get Maxwell’s demon to separate the plasma into positive and negative charges, effectively creating a capacitor, then discharge it directly over some HVDC lines!

Throwing water into a star wouldn't get you steam, it'd just fuel the star XD

Nah. You'll probably want several shells operating above any sane temperature for steam. You don't want to lose that extremely high temperature by just heating water to 600 °C or so.

A good example of how you can do amazing things with steam is looking at the very last of the steam locomotives. Before they switched to diesel or electric, the steam locomotives were engineering masterpieces. Yes, you still got the classic steam locomotive puffs of steam coming out of the locomotive, but they only let the steam go once they had extracted the maximum possible energy from it.

Here's a good video going over the whole design.

Also the water is just a medium for energy transfer; it can be reused & recycled in near perpetuity in a closed system.

We're used to open systems with water in power stations, including cooling towers etc, because water is abundant on earth so it's cheaper to just dump it back into the atmosphere; we probably take the whole thing for granted.

But it could be engineered to be a closed system a bit like a coolant in a refrigeration unit cycling back and forth. And it probably will need to be a closed system in the future in space where water will be incredibly precious.

Steam had several technical and power limitations. It was dropped very quickly when electrification was an option.

That depends on how you define "viable". And "generate".

Peltier devices generate a voltage from a heat differential passing through a bi-metalic matrix. It's not a huge voltage, so the definition of "viable" comes in there, but it can be used to power low power things and works well for heater accessories. I first saw its use for wood stove fans that get powered just by sitting on the stove. I've also seen them power USB chargers for pellet stoves.

And then there's batteries that generate a voltage from submerging two types of metal in acid. And more modern battery designs might be doing it a bit differently but still no spinning magnets and coils. Obviously they are viable for powering many things, but usually themselves are powered from another source rather than using fresh acid for each charge, so the "generate" bit comes into question.

I think there's some others. Like fiction can be used to generate a static voltage and I'm pretty sure I've seen some tesla coils that use friction to generate their voltage. If you continuously generate that voltage, you could make a circuit out of it rather than shock high school kids or make their hair stand up, though I don't know what kind of amperage you could generate like that (that 5 figure voltage isn't fatal because of a lack of amps).

I asked an AI out of curiosity and, while I won't paste the response (feel free to ask one yourself), it gave a list of 20 methods, though I'd say this thread on its own covers about 9 of them, since some are different specific ways of doing similar ones (eg there were 4 based on moving something relative to a magnetic field).

https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

https://en.wikipedia.org/wiki/Betavoltaic_device

We use steam because it is very efficient and lowest cost to maintain.