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MIT-designed project achieves major advance toward fusion energy

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Re: MIT-designed project achieves major advance toward fusion energy

#331

Post by zaarn »

nickik wrote: post #320
phscguy wrote: post #301

Earlier quoted context omitted.

Sadly no. While I think that it would work and probably be cheaper and easier than fusion, fission has an absolutely abysmal public image. People are terrified of radiation, even if the danger is very low. This means it becomes prohibitively difficult and hence expensive to build and run a fission plant because safety has to be prioritized so heavily. That is even if permission is granted to build in the first place.…

Fusion also produces radiation. So not sure why changing one word to the other should magically change public opinion. We can just rename fission to #goodenergy or something, that would be cheaper then developing fusion. People don't even know that nuclear reactors use fission, so the idea that this would change anything is crazy. People opposed will call fusion reactors 'nuclear' just like they do fission.

Fusion Radiation is only immediate, ie, only in the area where the reactor is. And it can be contained with comparatively little effort, even put to use to breed Tritium for more Fusion fuel.

If a Fusion reactor blows up, the radiation risk is basically 0, aside from the lack of potential melt downs.

Re: MIT-designed project achieves major advance toward fusion energy

#332

Post by Kelteseth »

ncmncm wrote: post #146
causality0 wrote: post #61

Earlier quoted context omitted.

Are those calculations of net gain referring to the total energy generated, or the amount we can realistically capture and put to use?

The amount of this we can realistically put to use is, always and forever, exactly zero . The only useful outcome of any of this work is a generation of plasma-fluid physicists with practical experience. Pray we can find them something useful to do when the whole enterprise finally collapses.

Huh, I heard the same (tinfoil) argument about climate change, that all scientist make up the crisis to keep their jobs/funding.

Re: MIT-designed project achieves major advance toward fusion energy

#333

Post by Aeolun »

codethief wrote: post #303
roenxi wrote: post #299

Earlier quoted context omitted.

We're talking a world where humanity has enough energy on tap that not only could it have feasibly evaporated the Pacific Ocean, but that it basically has evaporated the Pacific Ocean, as a side effect of doing something else. We can barely speculate about such a world, but interstellar travel would not be much of a challenge with that sort of energy abundance. We'll find a way.

> but interstellar travel would not be much of a challenge with that sort of energy abundance. I don't think I agree. 1) The extremely high (but still finite) amount of energy required to evaporate the Pacific Ocean is still much less than the infinite energy you need to accelerate even one single space traveler to the speed of light. Infinity is weird. Of course we won't be trying to reach the speed of light but the…

> The extremely high (but still finite) amount of energy required to evaporate the Pacific Ocean is still much less than the infinite energy you need to accelerate even one single space traveler to the speed of light.

True, but how many tons of space junk can you accellerate to 95% of light speed for the same amount of energy?

Re: MIT-designed project achieves major advance toward fusion energy

#334

Post by danuker »

codethief wrote: post #293
roenxi wrote: post #282

Earlier quoted context omitted.

If there is enough ambient energy to literally boil the seas then we're probably going to find it easy enough to leave the earth and go somewhere cooler.

I don't think it'll be easy . We would have the same (if not higher) energy consumption per capita on any other planet. And unless that planet is humongously large (which would also increase its surface-level gravity, thus rendering it uninhabitable), the relation between surface temperature and energy consumption will be similar[0]. Now there's only a finite number of planets in our solar system and leaving our sola…

> So the surface temperature issue there is just the same.

On an interstellar ship far from a star, I think you're more likely to freeze to death, because temperature in space is near zero Kelvin.

Inside the solar system however, you could reflect away the received radiation (and heat) using mirrors.

Re: MIT-designed project achieves major advance toward fusion energy

#335

Post by sgt101 »

kongin wrote: post #233
mchusma wrote: post #112

Earlier quoted context omitted.

You are right, people who flippantly dismiss fusion just don't understand it. -Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not). - Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon…

>You are right, people who flippantly dismiss fusion just don't understand it. I have a couple of physics degrees, hot fusion is the energy of the future and it always will be. This is not a physics problem, this is an engineering problem and we are just not willing to invest enough money to solve the engineering.

I had a chat with Professor Whyte about this about 5 years ago when he was starting on this quest. The key insight that he emphasized to me (that I could understand!) was the need to deal with the engineering. He told me that compact magnets would facilitate construction and maintenance because simply they would need less space and energy to be physically manipulated. This, as I understood it, would allow for huge reductions in cost because buildings and components scale in cost massively as their size increases. Small magnets won't need a huge building, they won't need special vehicles to move them, they won't need cranes to install, they can be swapped in and out during maintenance, and the work can be planned and executed by small teams at low risk. Who really cares if a team of 5 working for a week have a 10% overrun - that's 2.5 person days. On the other hand a team of 500 working for a year -> 50 person years. Scale is the overhead that they are targetting.

Re: MIT-designed project achieves major advance toward fusion energy

#336

Post by amelius »

codethief wrote: post #281
mchusma wrote: post #112

Earlier quoted context omitted.

You are right, people who flippantly dismiss fusion just don't understand it. -Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not). - Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon…

> Fusion is in theory something that could give us true energy abundance. Well, at least for a few hundred years but then: > if you plot the U.S. energy consumption in all forms from 1650 until now, you see a phenomenally faithful exponential at about 3% per year over that whole span. The situation for the whole world is similar. […] the Earth has only one mechanism for releasing heat to space, and that’s via (infrar…

The thermodynamics argument would hold only for a closed system. If we send big blobs of lava into space, and import big chunks of solid rock back to Earth, then theoretically we should have no problem.

Re: MIT-designed project achieves major advance toward fusion energy

#337

Post by fabian2k »

elihu wrote: post #312
fabian2k wrote: post #254

Earlier quoted context omitted.

I'm curious if they can push the magnetic field even higher in the near future. For smaller magnets in NMR spectrometers 20 Tesla has been commercially available for 20 years. Of course this is more difficult for larger magnets. The new superconductors that allow these larger magnets are also very recent, not in discovery but in actual mass production. So they don't have as much experience with using these as with th…

I think so far the ReBCO tape is manufactured in small quantities by a handful of suppliers. If there were million-dollar orders coming in regularly, I suppose there'd be a lot of competition to develop the highest quality product. I expect it'd be like batteries; there's a lot of incremental improvements, and then once in awhile a major chemistry change. There's probably other high-temperature superconductors just w…

I've visited a company that produces classical and high-temperature superconductors, though this was quite a few years back. I don't know the exact market size, but the MRI and NMR markets are probably not that small, though they use almost entirely classical superconductors right now. But they have hit the physical limits of classical superconductors in NMR, and the first NMRs with high-temperature superconductors are produced and sold now. So there might be some more development there even without the fusion angle.

One purpose of the support material that isn't super-conducting is thermal protection. If your superconducter quenches, you have to dissipate the energy contained in it without destroying the magnet. In classical ones they use copper wire around them as far as I remember, and the high-temperature ones are a very thin film of ReBCO deposited on metal tape, so the actual superconductor is always a small part of the material.

Re: MIT-designed project achieves major advance toward fusion energy

#338

Post by rnhmjoj »

baybal2 wrote: post #209
rnhmjoj wrote: post #50

Earlier quoted context omitted.

> But are they surmountable AND cheaper than existing nuclear or other energy sources? DT fusion solves the two biggest arguments that are always raised by nuclear energy opponents: storage of nuclear waste (it doesn't produce high-level waste) and safety (it's not perfect but it can't explode). I wouldn't call it a "meh", even if it comes off as much more expensive than fission.

> storage of nuclear waste (it doesn't produce high-level waste) It does. You cannnot fuse just D+T, other trace gasses, and lighter isotopes will be present as well.

No, it doesn't in any significant quantity [1]. Besides, there are practically no high Z elements in a fusion plasma. That's because they emit bremsstrahlung radiation (power grows like Z²) and rapidly cool off the plasma. If the reaction is to be self-sustained, the plasma charge averaged over the density (Zeff) must be kept as close as possible to 1. Considering that there's only a few grams of material in a full reactor, there are virtually no heavy elements.

The radiative losses do exist, but are caused by detached atoms from the plasma facing components. Everything close to the plasma is made of light elements and specifically chosen to not produce dangerous radioisotopes when neutron activated: no high-level waste materials, meaning the half-life is lower that 10 years and they can be recycled in around 100 years.

[1]: http://www.iter.org/faq#Can_you_declare_fusion_is_really_saf...

Re: MIT-designed project achieves major advance toward fusion energy

#339

Post by sgt101 »

zetalyrae wrote: post #49
dfdx wrote: post #34

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experim…

I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the ma…

Think cubically!

A 6m device occupies 666 (say) --216 m^3

a 10m device occupies 10 10 6 (say) -- 600 m^3

The scale of volume means that you have to build a much bigger facility to put it in (in order for the electronics to be kept dry and for people to be able to get around it to keep birds off it and things.

But worse - the weight. Concrete is 2400kg m ^3 so the small device might weigh 518 tonnes, but the bigger device is 1440 tonnes, so moving parts of it round becomes 3 * harder, the floors have to be 3* stronger, the supply chain has to be 3* better.

And then time - 3* scale, 3* engineering challenge -> many times more time to deliver, many more $$$ -> risk -> planning -> admin... the less capital at risk the less it's worth spending on avoiding the risk.. the less the overhead of the project is.

FWIW ITER is a science experiment - it's designed to find out more about fusion and that data will be very valuable for future reactor designs.

Re: MIT-designed project achieves major advance toward fusion energy

#340

Post by bjowen »

GordonS wrote: post #310
mcswell wrote: post #95

Earlier 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?

It’s a high-school level laboratory experiment. Nobody’s handing them out at birthday parties[0], but mostly because hydrogen likes to go bang loudly, not because it’s corrosive or toxic or anything.

[0] unless Mark Rober is involved in some way.

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