These are starting to sound like UFO pics. They’re always distant point of light.
MIT-designed project achieves major advance toward fusion energy
431–438 of 438 posts
Re: MIT-designed project achieves major advance toward fusion energy
#432Earlier quoted context omitted.
The issue with long distance transmission is not efficiency. It is the raw amount of material needed. Feeding 100% of Europe electricity use with solar panels in North Africa would required many years (!) of the world’s current aluminium production, just to build the transmission cables. Do the calculation, you’ll see. Long distance power lines do not work to transmit massive amount if electricity on a global scale.
I’m not sure why you imagine that building this at full-grid power levels might take less than a decade, nor why it might be an all-or-nothing proposition given every single gigawatt can be seen as as a (12GWh? I’m not sure but that magnitude) battery system not purchased, but I’ll gladly do the maths. 1) HVDC designs I’ve seen are copper (towers use aluminium because it’s light, IIRC) 2) http://www.necplink.com/docs…
Your calculations are mostly correct, but pretty optimistic when put in regard of your initial claim (“your winter is my summer”), so you end up with 3month or the worlds production where I end up with several years.
Couple examples: You put a line to cities in the south of Europe. But existing lines from there are nowhere large enough to take all that power, you will have to build lines from Milan and others all the way inside Europe. You can’t build a line to Gibraltar and call it a day, it has to go all the way up to Norway (albeit with tapering)
You also overestimate the efficiency of aluminium power lines, don’t take into account the amount of towers and/or plastic material that would be needed to wrap the lines if you make them underground.
We are talking about years of production, and that’s just for Europe, if you want to replicate this to other continents you quickly get a supply challenge, even if you spread this over 30years, at which point it will be too late, regarding global warming. Not to mention that m the CO2 emissions associated with building such massive lines would take decades (if ever) to be offset with the gains from the use of Solar, which was the point of the thing in the first place...
But in the end my point was not that this is impossible, but that efficiency is not the largest limiting factor here. Material supply is the largest problem. It is not insurmountable but it is a real challenge.
Re: MIT-designed project achieves major advance toward fusion energy
#433Earlier quoted context omitted.
>The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly. It's not that simple. The big problem with magnetic confinement fusion is that you need to control turbulence in the plasma so that you can contain the reactions for a reasonable amount of time to extract useful energy. However, turbulence increases with stronger magnetic field gradients, which…
>However, turbulence increases with stronger magnetic field gradients Mmm, this isn't right. The stronger magnetic field reduces turbulence, it's the gradient of the pressure that generates turbulence. As best as anyone can tell, SPARC should be able to get Q~10 without any miracles involved -- the engineering rules of thumb and the advanced simulations all say the same. https://www.cambridge.org/core/journals/journa…
>The stronger magnetic field reduces turbulence
That's why I specifically said field gradients - i.e. the thing that gets larger when you have a stronger field in a smaller volume.
>it's the gradient of the pressure that generates turbulence
How exactly do you think that pressure is created?
Also, that link you provided is an editorial from one of the directors behind SPARC. If you want an objective analysis that is not geered towards possible investors, you need to look elsewhere. FYI, anyone selling you Q~10 designs without a considerable theoretical breakthrough is almost certainly conning you. If you don't believe me just look at how Lockheed's compact fusion reactor panned out. Stronger magnets are not some kind of miracle solution that will enable fusion tomorrow.
Re: MIT-designed project achieves major advance toward fusion energy
#434Earlier quoted context omitted.
"Hydrogen is very corrosive and hard to work with" Corrosive compared to what? You can put it in a rubber balloon and hand it to a kid. "T is radioactive hydrogen": True, it emits low energy beta radiation, which is an electron, and is stopped by a sheet of paper. I used to have a wrist watch with a tritium dial; I haven't died of cancer yet.
> Corrosive compared to what? You can put it in a rubber balloon and hand it to a kid. I've never heard of hydrogen-filled balloons (at least not the kind of balloon you can hand to a kid) - we're you thinking of helium?
I know about helium balloons, but hydrogen is really cheap compared to helium. And it's nowhere near as dangerous as it's made out to be. The Hindenburg burned, it did not explode.
Re: MIT-designed project achieves major advance toward fusion energy
#435Earlier quoted context omitted.
We're not necessarily talking about a closed system, though. If you've got an energy supply that rounds to limitless, constructing planet-scale heatsinks starts to look tenable.
> We're not necessarily talking about a closed system, though. Short of shooting hot lava into space[0] we pretty much are because, once again, thermalization through radiation is governed by Stefan-Boltzmann's law and there's no way around that. [0]: https://news.ycombinator.com/item?id=28468182
Stefan-Boltmann talks about emission per surface area. So... increase the surface area. We're not limited to a sphere.
The same problem crops up when you're talking about moon bases and so on - you've got the same problem of venting heat from an ecosystem into a vacuum. For that situation, one of the solutions that got designed out was to basically spray an oil mist across a gap, catch it, and recycle it into the cooling system. As a fine mist, the oil has a colossal surface area compared to its mass, and all that surface area can radiate heat off into the vacuum.
So... scale that up? I realise it's a hell of a leap, to go from human-scale to humanity-scale, and I don't know exactly what it would need to look like, but limitless energy is a hell of a springboard.
Re: MIT-designed project achieves major advance toward fusion energy
#436Earlier quoted context omitted.
>Would you be willing to elaborate why "energy per unit mass" matters when the mass in question is a completely different substance with different cost and availability profile? Sure. Specific energy (or energy per unit mass) between different types of materials makes a huge difference. For example (Source here[0]): Material Type of generation Specific energy (MJ/Kg) Hydrogen Fusion 639,780,320 Coal Oxidation 24.0-35…
It's not that cost plays into it, it's that cost (broadly defined) matters, and the metric you have chosen doesn't matter. As a consumer I don't care how energy dense a fuel is; I care only about what it costs me to get that energy. You might try to argue high fuel energy density implies low cost, but this is clearly not the case in general.
Exactly, and fuel is only a part of the consideration.
Though it's also true that the infrastructure to process, deliver and store large amounts of fossil fuel comes at a higher cost than is usually considered (as some of it is subsidised and socialised), plus there's the pollution.
Re: MIT-designed project achieves major advance toward fusion energy
#437Oh, it sounds quite impressive. I want my project to achieve major advances as well, even though it's not really similar to fusion energy. Because of that, I decided to use the safety meeting checklist from https://fluix.io/safety-toolbox-talk-workflow , and I hope it'll be beneficial for my employees because I think the problem is in lack of their knowledge.
Re: MIT-designed project achieves major advance toward fusion energy
#438Earlier quoted context omitted.
I’m not sure why you imagine that building this at full-grid power levels might take less than a decade, nor why it might be an all-or-nothing proposition given every single gigawatt can be seen as as a (12GWh? I’m not sure but that magnitude) battery system not purchased, but I’ll gladly do the maths. 1) HVDC designs I’ve seen are copper (towers use aluminium because it’s light, IIRC) 2) http://www.necplink.com/docs…
Your calculations are mostly correct, but pretty optimistic when put in regard of your initial claim (“your winter is my summer”), so you end up with 3month or the worlds production where I end up with several years. Couple examples: You put a line to cities in the south of Europe. But existing lines from there are nowhere large enough to take all that power, you will have to build lines from Milan and others all the…
Thanks; sorry I didn’t reply sooner, I normally only look at the first page of my comments to see if I have replies.
> But existing lines from there are nowhere large enough to take all that power, you will have to build lines from Milan and others all the way inside Europe.
Really? Okay. All I can do is look at maps like this one:
https://www.researchgate.net/figure/7-Modelled-AC-transmissi...
Which look, to my completely non-expert eye, like a decent size grid already exists.
I know that picture doesn’t contain enough info even though this isn’t my domain, but it represents the limited level I’m coming from.