this post was submitted on 13 Mar 2025
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Asklemmy
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Uhm, we haven't even managed to make fusion produce net energy with a large reactor. What makes you think that we could do it on the scale of a car?
Edit: Now I read your comment. It doesn't matter where the pressure comes from. The hard part is sustaining and controlling the fusion in a way that we can extract more energy from it than we put in.
I don't imagine it being the size of a car?
I imagine it being a huge facility, with a steam generator attached utilizing the coolant heat and more.
The pistons would be similar in size to the pistons of a diesel ship.
Take the "Wärtsilä-Sulzer RTA96-C" as example.
So you mean more like a power plant? Are you thinking like brayton cycle, rankine cycle, or both (combined cycle)?
I don't know much about fusion, but a big part of how a brayton works at that scale is air. For a jet engine the combustion expands, spinning the turbine or afterwards, and this spins the axially connected compressor section which sucks and squeezes air prior to the combustion chamber. A piston engine would be less continuous, so might be better suited? But in any case, this relies on whether fusion moves a shitload of air like a combustion engine does, (and like I said idk if it does,) and if it does then I guess it could be possible so long as pressures and temperatures stayed within metallurgical limits. I also don't know how economical it could be, but let's pretend that this is entirely exploratory and costs don't matter. I'm not gonna shit on your idea because the truth is that I don't know and you could be predicting a breakthrough idea 100 or 50 or 20 years ahead. Is fusion something that can quickly explode like in a piston engine in the first place or would it be better to run continuously through a turbine? Is that even possible? Idk.
Regarding the rankine cycle, that's the assumed application of fusion power. It's just the newest, best idea for how to boil water to superheated steam to spin turbines and condense back to feedwater. I only even bring this up because you specifically mentioned a steam generator, and that really only makes sense if you're utilizing the rankine cycle. Combined cycle would be using that piston/turbine engine thing from earlier but recycle the exhaust heat to a HRSG which loops to a steam turbine and condenser and back. But you need a large volume of fairly continuous hot exhaust flow for this, so it's wholly dependent on that thing I said I don't know lol.
We need some input from people who know something about fusion. I don't really know how we would control fusion while throwing a shitload of air into it and getting an even bigger shitload of air out the other end. Without that input, idk how anything other than rankine could be managed.
Thank you for entertaining my thoughts.
I tried to draw what I am imagining.
Does this help you see what I am thinking of?
I don't know of any piston that can initiate a fusion reaction, but that doesn't mean it's never going to be possible. But I think that such a thing would take teams of top researchers decades to figure out with any sort of reliability.
Regarding the rankine cycle, the diagram would need to be much more detailed. From what I am understanding of your diagram, no it couldn't work that way. I don't know a lot about fusion, but from my experience in fission nuclear power plants and combined cycle natural gas plants, I can make some assumptions about what to expect from a rankine cycle plant regardless of fuel source. You would need to ensure that only superheated (dry) steam is ever touching the steam turbine blades, and there is a ton of essential equipment that does exactly that. There are a ton of resources out there to learn more about this, and I'd recommend searching "rankine cycle explained" on YouTube to get started. General overview stuff might touch on things like drums and reheaters and condensers and vacuum pumps, but every little piece like that could use its own deep dive, really. It's fascinating stuff.
Overall, I think there is already a general understanding of how to make a fusion rankine cycle power plant work, and it's now just a matter of getting a sustainable reaction and then finding the optimal design and operation to safely and reliably maximize the extraction of that thermal energy to perform work. Should this be more like a BWR or a PWR plant? What do refuel outages look like? What sort of preventive maintenance will be required? What sort of hazards will workers be exposed to, and how can we mitigate that?
I'd love to see commercial fusion reactor plants in my lifetime, but I don't think I'll see it. We're pretty close to seeing fission SMR plants really get going. As much as I hate AI shit, their data centers are power hungry af which has pushed these companies to think about providing their own on-site power to relieve strain from the grid, and these SMRs are kinda perfect for this. If we could see that scaled up or at least batched into array designs, we buy a lot of time to figure out fusion while shifting to a greener energy solution or at least replace the existing and very much aging fission plants we already have. And maybe SMRs can teach us something about fusion along the way.
Stay curious :)
thank you! 💜