MIT-designed project achieves major advance toward fusion energy • Hacker News Board

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

#321

Post by ziotom78 » Thu, Sep 09, 2021, 8:55 AM UTC

drexlspivey wrote: post #313

qPM9l3XJrF wrote: post #309

Earlier quoted context omitted.

"Fusion is in theory something that could give us true energy abundance." What does fusion give us that existing nuclear power plant tech doesn't?

The reactor can’t meltdown and contaminate the whole planet. Also there is no radioactive waste

Well, there is some radioactive waste [1], but its decay time is far smaller and is thus far easier to handle. (Moreover, there is a larger choice of elements.)

[1] https://en.wikipedia.org/wiki/Fusion_power#Radioactive_waste

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

#322

Post by codethief » Thu, Sep 09, 2021, 8:56 AM UTC

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…

Addendum to 1):

Thinking a bit further, just because we can produce a high amount of energy that doesn't necessarily mean we can automatically convert it into kinetic energy for a space ship very well. Most propulsion systems in space still require expelling a propellant and conservation of momentum means this is unlikely to change. (Sure, one could imagine solar sails but the little momentum exchanged there won't get half of humanity to Proxima Centauri very fast.) So while we might have unlimited energy we might still be constrained by momentum requirements.

The only way I can see to solve this conundrum would be producing enough propellant on board the space ship, e.g. (lots of) photons, using a laser. Definitely not impossible (especially not at these energy levels) but it'll be interesting to see what these propulsion systems will look like exactly. :)

Ideally, we would of course try to use the propellant to also get rid of the waste heat mentioned earlier but I'm not sure whether this would work entropy-wise.

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

#323

Post by nickik » Thu, Sep 09, 2021, 8:57 AM UTC

pfdietz wrote: post #202

gfodor wrote: post #201

Earlier quoted context omitted.

Your argument is that the stigma of nuclear meltdowns hasn’t impeded the deployment of nuclear energy?

If reactors were ten times safer but no cheaper, they still wouldn't be being built. If reactors were ten times cheaper but no safer, we'd be building them like hotcakes.

While this is true, its a fact that the regulatory and governmental outlook on fission has prevented these changes from happening.

The western world has made development of new fission plants practically impossible. Requiring 100s of millions in development before you might get a hint if the government would actually allow you to build a plant.

Thankfully this has finally started to change. Mostly in Canada and that's where we will likely see next generation fission first.

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

#324

Post by nickik » Thu, Sep 09, 2021, 9:02 AM UTC

cletus wrote: post #87

I've long been skeptical of ITER making any sense given its insane cost. I mean even it succeeds, then what? Here's the truth: there's no such thing as free energy. Even if the fuel is so abundant it's actually or effectively free (eg deuterium), the energy isn't. Say it takes $50B to build a plant that produces 1GW of power, which I'll estimate at about 7TWh/year based on [1]. Let's also say it has a lifespan of 40…

While I agree with your point about ITER.

Space based power generation to me is incredibly dumb. It would be far easier to build solar on earth and transport it around with high efficiency DC lines.

And if you are really looking into the cheapest possible energy a thorium breeder reactor could run for ever with no fuel cost and could be built with 70s technology. These reactor be produced in a factory at a manufacturing line and then dropped into a containment facility.

How this should be more expensive then space based solar makes no sense to me.

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

#325

Post by lyaa » Thu, Sep 09, 2021, 9:05 AM UTC

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 quoted argument is too simplistic and ignores feedback processes that would prevent reaching the catastrophic prediction. We can't predict 400 years so flippantly.

The population will most definitely not continue to grow (in fact it will start to decrease slightly the more countries reach "developed" status), and the energy consumption per-capita will also stagnate. After all, there is a huge difference between going from living in a log house to a modern apartment with utilities and AC, and not much of a difference between one laptop and a slightly better one some years down the line. Also, attitudes towards environmental protection are changing with the generations so we are likely making different decisions 50 years from now.

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

#326

Post by phreeza » Thu, Sep 09, 2021, 9:19 AM UTC

pjerem wrote: post #264

olau wrote: post #256

Earlier quoted context omitted.

There are two problems with this reasoning. First, you are comparing the cost of written-off plants, for a technology that has huge upfront costs and much lower fuel costs. Fission is not cheap if you build a new nuclear plant, not in the Western world. That's why almost no nuclear plants are being build. Making a safe plant is just really, really complicated. Second, this specific argument can be used to see why fus…

Maybe I’m wrong but fission also don’t need extreme cooling utilities. And fission seems to be way more secure than fusion. So, while I do agree on the « new tech » costs, I’m pretty confident we’ll be able to build this plants anywhere in the world and not only near rivers. But maybe I’m too optimistic :)

I think you mixed up fission and fusion there. Regardless, a fusion reactor will need similar amount of cooling infrastructure if you want to output a similar amount of electricity.

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

#327

Post by regularfry » Thu, Sep 09, 2021, 9:29 AM UTC

codethief wrote: post #297

ifdefdebug wrote: post #289

Earlier quoted context omitted.

Well if we transform solar into electric then into motion or bound carbon, that should actually help reduce the heat balance?

> into motion Kinetic energy will end up getting converted to waste heat nonetheless. > or bound carbon This seems hard to imagine. We're dealing with waste energy here, so a very high-entropy type of energy. Bound carbon is low-entropy, so the conversion is impossible[0] unless we put that entropy elsewhere. As an analogy, consider a fridge: It brings your food from a high-entropy (high-temperature) to a low-entropy…

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.

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

#328

Post by kamaal » Thu, Sep 09, 2021, 9:39 AM UTC

qPM9l3XJrF wrote: post #309

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." What does fusion give us that existing nuclear power plant tech doesn't?

>>What does fusion give us that existing nuclear power plant tech doesn't?

Water is more abundant than Uranium?

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

#329

Post by sigmoid10 » Thu, Sep 09, 2021, 9:47 AM UTC

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…

>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 is exactly what you get when making a smaller reactor chamber with stronger magnets. This wouldn't be the first project claiming to be able to build a small reactor, only to discover that it's virtually impossible without a major theoretical breakthrough. This is usually left out in the venture capital advertisements for these fusion startups. There's a reason why so much money and effort is spent on ITER - it is the only more or less guaranteed path to fusion with the tech and knowledge we have today.

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

#330

Post by regularfry » Thu, Sep 09, 2021, 9:50 AM UTC

AnthonyMouse wrote: post #222

tuatoru wrote: post #218

Earlier quoted context omitted.

Yeah, really, how? Fusion power plants still need land, buildings, generators, switchyards, wire, own power consumption, environmental impact reports, planning permits, regulations, inspections, and all the rest. And they need exotic materials and weird engineering in their construction. Really: how does fusion get us to ~1% (correction: ~5%) of current power prices? I've never seen a convincing explanation. Usually…

One of the big problems with existing power plants is that you have to build them near where people are. So then land is expensive and you get a bunch of regulations because people are worried about what's happening in their back yard. If you could hypothetically build a fusion plant that would generate several times more power than existing fission reactors at a similar construction cost, you would have so much powe…

> One of the big problems with existing power plants is that you have to build them near where people are.

I don't know how it works in the US, but this is notably not true in the UK and Europe. Gas plants are comparatively small and nestled in, but big coal (to a limited degree) and particularly fission plants are frequently in the middle of nowhere. They're somewhere near a village that can supply a workforce, but siting concerns for nukes were more based on making sure any criticality excitement could be shared with neighbours across whatever nearby border was handy than putting them anywhere near cities.